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Universidad del Turabo

Inference of Habitat Connectivity via Habitat Use by Resident and Migratory

Birds between Secondary Dry Forest and Mangroves in Jobos Bay National

Estuarine Research Reserve

By

Ivelisse Rodríguez-Colón BS, Biology, University of Puerto Rico in Cayey

Thesis

Submitted to the School of Science and Technology in partial fulfillment of the requirements for

the degree of

Master of Environmental Science

Specialization in Environmental Management

Gurabo, Puerto Rico

May, 2012

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Universidad del Turabo

A thesis submitted in partial fulfillment of the requirements for the degree of Master of Environmental Science

22 May, 2012 date of defense

Inference of Habitat Connectivity via Habitat Use by Resident and Migratory

Birds between Secondary Dry Forest and Mangroves in Jobos Bay National

Estuarine Research Reserve

Ivelisse Rodríguez-Colón

Approved: ____________________________ Fred C Schaffner, PhD Research Advisor ____________________________ __________________________ María Fernanda Barberena-Arias, PhD Samuel Flores, PhD Member Member ____________________________ Joseph M Wunderle Jr, PhD Member ____________________________ __________________________ Fred C Schaffner, PhD Teresa Lipsett Ruiz, PhD Associate Dean, Graduate Studies Dean and Research

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© Copyright 2012 Ivelisse Rodriguez-Colon. All Rights Reserved.

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Dedications

First, I want to dedicate this research to God, for all the blessings that he gives

me every day. To my father Fernando Rodríguez-Taboada, for being an excellent

human being, for always listening to me and providing guidance.

In memory of my mother, Paula Colón-Cruz, because she taught me how to

overcome obstacles, how to be strong and keep struggling with a smile on my face.

To all those who, like my parents, fight against cancer and disease every day.

For my husband Javier Arbelo-Decós, for your love, for understanding me,

providing support in all these years and be my eternal field assistant, even when you

were tired.

To all my family members for their good wishes and cheers and for being my field

companions when I couldn’t find anyone else.

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Acknowledgments

Completing this research would not have been possible without the help of many

people.

I wish to thank my thesis committee members: To my advisor Dr Fred Schaffner,

for all his advice, guidance and dedication. For sincerely teaching me all his knowledge

in ecology and ornithology, assisting me in mist netting field work and for his critical

review, comments and suggestions on this manuscript. For being more than an advisor

and guiding me as a father would do. To Dr Joseph Wunderle, for showing me how to

analyze point count and arthropod data and for providing a critical review and comments

on the manuscript. To Dr Maria Fernanda Barberena, for her assistance with statistical

analysis and arthropod identification. To Dr Samuel Flores and Dr Adaris Mas, for their

availability, guidance and comments of the manuscript.

To Jobos Bay Reserve personnel, especially the Director Carmen González for

her assistance, logistical support and for giving me the opportunity to work in Jobos

Educational Program, while I finished my research. To Mr Luis Encarnación, who initially

gave me the opportunity and access to the Jobos Bay Reserve and to all the Reserve

personnel that helped me in this process. To the Department of Natural Recourses

(DRNA) personnel, especially the Biologist Gilbert Bonilla, who taught me basic bird

identification in the field and to Hibrain Sued who initially gave me great

support and guidance.

I am very grateful for Dr Jaime Collazo, for his availability and suggestions in

different stages of this research. Also, Dr William Beltran, for his suggestions about

arthropod analysis and for his advice about bird diets. To Maritza Rodríguez, Viviana

González and Keishla M Rodríguez, for their great assistance and help in arthropod

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sorting and identification. To Brenda Carolina Torres for her great contribution in

statistical analysis. To Ingrid Flores, Emilio Font, Waleska Vázquez and Giselle

Caraballo, for assisting me with mist netting in the field. For all my field assistants:

Yeimelys Figueroa, Cristina Acosta, José Huertas, Dioricella Márquez, Arelis Ocasio,

Ariam Delgado and my family members: Keishla M Rodríguez, Alexander Rodríguez,

and Orlando Rodríguez that helped me in arthropod sampling and identification, birds

censuses and mist netting as well.

To the National Oceanic and Atmospheric Administration (NOAA), for the

Graduate Fellowship (GRF) program (NA10NOS4200023), and mini grants of School of

Science and Technology at Universidad del Turabo. Last, but not less important, to Dr

James Quinn of McMaster University for the loan of a field vehicle.

To all the other people who contributed to the success of this research.

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Vita

Ivelisse Rodriguez-Colón is a graduate student in the Environmental Sciences

program (Environmental Management specialty) at Universidad del Turabo, Gurabo,

Puerto Rico. She completed a Bachelor’s degree in Natural Science with a concentration

in Biology in May 2003, at the University of Puerto Rico in Cayey PR. She also

completed a Certification in Biotechnology at the Universidad de Puerto Rico, Cayey

Campus in 2007. She continues to broaden her knowledge and expertise, obtaining

professional certifications and attending workshops to enhance her technical knowledge

to support her career.

After completing her Bachelor’s degree, she had the opportunity to begin field

research, having one year of experience as an environmental consultant and five years

of experience in the Pharmaceutical Industry in quality control and chemical laboratories.

Moreover, she has experience in the agricultural industry. Her professional goal is to

develop a research career as an educator and university professor in the area of

Biodiversity, Natural Resource Conservation, and Environmental Management.

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Table of Contents

page

List of Tables...................................................................................................................ix

List of Figures..................................................................................................................xi

List of Appendices..........................................................................................................xiv

Abstract...........................................................................................................................xv

Resumen in Spanish.....................................................................................................xvii

Chapter One. Introduction…………….............................................................................1

1.1. Background and Problem.............................................................................1

1.2. Study Species.……………………………………………………………………3

1.3. Study Site...................................................................................................10

1.4. Research Objectives and Hypotheses……………………………………….12

Chapter Two. Methodology…...………..........................................................................14

2.1. Fixed-radius Point Counts..........................................................................14

2.2. Bird Movement Between Habitats..............................................................15

2.2.1. Observations From Blinds.............................................................15

2.2.2. Mist Netting...................................................................................16

2.3. Arthropod Sampling………………………….…………………………………17

2.3.1. Sampling Canopy Arthropods by the

Branch Clipping Technique..........................................................17

2.3.2. Sampling Ground Arthropods by the

Quadrat Technique.......................................................................19

Chapter Three. Results…………………........................................................................21

3.1. Fixed-Radius Point Counts.........................................................................21

3.2. Bird Movement between Secondary Dry Forest

and Combined Mangrove Forest...............................................................31

3.2.1. Observations From a Blind............................................................31

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3.2.2. Mist Netting...................................................................................35

3.3. Arthropod Sampling………………………….…………………………………43

3.3.1. Canopy Arthropods in Secondary Dry Forest and

Combined Mangrove Forest (Branch Clipping)............................43

3.3.2. Ground Arthropods in Secondary Dry Forest and

Combined Mangrove Forest (Quadrat Technique).......................50

Chapter Four. Discussion and Conclusions………………………..……………..............55

4.1. Habitat Use by Neotropical Migratory Birds................................................55

4.2. Habitat Quality and Optimal Foraging........................................................59

4.3. Habitat Preference, Social Dominance and Diurnal Migrations..................60

Literature Cited...............................................................................................................63

Appendices….................................................................................................................71

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List of Tables

page

Table 1.01. Diet, provisioning preferences and behavior of some

of the resident commonest birds, present in Jobos Bay

National Estuarine Research Reserve (JBNERR) in PR………..7

Table 1.02. Diet, provisioning preferences and behavior of some

migratory birds of interest present in Jobos Bay

National Estuarine Research Reserve (JBNERR) in P.R…….....8

Table 3.01. Summary of presence (+) or absence (-) of species

in a given habitat type during 25-m, 6-min duration

fixed-radius point counts, Sept. 2010 to Sept. 2011

and mist netting during Feb. 2011 to the end of

Apr. 2011 in southern Puerto Rico……………………………….22

Table 3.02. Species richness and presence or absence of warblers

and vireos per habitat type and season, including:

(NM) non-migratory, (M1) wet migratory and

(M2) dry migratory seasons……………………………………….24

Table 3.03. Means SE’s of counts per point of the five most

common warblers and vireos in Jobos Bay per habitat

and season……………………………………………………...…26

Table 3.04. Major directionality of birds captured moving

between mangroves and dry forest, during mist

netting conducted Feb –Apr 2011………………………………34

Table 3.05. Mayor directionality of birds captured moving

between mangroves and dry forest, during mist

netting conducted Feb–Apr 2011 and Chi-Square results…….42

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Table 3.06. Biomass and prey Items of arthropods collected via

branch clipping, by habitat type…………………………………..44

Table 3.07. Biomass and prey Items of arthropods collected via

clipping, by habitat type, excluding Odonata……………………45

Table 3.08. Branch clipping sampling of arthropods by sampling dates

in mangrove and secondary dry forest. Samples

were conducted March-May 2011………………………………..49

Table 3.09 Biomass and prey items of arthropods sampled

in quadrats, habitat type and a two-sample t-test with

log transformed data, excluding orders Diplopoda

and Milipeda………...………………………………………………52

Table 3.10. Arthropod sampling by quadrats technique by sampling

date in mangrove and secondary forest. Samples

were conducted March-May 2011………………………………..54

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List of Figures

page

Figure 1.01. Adelaide’s Warbler (Setophaga adelaide)………………………..4

Figure 1.02. Northern Waterthrush (Parkesia noveboracensis)

captured by mist netting and banded……………………………...4

Figure 1.03. Yellow Warbler (Setophaga petechia) captured by mist

netting and banded………………………………………………….5

Figure 1.04. Prairie Warbler (Setophaga discolor) captured by mist

netting and banded…………………………………………………5

Figure 1.05. American Redstart (Setophaga ruticilla) captured by mist

netting and banded………………………………………………….6

Figure 1.06. Aerial View of Jobos Bay National Estuarine Research

Reserve, Salinas Puerto Rico and Reserve Boundary Map…10

Figure 2.01. Locations of 6-min, 25-m fixed-radius point count

sampling from Sep 2010 to Sep 2011 at Jobos Bay

Estuarine Research Reserve (JBNERR)………………………..15

Figure 2.02. Blinds for bird movement observation, established

in a gap between secondary dry forest and mangrove forest…17

Figure 2.03. Arthropod sampling by the branch clipping technique…………18

Figure 2.04. Sampling of ground arthropods by Quadrat Technique………..20

Figure 3.01. Mean number of Adelaide’s Warblers (ADWA) observed per

25-m-fixed radius, 6-min duration point counts…………………27

Figure 3.02. Mean number of Yellow Warblers (YEWA) observed per

25-m-radius, 6-min point counts………………………………….28

Figure 3.03. Mean number of Prairie Warblers (PRAW) observed per

25-m-radius, 6-minute duration point counts…………………...29

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Figure 3.04. Mean number of Northern Waterthrushes (NOWA) observed

per 25-m-radius, 6-min duration point counts…………………...30

Figure 3.05. Mean number of Black-whiskered Vireos (BWVI) observed

per 25-m-radius, 6-minute point counts…………………………31

Figure 3.06. Directional observations from a blind between November

2010 to January 2011……………………………………………...32

Figure 3.07. Capture Rate per net hour. Complete Session.

February 18, 2011………………………………………………….36

Figure 3.08. Capture Rate per net hour, complete session. March 7, 2011.38

Figure 3.09. Capture Rate per net hour, complete composite day.

March 21, 2011 AM and March 20, 2011……………………….39

Figure 3.10. Capture Rate per net hour, complete composite day.

April 11 2011, AM and April 10 2011, PM………………………40

Figure 3.11. Capture Rate per net hour, complete composite day.

April 26 2011, AM and April 27 2011…………………………….41

Figure 3.12. Median of prey items per sampling date by branch

clipping technique, between secondary dry forest

and combine (red, black and white) mangrove forest,

between March 26 and April 11 on 2011………………………..46

Figure 3.13. Median arthropod biomass in (mg) per sampling dates

by branch clipping technique, between secondary dry forest

and combine (red, black and white) mangrove forest,

between March 26 and April 11 on 2011……………………….47

Figure 3.14. Median of biomass in mg/g of branch clipped per

sampling dates, by branch clipping technique,

between secondary forest and mangrove forest,

between March 26 and April 11 on 2011………………………..47

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Figure 3.15. Median of prey items per sampling date by quadrats

technique, between secondary dry forest mangrove forest,

between February 9 and April 21 on 2011………………………51

Figure 3.16. Median of Arthropod biomass per sampling dates by

quadrats technique, between secondary dry forest and

mangrove forest, between February 9 and April 21 on 2011….53

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List of Appendices

page

Appendix One Canopy Arthropod Sampling……………………………………...71

Appendix Two Ground Arthropod Sampling………………….…………………..85

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Abstract

IVELISSE RODRÍGUEZ-COLÓN. (MS, Master of Environmental Science)

Inference of Habitat Connectivity Via Habitat Use By Resident and Migratory Birds

between Secondary Dry Forest and Mangroves in Jobos Bay National Estuarine

Research Reserve (May/2012)

Abstract of a master’s thesis at the Universidad del Turabo.

