rainfall influence on lizard activity patterns in a piñon-juniper woodland vivien enriquez

Rainfall Influence on Lizard Activity Patterns in a Piñon-

Juniper Woodland

Vivien Enriquez Beloit College Summer 2013

Introduction

Focal species

1) Chihuahuan Spotted Whiptail (Aspidoscelis exsanguis)2) New Mexico Whiptail (Aspidoscelis neomexicana)

Natural History

1) Native to the North American southwest 2) All female species 3) Active foragers 4) Active in the early morning and late afternoon

Aspidoscelis exsanguis

Aspidoscelis neomexicana

Introduction

• Sensitive to changes in habitat structure and function

• Altered whiptail abundance in response to climate change/drought stress

2011 Precipitation and lizard abundance

May 27th-August 9th

Introduction

Red = rainfall plotsGreen = drought plots Blue = weekly precipitation

Grah: Ryan, 2011

Introduction

• Rainfall pulses impact lizard abundance and activity

• Using this data to form new questions about what drives lizard behavior

• Using activity time budgets to illustrate daily behavior and habitat use

Introduction

Questions:

1) How does long term artificial drought and rainfall addition influence lizard behavior and habitat use?

MethodsResearch took place at the Sevilleta National Wildlife Refuge

New Mexico

Rainfall Manipulation Experiment, Piñon-Juniper Woodland, Los Piños Mountains

Methods

Treatment 6 Total

Drought 11 observations

Rainfall 11 observations

Methods

30 minute surveys per plot, 2 times a week

• Start at 8:30 a.m.

• Drought and rainfall treatment plots are surveyed at every visit.

• Various plots are substituted for others throughout the week.

Behavioral observation and recording: 12 minute observational period, 22 individuals

• Videos recorded and then analyzed

• Individual behaviors timed (in seconds) and categorized

• Behaviors and habitats organized in a template

• Activity time budget calculated

Methods

Behavior & Habitat Codes:

BA - basking OH - open habitat

AF - active foraging SH - shaded habitat

o searchingo diggingo scratching

WA - walking

PC - prey capture

CL - climbing

Methods

Lizard ID: 0913.ASPEXS.PJ6.22

Activity Time Budgets: a measurement of time spent on each behavior.

• Total time of each activity divided by the total amount of time spent observing (in seconds), then multiplied by 100.

Methods

Behavior AF AF BA BA CL In Plot Out Plot

Habitat OH SH OH SH OH AF AF

Time (s) 20 5 40 65

Drought:

Rainfall:

ResultsBasking

Active foraging

ResultsDrought Treatments

ID: 0836.ASPEXS.PJ1.6

AF (SH) AF (OH) BA (OH) BA (SH) WA (OH) PC (OH)

6.9% 48.06% 24.24% 11.58% 8.3% .71%

AF (OH)

AF (SH)

BA (OH)

BA (SH)

WA (OH)

PC (OH)

Results Rainfall Plots

0936.ASPEXS.PJ4.8

AF (SH)

AF (OH)

BA (SH)

WA (OH)

WA (SH)

PC (SH)

AF (SH) AF (OH) BA (SH) WA (OH) WA (SH) PC (SH)

44.8% 14.44% 20.34% 2.9% 8.6% 8.6%

Results Active-Foraging by Treatment (Aspidoscelis exsanguis)

Active-Foraging in shade Active-Foraging in open habitat

Kruskal-Wallis TestChi-Square 8.9219

Chi-Square 1.6694DF 1

DF 1Prob>Chisq 0.0028 Prob>Chisq 0.1963

Results Basking by Treatment (Aspidoscelis exsanguis)

Basking in shade Basking in open habitat

Kruskal-Wallis TestChi-Square 2.9413

Chi-Square 1.2172DF 1

DF 1Prob>Chisq 0.0863 Prob>Chisq 0.2699

Discussion

Question: How does long term artificial drought and rainfall addition influence lizard behavior and habitat use?o Affects the amount of time lizards spend

performing certain behaviors in the shade vs. open habitat

o Promotes different common behaviors depending on which treatment the lizard is located in

Discussion• Future directions: project replication after rainfall

manipulation experiment ends.

- Other factors: vegetation cover/health, soil quality, prey abundance

1) Will we see similar results?

2) If drought landscape recovers, will lizard behavior adapt?

Acknowledgements

I would like to thank: Mentor - Mason Ryan

Elizabeth GallagherREU Program - Amaris Swann and

studentsSevilleta National Wildlife Refuge

Questions?