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ROBERTS BANK TERMINAL 2

TECHNICAL DATA REPORT

Coastal Birds

Migratory Connectivity of Western Sandpipers using

the Fraser River Estuary Prepared for: Port Metro Vancouver 100 The Pointe, 999 Canada Place Vancouver, BC V6C 3T4 Prepared by: Hemmera Envirochem Inc. 18

th Floor, 4730 Kingsway

Burnaby, BC V5H 0C6 File: 302-042.02 December 2014

Port Metro Vancouver Hemmera RBT2 – WESA Migratory Connectivity December 2014

Technical Report / Technical Data Report Disclaimer

The Canadian Environmental Assessment Agency determined the scope of the proposed Roberts Bank

Terminal 2 Project (RBT2 or the Project) and the scope of the assessment in the Final Environmental

Impact Statement Guidelines (EISG) issued January 7, 2014. The scope of the Project includes the

project components and physical activities to be considered in the environmental assessment. The scope

of the assessment includes the factors to be considered and the scope of those factors. The

Environmental Impact Statement (EIS) has been prepared in accordance with the scope of the Project

and the scope of the assessment specified in the EISG. For each component of the natural or human

environment considered in the EIS, the geographic scope of the assessment depends on the extent of

potential effects.

At the time supporting technical studies were initiated in 2011, with the objective of ensuring adequate

information would be available to inform the environmental assessment of the Project, neither the scope

of the Project nor the scope of the assessment had been determined.

Therefore, the scope of supporting studies may include physical activities that are not included in the

scope of the Project as determined by the Agency. Similarly, the scope of supporting studies may also

include spatial areas that are not expected to be affected by the Project.

This out-of-scope information is included in the Technical Report (TR)/Technical Data Report (TDR) for

each study, but may not be considered in the assessment of potential effects of the Project unless

relevant for understanding the context of those effects or to assessing potential cumulative effects.

https://www.ceaa-acee.gc.ca/050/documents/p80054/97463E.pdf

https://www.ceaa-acee.gc.ca/050/documents/p80054/97463E.pdf

Port Metro Vancouver Hemmera RBT2 – WESA Migratory Connectivity - i - December 2014

EXECUTIVE SUMMARY

Port Metro Vancouver (PMV) is assessing the potential to develop the Roberts Bank Terminal 2 Project

(RBT2 or the Project), a new three-berth marine terminal at Roberts Bank in Delta, B.C. The Project is

part of PMV’s Container Capacity Improvement Program (CCIP), a long-term strategy to deliver projects

to meet anticipated growth in demand for container capacity to 2030.

Hemmera has been retained by PMV to undertake environmental studies related to the Project. This

technical data report documents the Migratory Connectivity of Western Sandpipers using the Fraser River

Estuary Study. The Fraser River estuary (FRE) is one of the most important stopover sites for western

sandpipers (Calidris mauri) during their northward migration to breeding areas. The study’s objective was

to identify the major wintering regions from which sandpipers in the FRE originate, and whether there was

any temporal or spatial variation in how birds from different wintering areas use the FRE during the

migration period.

Elemental analysis of stable isotopes and trace elements in western sandpiper feathers was used to

identify the winter origins of migrants. Sandpipers were captured at 18 sites across their wintering range

and an elemental winter base map was created using three stable isotopes (δ2H, δ

13C, and δ

15N) and 15

trace elements (B, Ba, Ca, Cu, Fe, Hg, Mn, Na, Ni, P, Pb, Rb, S, U, and V). Feathers from migrant

sandpipers were collected from three different sites (Sturgeon Bank, Roberts Bank, and Boundary Bay)

within the FRE during the spring 2012 migration. Linear discriminant function analysis was used to assign

migrants to five potential areas of winter origin (western North America, Baja California, the Gulf of

California, the Atlantic coast, and South America).

Although, western sandpipers using the FRE during the northward migration came from all areas of the

wintering range, the majority of migrants originated from western North America. Many migrants also

originated from the Gulf of California region of Sinaloa and Sonora provinces in western Mexico, and

eastern areas along the Atlantic and Caribbean coasts. Few migrants originated from either the Baja

Peninsula or South America, despite the relatively large proportion (nearly a third) of the global population

that winters in these two areas.

Results indicate that passage of migrants from different wintering areas through the FRE is separated

temporally, but less so spatially. Birds from western North America tended to migrate earlier in the season

during the middle of the migration period (April 24 to 30), while a large proportion of later migrants (May 1

to 6) was comprised of birds from the Gulf of California and the Atlantic coast. While birds from different

wintering areas differed in when they passed through the FRE, with the exception of slightly more use of

Sturgeon Bank by western North America female sandpipers, site use by birds of different winter origin

did not differ between Roberts Bank, Sturgeon Bank, and Boundary Bay.