Thesis supervised by Dr Fred C Schaffner. No. of pages in text 99

This research addressed whether several species of migrant birds moved between

mangrove night-roosts and daytime foraging habitat in dry secondary forest. Early

morning fixed-radius point counts performed between (Sep 2010-August 2011), revealed

eleven (11) migratory and resident warbler species in black mangrove, red mangrove

and secondary dry forest. Observations from blinds established in gaps between

mangrove and dry forest within two hours of sunrise and sunset revealed nearly

unidirectional movement by several species tree-hopping through the corridor from

mangroves after sunrise and to mangroves before sunset. Mist netting during February –

April 2011 (a single line of 6, or 8, 12 m length, 30 or 38 mm mesh nets set to intercept

observed flight lines) during the first and last two hours of the day revealed diurnal

mostly unidirectional movements in Prairie Warblers (Setophaga discolor), Northern

Waterthrushes (Parkesia noveboracencis), Yellow Warblers (Setophaga petechia),

American Redstarts (Setophaga ruticilla), Northern Parulas (Parula americana) and

Western Palm Warblers (Setophaga palmarum). This movement was most intense

shortly before sunset. Migrants represented 62% of 312 captures during February-April,

2011 (the dry migratory season). Migrant Ovenbirds (Seiurus aurocapilla), Common

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Yellowthroats (Geothlypis trichas), breeding resident Adelaide’s Warbler (Setophaga

adelaide) and breeding migrant Black-Whiskered Vireos (Vireo altiloquus) were detected

only in dry forest, and did not move between habitats. Mid-day censuses and active

searches in mangrove habitat revealed only Northern Waterthrushes and Yellow

Warblers. Arthropod samples were collected in mangrove forest and secondary dry

forest using active searching on the ground with the quadrat technique and in the

canopy foliage by the branch clipping technique. Results from this analysis showed that

the number of prey availabile in canopy samples is higher in secondary dry forest than in

mangrove forest, but biomass of prey did not differ significantly between the two

habitats. Ground samples reveled that secondary dry forest provides a good source of

arthropod biomass as well. These results underscore the importance of secondary dry

forest to this avian guild, despite the preference by most species for mangroves as

nighttime roosts.

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Resumen

IVELISSE RODRIGUEZ-COLÓN. (MS, Maestría en Ciencias Ambientales)

Inferencia de Conectividad vía el uso de hábitat por aves migratorias y residentes entre

bosque seco secundario y manglares en la Reserva Nacional de Investigación Estuarina

de la Bahía de Jobos (mayo/2012)

Resumen de una tesis de maestría en la Universidad del Turabo.

Tesis Supervisada por el profesor Dr Fred C Schaffner. No. de páginas en el texto 99

Esta investigación evalúa cuando múltiples especies de aves migratorias se

mueven entre sus dormideros en el bosque de mangle y el hábitat de aprovisionamiento

diurno en el bosque seco secundario. Puntos de conteo de radio fijo llevados a cabo

temprano en la mañana entre (Septiembre 2010- Agosto 2011), revelaron once (11)

especies de reinitas residentes y migratorias en el mangle negro, mangle rojo y bosque

seco secundario. Observaciones llevadas acabo en puntos escondidos establecidos en

la interface entre el bosque de mangle y el bosque seco secundario, dos horas después

del amanecer y dos horas antes del atardecer durante (Febrero-Abril 2011), revelaron

un movimiento prácticamente unidireccional por varias especies de aves a través del

corredor, desde los mangles al amanecer y hacia los mangles en el atardecer. Las

redes de niebla fueron establecidas utilizando una línea sencilla de redes de 12 m de

largo y 38 mm, cuya función fue interceptar el movimiento de las aves entre ambos

hábitats, durante las primeras dos y últimas dos horas del día. Fueron detectadas varias

aves migratorias llevando acabo movimientos diarios a través de dicho corredor, entre

ellas: la Reinita Galana (Setophaga discolor), la Pizpita de Mangle (Parkesia

noveboracencis), el Canario de Mangle (Setophaga petechia), la Candelita (Setophaga

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ruticilla), la Reinita Pechidorada (Parula americana) y la Reinita Palmera (Setophaga

palmarum). El movimiento de las aves fue mas intenso justo antes del anochecer. Las

aves migratorias representan el 62% de 312 capturas durante la temporada seca.

La Reinita Mariposera (Setophaga adelaide), la cual es un ave residente y

endémica, fue observada cerca en el bosque seco secundario, pero no en los

corredores. Las aves migratorias o no residentes: Pizpita Dorada (Seiurus aurocapilla),

Reinita Pica Tierra (Geothlypis trichas), y el Julian Chiví (Vireo altiloquus), fueron

detectados solo en el bosque seco secundario. Ninguna especie fue detectada solo en

los mangles. Muestras de artrópodos fueron colectadas tanto en el mangle como en el

bosque mediante la técnica de búsqueda activa, utilizando cuadrates en el suelo y

cortado de rama en el follaje. Las muestras colectadas, fueron luego cuantificadas para

determinar la biomasa promedio por muestra, en cada tipo de hábitat. Los resultados de

este análisis mostraron que la disponibilidad de alimento en las muestras del dosel es

mayor en el bosque seco secundario que en el bosque de mangle, pero su biomasa no

representa una diferencia significativa. Muestras de artrópodos tomadas en el sustrato

revelaron que el bosque seco secundario provee una excelente fuente de biomasa de

artrópodos, por lo que este representa una fuente esencial de alimento par las aves. Los

resultados de esta investigación realzan la importancia del bosque secundario para este

grupo de aves, independientemente la preferencia de la mayoría de las especies por los

mangles a la hora de descanso al anochecer.

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Chapter One

Introduction

1.1. Background and Problem

At its most fundamental level, connectivity is inherently about the degree of

movement of organisms among vegetation patches, the more movement, the more

connectivity (Crooks and Sanjayan 2006). In particular, landscape context may affect the

availability and quality of food for refueling during stopovers of intercontinental migrants,

which is critical for successful migration (Ktitorov et al. 2008). Migratory birds are clearly

capable of moving very long geographical distances from their breeding to the non-

breeding grounds (Greenberg and Marra 2005), and Neotropical avian diversity

increases during the northern winter when Nearctic breeders migrate to the tropics and

join communities of year-round resident (nesting) species (Holmes et al. 1989; Lefebvre

et al. 1992, 1994; Confer and Holmes 1995; Gill 2007; Lefebvre and Poulin 1996; Strong

and Sherry 2000).

At the population level, events on the wintering grounds may affect population

dynamics on the breeding grounds, and this may be particularly important to understand

during times of rapid habitat alteration and climate change. On the wintering grounds

weather conditions and territory quality may affect later reproductive success on the

breeding grounds (Greenberg and Marra 2005). Habitat varies not only across space,

but also across time. Many habitats occupied by wintering migrants are seasonally

dynamic during the winter, because this period coincides with annual dry season

(Murphy and Lugo 1986; Sherry et al. 2005; Smith 2008). On the wintering grounds

migrants also must manage the demands of finding sufficient food, and protection from

predators.

Puerto Rico is an important area of co-occurrence of migrants and year-round

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residents, including those that are known to occur in both secondary dry forest and

coastal mangroves, in southwestern and southeastern Puerto Rico (Staicer 1991, 1992;

Baltz 2000; Reitsma et al. 2002, 2004; Hunt et al. 2005; Smith 2008; Toms 2011). A

summary of reports across a broad geographic area within the non-breeding range,

reveals a common pattern of off-home range movements between diurnal home ranges

and nocturnal roost sites by a diversity of migrant and resident species (Post 1978,1982;

Holmes et al. 1989; Alsop III 1995; Reitsma et al. 2002; 2004; Burson III et al. 2005;

Hunt et al. 2005; Smith 2008; Smith et al. 2008), often moving through, and foraging in,

a variety of habitat types in a single day.

This connectivity concept is based fundamentally on the degree of movement of

organisms or processes (Crooks and Sanjayan 2006). For residents and migrants in

Puerto Rico, movement between distinct habitat types may be enhanced as birds seek

to achieve an optimal balance between the pressures of locating a safe (predator-free)

night roost and feeding. A diversity of both insects and flora makes an ideal habitat for

tropical birds, but when patch size is small, or when habitat is fragmented, connectivity,

including daily movements between habitats (ephemeral habitat occupancy) may

increase (see Stutchbury 1994; Strong and Sherry 2000). This is an especially important

conservation issue when species move naturally between protected and unprotected

habitats (Powell and Bjork 1995), including dry forest habitats that may be in a diversity

of stages of secondary succession.

Some specialized species can have stable populations in the tropics, but may be

vulnerable to climate and habitat changes, therefore making it important to understand

the relationships between movement, foraging behavior and successional stage is

crucial (Reitsma et al. 2002, 2004; Smith 2008; Smith et al. 2008). These authors

focused on the connectivity issues and found that daily movement by migrants between

distinct foraging habitat (scrub and dry forest) and night roosts (mangroves) was

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common.

In Puerto Rico and the Virgin Islands, avian communities include some 350

species and consist of both residents and non-residents during some parts of the year

(Raffaele 1989; Oberle 2006). About a third of these species are accidental that have

occurred rarely, while about 120 species breed in Puerto Rico, including native species,

of which 17 are considered endemic (Oberle 2006, 2010).

1.2. Study Species

Birds of the Passeriformes order and Parulidae family are the principal subjects

of this research, specifically those species that inhabit the coast. Resident and migratory

principally insectivorous species were evaluated in multiple habitats (Tables 1.01-1.02).

Passerines of interest found in this study around Jobos Bay include the migratory

Parkesia noveboracensis (Northern Waterthrush, NOWA) migratory and nesting resident

Setophaga petechia (Yellow Warbler, YEWA), migratory S discolor (Prairie Warbler,

PRAW), S americana (Northern Parula, NOPA), and S ruticilla (American Redstart,

AMRE), nesting resident S adelaide (Adelaide’s Warbler, ADWA) and Vireo altiloquus

(Black-whiskered Vireo, BWVI), and other, mostly migrant species including Protonotaria

citrea (Prothonotary Warbler, PROW), S striata (Blackpoll Warbler, BPWA), Seiurus

aurocapilla (Ovenbird, OVEN), Geothlypis trichas (Common Yellowthroat, COYE), and

others of the family Emberezidae (Parulidae) and Vireonidae that occur in the study area

(Raffaele 1989; Oberle 2010; Figures 1.01-1.05).

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Figure 1.01. Adelaide’s Warbler. Photo by Mike Morel

Figure 1.02. Northern Waterthrush, captured by mist netting and

banded.

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Figure 1.03. Yellow Warbler, captured by mist netting and banded.

Figure1.04. Prairie Warbler, captured by mist netting and

banded.

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Figure 1.05. American Redstart, captured by mist netting and

banded.

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Table 1.01. Diet, provisioning preferences and behavior of some of the common resident

birds, present in Jobos Bay National Estuarine Research Reserve (JBNERR) in PR.

______________________________________________________________________

Species Provisioning Preference Feeding Behavior and Diet Sources

*Low *Medium *High

_____________________________________________________________________________

Setophaga x x x Most foraging is by gleaning and Oberle (2006,2010)

petechia in open outer portion of the foliage Dunn and Garrett (1997)

beetles, crickets, flies cicadas,

caterpillars, dragon flies and earwigs

Setophaga x x Gleaning behavior, caterpillars, Oberle (2006, 2010)

adelaide flies, stink, bugs and spiders.

grasshoppers, lantern flies, weevils,

Vireo x x Search through foliage for insects Oberle (2006, 2010)

latimeri caterpillars, grasshoppers, cicadas,

beetles, aphids and also spiders.

_________________________________________________________________________

* Height level above ground.

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Table 1.02: Diet, provisioning preferences and behavior of some migratory birds of interest present in Jobos Bay National Estuarine Research Reserve

(JBNERR) in PR.

Species Migratory Period in PR

Provisioning Preferences

Feeding Behavior Diet

Sources

Low* Medium*

High*

Parkesia

noveboracensis

Winter September to

April

X X

gleaning prey from the

undersides of the

leaves and forage on

the ground

Insects, spiders and

occasionally

tiny crabs

Oberle (2006)

Dunn and Garrett (1997)

Vireo altiloquus February to September X X gleans insects off

leaves, sometimes

hovering to pluck and

insect

spiders, caterpillars, mantis,

walking sticks, grasshoppers,

cicadas, weevils, other beetles,

bugs, wasp and ants

Oberle (2006)

Parula americana August to June X gleaning off leaves and

branches, hover or

hawks in mid-air

beetles, caterpillars, lantern flies,

bugs, and some wasps

Spider make up a large part

of the diet

Oberle (2006)

Raffaele (1989)

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* Altitude level above ground.

Setophaga tigrina November to March X X forage along edges off

moist forest, dry forest

and mangroves

insects and spiders

Oberle (2006)

Raffaele (1989)

Setophaga striata

Fall (October-November)

uncommon in September.

X haunts in low branches,

often by gleaning

- Oberle (2006)

Raffaele (1989)

Dunn and Garrett (1997)

Setophaga

discolor

August to April X gleans insects off

leaves

insects Oberle (2006)

Raffaele (1989)

Setophaga

ruticilla

September to April with

records in early May

X X X Snatches insects in mid

air or hover to pick

insects off leaves, also

creeps along trunks

Beetles, flies, lantern flies,

small wasp, and spiders

Oberle (2006)

Raffaele (1989)

Dunn and Garrett (1997)

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1.3. Study Site

This research was conducted at the Jobos Bay National Estuarine Research

Reserve (JBNERR), located on the south-central coast of Puerto Rico near Ponce

17˚57’N and 66˚14’W, between the municipalities of Guayama and Salinas (Figure 1.06).

This reserve was designated as a reserve in 1981 via an agreement between the

Commonwealth of Puerto Rico Department of Natural and Environmental Resources

(DNER) and the National Oceanic and Atmospheric Administration (NOAA). The

Reserve comprises an area of 1120 ha, located at the west end of Jobos Bay, while the

Aguirre State Forest (total area 957 ha, or 2,393 acres) borders the north shore and the

east end of the Bay (Ewel and Whitmore 1973; González 2001) (Figure 1.06).

Figure 1.06. Aerial View of Jobos Bay National Estuarine Research Reserve,

Salinas Puerto Rico. Reserve boundary is shown in red. Source: National

Oceanic and Atmospheric Administration (NOAA).

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The ecosystems within the Reserve include mangrove forests, lagoons, salt flats,

a dry forest and sea grass beds. Mangrove forests are one of the most severely

impacted habitats throughout the Caribbean and Central America, and many native,

endangered and threatened bird species share the mangrove forest as their main habitat

in JBNERR (Laboy et al. 2006; Laboy 2009). Recent studies show that the mangrove

forest in JBNERR has experienced massive mortality (Morris 2000) likely resulting from

land use changes and agricultural practices that impact the hydrological conditions

necessary to sustain mangrove and wetland ecosystems.

The Jobos Bay Reserve and its surroundings are a substantially fragmented area

(Figure 1.06). Fragmentation is a threat to biodiversity even in a relatively stable world.

Biological communities and ecological processes may change substantially as a result of

edge effects, and is a major cause for the decline of forest birds in heavily fragmented

landscapes (Noss et al. 2006 (Chapter 7) in Groom et al. 2006).

Much of the existing dry forest habitat in Jobos Bay includes successional habitat

arising from recently abandoned agricultural land that lies outside of the Reserve

(Gonzalez 2001; Laboy-Nieves 2009). Mangroves in the Reserve include Red Mangrove

(Rhizophora mangle), Black Mangrove (Avicennia germinans), White Mangrove

(Laguncularia racemosa), and Buttonwood (Conocarpus erectus), and extensive stands

of these mangroves have suffered heavy mortality during the previous 2 decades,

creating areas of low, early successional recovering mangroves close to the coast. All

dry forest in the area is secondary and includes a mix of native and exotic species

dominated in most areas by exotic mesquite (Prosopis juliflora), though the youngest (<

15 years) patches, especially those not previously used for livestock grazing, are

dominated by exotic Leucaena leucocephala, often in monocultural stands. Much of this

habitat is in public ownership for agricultural purposes, but little enjoys any legal

protection and is largely perceived by the general public and local government as

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“trash”; thus, it is in even greater peril than mangrove habitat that has already suffered

significant destruction and alteration throughout the Caribbean. Wunderle et al. (2010)

underlined the importance of anthropogenically disturbed early-successional habitat to

migrants, heightening the urgency for better understanding and protecting these

ecosystems.

1.4. Research Objectives and Hypotheses

The principal objectives of this research are to (1) determine whether migratory

and resident species are using multiple habitats during the winter and through the year,

(2) determine whether individuals move routinely (daily) between and (3) determine

potential differences in food (invertebrates) abundance and quality in the canopy and

floor of the various habitats used by the birds. The Northern Waterthrush, Parkesia

noveboracensis is of special interest because it has already shown connectivity

movement between mangrove and dry secondary forest agroecosystems (Reitsma et al.

2002, 2004; Smith 2008; Smith et al. 2008; 2010) nearby at the former Roosevelt Roads

Navy Base on the east coast of Puerto Rico.

Specific hypotheses can be articulated according to each objective:

1. The first objective of this research is to determine bird occurrence by resident

and migratory birds year round in multiple habitats.

H0 - Each species of resident and migratory warbler or vireo occurs in a

single, specific habitat.

H1 -Each species of resident and migratory warbler or vireo occurs in multiple

habitats.

2. The second objective of this research is to determine if mangrove-roosting birds

move to secondary dry forest in search of food at dawn and return to the

mangrove forest at dusk, in order to infer connectivity during the dry migratory

season (February – April 2011).

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H0- Mangrove-roosting migrants are sedentary in mangrove forest and do not

move between mangroves and other habitats.

H1- Mangrove-roosting migrants make daily movements from mangroves to

secondary forest at dawn, and return to the mangrove forest at dusk

(connectivity between habitats).

3. The third objective of this research is to determine arthropod biomass in

secondary dry forest and mangrove forest. Which habitat offers potentially

greater food abundance (or biomass) of arthropods, the canopy or the ground,

mangrove forest or secondary dry forest?

H0- Arthropod biomass will not change between secondary forest and

mangrove forest, in the canopy and on the ground.

H1- Arthropod biomass will be higher in mangrove forest than in secondary

forest, in the canopy and on the ground.

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Chapter Two

Methodology

2.1. Fixed-radius Point Counts

In order to assess presence or absence, relative abundance and an index of

seasonal trends in occurrence of migrant and resident warblers and vireos, a series of 6-

minute, 25-meter fixed-radius point counts were used in plots of four habitat types: red

mangrove forest, black and white mangrove forest (= “black” mangrove), secondary dry

forest and cultivated areas (Wunderle 1994) (Figure 2.01). The point counts were

established randomly within each habitat type and located at least 100 m apart (a

stratified random design). The number of points placed in each habitat type varied due

to the site size and accessibility, and each point was no closer than 25 m from a habitat

edge. The radius of each point was fixed at 25 m and counting time was standardized at

6 min in each point during one year, from Sep 2010 through Sep 2011. Counts were

initiated at sunrise and terminated before 1100 AM.

Thirty-two points were sampled: 16 in secondary dry forest, 6 in black and white

mangrove (“black”) forest, 7 in red mangrove forest and 3 in cultivated areas (Figure

2.01). All point counts were sampled during the entire year, except red mangroves,

which were sampled from Feb 2011 through Aug 2012 only, due to limited access (lack

of availability of boat transportation). A non-parametric Kruskal Wallis test was

performed to evaluate differences through the year and between habitats for bird

species detected in these counts.

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Figure 2.01. Locations of 6-min, 25-m fixed-radius point count sampling

from Sep 2010 to Sep 2011 at Jobos Bay Estuarine Research Reserve

(JBNERR).

2.2. Bird Movement Between Habitats

2.2.1. Observations from Blinds

In order to determine whether small passerine birds moved between habitat

types, and to evaluate relative activity at various points along the mangrove/dry forest

interface flights between mangroves (black mangroves) and secondary dry forest were

quantified using a blind that was established in several areas of the interface between

mangrove and secondary dry forest. Preliminary observation points were established

along the interface between secondary dry forest and mangrove forest, from Nov 2010

until Jan 2011, (Points: A, B, C and D) (Figure 2.02). These observations were carried

out twice a week, beginning at pre-dawn full darkness until at least one hour after

sunrise, and also at dusk from at least one hour before sunset until full darkness, at each

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point. Areas of documented between-habitat movement are henceforth referred to as

“corridors”. Additional visual observations were conducted to find the locations of day

roosts and night roosts.

2.2.2. Mist Netting

Mist netting was conducted at the most active corridor point (Point B) during dry

migratory (M2) period, from Feb 2011 to Apr 2011 (Figure 2.02). A series of 6 to 10

four-trammel 2.5 m tall mist nets of 30 mm or 38 mm mesh, and 12 m length, was used

to capture small warblers and other passerines. An initial mist-netting session was

conducted in secondary dry forest habitat on Feb 4 2011 for 5 hours, beginning at 8:00

AM and ending at 1:45 PM. Subsequently, mist nets were established in corridor point

“B” in a gap between mangrove and dry forest, the most active point of this corridor

based on blind observations. Netting was conducted from Feb 18 to April 27. Thereafter,

to detect bird movements between habitats (Smith 2008), mist netting was conducted

from full darkness before dawn until two hours after dawn, and from two hours before

dusk until full darkness after dusk. Multiple species were captured in order to quantify

directionality, intensity and time of movement. All birds captured were identified,

weighted, banded and released. A Chi-squared Test was performed to assess

differences among bird movements between secondary dry forest (SF) and mangrove

forest (M) at sunrise (“AM”) and at dusk (“PM”).

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Figure 2.02. Blinds for bird movement observation, established at points A, B, C,

D and E, in a gap between secondary dry forest and mangrove forest. Mist nets

were established at the most active site point “B”.

2.3. Arthropod Sampling

2.3.1. Sampling Canopy Arthropods by the Branch Clipping Technique

Total abundance of arthropods in an environment does not necessarily

correspond to the amount of food available for foraging predators, due to the bird’s

selection of prey and foraging microhabitats (Hutto 1990; Johnson and Sherry 2001). For

that reason, the branch clipping technique was chosen. Many migrants and resident

warblers feed at mid to high heights above the ground. Examples include Yellow

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Warblers, Adelaide’s Warblers, Prairie Warblers, American Redstarts and Northern

Parulas (Raffaele 1989; Dunn and Garrett 1997; Oberle 2010).

Figure. 2.03. Arthropod sampling by the branch clipping technique.

The branch clipping technique allows sampling of microhabitats within the canopy

foliage normally used by warblers (Johnson 2000a,b; Johnson and Sherry 2001). An

active searching technique was used to collect arthropod samples. When a bird was

located, a sample was taken nearby, without disturbing the bird (Strong and Sherry

2000; Smith 2008). A total of 63 samples was taken; 31 in secondary dry forest and 32

in mangrove forest. Branch clipping was conducted from March 26 through April 11,

2011, according to the availability of transportation. To carry out the branch clipping

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technique a collapsible bag was positioned in the vegetation at height of 9-20 m, with the

aid of extension poles. The bag was placed quickly over the edge of the branch and the

mouth of the bag was closed tightly around the branch. The branch was clipped free with

the aid of a telescopic tree pruner, and then the bag and branch were lowered. Samples

were extracted and collected with the aid of a modified vacuum manufactured by Bioquip

Corporation for further quantification and biomass determination. Individuals per branch

clipped were counted and dried to constant mass to the nearest 0.1 mg. The mass of

each sample was expressed in mg of total biomass of arthropods per g of clipped

vegetation (wet mass) (Johnson 2000a,b; Johnson and Sherry 2001). To test the

prediction that arthropod biomass was higher in mangrove forest than in secondary dry

forest, during the dry migratory season, a 2 sample t-test was used.to compare means

between two groups.

2.3.2. Sampling Ground Arthropods by the Quadrat Technique

The quadrat technique was used to sample arthropods on the surface of the leaf

litter (Figure 2.03). Active searching was used because the Northern Waterthrush is an

active leaf-tosser during foraging (Smith 2008), and Ovenbirds feed from the leaf litter

surface (Strong and Sherry 2000). A total of 60 samples were taken, 30 in secondary

dry forest and 30 in mangrove forest. Each time a bird was located, a direct search of

the ground substrate was carried out within a 0.25 m2 quadrat. Samples were taken as

close as possible to the exact location that the bird was observed, without disturbing the

bird (Strong and Sherry 2000; Smith 2008). All samples were collected for further

quantification and biomass determination. Arthropod samples were counted and then

dried to constant mass to the nearest 0.1 mg. To test the prediction that arthropod

biomass was higher in mangrove forest that in secondary dry forest, during the dry

migratory season, the 2 sample t-test was used to compare means between two groups.

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Figure. 2.04. Sampling of ground arthropods by Quadrat Technique.

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Chapter Three

Results

3.1. Fixed-radius Point Counts

Multiple point counts with a fixed radius of 25 m and 6 minute duration were

conducted in four habitats: secondary dry forest, black and white mangrove forest, red

mangrove forest and cultivated habitats. Censuses were conducted from September

2010 to August 2011. The data collected include presence or absence of each bird

species detected, as well as the number of each species observed per point.

Prairie Warblers and Yellow Warblers were found in all habitat types (Table

3.01). Northern Waterthrushes and American Redstarts were found in secondary dry

forest, black mangrove forest and red mangrove forest, but not in agricultural areas.

Several migratory species were observed only in two habitat types, secondary dry forest

and black mangrove forest. Those species are: Northern Parulas, female American

Redstarts, Western Palm Warblers, and Black-and-white Warblers. In addition, the

Adelaide’s Warbler was only detected in two habitat types, secondary dry forest and

black mangrove forest (Table 3.01), and in the latter habitat nearly always in areas

adjacent to dry forest. The resident, Black-Whiskered Vireo and the three migrants,

Blackpoll Warbler, Common Yellowthroat and Ovenbird were detected only in secondary

dry forest. Blackpoll Warblers were detected only in the first migratory season (M1, Sep-

Dec), as this species commonly uses Puerto Rico as a stopover area (Baltz 2000). All

species were detected with fixed-radius point counts, except Western Palm Warbler and

Ovenbirds, which were detected only by mist netting during the dry migratory season

from February to April 2011.

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Table 3.01. Summary of presence (+) or absence (-) of species in a given

habitat type during 25-m, 6-min duration fixed-radius point counts, Sept,

2010 to Sept, 2011 and mist netting during Feb. 2011 to the end of Apr,

2011 in southern Puerto Rico. Note that sex is listed separately for AMRE

males (M) and females (F).

_______________________________________________________

Secondary Black Red Dry forest Mangrove Mangrove Agriculture

_______________________________________________________

PRAW + + + + YEWA + + + + NOPA + + - - NOWA + + + - WPWA* + + - - M AMRE + + + - F AMRE + + - - COYE + - - - OVEN* + - - - ADWA + + - - BWVI + + - - BWWA + + - -

_______________________________________________________

*Detected by mist netting only.