Port Metro Vancouver Hemmera RBT2 – WESA Migratory Connectivity - ii - December 2014

TABLE OF CONTENTS

EXECUTIVE SUMMARY ............................................................................................................................... I

1.0 INTRODUCTION .............................................................................................................................. 1

1.1 PROJECT BACKGROUND ........................................................................................................ 1

1.2 WESA MIGRATORY CONNECTIVITY OVERVIEW ....................................................................... 1

2.0 REVIEW OF AVAILABLE LITERATURE AND DATA ................................................................... 2

3.0 METHODS ....................................................................................................................................... 4

3.1 STUDY AREA ......................................................................................................................... 4

3.2 TEMPORAL SCOPE................................................................................................................. 4

3.3 STUDY METHODS .................................................................................................................. 4

3.3.1 Western Sandpiper Feather and Morphometric Data Collection ........................... 4

3.3.2 Isotope and Trace Element Analysis ..................................................................... 7

3.4 DATA ANALYSIS ..................................................................................................................... 8

3.4.1 Data Preparation .................................................................................................... 8

3.4.2 Wintering Regions .................................................................................................. 9

3.4.3 Cross-validation with Known-origin Data ............................................................... 9

3.4.4 Assignment of Migrants to Region of Winter Origin ............................................... 9

3.4.5 Confidence in Assignments ................................................................................. 10

3.4.6 Goodness of Fit Tests .......................................................................................... 10

3.4.7 Temporal and Spatial Variation in Winter Origins ................................................ 10

4.0 RESULTS ...................................................................................................................................... 11

4.1 CROSS-VALIDATION ............................................................................................................. 11

4.2 WINTER ORIGINS OF MIGRANT WESA .................................................................................. 11

4.3 TEMPORAL VARIATION ......................................................................................................... 14

4.4 SPATIAL VARIATION ............................................................................................................. 15

5.0 DISCUSSION ................................................................................................................................. 16

5.1 DISCUSSION OF KEY FINDINGS ............................................................................................. 16

5.2 DATA GAPS AND LIMITATIONS .............................................................................................. 17

6.0 CLOSURE ...................................................................................................................................... 18

7.0 REFERENCES ............................................................................................................................... 19

8.0 STATEMENT OF LIMITATIONS ................................................................................................... 23

Port Metro Vancouver Hemmera RBT2 – WESA Migratory Connectivity - iii - December 2014

List of Tables

Table 1 WESA Migratory Connectivity Study Components and Major Objectives .......................... 1

Table 2 Sample Sizes According to Capture Date across the Migration Period ............................. 1

Table 3 Sampling Locations, Regional Groups, and Sample Sizes for All Winter Sites ................. 2

Table 4 The Relative Abundance of Western Sandpipers Across Wintering Regions as a

Proportion of the Total Population ...................................................................................... 3

List of Figures

Figure 1 Study Area and Study Sites (Sturgeon Bank, Roberts Bank, and Boundary Bay) where

Western Sandpipers were Captured for Feather Sampling ................................................ 5

Figure 2 Map of All Winter Sites where Feather Samples were Collected from Western Sandpipers

(modified from Franks et al. 2012) ...................................................................................... 6

Figure 3 Results of the LDA Cross-validation of Winter Data ......................................................... 12

Figure 4 Distribution of Winter Origins of Male and Female Migrants in the FRE .......................... 13

Figure 5 The Distribution of Winter Origins of Male (Dark Bars) and Female (Light Bars) Migrants

During the Early, Mid, and Late Migration Periods ........................................................... 14

Figure 6 The Distribution of Winter Origins of Male (Dark Bars) and Female (Light Bars) Migrants

at the Three Sampled Mudflats in the Study Area ............................................................ 15

List of Appendices

Appendix A Tables

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Port Metro Vancouver Hemmera RBT2 – WESA Migratory Connectivity - 1 - December 2014

1.0 INTRODUCTION

This section provides an overview of the study, including project background and study components and

major objectives.

1.1 PROJECT BACKGROUND

The Roberts Bank Terminal 2 Project (RBT2 or Project) is a proposed new three-berth marine terminal at

Roberts Bank in Delta, B.C. that could provide 2.4 million TEUs (twenty-foot equivalent unit containers) of

additional container capacity annually. The project is part of Port Metro Vancouver’s Container Capacity

Improvement Program, a long-term strategy to deliver projects to meet anticipated growth in demand for

container capacity to 2030. Port Metro Vancouver (PMV) has retained Hemmera to undertake

environmental studies to inform a future effects assessment for the Project. This technical data report

describes the results of the western sandpiper (Calidris mauri, hereafter referred to as WESA) migratory

connectivity study.

1.2 WESA MIGRATORY CONNECTIVITY OVERVIEW

A review of available information and the state of knowledge concerning WESA migratory connectivity

was completed to identify key data gaps and areas of uncertainty within the general RBT2 area. This

technical data report describes the study findings for key components identified from this gap analysis.

Study components, major objectives and a brief overview are provided in Table 1.