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Species richness was evaluated in mangrove forest and secondary dry forest

during one entire year, Sep 2010 to Sep 2011. The year was divided into three seasons:

M1 = the migratory wet season that covers Sep-Dec 2010; M2 = the migratory dry

season, Jan-Apr, 2011; and NM = the non-migratory season, May-Aug 2011 (Table

3.02). Both secondary dry forest, and combined red and black mangrove habitats,

reached their highest species richness in the second (dryer, M2) migratory season. Ten

species were found in the M2 season in mangrove forest. All species were detected by

point counts, except two species that were detected only by mist netting – Ovenbird and

Western Palm Warbler. All species above were also detected in secondary dry forest in

the M2 season except the Prothonotary Warbler, which was observed accidentally. Only

three breeding species (Oberle 2010) were found during the non-migratory season (NM),

in both habitats including: Adelaide’s Warbler, Yellow Warbler and Black-Whiskered

Vireo. During the M1 season, seven species were found in combined mangrove habitat.

In addition, secondary forest richness during M1 included eight species (Table 3.02).

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Table 3.02. Species richness and presence or absence of warblers and

vireos per habitat type and season, including: (NM) non-migratory, (M1) wet

migratory and (M2) dry migratory seasons. N is equivalent to the number of

point counts sampled in each of the designed periods and habitats.

________________________________________________________________

Mangrove Forest Secondary Dry Forest

Species NM M1 M2 NM M1 M2

N = 67 N = 89 N = 90 N = 90 N = 230 N = 1 20

________________________________________________________________

NOWA - X X - X X

YEWA X X X X X X

ADWA X X X X X X

PRAW - X X - X X

NOPA - - X - X X

AMRE - - X - - X

BPWA - - - - X -

BWWA - X X - X X

OVEN* - - - - - X

WPWA* - - X - - X

PROW - X X - - -

BWVI X X X X X X

__________________________________________________________________________

Total 3 7 10 3 8 10

_______________________________________________________________________

*Detected only by mist netting.

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Fixed-radius point counts were conducted from Sep 2010 to Sep 2011 in multiple

habitats, including secondary dry forest, red mangrove and black mangrove forest and

cultivated areas (Agriculture). For the purpose of the following analyses, the two major

habitats are considered; (1) secondary dry forest and (2) combined (black and red)

mangrove forest. Although twelve species of warblers and vireos were observed in this

research, only data for the five most common species at Jobos Bay Reserve were

evaluated in detail (Table 3.03). A non-parametric Kruskal Wallis test was performed to

evaluate differences between habitat and season.

The resident Adelaide’s Wabler occurred in both major habitats during all

seasons over the entire year. Adelaide’s Warbler was less common in mangrove forest

than in secondary dry forest (Figure 3.01) and tended to occur in areas where the

canopy cover seemed greater (pers. Obs.). Adelaide’s Wabler occurrence differed

significantly between habitats (H = 99.43, df =1, p<0.001), probably because it was more

frequently detected in secondary dry forest than mangrove forest during the entire year.

Moreover, Adelaide’s Wabler was seen in all seasons as it is a resident species, but a

significant difference in abundance was obtained among seasons (H=6.82 df=2,

p<0.003). It also was more commonly detected in secondary dry forest in the non-

migratory season (May-Aug 2011), which also is its primary nesting season. The highest

mean for Adelaide’s Wabler was in secondary dry forest, during the non-migratory

season (Table 3.03, Figure 3.01).

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Table 3.03. Means SE’s of counts per point of the five most common warblers

and vireos in Jobos Bay per habitat type (mangrove or secondary dry forest) and

season, including: (NM) non-migratory, (M1) wet migratory and (M2) dry migratory

seasons.

___________________________________________________________________________

Mangrove Forest Secondary Dry Forest

Species NM M1 M2 NM M1 M2

___________________________________________________________________________

ADWA 0.28 0.92, 0.25 0.61, 0.07 0.34, 1.27 1.13, 0.85 1.17, 0.95 1.35

YEWA 3.60 2.42, 0.94 1.41, 1.92 1.81, 1.92 2.18, 0.32 0.86, 0.91 1.47

PRAW 0.00 0.00, 0.10 0.37, 1.42 1.52, 0.00 0.00, 0.17 0.49, 0.10 0.30

NOWA 0.00 0.00, 1.80 2.53, 1.42 1.52, 0.00 0.00, 0.53 1.29, 0.57 1.23

BWVI 0.37 0.83, 0.02 0.21, 0.01 0.11, 0.38 0.65, 0.01 0.09, 0.06 0.24

____________________________________________________________________________

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Figure 3.01. Mean number of Adelaide’s Warblers (ADWA) observed per 25-m-fixed

radius, 6-min duration point counts in mangroves and secondary dry forest during three

seasons. Vertical bars represent SE. The total number of observations (fixed-radius

point counts sampled) is indicated above each column. Migratory season 1 occurs

during Sep 2010-Dec 2010; migratory season 2 occurs during Jan 2011-April 2011, and

non-migratory season occurs between May 2011 and August 2011.

Yellow Warblers occurred in both habitats during the entire year (Figure 3.02).

The migratory or resident status of this species in Jobos Bay was not defined well at the

time of this analysis; therefore wing measurements were taken in the following non-

migratory season of 2012 for further analysis. This species occurred more frequently in

mangrove forest than in secondary forest (Kruskal-Wallis: H = 82.51, df = 1, p < 0.001) in

all three seasons, and appeared to be more abundant during the non-migratory season

(Kruskal-Wallis: H = 125.70, df = 2, p < 0.001), when the peak of reproduction occurs.

Thus, Yellow Warblers occurrence was significantly different for both habitat and season

(Table 3.03, Figure 3.02).

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Figure 3.02. Mean number of Yellow Warblers (YEWA) observed per 25-m-radius, 6-min

point counts in mangroves and secondary dry forest during three seasons. Vertical bars

represent SE. The total number of observations (fixed-radius point counts sampled) is

indicated above each column. Migratory season 1 occurs during Sep 2010-Dec 2010;

migratory season 2 occurs during Jan 2011-April 2011, and non-migratory season

occurs between May 2011 and August 2011.

Migratory Prairie Warblers occurred in both habitats during the M1 and M2

seasons, but not in NM season (Table 3.03). The highest occurrence of this species was

found in mangrove habitat during the M2. The lowest occurrence was found during M1 in

mangrove forest and during M2 in secondary dry forest (Figure 3.03). However, a

Kruskal-Wallis test revealed that Prairie Warblers occurrence differed significantly

between seasons (H =18.31, df = 2, p < 0.001) and habitats (H = 5.98, df = 1, p < 0.001).

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Figure 3.03. Mean number of Prairie Warblers (PRAW) observed per 25-m-radius, 6-

minute duration point counts in mangroves and secondary dry forest during three

seasons. Vertical bars represent SE. The total number of observations (fixed-radius

point counts sampled) is indicated above each column. Migratory season 1 occurs

during Sep 2010-Dec 2010; migratory season 2 occurs during Jan 2011-April 2011,

and non-migratory season occurs between May 2011 and August 2011.

Migratory Northern Waterthrushes occurred in both habitats only during the M1

and M2 seasons (Figure 3.04). The highest occurrence of this species was found in

mangrove forest during the M1. A Kruskal-Wallis Test revealed that the Northern

Waterthrush occurrence differed significantly between seasons (H=76.16, df=2, p<

0.001) and habitats (H= 49.49, df = 1, p< 0.001).

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Figure 3.04. Mean number of NOWAs observed per 25-m-radius, 6-min duration

point counts in mangroves and secondary dry forest during three seasons. Vertical

bars represent SE. The total number of observations (fixed-radius point counts

sampled) is indicated above each column. Migratory season 1 occurs during Sep

2010-Dec 2010; migratory season 2 occurs during Jan 2011-April 2011, and non-

migratory season occurs between May 2011 and August 2011.

Black-whiskered Vireos occurred in both habitats and highest occurrences were

found in mangrove forest in NM and in secondary dry forest in NM since this species

breeds in Puerto Rico (Figure 3.05). A low occurrence of this species was found in

mangrove forest and secondary dry forest, respectively during wet migratory season,

because this species migrates to South America during the non-nesting season. Also,

low occurrences were found during M2 in mangrove forest and secondary dry forest

(Table 3.03). A Kruskal-Wallis test reveled that this species did not differ significantly

between mangrove forest and secondary forest (H= 0.13, DF= 1, p< 0.721) but differed

between seasons (H= 100.85, DF= 2, p< 0.00).

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Figure 3.05. Mean number of Black-whiskered Vireos (BWVI) observed per 25-m-

radius, 6-minute point counts in mangroves and secondary dry forest during three

seasons. Vertical bars represent SE. Number of observations (fixed-radius point

counts sampled) is indicated above each column. Migratory season 1 occurs during

Sep 2010-Dec 2010; migratory season 2 occurs during Jan 2011-April 2011, and

non-migratory season occurs between May 2011 and August 2011.

3.2. Bird Movement between Secondary Dry Forest and Combined (Red, Black

and White) Mangrove Forest.

3.2.1. Observations from a Blind

To assess the hypothesis that mangrove-roosting birds move to secondary dry

forest in search of food at dawn and return to the mangrove forest at dusk, preliminary

observations using a blind along the interface between secondary forest and mangrove

forest were conducted in 5 different observation points (Figure 2.02). Corridor “B” was

the most active site, thus mist netting was conducted in this corridor (Figure 3.06). A

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total of 213 birds were observed in 8h duration period, from November 2010 to January

2012 in corridor “B”. All birds were found moving from mangrove forest to secondary dry

forest in the first half hour after dawn and 95% of birds observed moved from secondary

dry forest to mangrove forest, the last half hour before dusk. These data also suggest

that Prairie Warblers are the most abundant species moving through this corridor. A

substantial portion of the birds observed were unidentified because of the low visibility

during the first observation half-hour after dawn (Figure 3.06).

Figure 3.06. Directional observations from a blind, documenting bird movements

between mangroves (south, S) and secondary dry forest (north, N) during the

mornings and the evenings of November 2010 to January 2011 (AM/PM session).

Major directionality of birds captured moving between mangroves forest and

secondary dry forest while mist netting was evaluated during Feb–Apr 2011 (Table

3.04). A total of 18 bird species was captured. The majority of bird species moved from

mangrove forest to secondary dry forest in the morning and from dry forest to mangrove

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forest in the afternoon. Both, resident and migratory birds showed this pattern of

movement. Six species including Northern Parula, Western Palm Warbler, American

Redstart, Gray Kingbird, Yellow-faced Grassquit and Northern Mockingbird, moved in

this pattern, showing that 100% of birds captured in the morning moved to dry secondary

forest and to mangrove forest in the afternoon. Also, this same directionality pattern of

movement in the morning was observed Yellow Warbler, Northern Waterthrush and

Prairie Warbler, all of which showed a high incidence of directionality (92%, 92% and

91% for the three species respectively). All species in morning showed over 80%

directionality, from mangrove forest to secondary forest (Table 3.04). A total of six

migrant species showed a 100% of movement from mangrove to dry secondary forest

(Northern Waterthrush, Northern Parula, Western Palm Warbler and American Redstart)

and two resident species (Black-faced Grassquit, Gray Kingbird). Also Prairie Warbler

follow the same pattern with 96% of directionality (Table 3.04).

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Table 3.04. Major directionality of birds captured moving between mangroves

(M) and dry forest (DF) during mist netting conducted Feb –Apr 2011. “Status”

includes resident nesting species (R) and Migratory (M) species.

________________________________________________________ Major Directionality

Morning Afternoon

Status M-DF DF-M % DF-M M-DF %

________________________________________________________

PRAW M 32 3 91 55 2 96

YEWA M/R1 2 1 92 12 3 80

NOPA M 3 0 100 4 0 100

NOWA M 11 1 92 16 0 100

WPWA M 4 0 100 1 0 100

AMRE M 3 0 100 4 0 100

COYE M 0 2 0 0 0 0

OVEN M 2 0 100 0 0 0

ADWA* R 0 0 0 0 0 0

BWVI* M 0 0 0 0 0 0

BWWA* M 0 0 0 0 0 0

NOMO R 2 0 100 3 1 75

BANA R 15 3 83 15 3 83

BFGR R 28 5 85 4 0 100

YFGR R 3 0 100 0 0 0

COGD R 20 1 95 3 3 50

PRFL R 3 0 100 0 0 0

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GRAK R 2 0 100 6 0 100

MACU R 0 1 0 0 0 0

SHCC R 2 1 67 0 0 0

GAGR R 0 0 0 0 1 0

_______________________________________________________

*Birds detected only by Fixed-radius Point Counts.

3.2.2. Mist Netting

Mist netting was used to test the hypothesis that mangrove-roosting migrants

make daily movements from mangroves to secondary dry forest at dawn, and return to

the mangrove forest at dusk inferring (connectivity between habitats). The dependent

variables included: capture rate per net hour, percent of directionality and capture

interval (first bird to the last bird) were analyzed in each of the five mist netting sessions.

A chi-square test was used to verify if directionality of movement during Feb-Apr 2011

was significant for the different bird species and groups of species (Table 3.05). Yellow

Warblers individuals were analyzed separately due to this species’ unclear status: some

individuals are residents and others migrants. Thus wing measurements were taken in a

second mist netting season in 2012 (Pyle 1997), in order to define Yellow Warbler status

in this habitat (data analysis not yet complete).

Mist netting began on 18 Feb 2011, with a 6-net line set at 8:00 AM in secondary

dry forest habitat away from the inter-habitat corridor and continued until 1:45 PM that

same day (Figure 3.07). Considering only the migratory species a total of 10 (100%) of

individuals were captured moving in the predicted direction of mangrove to secondary

dry forest. Four migratory species were captured in this session, between them: Prairie

Warbler (n=6), Northern Waterthrush (n=6), Western Palm Warbler (n=2) and Yellow

Warbler (n=1). For a better understanding of the movement dynamics of this inter-habitat

corridor throughout the morning, the time was categorized in three periods: first half

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hour, subsequent 1.5 hours and complete AM session (4H), after the sunrise. The first

half hour had the highest capture rate (2 birds per net hour) and a capture interval (first

bird to the last bird) of one bird each 5 min. The capture rate obtained in the subsequent

1.5 h after the sunrise was 0.4 birds per net hour and a capture interval (first bird to the

last bird) of one bird each 85.7 minutes, which indicates that bird activity or movement in

this corridor was considerably lower than in the first half hour. The complete session

capture rate was 0.5 birds per net hour and a capture interval (first bird to the last bird) of

one bird each 24 min (Figure 3.07).

Figure 3.07. Capture Rate per net hour. Complete Session. February 18, 2011 (AM).

Mangroves are to the south (S) and secondary dry forest to the north (N).

A second complete day session of mist netting was conducted on 7 Mar 2011,

with 8-net line, starting at 6:30 AM and closing at 6:30 PM (Figure 3.08). The day was

divided in two periods (AM) and (PM). In the morning, 91% of all birds captured (N=20),

moved from secondary dry forest to mangrove forest. Capture rate per net hour and

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capture interval (first to the last bird), were assessed in each time category. In the first

half hour after dawn, a capture rate of one bird per net hour was obtained with a capture

interval (first to the last bird) of one bird each five minutes, indicating high movement

activity in this corridor. Similarly, the subsequent 1.5 hours after sunrise, were extremely

active too with a capture rate of 1.3 birds per net hour and a capture interval (first to the

last bird) of one bird each 3.8 min. These two time periods after dawn illustrate the high

level of movement activity early in the morning, when the most abundant species were

Prairie Warbler (n=10) and Northern Waterthrush (n=5), but also individuals of Yellow

Warbler, Western Palm Warbler and American Redstart were captured and Northern

Parula was not detected. Moreover, it was the most active morning in all the dry seasons

assessed (Feb–Apr 2011).

The activity started to diminish the third and fourth hour after the sunrise and mid-

day hours capture rates were very low as expected. A low capture rate of 0.1 birds per

net hour and a capture interval (first to the last bird) of one bird each 6.1 min, were

obtained (Figure 3.08). Mist nets were closed between 2:00 PM to 4:00 PM, due to a low

level of activity (movement).

In the afternoon session after 4:00 PM, the prior 1.5 hours before dusk, were

assessed and a capture rate of 2 birds per net hour was obtained. Furthermore, a

capture interval (first to the last bird) of one bird each 2.7 min was founded. However, in

contrast to direction movement in the morning, 98% of all afternoon captures (N=41)

moved N-S from secondary dry forest to mangrove. In the last half hour before dusk, an

exceptional intensity of movement was observed with a capture rate of 3.5 birds per net

hour and a capture interval of one bird each 1.2 min. The most abundant species

detected in the afternoon were Prairie Warbler (n=22) and Northern Waterthrush (n=12)

with lower captures of Yellow Warbler, American Redstart, and Northern Parula, but no

Western Palm Warbler captures. This afternoon session was the most active session in

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the entire assessment period (Figure 3.08).

A third session of mist netting was conducted the afternoon of 20 Mar 2011 and

the following morning 21 Mar 2011. After a complete day of mist netting was assessed

on March 7 2011, a new strategy of composite days was conducted taking in

consideration the most active hours of the corridor. The morning of March 21, 100% of

migrant birds moved in the expected direction from mangrove forest to secondary dry

forest (N=27) and 90% (N=38) of birds moved in the opposite direction in the afternoon

of March 20 2011. Prairie Warblers were the most active birds in the corridor and

Western Palm Warblers were not detected. The most active movement period was the

first half hour after dawn with 5.3 birds/ net h and a capture interval of 1.9 min per bird

and also the last half hour before dusk with 4.3 birds/ net h and a capture interval of 2.3

min per bird (Figure 3.09).

Figure 3.08. Migrant capture rate per net hour, complete session during March 7,

2011. Mangroves are to the south (S) and secondary dry forest to the north (N).

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Figure 3.09. Migrant capture rate per net hour for complete composite day. March 21,

2011 AM and March 20, 2011, PM. Mangroves are to the south (S) and secondary

dry forest to the north (N).

The fourth session of mist netting was conducted evaluating a complete

composite day, including the afternoon of April 10 and the morning of April 11 (Figure

3.10). This session also confirmed the predicted behavior in this corridor; in the

morning, 75% of birds captured moved from mangrove forest to secondary dry forest

and in the afternoon, 100% were captured moving from secondary dry forest to

mangrove forest. The first half hour in the morning after dawn and the last half hour just

before dusk were the most active periods of movement in this corridor. Morning session

movement was more intense because the capture interval obtained in the first half hour

in the morning was one bird each 2.5 min. However, there were fewer total migrants in

this session than captured in the previous sessions in February and March (Figure

3.10).

The last mist netting session in the dry migratory season was conducted to

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evaluate a complete composite date, the afternoon of April 26 and the subsequent

morning on April 27 (Figure 3.11). Only five migrant individuals were captured, indicating

that the migratory season was ending. Only individuals of Yellow Warblers and Northern

Parulas were present, but the species previously most abundant in this corridor Prairie

warblers and Northern Waterthrushes were absent, as were American Redstart and

Western Pam Warblers. Despite fewer migrants, unidirectionality in the corridor was

100% in morning from mangrove secondary forest and in afternoon secondary forest to

mangrove forest. Similar to other dates, the highest intensity of bird movement occurred

in the first half hour after dawn and the last half hour before dusk (Figure 3.11).

Figure 3.10. Migrant capture rate per net hour for a complete composite day,

including April 11 2011, AM and April 10 2011, PM. Mangroves are to the south (S)

and secondary dry forest to the north (N).

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Figure 3.11. Capture Rate per net hour for a complete composite day. April 26 2011,

AM and April 27, 2011, PM. Mangroves are to the south (S) and secondary dry forest

to the north (N).

Considering all 291 birds of 18 species whose directionality of movement was

known (i.e., direction they were moving when they entered the net), directionality was

dramatic and statistically significant, with 88.9% of birds captured in the morning moving

from mangroves to secondary dry forest, and 89.9% of birds captured in the afternoon

moving from secondary dry forest back to the mangroves or (X2= 180.13; df=1, p<0.001)

(Table 3.05). Overall, 150 of 291 birds (51.5%) were captured moving from secondary

forest to mangrove forest, while 48.5% were captured moving from mangrove forest to

secondary dry forest, but this is simply a reflection of the fact that slightly more birds

were captured during morning sessions (53.3%), than in the afternoon (47.4%) (Table

3.04).

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Table 3.05. Major directionality of birds captured moving between mangroves (M) and

dry forest (DF) during mist netting conducted Feb–Apr 2011 and Chi-Square results.

Major directionality of birds was evaluated in 4 groups: migratory birds, resident birds,

YEWA and all birds that were captured.

_____________________________________________________________________________

Major Directionality

Morning Afternoon Overall

Specie M-DF DF-M Total, % DF-M M-DF Total, % DF-M, % M-DF, % N

_____________________________________________________________________________

Migratory 53 5 58; 91.4 80 2 82; 97.6 85; 97.6 55; 39.3 140*

Residents 71 11 82; 86.6 32 9 41; 78.0 43; 35.0 80; 65.0 123*

**YEWA 12 1 13; 92.3 12 3 15; 80.0 13; 46.4 15; 53.6 28*

All Species 136 17 153; 88.9 124 14 138; 89.9 141; 48.5 150; 51.5 291*

_____________________________________________________________________________

*A Chi-square, p< 0.001.

** A separated Chi-Square was done for Yellow Warblers individuals, because the population

may include both resident and migratory birds.

A second chi-square analysis was performed to determine if differences in the

movement and directionality of migratory individuals alone in the morning and at night

were statically significant. A total of seven migratory species were considered in this

analysis: Northern Waterthrush, Prairie Warbler, Northern Parula, Western Palm

Warbler, American Redstart, Common Yellowthroat, and Ovenbird (Table 3.04). Of 140

migrant individuals captured during all mist netting sessions, a significant number of

individuals (85 or 60.7%) moved from dry secondary forest to mangrove forest (X2=

112.66; df=1, p<0.001). A total of 53 of 58 migratory individuals (91.4%) were captured

moving in the morning from mangroves to secondary dry forest and 80 of 82 individuals

(97.6%), were captured in the afternoon, moving from secondary dry forest back to the

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mangroves.

Directionality was also analyzed for resident birds in the corridor during all

sessions and 10 resident species were captured (Table 3.04). A total of 123 resident

individuals were captured, of which 35.0% of the individuals moved from secondary dry

forest to mangrove forest in the afternoon, while 65.0% were captured moving from

mangrove forest to secondary dry forest in the morning (X2= 50.22; df=1, p=0.00). A

significant percentage of resident birds (86.6%) moved from mangrove forest to

secondary dry forest in the morning and 78% moved from secondary dry forest to

mangrove forest in the afternoon (Table 3.05).

A separate directionality analysis was conducted for Yellow Warblers given the

potential for the population to contain both residents and migrants. Directionality was

dramatically intense in the morning where 92.3% of the individuals were captured

moving from mangrove to secondary dry forest in the morning and 80.0% of individuals

moved from secondary dry forest to mangrove forest in the afternoon (X2= 14.64; df=1,

p<0.001) (Table 3.05). Overall, 53.6% of individuals were captured moving from

mangrove forest to secondary dry forest and 86.7%, moved from secondary dry forest to

mangrove forest (Table 3.05).

3.3. Sampling of Arthropods in Secondary Dry Forest and Mangrove Forest

3.3.1. Canopy (Branch Clipping)

Biomass and prey item availability were quantified in the dry season using the

branch clipping technique to compare arthropod availability between habitats for birds

that feed at medium to high levels (Adelaide’s Warbler, Yellow Warbler, Prairie Warbler,

Northern Parula and American Redstart). Availability was determined for total individual

arthropods, total arthropod individuals per branch clip, and total arthropod biomass. Data

were transformed and a two sample t-test was used to evaluate the significance of

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differences between arthropods biomass between secondary dry forest and combined

red and black mangrove forest.

The mean number of prey items was significantly higher (t= 2.63 p<0.01) in

mangrove forest than secondary dry forest (Table 3.06). Those high numbers in

mangrove forest were specifically found in samples that came from black mangrove.

Secondary dry forest exhibited fewer prey items per branch clip.

Table 3.06. Biomass and prey items of arthropods sampled by branch clipping, by

habitat type using a two-sample t-test with log-transformed data.

______________________________________________________________________

Mangrove Forest Secondary Dry Forest

Mean SE Mean SE

Analysis Type N = 32 N= 30 1p value

______________________________________________________________________

Prey Items 1.69 0.13 1.16 0.15 <0.01

Biomass (mg) 0.51 0.28 0.95 0.18 <0.01

Biomass in mg/g of 1.61 0.28 2.05 0.18 <0.19

branch clipped ______________________________________________________________________

1 Results of the log transformed two-sample t-test.

Unlike prey item results, prey biomass differences between both habitats were

significantly higher in secondary dry forest than in mangrove forest (t=4.40, p<0.01),

which suggests that canopy foliage in the mangrove forest has more prey items but

probably smaller in biomass than secondary forest (which has fewer prey items but with

a higher biomass). Moreover, standardized data (mg biomass/per g of branch clipped),

indicated no significant difference between mangrove and secondary dry forest (t=1.32,

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p=0.19; (Table 3.06). It appears that mangrove forest offers more individual prey items

per branch clip than do the branch clips from the secondary dry forest, even if the overall

biomass is not higher. This suggests that the probability of catching a food item for an

insectivorous bird may be higher in mangrove than in secondary dry forest (Table 3.06).

However, a second statistical analysis was performed excluding the order

Odonata, because it is not a major part of the warblers’ diet. A log transformed two-

sample t-test revealed no significant difference between prey items of mangrove forest

and secondary dry forest (t=0.85, p=0.40) (Table 3.07). Biomass initially appeared

higher in mangrove forest than in secondary dry forest, but it was not significant (t=-0.53,

p=0.598). Moreover, standardized data (mg biomass/g of branch clipped), indicated that

prey biomass in secondary dry forest was higher, after excluding Odonata (Table 3.07).

Table 3.07. Biomass and prey items of arthropods sampled by branch clipping, by

habitat, excluding the order Odonata, two-sample t-test with log transformed data.

______________________________________________________________________

Mangrove Forest Secondary Dry Forest

Mean SE Mean SE

Analysis Type N = 32 N= 30 1p value ______________________________________________________________________

Prey Items 2.09 0.18 2.29 0.15 <0.40

Biomass (mg) 1.02 0.25 0.86 0.18 <0.60

Biomass in mg/ g of 1.43 0.26 1.96 0.18 <0.10

branch clipped ______________________________________________________________________

1 Results of the two-sample t-test.

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A detail analysis was conducted considering the dates when arthropod samples

were taken. The highest median value of prey items per branch clipped was obtained on

March 30 (median=16, n=6) in mangrove forest, which suggests an outbreak of

arthropods. Median prey items in secondary dry forest samples remained relatively

constant in the same period (Figure 3.12). Moreover, a higher biomass of arthropods

was also obtained on March 30 in mangrove forest (median=13.05, n=6), but also a

notable median biomass (mg) of arthropods was obtained in April 8 (median=6.85,

n=12). Medians of arthropod biomass in secondary forest remained constant between

sampling dates (Figure 3.13).