Table 1 WESA Migratory Connectivity Study Components and Major Objectives

Component Major Objective Brief Overview

1) Identify winter origins of migratory WESA population using the study area

Identify the major wintering regions from which WESA in the study area originate

Determine the relative number of wintering regions represented by the WESA population in the study area

Stable isotope and trace element analyses of feathers of winter-caught WESA will be used to create an elemental ’map‘ of the WESA wintering range

Migrant WESA will be assigned to an area of winter origin based on the stable isotope and trace element values of their feathers


2.0 REVIEW OF AVAILABLE LITERATURE AND DATA

Shorebirds rely on estuaries and mudflats along the B.C. coast, using them as stopover areas where they

can forage on intertidal invertebrates and replenish fat stores on their migration between breeding and

wintering sites. Western sandpipers are small migratory shorebirds that breed in western Alaska and far-

eastern Siberia (Wilson 1994). They winter predominantly on the Pacific coast between California and

Peru, and in smaller numbers on the Atlantic coast between South Carolina and Venezuela. Northward

migration primarily follows the Pacific coast, with major stopover areas supporting over 100,000 birds

including San Francisco Bay, CA, Grays Harbor, WA, the Fraser River estuary, B.C., and in Alaska, the

Stikine and Copper River deltas, Kachemak Bay and Cook Inlet (Iverson et al. 1996, Bishop and Warnock

1998, Page et al. 1999, Bishop et al. 2000, Butler and Lemon 2001, Buchanan 2005, Alaska Shorebird

Group 2008, Johnson et al. 2008, Fernández et al. 2010). The Fraser River estuary (FRE) is the

most important stopover site in Canada for western sandpipers on their northward migration (Fernández

et al. 2010).

Predicting the consequences of environmental change and developing conservation strategies for

migratory shorebird populations requires knowing how those populations are spatially connected between

different periods of the annual cycle – that is, the degree of migratory connectivity, or the degree to which

individuals in a population co-occur in different seasons (Webster et al. 2002, Marra et al. 2006, Norris and

Marra 2007). To better understand WESA spring migration and ultimately population demographics,

detailed and robust baseline information needs to be collected to determine the overwintering origin of

migrant birds. Currently, the extent to which WESA using the FRE originate from one, few, or many

wintering locations is uncertain.

Stable isotope analysis of inert tissues such as feathers has been widely used to identify the geographic

origins of migratory animals (Hobson and Wassenaar 1997, Clegg et al. 2003, Kelly et al. 2005, Bensch

et al. 2006, Jones et al. 2008, Miller et al. 2011, Franks et al. 2012). This method relies on spatial

variation in stable isotopes such as carbon (δ13

C), nitrogen (δ15

N), and hydrogen (δ2H) in the

environment, which are then reflected in animal tissues grown in that environment (e.g. feathers), acting

as a location fingerprint. WESA molt and grow new feathers on the overwintering grounds, incorporating

local stable isotopes into their feathers via the food they eat. Less commonly used to estimate migratory

connectivity is trace element analysis. The concentrations of many elements vary in the environment

according to local geology and other abiotic and anthropogenic (e.g. industrial waste) factors. Elements

are incorporated in trace concentrations in tissues grown in these environments via the same process as

stable isotopes. Previous studies using trace element analysis indicate that the addition of trace elements

to stable isotope analysis can be a powerful tool in identifying geographic origins (Szép et al. 2003, 2009).

Stable isotopes provide information on geographic origins at a very broad scale, and their utility can be

hindered by weak spatial patterns in variability. Trace elements can improve the large scale resolution of

stable isotope analysis, and provide information on origins at quite small spatial scales (Norris et al. 2007,

Poesel et al. 2008).


Previous work using stable isotopes to estimate patterns of migratory connectivity of migrant WESA in the

FRE indicates that WESA originate from across the wintering range (Franks et al. 2012). Low certainty in

these estimates and a lack of information on whether: 1) WESA from different wintering areas use

different areas of the FRE; and 2) birds from different areas migrate at different times during the spring

migration season, mean that a more in depth study with the ability to detect winter origins with greater

certainty is required.

Prior research has shown that trace element analysis is an effective method to assign birds to wintering

locations with a high degree of spatial accuracy (Norris et al. 2007). To test the ability of trace element

analysis to correctly classify WESA to wintering locations, Norris et al. (2007) analysed the concentrations

of 42 trace elements within feathers collected from 26 WESA from five wintering sites ranging from San

Francisco Bay to the Bay of Panama. Using results from the trace element analysis, Norris et al. (2007)

were able to correctly assign all WESA to their proper overwintering site.


3.0 METHODS

Descriptions of the study spatial and temporal scopes, and study and data analysis methods are

provided below.

3.1 STUDY AREA

The study area includes the intertidal mudflats in proximity to the FRE and is comprised of three study

sites: Roberts Bank, Sturgeon Bank, and Boundary Bay (Figure 1). These sites were selected because

WESA using the Pacific Flyway (i.e., the area along the Pacific coast, west of the Rocky Mountains)

frequent intertidal mudflats at coastal estuaries during migration. Roberts Bank, Sturgeon Bank, and

Boundary Bay were selected to investigate differences in use between the three sites and to put Roberts

Bank in an appropriate context.

3.2 TEMPORAL SCOPE

Migratory connectivity studies were intended to capture current-day (baseline) information on the

wintering origins of migratory WESA in the FRE. Because it is not known whether WESA from different

wintering areas migrate at different times over the course of the spring migration season, samples were

collected at three intervals (early migration, mid-migration, late migration) throughout the 2012 spring

migration season to address this potential temporal variability (April 18 to May 6, Appendix A: Table 2).

Early migration was defined as April 18 to 22, mid-migration as April 23 to 30, and late migration as May 1

to 6. Dates chosen for migration intervals were based on prior knowledge of patterns in migrant WESA

abundance in the FRE (Butler et al. 1987, Butler and Lemon 2001).