Figure 3.12. Median prey items collected by branch clipping per sampling date,

compared between secondary dry forest and combined (red, black and white)

mangrove forest, between March 26 and April 11, 2011.

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Figure 3.13. Median arthropod biomass in (mg) per (g) foliage clip,

obtained in combined mangroves (red, white, black) and secondary dry

forest on different dates between March 26 and April 11, 2011.

Figure 3.14. Median arthropod biomass in (mg) per g foliage clip obtained

in mangroves (red, white, black) and secondary dry forest on different

dates between March 26 and April 11, 2011.

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An analysis of arthropod biomass in mg per g branch clip was also conducted.

Medians on March 30 and April 8 were considerably higher in mangroves than

secondary dry forest (Median=15.60, n=6) and (19.45, n=12) respectively, when

compared with secondary dry forest samples (Figure 3.14).

A detailed analysis of arthropod biomass and standardized biomass per branch

clip showed an apparently large difference between mangrove forest and secondary dry

forest results, a log transformed two way t-test analysis of all samples, revealed no

significant difference in prey items and biomass determination analysis between the two

habitats (Table 3.06).

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Table 3.08. Branch clip (BC) samples of foliage arthropods per sampling date in secondary dry forest and mangrove forest for

samples collected March-April 2011.

_________________________________________________________________________________________________

Secondary Dry Forest Mangrove Forest

Branch Mass Prey Items/

Spl Mass Mass/ Mass/BC Branch Mass Prey items/ Spl Mass Mass/ Mass/BC

(g) 0.25 (m2) quadrat (mg) Prey Items (mg) (mg)/(g) (g) 0.25 (m

2) quadrat (mg) Prey Items (mg) (mg)/(g)

N 30 30 30 30 30 32 32 32 32 32

Mean 31.79 5.03 3.87 1.09 13.04 75.43 7.53 6.27 0.97 12.24

Median 29.15 3.00 2.95 0.95 7.00 75.60 5.00 3.25 0.72 5.65

SD 9.50 8.44 4.48 0.86 21.69 33.49 6.09 7.24 1.35 14.76

SE 1.73 1.54 0.82 0.16 3.96 5.92 1.08 1.28 0.24 2.61

Range 35.78 47.00 25.00 3.49 122.50 27.20 21.00 27.20 6.80 65.40

(19.4-55.21) (1-48) (0.1-25.1) (0.1-3.59) (0.5-123) (0.2-27.4) (2-23) (0.2-27.4) (0.1-6.9) (0.2-65.6)

_________________________________________________________________________________________________________

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3.3.2. Ground Arthropods in Secondary Dry Forest and Combined Mangrove

Forest (Quadrat Technique)

Ground samples were collected by active searching using a quadrant technique

to assess arthropod abundance in combined mangrove forest and secondary dry forest.

Sample plots were placed 1 m away from the foraging locations where individuals of

Northern Waterthrush were observed feeding on the ground. Using this technique and

excluding the orders Diplopoda and Millipeda (which are not food items of these birds)

from the analysis, I found significantly higher (two-way t-test, t=3.28, p<0.01) number of

prey items in sample quadrats of secondary dry forest than in combined mangroves

(Table 3.09). The microhabitats where Northern Waterthrushes were found foraging

were usually wet areas near a pond or a water channel and mangrove samples were

taken mainly in black mangrove habitats, because red mangrove were less accessible.

The biomass of ground arthropods was greater in secondary dry forest than mangroves

forest (t=1.96, p=0.05). Thus, secondary dry forest (at least some areas) provides a

higher number of prey items and provides arthropod biomass (food) at least equivalent

to the mangroves for ground foraging warblers, like the Northern Waterthrush.

The main orders of arthropods found in secondary dry forest were: Collembolla,

Hymenoptera (including wasps and ants), Orthoptera, Coleoptera, Dictioctera, Aranae

and Acari. In mangrove forest the main orders of arthropods found were:

Pseudoscorpions, Aranae, Coleoptera and Hymenoptera (including wasps and ants)

(Appendix Table A2.04.).

A detailed analysis was conducted based on the dates when arthropod samples

were taken. A large median number of prey items was obtained in general in secondary

dry forest ground samples, but on March 6 an exceptionally large number of prey items

was observed, due to the high numbers of Acari and Collembolla present in these

samples (Figure 3.15, see also Appendix Table A2.01, A2.04).

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Figure 3.15. Median ground arthropod prey per 5 min scan of 0.25 m2

quadrats in secondary forest and combined mangrove forest (red, black

and white) gathered on separate dates between February 9 and April 21,

2011.

In addition, a detailed analysis of biomass of ground arthropods per quadrat

was conducted to compare secondary dry forest and mangrove forest and indicated

that mangrove forest had a large median biomass value on February 26, due to an

abundance of Diplopoda and Acari (Figure 3.16). Arthropods from the order Millipeda,

Acari, Collembolla, Isopoda and Aranae contributed to this exceptionally large

biomass sample. On April 21, the main orders that contributed to this high biomass

were: Diplopoda, Aranae and Acari. Mangrove Forest ground sample medians were

practically constant between dates and lower than the secondary dry forest medians.

The main orders found in mangrove forest samples in general were: Hymenoptera,

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Aranae and Coleoptera which were found in low numbers (Figure 3.16 and Appendix

Table A2.03), but which may provide adequate food for birds that feed on the ground

(i.e., Northern Waterthrushes and Ovenbirds).

Table 3.09. Biomass and prey items of arthropods collected in 0.25 m quadrats, by

habitat type, a two-sample t-test with log transformed data, excluding Diplopoda and

Millipeda orders.

______________________________________________________________________

Mangrove Forest Secondary Dry Forest

Mean SE Mean SE

Analysis Type N = 30 N= 30 1p value ______________________________________________________________________

Prey Items 0.88 0.08 1.26 0.09 <0.01

Biomass (mg) 0.01 0.10 0.28 0.09 =0.05

______________________________________________________________________ 1 Results of the two-sample t-test.

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Figure 3.16. Median ground arthropod biomass per 5 min scan of 0.25 m2

quadrats in secondary forest and combined mangrove forest (red, black

and white) gathered on separate dates between February 9 and April 21,

2011.

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Table 3.10. Ground arthropod abundance obtained by scanning a 0.25 m2 ground quadrats for 5 min in mangrove forest and

secondary dry forest for various dates from March 26 to April 7, 2011. Abundance was tallied for number of individuals per quadrat

and biomass per quadrat.

____________________________________________________________________________________________________________________

Secondary Dry Forest Mangrove Forest

Individuals/ Sample Mass (mg) Mass (mg) /Individual Individuals/ Sample .Mass (mg) Mass (mg) /Individual

(0.25 m2) quadrat (0.25 m

2) quadrat

N 30 30 30 30 30 30

Mean 24.03 13.15 0.71 8.23 3.88 0.47

Median 13.50 8.90 0.46 7.50 3.70 0.44

SD 20.97 12.24 0.80 4.23 2.38 0.18

SE 3.83 2.23 0.15 0.77 0.43 0.03

Range 88 47.50 4.02 17.00 11.29 0.86

(6-94) (2.10-49.60) (0.12-4.13) (2-19) (0.11-11.40) (0.02-0.88)

____________________________________________________________________________________________________________________

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Chapter Four

Discussion and Conclusions

4.1. Habitat Use by Neotropical Migratory Birds

This study discovered that (1) six species of migratory warblers occurred in

multiple habitats in the coastal area around Jobos Bay, and that (2) these species were

not sedentary within each habitat, i.e., that some or all of the individuals of these

populations had a night-roosting habitat (mangroves) that was distinct and

geographically separated from their foraging habitat. These findings are significant in

terms of (1) accurately interpreting the results of census data, (2) understanding the

fundamental evolutionary and behavioral ecology (life history characteristics) of these

species, and (3) habitat conservation for these species in the coastal zone. Census data

in this study, as with most studies, were collected mostly in the morning concurrent with

the inter-habitat movements of the birds. This means that mid-day populations in the

destination habitats are probably greater than those revealed by morning censuses and

that mid-day populations in the night-roost (originating) habitats are less than those

revealed by morning censuses.

To refine the results of morning census results future studies should consider

including mid-day census surveys, mid-day or all-day mist netting within core areas of

each habitat type, and mapping daytime foraging territories or home ranges of color-

marked or radio-telemetered individuals. Over-wintering life history characteristic may

differ dramatically between species as well. In some species, like Northern Parulas and

Prairie Warblers, the entire population may be making daily movements (diurnal

migrations) between habitats (see Latta and Faaborg 2001 and below) in which others,

like the Northern Waterthrush, dominance hierarchies may be formed (possibly based on

data of arrival, body size, or latitude of origin), wherein dominant, or “despotic” high-

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ranking individuals remain in the night-roosting habitat all day and displace lower-ranking

individuals to less preferred or less optimal habitat (see Fretwell 1980; Smith 2008,

Smith et al. 2010, Smith et al 2011a, 2011b, and below). Yellow Warblers are especially

interesting in that, like Northern Waterthrushes, individuals may be present all day in

both mangroves and secondary dry forest, and the winter population may include both

migrants and nesting residents (Arendt et al. 2004). Direct and indirect interspecific

competition is an additional topic that merits further investigation in these habitats at

Jobos Bay (see Case et al. 1983, Toms 2011).

Interdependent multiple habitat use also has profound implications for the

conservation of these species because the loss of a particular habitat will affect all or

most of the population. Habitat loss could be either directly anthropogenic, or indirectly

anthropogenic, resulting from climate change. Resource managers must consider this

when making decisions or taking actions regarding habitat management and the

protection and acquisition of additional habitat.

A profound and alarming effect of global climate change, beyond greater

extremes (including increasing winter droughts) and a general warming trend (Neelin et

al. 2006; Blunden et al. 2011) will be the dramatic increase in sea level that will bring

about the transformation, reorganization, and possible elimination of habitats essential to

the survival of wintering North American migratory land birds. This research examined

an emerging paradigm in the evolutionary ecology of migratory land birds, the “Reitsma-

Smith” (see below) model of local diurnal interhabitat migrations, in multiple (6) species

of North American migrants that depend simultaneously on interconnected mangrove

and dry forest habitat in the low-lying coastal region of Jobos Bay (JBNERR), on Puerto

Rico’s eastern south coast, that are imperiled by sea level rise.

Global climate change already is presenting significant challenges related to the

population regulation and limitation of North American-breeding migratory songbirds that

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winter in the Caribbean (Studds and Marra 2007; Faaborg et al. 2010a,b; Smith et al.

2010). Sea level rise will dramatically transform coastal morphology, bringing marine and

estuarine habitats such as mangroves inland, and shrinking or forcing further inland (if

space is available) existing coastal dry forest habitat (IPCC 2002; Kerr 2009; Blunden et

al. 2011). This transformation is particularly alarming for the low-lying coastal and

estuarine areas in and around the JBNERR on Puerto Rico’s eastern south coast.

Space and habitat use strategies are means of maximizing survival probability of

migratory populations in winter (Sherry and Holmes 1995,1996). Migratory bird

populations can be limited in size by factors such as reproductive success and parental

survival rates during the breeding season, and by individual survival during the

nonbreeding season (see also Marra et al. 1993), as well as during the long distance

migration between these two sites (see Paxton et al. 2007, 2008; Faaborg et al.

2010a,b).

Marra and co-workers (Marra et al. 1993, 1998; Marra 2000; Marra and Holmes

2001; Reudinck et al. 2009), presented a model of sexual habitat segregation in the

American Redstarts based on the behavioral dominance of older males. Though not

addressed directly in these studies, there is an inherent presumption that birds night-

roosted in their foraging habitat, especially in some core area of a foraging territory, as in

the case of solitary roosting Ovenvirds (Brown and Sherry 2008). This model of

defended foraging territories and the documentation or presumption of night roosting

within these territories has become a powerful paradigm influencing the understanding of

wintering ecology and has enjoyed significant corroboration. Latta and Faaborg (2001)

found that Prairie Warblers in the Dominican Republic were territorial foragers, with few

floaters, in both high altitude pine forest and lowland scrub and desert, but they believed

that only the lowland birds night-roosted off of their foraging territories, in mangroves.

Latta and Faaborg (2002) also studied territorial Cape May Warblers (Setophaga tigrina)

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in the Dominican Republic and linked both population responses and the individual

condition of nonbreeding birds to prevailing ecological conditions across divergent

habitats, but did not directly address night roosts. Townsend et al. (2010) found in

Bicknell’s Thrushes (Catharus bicknelli) that exclusive territoriality was the predominant

winter social system, that most birds night roosted on their foraging territories, and there

were few non-territorial floaters. Thus, this paradigm suggests that where foraging is

mostly territorial, most birds night-roost on their territories in their foraging habitat.

In a series of studies of Northern Waterthrushes begun in southwestern Puerto

Rico by Reitsma et al. (2002) and continued in greater detail at the former Roosevelt

Roads Naval Station in eastern Puerto Rico, Reitsma and coworkers (Reitsma et al.

2004; Burson et al. 2005; Hunt et al. 2005; Smith 2008; Smith et al. 2008, 2010, 2011,

(the “Reitsma-Smith” model)), found that 87% of birds during three January-April (dry

season) field seasons made diurnal migrations between disjunct red mangrove night-

roosts and daytime foraging sites in black and white mangroves, and especially

secondary dry forest and scrub up to 2 km distant. Red mangrove was the optimal and

preferred foraging habitat and high ranking territorial or “despotic” individuals (mostly

males, Fretwell 1980) forced lower ranking individuals to other habitats for foraging,

including both floaters and territorial (core area) foragers that may change locations as

the dry season (February-March) progressed. However, each habitat type was required

for the maintenance and success of the wintering population. Night-roosting occurred

mostly in red mangrove, individually, in loose groups of 3-5, or individually within the

core areas of despots.

Latta and Faaborg (2001) believed lowland-foraging, mangrove-roosting Prairie

Warblers night-roosted communally. Staicer (1992) found off-foraging-site communal

roosting in Northern Parulas) and Cape May Warblers and in non-territorial Prairie

Warblers that foraged in overgrown pastures in southwestern Puerto Rico (Staicer 1992;

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Baltz 2000, Toms 2011). Advantages of off-site and communal roosting may include

predator avoidance and information exchange (Townsend et al. 2009; Smith et al. 2008).

Recently Jirinec et al. (2011) documented diurnal migrations by Black-throated Blue

Warblers (Setophaga caerulescens) moving between shade coffee foraging sites and

night-roost sites in adjacent forest patches, demonstrating how landscape composition

may affect the delivery of an ecosystem service (insect control). Thus, the findings of

Reitsma and Smith, of diurnal interhabitat migrations is likely to become another

important and influential paradigm guiding the understanding of processes of population

regulation in wintering migrant songbirds.

4.2. Habitat Quality and Optimal Foraging

Previous results by Smith (2008) and Smith et al. (2008, 2010, 2011) showed a

gradient from red mangrove to black mangrove to secondary dry forest in in terms of

both habitat preference by Northern Waterthrush and foraging habitat quality, and that

these gradients also were consistent with moisture gradients across the three habitat

types. In this study, logistics limited access to red mangrove and required that red

mangrove and black mangrove be combined to a single “mangrove” category that was

predominantly black mangrove. Despite this truncation of extremes, branch clipping

results of this study suggest the mangrove canopy may provide slightly larger individual

prey items (0.83 g) than secondary dry forest canopy (0.79 g) and thus, an optimal

foraging model Smith (2008) and Smith et al. (2008, 2010, 2011a, 2011b) suggesting

that the mangrove canopy would be preferable foraging habitat for larger-bodied

warblers like the Northern Waterthrush, but less preferable to smaller species like Prairie

Warblers and Northern Parulas which may have difficulty handling larger prey items.

This is consistent with the previous findings of Smith (2008) and Smith et al. (2008,

2010) for Northern Waterthrush, as well as the observations of Latta and Faaborg (2001)

who found that Prairie Warblers established foraging territories in coastal secondary dry

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forest, but departed each evening towards the mangroves. Observations by Staicer

(1990, 1992) and Baltz (2000) are also consistent with this scenario.

Results from quadrat sampling of the forest floor suggest that the mangrove

forest floor also provides the largest individual prey items (0.47 g versus 0.13 g), and

more biomass overall, that Northern Waterthrushes would prefer than the secondary dry

forest floor according to an optimal foraging model. Moreover, many of the small items

on the secondary dry forest floor were ants, which would suggest competition with

Ovenbirds, a specialist in foraging for ants.

Northern Waterthrushes (and Yellow Warblers) also were commonly detected in

the mangroves during mid-day observations, and thus present to some degree in all

habitats during the entire day, while Prairie Warbler and Northern Parula were not. This

suggests that for these smaller species secondary dry forest was the preferred foraging

habitat, and mangroves were the preferred night-roosting habitat (perhaps as a defense

against predation) and their diurnal migrations were not the result of competition with

larger species for food in the mangroves. On the other hand, diurnal interhabitat

migrations by Northern Waterthrush (and probably migrant Yellow Warbler) most

certainly were related to competition with dominant Northern Waterthrush for preferred

foraging habitat that co-occurred with their night roosts, consistent with the results of

Reitsma et al. 2002, 2004; Smith (2008) and Smith et al. (2008, 2010).

4.3. Habitat Preference, Social Dominance and Diurnal Migrations

Optimal delivery of ecosystem services in the Jobos Bay National Estuarine

Research Reserve (JBNERR) and similar areas will require better understanding,

protection and maintenance of these habitats and interhabitat connectivity as the optimal

delivery of ecosystem services by either component depends on the protection of the

other.

Unlike many previous studies that focused only on the drier half of the migratory

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season, future research derived as an extension of this study could address and

examine multiple space use strategies of all six species that exhibit diurnal migrations

(the Reitsma-Smith model), the entire September-April migratory season, during at least

three years, with priority given to the three most observable species: Northern

Waterthrush, Yellow Warblers and Prairie Warblers.

The first set of questions falls within the following categories: (1) Site fidelity and

philopatry: What is the residence time of individuals at the study site (including how

many of the detected birds actually winter at this site versus those passing through to

another wintering site) and what is the year-to-year fidelity of birds at this site? (2)

Population structure: What proportion of the population remains in preferred habitat and

what proportion must leave each day? What proportion of diurnal migrants establishes

daytime foraging defended areas and home ranges, versus the proportion of non-

territorial floaters? What are the physical characteristics, ages and sexes of birds

employing each strategy (despots, core-area foragers and floaters)? These phenomena

should be addressed and tracked as they develop from September through April.

The second set of questions relates to how the breeding origin of the diurnal

migrant species may be related to the arrival and departure dates of individuals in their

wintering habitat and how these factors may affect social structure on the wintering

grounds: (1) Do dominants (despots) come from distinct breeding populations versus

those of subdominants? (2) Is there an advantage to early arrival on the wintering

grounds? (3) If these migrants arrive from distinct populations, do they employ the “leap

frog” wherein strategy wherein higher latitude birds precede and overfly lower lat itude

birds, or do they employ a chain migration strategy? The third set of questions relates

specifically to possible intraspecific and interspecific competition: (1) Competition

between migrant and resident Yellow Warblers, which are morphometrically distinct, are

mangrove-foraging individuals predominantly territorial nesting residents or are they

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predominantly migrants? Are Prairie Warblers communal night-roosters and are they

pushed out of the mangroves each morning by larger, more aggressive species (e.g.,

Northern Waterthrushes and Yellow Warblers)? Future studies should be conducted at

JBNEER and elsewhere to address these questions.

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Appendices

Appendix One

Canopy Arthropod Sampling

Table A1.01. Median arthropod prey items collected via branch clipping in

mangrove forest and secondary dry forest between March 26 and April

11, 2011.

___________________________________________________________

Mangrove Forest Secondary Dry Forest

Dates Median Range N Median Range N

___________________________________________________________

March 26 3.00 9.00 7 - - -

March 28 3.50 7.00 6 - - -

March 30 - - - 16.00 21.00 6

April 7 3.00 47.00 16 - - -

April 8 5.00 0 1 4.50 17.00 12

April 11 - - - 4.50 11.00 14

___________________________________________________________

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Table A1.02. Median arthropod biomass (mg) per branch, collected by

branch clipping between secondary forest and mangrove forest obtained

between March 26 and April 11, 2011.

___________________________________________________________

Mangrove Forest Secondary Forest

Dates Median Range N Median Range N

___________________________________________________________

March 26 3.00 4.60 7 - - -

March 28 2.30 5.70 6 - - -

March 30 - - - 13.05 18.50 6

April 7 2.85 24.40 16 - - -

April 8 2.30 0 1 6.85 27.20 12

April 11 - - - 1.15 5.00 14

____________________________________________________________

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Table A1.03. Median arthropod biomass in mg / g of branch clipped by

branch clipping technique between secondary forest and mangrove forest,

between March 26 and April 11, 2011.

___________________________________________________________

Mangrove Forest Secondary Forest

Dates Median Range N Median Range N

___________________________________________________________

March 26 9.10 13.50 7 - - -

March 28 8.50 17.10 6 - - -

March 30 - - - 15.60 37.60 6

April 7 6.65 121.00 16 - - -

April 8 5.70 0 1 19.45 65.20 12

April 11 - - - 1.60 4.80 14

___________________________________________________________

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Table. A1.04. Branch clipping arthropod samples taken in secondary dry forest, in the dry season, between March 26, 2011

and April 11, 2011. Arthropods samples were quantified and classified to order and also biomass (mg) was determined.

______________________________________________________________________________________________________________

Sample Tree* Date Order Number of Total number of Biomass in Total mass mg of arthropods

Number Prey Items Prey Items (mg) (mg) per g of foliage

______________________________________________________________________________________________________________

1 L.leucocephala March 26 Orthoptera 1 1.1

Collembolla 1 2 1.9 3.0 10.4

2 L.leucocephala Homoptera 8 0.3

Blattaria 1 0.7

Orthoptera 2 11 0.6 1.6 4.2

3 L.leucocephala Odonata 2 3.4

Diptera 1 3 0.7 4.1 17.0

4 P. dulce Homoptera 1 2.2

Diptera 1 1.6

Thysanoptera 1 3 1.7 5.5 17.1

5 P. dulce Aranae 3 1.5

Homoptera 1 4 1.1 2.6 6.3

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6 L.leucocephala Hymenoptera 2 2 0.9 0.9 3.6

7 L.leucocephala Aranae 3 3 3.1 3.1 9.1

8 P. dulce March 28 Aranae 1 1.2

Isoptera 5 2.2

Orthoptera 1 2.9

Odonata 1 8 0.6 6.9 22

9 L.leucocephala Coleoptera 1 0.7

Hymenoptera 1 2 0.5 1.2 4.9

10 L.leucocephala Hemiptera 1 1.1

Odonata 1 0.2

Homoptera 2 0.3

Larvae 1 5 0.4 2 7

11 G. herbaceum Hymenoptera 1 1 2.3 2.3 10

12 G. herbaceum Homoptera 2 1.1

Diptera 1 3 0.6 1.7 7

13 L.leucocephala Odonata 1 2.1

Coleoptera 2 1.7

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Aranae 1 4 0.5 4.3 14.8

14 P. dulce April, 7 Hemiptera 6 23.9

Aranae 1 7 1.2 25.1 123.1

15 L.leucocephala Aranae 2 2 2.9 2.9 9.9

16 L.leucocephala Aranae 1 0.8

Isoptera 2 2.3

Coleoptera 1 4 1.1 4.2 14.9

17 L.leucocephala Homoptera 1 2.3

Coleoptera 1 0.9

Larvae 2 2.1

Acari 1 5 0.7 6 22.4

18 L. leucocephala Coleoptera 1 1 0.1 0.1 0.5

19 L. leucocephala Coleoptero 1 0.1

Hymenoptera 1 2 0.4 0.5 2.6

20 P. dulce Coleoptera 5 2.2

Aranae 1 1.3

Collembolla 1 7 0.1 3.6 6.7

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21 L. leucocephala Mantodea 1 2.1

Aranae 2 1.7

Homoptera 1 4 0.8 4.6 14.3

22 G. herbaceum Isoptera 1 1.7

Homoptera 45 4

Aranae 2 48 2.2 7.9 23.1

23 L.leucocephala Hymenoptera 1 1 1.2 1.2 2.9

24 L leucocephala Homoptera 1 1 0.7 0.7 2.1

25 L leucocephala Mantodea 1 5.6

Aranae 1 2 1.5 7.1 28.9

26 L.leucocephala Aranae 1 1 1.8 1.8 6.6

27 L leucocephala Hymenopera 1 0.6

Aranae 2 3 1.9 2.5 8.2

28 L.leucocephala Coleoptera 1 0.9

Aranae 1 1.3

Homoptera 1 3 1.1 3.3 6.3

29 L. leucocephala Thysanoptera 1 0.4

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Hymenoptera 1 0.5

Aranae 2 4 2.3 3.2 5.8

30 L. leucocephala Aranae 3 2.2

Coleoptera 2 5 0.1 2.3 5.7

___________________________________________________________________________________________________

* Trees - complete scientific names: Leucaena leucocephala, Pithcellobium dulce, Gossypium herbaceum.

Table A1.05. Branch clipping arthropod samples taken in mangrove forest, in the dry season, between March 4, 2011 and

April 11, 2011. Arthropods samples were quantified and classified to order and also biomass (mg) was determined.