3.3 STUDY METHODS

Descriptions of the field sampling methodology and isotope and trace element analysis are provided

below.

3.3.1 Western Sandpiper Feather and Morphometric Data Collection

Western sandpiper feathers were collected at 18 wintering sites between November and February of

2008-09 (Franks et al. 2012, Figure 2, Appendix A: Table 3), and at three migration stopover sites in the

FRE during the spring of 2012. Sandpipers were captured using mist nets and banded. Morphometric

measurements (flattened wing chord, exposed culmen, full tarsus length, weight), sex, and age were

recorded. Sex was determined using culmen length measurement (Page and Fearis 1971) and birds were

aged in the field as either adult (hatched at least two summers ago) or young (hatched the previous

summer) by examining the edging colour of inner median coverts and the degree of flight feather wear

(Prater et al. 1977, Franks et al. 2009). To avoid excessively impeding flight capacity of sandpipers, an

inner primary feather was collected. Western sandpipers generally shed and grow the first five inner

primaries simultaneously, so 1st primaries on each wing were collected for stable isotope and trace

element analysis.


Figure 1 Study Area and Study Sites (Sturgeon Bank, Roberts Bank, and Boundary Bay) where Western Sandpipers were Captured for Feather Sampling

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Figure 2 Map of All Winter Sites where Feather Samples were Collected from Western Sandpipers (modified from Franks et al. 2012)

Note: Circled sites indicate regional groups (see Appendix A: Table 3).


3.3.2 Isotope and Trace Element Analysis

3.3.2.1 Isotope Analysis

Feathers were analysed at the Queen’s Facility for Isotope Research in Kingston, Ontario. Feathers were

washed in a 1:1 chloroform:methanol solution and allowed to equilibrate with the local atmosphere for

72 hours. Approximately one-quarter of an individual sample (half of one primary feather) was allocated to

isotope analysis, while the remaining sample (half plus one full feather) was allocated to trace element

analysis. Samples for δ2H analysis (0.1 - 0.2 mg) were loaded into silver capsules and placed in an oven

at 100°C for 24 hours to remove surface water. Capsules were then crushed and loaded into a reduction

furnace (Finnigan TC/EA) at 1450oC and introduced on-line to an isotope ratio mass spectrometer

(DeltaPlus

XP). Samples for δ13

C and δ15

N analysis (0.2 – 0.4 mg) were loaded into tin capsules, crushed,

converted to gas in an oxidation/reduction furnace (Costech ECS 4010 elemental analyser), and

introduced on-line to an isotope ratio mass spectrometer (DeltaPlus

XP). Isotope analyses of winter feather

samples were conducted between October 2009 and January 2010, while migration samples were

analysed between December 2012 and January 2013. Stable isotope ratios are reported in delta (δ)

notation in per mil (‰) units, where δX = ((Rsample/Rstandard) - 1) x 1000. For hydrogen (δ2H), R =

2H/

1H and

Rstandard is Vienna standard mean ocean water; for carbon (δ13

C), R = 13

C/12

C and Rstandard is PeeDee

belemnite; for nitrogen (δ15

N), R = 15

N/14

N and Rstandard is air. For every 17 hydrogen samples, three

laboratory standards (mean ± SD) were run: brucite from the University of Michigan (--95 ± 6 ‰, n = 137,

Georgia kaolinite clay (-62 ± 5 ‰, n = 163), and two in-house feather standards from a captive blue-

fronted amazon (Amazona aestiva) maintained on a constant diet (-85 ± 3 ‰, n = 60) and a double-

crested cormorant (Phalacrocorax auritus) (-67 ± 6 ‰, n = 5). For every 50 carbon/nitrogen samples,

three out of the following four laboratory standards in 2009 to 2010 (mean ± SD) were run: domestic

chicken (Gallus gallus) blood (δ13

C = -20.1 ± 0.3 ‰, δ15

N = 3.9 ± 0.3 ‰, n = 29), carbon standard ‘uc1’

(δ13

C = -25.4 ± 0.1 ‰, n = 21), carbon standard ‘q-c’ (δ13

C = -25.7 ± 0.1 ‰, n = 7), and nitrogen standard

silver nitrate ‘eil62’ (δ15

N = 16.8 ± 0.2 ‰, n = 4). In 2012 to 2013, the following standards were run for

every 50 carbon/nitrogen samples: cormorant feather (δ13

C = -16.3 ± 0.4 ‰, δ15

N = 13.9 ± 0.2 ‰, n = 6),

carbon standard NBS21 (δ13

C = -27.5 ± 0.2 ‰, n = 5), and nitrogen standard NIST8551 (δ15

N = 53.2 ±

0.3 ‰, n = 5).

Within each run, duplicates were run from the same individual and feather, which produced a difference

(mean ± SD) of 4.0 ± 3.1 ‰ (n = 141) for hydrogen samples, 0.35 ± 0.38 ‰ (n = 84) for carbon samples,

and 0.41 ± 0.47 ‰ (n = 84) for nitrogen samples.

3.3.2.2 Trace Element Analysis

Samples for trace element analysis were washed in deionised water in an ultrasonic bath for five minutes.