______________________________________________________________________________________________________________

Sample Tree* Date Order Number of Total number of Biomass in Total mass mg of arthropods

Number Prey Items Prey Items (mg) (mg) per g of foliage

______________________________________________________________________________________________________________

1 A. germinans March 4 Homoptera 16 12.5

Aranae 1 4.5

Orthoptera 3 20 1.1 18.1 22.70

2 A. germinans Homoptera 17 20.4

Hymenoptera 6 23 0.2 20.6 43.49

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3 A. germinans Aranae 1 1.9

Diptera 1 2 1.9 3.8 6.79

4 A. germinans Homoptera 11 11 2.1 2.1 5.90

5 A. germinans Homoptera 18 14.5

Aranae 2 20 1.2 15.7 13.29

6 A. germinans Homoptera 11 10.2

Hymenoptera 1 12 0.2 10.4 17.89

7 A. germinans April 8 Homoptera 5 5 19.8 19.8 33.32

8 L racemosa Diptera 1 7.7

Aranae 1 2 1.1 8.8 13.75

9 A. germinans Aranae 2 2 1.1 1.1 2.71

10 R. mangle Hymenoptera 1 1.9

Coleoptera 2 2

Neuroptera 1 4 0.6 4.5 9.37

11 A. germinans Aranae 1 1.3

Homoptera 7 8.4

Odonata 1 9 5.7 15.4 24.70

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12 A. germinans Coleoptera 1 3.1

Hymenoptera 2 3 0.1 3.2 21.15

13 A. germinans Homoptera 7 6.2

Odonata 1 8 3.1 9.3 14.51

14 A. germinans Homoptera 14 4.9

Larvae 1 0.7

Aranae 2 0.4

Coleoptera 1 1.7

Hymenoptera 1 19 0.4 8.1 17.69

15 A. germinans Hymenoptera 1 12.9

Aranae 1 1.7

Orthoptera 2 4 12.8 27.4 26.32

16 A. germinans Hemiptera 1 1.7

Coleoptera 1 0.1

Aranae 3 5 0.2 2 2.19

17 A. germinans Homoptera 4 3.1

Aranae 3 2.5

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Larvae 3 10 0 5.6 6.56

18 L. racemosa Aranae 1 0.1

Larvae 1 2 0.1 0.2 0.42

19 R. mangle April 11 Homoptera 5 5 0.4 0.4 0.36

20 A. germinans Hymenoptera 7 0.2

Homoptero 3 0.3

Collembolla 2 0.1

Aranae 1 13 0.3 0.9 2.09

21 T. populnea Diptera 1 0.1

Coleoptera 1 0.1

Aranae 2 0.5

Hymenoptera 1 5 0.3 1 1.08

22 R. mangle Diptera 4 4 0.2 0.2 0.20

23 R. mangle Aranae 2 0.3

Orthoptera 2 4 0.4 0.7 0.89

24 R. mangle Aranae 1 0.2

Orthoptera 2 3 0.1 0.3 0.41

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25 R. mangle Aranae 1 0.1

Hymenoptera 3 1.1

Orthoptera 3 7 0.1 1.3 3.56

26 A. germinans Odonata 2 1.3

Coleoptera 2 0.1

Homoptero 1 0.2

Hymenoptera 2 7 3.7 5.3 5.44

27 A. germinans Aranae 1 0.3

Hymenoptera 1 2 1.6 1.9 0.99

28 A. germinans Diptera 1 0.6

Orthoptera 1 0.4

Hymenoptera 2 2.1

Orthoptera 1 1.1

Aranae 2 7 0.5 4.7 5.06

29 L. leucocephala Mecoptera 1 0.5

Dictioctera 1 0.1

Coleoptera 1 0.6

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Orthoptera 1 0

Larvae 1 5 1.3 2.5 2.56

30 R. mangle Aranae 1 0.1

Orthoptera 1 2 1.6 1.7 2.09

31 R. mangle Plecoptera 1 2.9

Orthoptera 1 0.1

Homoptero 1 3 0.3 3.3 4.89

32 T populnea Orthoptera 1 0.1

Homoptero 1 0.1

Hemiptera 1 3 0.1 0.3 0.57

________________________________________________________________________________________________________

* Trees complete scientific names: Avicennia germinans, Laguncularia racemosa, Rhizophora mangle, Thespesia populnea,

Leucaena leucocephala.

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Appendix Two

Ground Arthropods Sampling

Table A2.01. Median arthropod prey items per 5 min scan of 0.25 m2

quadrat, obtained in mangrove forest and secondary dry forest, between

March 26 and April 11, 2011.

___________________________________________________________

Mangrove Forest Secondary Dry Forest

Dates Median Range N Median Range N

___________________________________________________________

February 9 15 11 9 - - -

February16 - - - 11 4 2

February 20 - - - 25 0 1

February 26 - - - 16.5 9 2

March 6 8.5 7 2 72.5 65 4

March 13 - - - 20 36 7

March 14 3 10 5 - - -

March 16 5 5 4 - - -

April 14 8 8 9 - - -

April 16 11 12 7 - - -

April 20 - - - 14.5 10 8

April 21 - - - 15 16 8

____________________________________________________________

88

86

86

Table A2.02. Median arthropod biomass (mg) per 5 in scan of 0.25 m2

quadrat, obtained in mangrove forest and secondary forest, between

March 26 and April 11, 2011.

___________________________________________________________

Mangrove Forest Secondary Dry Forest

Dates Median Range N Median Range N

___________________________________________________________

February 9 3.9 6.4 9 - - -

February16 - - - 3.4 1.2 2

February 20 - - - 6.5 0 1

February 26 - - - 45.15 8.9 2

March 6 3.5 0.7 2 12.6 16.5 4

March 13 - - - 7.9 10.9 7

March 14 1.9 4.1 5 - - -

March 16 2.1 3.9 4 - - -

April 14 3.6 3.5 9 - - -

April 16 4.4 8.9 7 - - -

April 20 - - - 6.95 14.4 8

April 21 - - - 10.4 37.1 8

____________________________________________________________

87

87

Table A2.03. Ground arthropod samples taken in mangrove forest, in the dry season, between February 9, 2011

and April 16, 2011, using a 5 min scan of each 0.25 m2 quadrat. Arthropods samples were quantified and classified

to order and also biomass (mg) was determined. Samples were taken from (BM) black and (RM) red mangrove.

____________________________________________________________________________________________

Sample Habitat Date Order Number of Total number of Biomass in (mg) Total mass (mg)

Number Prey Items Prey Items

______________________________________________________________________________________________________

1 BM Feb 9, 2011 Aranae 2 1.8

Collembolla 1 0.2

Hymenoptera 7 10 1.9 3.9

2 BM Aranae 4 1.5

Isopoda 1 5 0.2 1.7

3 BM Isopoda 1 0.2

Coleoptera 2 0.9

Orthoptera 2 2.3

Aranae 9 15 4.7 8.1

4 RM March 6, 2011 Aranae 5 5 3.1 3.1

5 BM Aranae 4 1.3

88

88

Hymenoptera 8 12 2.5 3.8

6 BM March 16, 2011 Hymenoptera 5 5 0.11 0.11

7 BM Aranae 3 2.4

Hymenoptera 3 6 0.9 3.3

8 BM Aranae 1 1.2

Hymenoptera 4 5 1.3 2.5

9 BM Aranae 3 3 1.7 1.7

10 BM March 14, 2011 Pseudoscorpions 2 0.4

Hymenoptera 8 2.3

Aranae 1 0.8

Collembolla 1 12 0.3 3.8

11 BM Orthoptera 1 0.9

Lepidoptera 1 1.3

Collembolla 2 1.8

Hymenoptera (wasp) 1 5 0.4 4.4

12 RM Isopoda 1 0.1

Hymenoptera 1 2 0.2 0.3

89

89

13 RM Aranae 1 0.5

Hymenoptera 1 2 0.3 0.8

14 RM Aranae 2 1.6

Isopoda 1 3 0.3 1.9

15 RM Pseudoscorpions 1 1 0.5 0.5

16 RM April 14, 2011 Aranae 2 0.8

Hymenoptera 2 0.7

Psocoptera 3 0.4

Collembolla 3 1.2

Coleoptera 3 13 2.7 5.8

17 RM Pseudoscorpions 3 0.7

Hymenoptera 6 1.7

Aranae 1 0.7

Collembolla 2 12 0.5 3.6

18 RM Orthoptera 2 1.8

Lepidoptera 1 1.2

Collembolla 2 1.5

90

90

Hymenoptera 1 6 0.4 4.9

19 RM Isopoda 1 0.2

Aranae 3 1.7

Hymenoptera 2 6 0.5 2.4

20 BM Hymenoptera 5 1.3

Aranae 4 9 2.5 3.8

21 RM Aranae 3 1.7

Hymenoptera 2 5 0.6 2.3

22 BM Aranae 5 4.1

Hymenoptera 4 9 1.4 5.5

23 RM Hymenoptera 4 1.3

Aranae 2 1.6

Isopoda 2 8 0.6 3.5

24 BM April 16,2011 Aranae 12 6.3

Hymenoptera 9 21 3.2 9.5

25 BM Aranae 3 2.6

Collembolla 1 0.3

91

91

Hymenoptera 8 12 1.9 4.8

26 BM Aranae 4 1.8

Hymenoptera 5 2.4

Isopoda 1 10 0.2 4.4

27 BM Isopoda 2 0.4

Coleoptera 3 1.8

Psocoptera 2 7 0.3 2.5

28 BM Orthoptera 3 3.6

Aranae 15 7.3

Pseudoscorpion 1 19 0.5 11.4

29 RM Aranae 3 1.6

Hymenoptera 5 2.4

Psocoptera 3 11 0.4 4.4

30 RM Collembolla 3 1.2

Coleoptera 4 4.1

Aranae 2 9 1.2 6.5

___________________________________________________________________________________________

92

92

Table A2.04. Ground arthropod samples obtained in secondary dry forest, in the dry season, between February 9,

2011 to April 16, 2011 using 5 min scans of 0.25 m2 quadrats. Arthropods samples were quantified and classified at

order level and also biomass (mg) was determined.

Sample Number Date Order Number Total Prey Items Biomass in (mg) Total mass (mg)

Prey Items

______________________________________________________________________________________________________

1 Feb 16, 2011 Collembolla 1 0.4

Hymenoptera 6 1

Aranae 1 0.5

Diptera 1 9 0.9 2.8

2 Feb 20, 2011 Collembolla 3 2.6

Hymenoptera 1 0.2

Acari 20 2.2

Diptera 1 25 1.5 6.5

3 Feb 26, 2011 Hymenoptera 7 1.5

93

93

Aranae 7 2.9

Orthoptera 1 1.4

Collembolla 4 3.6

Diplopodo 1 31.2

Larva 1 21 0.1 40.7

4 Diplopoda 2 46.9

Aranae 2 1.6

Orthoptera 2 0.5

Hymenoptera 5 0.2

Acari 1 12 0.4 49.6

5 March 6, 2011 Acari 73 2.5

Hymenoptera 10 0.3

Diptera 5 3.1

Collembolla 3 1.6

Millipeda 1 2.6

Homoptera 2 94 0.9 11

6 Hymenoptera 18 3.4

94

94

Acari 36 3.1

Millipeda 1 2.8

Collembolla 15 4.3

Dictioctera 1 71 0.5 14.1

7 Orthoptera 1 1.6

Hymenoptera 7 1.2

Acari 15 1.8

Collembolla 3 1.7

Diptera 3 29 1.4 7.7

8 Aranae 5 4.8

Acari 33 3.8

Collembolla 16 7.1

Hymenoptera 5 2.6

Isopoda 12 4.5

Hemiptera 1 0.7

Coleoptera 1 0.6

Larva 1 74 0.1 24.2

95

95

9 March 13, 2011 Aranae 3 1.4

Hymenoptera 9 1.9

Diptera 1 13 0.7 4

10 Orthoptera 10 2.3

Hymenoptera 2 0.5

Aranae 1 13 2 4.8

11 Hymenoptera 8 4.8

Aranae 1 0.8

Orthoptera 1 0.6

Acari 6 16 0.3 6.5

12 Hymenoptera 12 0.6

Aranae 8 4.9

Orthoptera 2 0.4

Larva 5 27 0.5 6.4

13 Hymenoptera 5 0.9

Aranae 11 6.6

Diptera 2 3

96

96

Collembolla 2 20 1.2 11.7

14 Hymenoptera 7 1.6

Aranae 8 8.8

Hemiptera 2 0.2

Orthoptera 2 19 3.8 14.4

15 Hymenoptera 2 0.4

Hemitera 7 0.1

Orthoptera 4 2.6

Collembola 3 1.5

Acari 33 49 3.3 7.9

16 Hemiptera 1 0.8

Aranae 2 1.2

Orthoptera 5 5.7

Larva 1 0.1

Hymenoptera 19 4.5

Aranae 3 3.1

Thysanoptera 1 32 0.3 15.7

97

97

17 April 20, 2011 Aranae 3 3.6

Hymenoptera 6 1.7

Collembolla 2 11 1.6 6.9

18 Hymenoptera 8 1.8

Diptera 2 0.8

Dictioctera 1 0.4

Coleoptera 2 13 1.1 4.1

19 Acari 15 14.4

Hymenoptera 4 19 2.1 16.5

20 Hymenoptera 6 2.9

Aranae 4 4.3

Orthoptera 2 2.5

Collembola 4 16 2.9 12.6

21 Diptera 3 2.1

Collembolla 4 2.1

Millipeda 1 2.3

Homoptera 1 9 0.5 7

98

98

22 Hymenoptera 5 2.8

Collembolla 2 0.7

Acari 9 2.1

Orthoptera 2 1.5

Hemiptera 1 19 0.3 7.4

23 Aranae 7 3.0

Diplopoda 1 26.1

Diptera 1 9 0.8 29.9

24 April 21, 2011 Collembolla 10 4.3

Diptera 2 22 0.3 4.6

25 Hymenoptera 9 10

Diplopoda 1 31.2

Collembolla 4 3.6

Aranae 7 21 2.9 47.7

26 Hymenoptera 7 1.5

Orthoptera 2 0.6

Diptera 3 2.3

99

99

Collembolla 2 0.7

Aranae 5 19 3.9 39.2

27 Hymenoptera 7 2.4

Diptera 2 1.6

Collembolla 1 19 0.4 9.9

28 Hymenoptera 4 1

Collembolla 3 0.9

Acari 6 5.9

Hymenoptera 3 0.5

Millipeda 1 17 2.3 10.6

29 Orthoptera 4 2.7

Hemiptera 5 9 0.1 2.8

30 Hymenoptera 3 3 0.6 0.6

______________________________________________________________________________________________________

100

10

0