Water was decanted and samples were allowed to dry overnight. Samples were then weighed into

Savillex Teflon sample vials. Approximately 3 mL of 1X concentrated nitric acid was added to each vial,


and samples were left capped for 24 to 48 hours on a hotplate at 70°C to digest. Samples were then

removed from the hotplate and allowed to cool for one hour at room temperature. Approximately 0.5 mL

of hydrogen peroxide was added. Samples were left capped at room temperature for two hours, and then

placed on a hotplate at 70°C for three to four hours. Approximately 1 mL of 2% nitric acid with Indium was

added to samples. Indium is used as an internal standard to correct for instrumental and environmental

variations in signal. Samples were then diluted into sample tubes to 3-4 mg with 2% nitric acid with

Indium, and their weight recorded. Five procedural blanks and five laboratory standards (turkey feathers)

were included as controls.

Samples were analysed using a Thermo Scientific Element 2 XR, a high resolution instrument that can

measure elements at low (R=300), medium (R =4000), and high (R=10000) resolution. The Element 2

can measure down to very low concentrations (ppt to ppq levels), and up to approximately 500 ppb. Its

detectors measure count rates (in counts per second, or cps) and calibration solutions of known

concentrations were used to determine what intensity in cps corresponds to what concentration in a

sample. Calibration solutions used for the samples ranged from 50 ppt to 500 ppb. Samples were loaded

in an ESI SC-2 autosampler, self-aspirated using a teflon take-up tube, then passed through a teflon

nebuliser to convert samples into aerosol form, and introduced into the Ar plasma. Samples were then

ionised, and the resulting ion beam was shaped and focused and passed through resolution slits, before

passing through a magnetic field which made the ions deviate based on their mass over their charge. The

ion beam then passed through an electrostatic analyser (ESA) and further lenses and resolution slits to

further resolve the beam before it hit the detector. The data were then undiluted, and lab staff checked

for detection limits and relative standard deviation. In total, 63 trace elements had concentrations above

detection limits for at least one sample (Al, As, Au, B, Ba, Be, Bi, Ca, Cd, Ce, Co, Cr, Cs, Cu, Dy, Er, Eu,

Fe, Ga, Gd, Ge, Hf, Hg, Ho, K, La, Li, Lu, Mg, Mn, Mo, Na, Nb, Nd, Ni, P, Pb, Pd, Pr, Pt, Rb, Re, S, Sb,

Sc, Se, Si, Sm, Sn, Sr, Tb, Te, Th, Ti, Tl, Tm, U, V, W, Y, Yb, Zn, Zr).

3.4 DATA ANALYSIS

Linear discriminant analysis (LDA) was used to classify samples from the FRE to a region of winter origin.

LDA is a form of discriminant function analysis (DFA), a multivariate classification method that extracts a

linear combination of explanatory variables that differentiates between groups, or classes, of observations

by maximizing the among-group relative to the within-group variance (Zuur et al. 2007). All analyses were

conducted in the R statistical environment using the MASS package for linear discriminant analysis

(Venables and Ripley 2002, R Development Core Team 2011).

3.4.1 Data Preparation

Adult WESA grow their flight feathers on the wintering grounds, while juveniles grow their flight feathers at

Arctic latitudes and retain them through their first three migrations; therefore, stable isotope and trace

element analysis can only reliably be used to identify the winter origins of adult migrants. Previous work


suggests that some individuals identified as adult by plumage characteristics have feathers with Arctic-

type stable isotope values (Franks et al. 2009, 2012; Yohannes et al. 2012). These so-called ‘cryptic

juveniles’ (n = 5) were identified and removed from the migrant dataset using the same method as Franks

et al. (2012).

Explanatory variables used to discriminate birds from different wintering regions included the following

stable isotope and trace element variables: δ2H, δ

13C, δ

15N, B, Ba, Ca, Cu, Fe, Hg, Mn, Na, Ni, P, Pb, Rb,

S, U, and V. Of the 63 measured trace elements, 20 had concentrations that were above detection limit

(DL) for all samples. As it is impossible to differentiate zero values from readings below detection limit,

only elements where all samples recorded concentrations above DL were used in the analysis. In

addition, pairwise scatterplots and a correlation matrix showed that some trace element variables were

strongly collinear (r > 0.7). In order to meet assumptions of DFA, one variable from strongly collinear pairs

was removed. Trace element values were log-transformed to meet assumptions of normally distributed

data. Following transformation, two values in the winter dataset (one from Panama and one from Alto

Golfo) were identified as extreme outliers in the trace element U, and were removed from subsequent

analyses.

3.4.2 Wintering Regions

The wintering range was divided into five broad regions (Figure 2) that are geographically and

biologically relevant in relation to WESA distribution and life history patterns: western North America, Baja

California, the Gulf of California region of western Mexico, Central and South America (called South

America), and the Atlantic and Caribbean (called Atlantic).

3.4.3 Cross-validation with Known-origin Data

In order to test the ability of LDA to accurately classify migrants to different winter regions, its ability to

correctly classify known-origin (winter) individuals was first assessed using LDA with leave-one-out cross-

validation. In leave-one-out cross-validation, a linear discriminant function was built using all winter birds

except one. The group classification of this individual was then predicted by the discriminant function.

This two-step process was repeated for all winter individuals. The rate of correct assignment (the

proportion of individuals from a winter region correctly assigned to that region by leave-one-out cross-

validation) could then be assessed.

3.4.4 Assignment of Migrants to Region of Winter Origin

Migrants were assigned to a region of winter origin by predicting their group membership using the

discriminant function created from the winter dataset. LDA classification of unknown-origin observations

includes a posterior probability of group membership. Determining the group classification of an individual

based solely on stable isotope and trace element values assumes an equal prior probability of origin among

all regions. A more appropriate set of prior probabilities reflects the winter distribution of WESA across their


non-breeding range (relative abundance). Winter relative abundance was estimated as in Franks et al.

(2012) by gathering population estimates for WESA from local survey data, published atlases, and the

literature for use in estimating relative abundance (Spaans 1979; Morrison and Ross 1989, 2009;

Fernández et al. 1998; Morrison et al. 1998, 2001; Page et al. 1999; Sociedad Ornitológica

Puertorriqueña Inc. pers. comm., see Appendix A: Table 4). Because male and female WESA exhibit

latitudinal segregation on the wintering grounds, the relative abundance of males and females in each winter

region was estimated separately using the proportion of each sex captured in Franks et al. (2012) and in a

study conducted by Nebel et al. (2002).

3.4.5 Confidence in Assignments

Confidence in assignments was assessed by examining a frequency distribution of the posterior

probability of group membership. Under a null hypothesis that any population of sandpipers will comprise

a completely random distribution from all wintering locations, a 20% probability of originating from each

wintering region would be expected. A high proportion of individuals assigned with very high probabilities

of group membership (e.g. > 90%) indicates stronger certainty in assignments, while a high proportion of

individuals assigned with lower probabilities of group membership (e.g. < 50%) is indicative of a high

uncertainty in assignments.

3.4.6 Goodness of Fit Tests

The degree of WESA migratory connectivity between the FRE and wintering areas was quantified with a

chi-square goodness of fit test using Monte Carlo resampling methods (with 2000 replicates) to simulate

the sampling distribution of the test statistic due to small expected frequencies. The observed frequency

distribution of winter origins for each breeding and migrant population was compared against the null

hypothesis—that is, the frequency distribution expected based on patterns of sex-specific winter relative

abundance patterns.

3.4.7 Temporal and Spatial Variation in Winter Origins

A chi-square goodness of fit test with Monte Carlo simulation (2000 replicates) was used to determine

whether the distribution of WESA from different wintering areas differed between migration periods, and

whether WESA from different wintering areas tended to use specific mudflats in the FRE.


4.0 RESULTS

4.1 CROSS-VALIDATION

Seventy-eight percent (84/107) of wintering individuals were correctly assigned back to their region of

origin. Western North America had the highest rate of correct assignment at 88% (14/16), followed by the

Gulf of California at 86% (30/35), the Atlantic at 76% (19/25), Baja California at 68% (13/19), and South

America at 67% (8/12, Figure 3). In each winter region, the majority of individuals correctly assigned to

their region of origin had a high probability (> 90%) of group membership, while those individuals who

were incorrectly assigned often had lower probabilities (< 70%) of group membership (Figure 3). This

relatively high degree of confidence in the assignments produced by the cross-validation step indicates

that stable isotopes and trace elements together perform well in accurately classifying sandpipers to their

region of winter origin.

4.2 WINTER ORIGINS OF MIGRANT WESA

The distribution of winter origins of migrants in the FRE differed significantly from that expected based on

patterns of winter relative abundance (Figure 4), both for males (2

= 42.31, p = 0.0005) and females

(2 = 228.48, p = 0.0005). Overall, birds from western North America made up the greatest proportion of

migrants (males = 53%; females = 50%), followed by the Gulf of California (males = 35%; females = 27%)

and the Atlantic (males = 10%; females = 19%). Baja California and South America were represented by

only a few individuals.

Confidence in assignment of migrant birds to winter regions was greater than 90% for over 50% (69/128)

of individuals and was greater than 70% for 79% (101/128) of individuals. All but a few individuals

(121/128) were classified to a region of winter origin with greater than 50% probability.


Figure 3 Results of the LDA Cross-validation of Winter Data

Note: Large bar plots with dark grey bars show the proportion of individuals from a winter region classified to each of the five winter regions. Small histograms

with light grey bars show the frequency distribution of the probability of group membership for correctly assigned individuals. Small histograms with white bars show the frequency distribution of the probability of group membership for incorrectly assigned individuals.


Figure 4 Distribution of Winter Origins of Male and Female Migrants in the FRE

Note: Inset bar plots show the expected distribution based on sex-specific patterns of winter relative

abundance (the null hypothesis). Histograms show the frequency distribution of the probability with which birds were assigned to a winter region.


4.3 TEMPORAL VARIATION

Migrants from different wintering areas tended to pass through the FRE at different times during the

northward migration period (Figure 5). Migrants from western North America predominated during the

peak of the migration, with some individuals from the Gulf of California and the Atlantic present during this

period. Later in migration, more migrants from the Gulf of California and the Atlantic were present. The

distribution of males from different winter regions differed somewhat significantly between the early, mid,

and late migration periods (2

= 13.40, p = 0.056), while the distribution of females from different

winter regions showed a tendency towards being different during the three migration periods (2

= 18.87,

p = 0.07).

Figure 5 The Distribution of Winter Origins of Male (Dark Bars) and Female (Light Bars) Migrants During the Early, Mid, and Late Migration Periods

Note: No females were captured during the early migration period. Inset bar plots show the expected distribution

based on sex-specific patterns of winter relative abundance (the null hypothesis).


4.4 SPATIAL VARIATION

Birds from different wintering areas distributed themselves similarly across the three mudflats in the FRE

during the spring migration (Figure 6), although females at Sturgeon Bank tended to have a slightly

greater representation from western North America, while at Roberts Bank and Boundary Bay, the winter

origins of birds were more evenly distributed between western North America, the Gulf of California, and

the Atlantic (2

= 12.03, p = 0.16). The distribution of winter origins of males at Boundary Bay, Roberts

Bank, and Sturgeon Bank did not differ significantly (2 = 2.75, p = 0.93).

Figure 6 The Distribution of Winter Origins of Male (Dark Bars) and Female (Light Bars) Migrants at the Three Sampled Mudflats in the Study Area

Note: Inset bar plots show the expected distribution based on sex-specific patterns of winter relative abundance (the

null hypothesis).


5.0 DISCUSSION

A discussion of the major results arising from the WESA migratory connectivity study and data gaps are

provided below.

5.1 DISCUSSION OF KEY FINDINGS

Western sandpipers using the FRE during the northward migration came from all areas of the wintering

range; however, the results of this study suggest that the FRE is a particularly important stopover site for

migrants from western North America. Of the estimated 600,000 western sandpipers stopping over at just

the Roberts Bank mudflat during the spring migration (M. Drever, Environment Canada, unpublished

data), this study suggests that just over 50% originated from western North America overwintering sites,

an area comprising the Pacific coast from northern California to the very northern part of the Baja

Peninsula. This represents a proportion of males and females from western North America overwintering

sites that is 2 and 10 times greater, respectively, than the proportions expected in the FRE based on

the number of male and female birds wintering in western North America (Figure 4 and Appendix A:

Table 4). Many migrants also originated from the Gulf of California region of Sinaloa and Sonora

provinces in western Mexico, and eastern areas along the Atlantic and Caribbean coasts. Surprisingly few

migrants originated from the Baja Peninsula or South America, despite the relatively large proportion

(nearly a third) of the global population that winters in these two areas.

The results of the study also indicate that migrants from different wintering areas are separated

temporally, but less so spatially, on stopover in the FRE. Birds from western North America tended to

migrate earlier in the season during the middle of the migration period (April 24 to 30), while a larger

proportion of later migrants (May 1 to 6) was comprised of birds from the Gulf of California and the

Atlantic coast. This finding suggests that during the peak period, migration of birds from western North

America is likely at its peak while the numbers of individuals from more distant wintering sites is beginning

to increase, peaking slightly later. Despite a lack of consistent supporting evidence, the arrival time

hypothesis suggests that birds wintering closer to their breeding sites may migrate and arrive on the

breeding grounds earlier (Ketterson and Nolan 1976, Myers 1981). Previous work with WESA has

suggested that birds wintering at more southern sites may simply depart wintering areas earlier and thus

catch up with more northerly populations (Fernández et al. 2001). The results of this study provide the

first evidence supporting this hypothesis in WESA, with individuals wintering at more distant sites further

south and east passing through the FRE slightly later than those wintering closer. While birds from

different wintering areas differed in when they passed through the FRE, they did not differ in which of the

three main mudflats in the study area they used, although Sturgeon Bank was slightly more heavily used

by females from western North America. Currently, there is no other evidence to suggest WESA from

different parts of the wintering range differ in their spatial usage of the FRE.


Combining trace element with stable isotope analysis provided much greater certainty in assignments to

wintering region compared to using stable isotopes alone, particularly during the cross-validation step.

When using both stable isotopes and trace elements to assign known-origin birds, 72% of individuals

were correctly assigned with a probability greater than 70% to their region of origin. Using stable isotopes

alone, only 49% of individuals were correctly assigned with greater than 70% probability (Franks et al.

2012). Adding trace elements to stable isotope analysis not only improved the quality of the elemental

base map of the WESA wintering range, it also increased the certainty with which migrants could be

assigned to a wintering region: 53% of migrants could be assigned with greater than 90% probability to a

wintering area using both stable isotopes and trace elements, while only 45% could be assigned at this

level of confidence using stable isotopes alone (Franks et al. 2012).

5.2 DATA GAPS AND LIMITATIONS

While every attempt was made to sample evenly over the duration of the northward migration, few birds

were captured during the early part of the spring migration compared to the mid and late periods. If

individuals from different wintering areas differ in their timing of migration, as suggested by the results,

the study may have failed to capture the migration of birds from certain parts of the wintering range. Birds

from the Baja Peninsula and South America were under-represented on stopover in the FRE, despite

forming a large proportion of the global population, and it is possible that birds from these areas migrated

earliest in the season; however, the study’s findings suggest that birds wintering at more distant wintering

sites (Mexico and the Atlantic) migrate slightly later than those wintering closer (western North America).

Birds from under-represented wintering areas may instead stop at other sites along the northward

migration route, bypassing the FRE. Alternatively, birds wintering in these areas may in fact grow their

feathers at other locations, masking their true winter origins and leading to them being erroneously

classified as wintering elsewhere by elemental analysis. While many WESA moult and grow new feathers

every year as soon as they arrive on their wintering grounds, previous work at a migration stopover site

suggests that about 50% of adult WESA may in fact use a ‘moult-migration’ strategy, completing their

flight feather moult at stopover sites during the southward migration before continuing on to wintering

sites (S. Franks unpublished data). The findings of this study thus potentially over-represent the number

of birds originating from certain areas while under-representing the true origins of other individuals.

The study also assumes that there is little inter-annual variation in stable isotope and trace element

values of winter-grown WESA feathers. Little is known about the degree of inter-annual variation in

elemental values, and so any potential variation could not be modelled and accounted for in the statistical

analysis. Because migrant feathers were sampled in a different year than winter feathers, the study’s

findings must be taken as a conservative estimate of the winter origins of migrant sandpipers.


6.0 CLOSURE

Major authors and reviewers of this technical data report are listed below, along with their signatures.

Report prepared by: Hemmera Envirochem Inc.

Samantha Franks, PhD Biologist Report peer reviewed by: Hemmera Envirochem Inc.

James Rourke, M.Sc. R.P.Bio. Coastal Birds Discipline Lead Report peer reviewed by: Simon Fraser University

Ron Ydenberg, PhD Professor, Centre for Wildlife Ecology Director


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8.0 STATEMENT OF LIMITATIONS

This report was prepared by Hemmera Envirochem Inc. (“Hemmera”), based on fieldwork conducted by

Hemmera, for the sole benefit and exclusive use of Port Metro Vancouver. The material in it reflects

Hemmera’s best judgment in light of the information available to it at the time of preparing this Report.

Any use that a third party makes of this Report, or any reliance on or decision made based on it, is the

responsibility of such third parties. Hemmera accepts no responsibility for damages, if any, suffered by

any third party as a result of decisions made or actions taken based on this Report.

Hemmera has performed the work as described above and made the findings and conclusions set out in

this Report in a manner consistent with the level of care and skill normally exercised by members of the

environmental science profession practicing under similar conditions at the time the work was performed.

This Report represents a reasonable review of the information available to Hemmera within the

established Scope, work schedule and budgetary constraints. The conclusions and recommendations

contained in this Report are based upon applicable legislation existing at the time the Report was drafted.

Any changes in the legislation may alter the conclusions and/or recommendations contained in the

Report. Regulatory implications discussed in this Report were based on the applicable legislation existing

at the time this Report was written.

In preparing this Report, Hemmera has relied in good faith on information provided by others as noted in

this Report, and has assumed that the information provided by those individuals is both factual and

accurate. Hemmera accepts no responsibility for any deficiency, misstatement or inaccuracy in this

Report resulting from the information provided by those individuals.

APPENDIX A

Tables

Port Metro Vancouver APPENDIX A Hemmera RBT2 – WESA Migratory Connectivity - 1 - December 2014

Table 2 Sample Sizes According to Capture Date across the Migration Period

Site

Migration period

Date Total Sturgeon Bank Roberts Bank Boundary Bay

Early 8

19 Apr 1

22 Apr 7

Mid 63

24 Apr 11 11

26 Apr 18 3

27 Apr 22

Late 65

2 May 18 7

4 May 4

5 May 9

6 May 4 21


Table 3 Sampling Locations, Regional Groups, and Sample Sizes for All Winter Sites

Region Site Latitude (degrees) Longitude (degrees) n

Atlantic

Cuba, Rio Maximo 21.73 -77.52 2

Cuba, Tunas de Zaza 21.64 -79.54 0

Puerto Rico 17.97 -67.20 5

Yucatán 21.60 -87.98 10

Florida 30.10 -84.15 1

South Carolina 33.18 -79.22 4

Texas 26.32 -97.35 3

Baja Guerrero Negro 27.58 -114.10 9

La Paz 24.10 -110.37 10

Gulf of California

Alto Golfo 32.00 -114.83 10

Bahía Santa María 24.94 -107.91 9

Caimanero 22.99 -106.04 10

Ensenada Pabellones 24.45 -107.47 7

South America Ecuador -2.20 -80.73 3

Panamá 9.00 -79.45 10

Western North America

Humboldt 40.83 -124.08 6

Punta Banda 31.75 -116.63 1

San Francisco 38.10 -122.40 9


Table 4 The Relative Abundance of Western Sandpipers Across Wintering Regions as a Proportion of the Total Population

Region Overall

Abundance Male

Abundance Female

Abundance Source

Western North America

0.1427 0.2174 0.0581 Page et al. (1999)

Baja 0.1432 0.1823 0.0990 Fernández et al. (1998)

Gulf of California 0.3787 0.3966 0.3583 Morrison and Ross (2009)

South America 0.1700 0.0881 0.2626 Spaans (1979), Morrison and Ross (1989), Morrison et al. (1998)

Atlantic 0.1655 0.1156 0.2219 Morrison et al. (2001), Morrison and Ross (2009), Sociedad Ornitológica Puertorriqueña (pers. comm.)

Note: Sex ratio data used to determine male and female abundance was obtained from this study and Nebel et al. (2002). Population estimate data was gathered from local survey data, published atlases, and available literature and generated an estimated world population of 1,292,550.

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