__________________

Breeding bird diversity, density, nesting success and nest predators

in the Olak region of the Teshekpuk Lake Special Area – 2007

Annual report

A report prepared by Joseph Liebezeit & Steve Zack

Wildlife Conservation Society

Pacific West Program

718 SW Alder Street, Suite 210

Portland, OR 97205

For

The North Slope Borough, U.S. Fish and Wildlife Service (Arctic NWR), and the Bureau of

Land Management

December 2007

Photo: S. Zack

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Executive summary

The main objective of this report is to summarize annual results from the 2007 field season at

the Teshekpuk Lake – Olak study site in the Teshekpuk Lake Special Area (TLSA) of the

National Petroleum Reserve (NPR-A). We report pertinent nesting information including

breeding bird abundance and diversity, nesting success, nest density and nest initiation dates.

We also assess potential nest predator abundance and summarize other factors that may impact

nest predation rates including lemming abundance, nest concealment, habitat type, snow cover,

and temperature. Finally, we compare the 2007 results from Teshekpuk to that of 2005 and 2006

and to that of a nearby study site at the Prudhoe Bay Oilfield.

In 2007, WCS continued the third year of this study conducting field work on 16 10-ha study

plots near the SE shore of Teshekpuk Lake. We discovered and monitored 191 nests of 16

species from 11 June to 16 July. Lapland Longspurs, Pectoral Sandpipers, Semipalmated

Sandpipers, and Red Phalaropes accounted for the majority (65%) of those found. Among all

species, 100 nests successfully hatched/fledged, 70 failed, and 21 nests were of unknown fate.

Nest predation was the most important cause of nest failure (90%). Other sources of nest failure

included abandonment and predation due to observers.

Program MARK constant survivorship model (Mayfield) estimates of nesting success ranged

from 29 to 71% (n ≥ 10) and were relatively high for most species sampled (>50% for 6 of 8

species) compared to other sites and years. Overall nest density was 100.1 nests / km2,

noticeably lower than at Teshekpuk in 2006 (132.4 nests / km2) but high compared to the

Prudhoe Bay site this year (59.8 nests / km2). Species-specific nest densities were variable but

within the range of those found at other studies on the North Slope.

Lemming abundance fell from relatively high levels observed in 2006 to low levels similar to

those observed in 2005. Cyclical lemming population booms are a known phenomenon in the

Arctic and 2006 was the first apparent “high lemming” year in this region in at least six years.

Correspondingly, Pomarine Jaegers and Snowy Owls were rarely detected and, unlike in 2006,

did not nest in the study area in 2007. Overall eight species of potential nest predators were

detected during timed surveys with the most common being Parasitic Jaegers, Long-tailed

Jaegers and Glaucous Gulls. “Human-adapted” predators (i.e. Glaucous Gulls, Common Ravens,

and arctic fox) were detected more frequently at the Prudhoe Bay site compared to Teshekpuk,

while jaegers were abundant at both sites.

The nesting success results from 2005-07 at both study sites suggest that the nest

survivorship at Teshekpuk is robust whether in a lemming boom year or not. On the other hand,

nest survivorship evidence at Prudhoe Bay suggests higher predation rates in low lemming years,

but comparable nest survivorship to Teshekpuk in high lemming years.

Nests were found in nine of 15 landform types (“habitat” types). As in previous year, most

nests were located in Unit 7 (strangmoor and disjunct polygon rims) and Unit 2 (High-center

polygons, center-trough relief <0.5m) landform types. We did not detect any advantage in

nesting success due to vegetative concealment for the most common nesting species, although

Lapland Longspurs had higher nest concealment than shorebird species.

Snow melt and subsequent tundra exposure has occurred successively earlier at Teshekpuk

from 2005 to 2007 (by up to 4 days) and has occurred even earlier at Prudhoe Bay during this

same period. Correspondingly, nest initiation dates for most species were earlier at Teshekpuk

this year compared to previous years and earlier at Prudhoe Bay for most species. Despite earlier

snow melt in 2007, air temperature at the site was substantially lower than the previous year

when snow melt was completed ~ 1 day later. This contradictory result may be explained by the

lower snow depths observed at Teshekpuk this year.

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TABLE OF CONTENTS

Executive summary..................................................................................................................... 2

LIST OF FIGURES .................................................................................................................... 4

LIST OF TABLES...................................................................................................................... 5

LIST OF APPENDICES............................................................................................................. 5

INTRODUCTION & BACKGROUND..................................................................................... 6

OBJECTIVES............................................................................................................................. 7

STUDY AREA ........................................................................................................................... 7

METHODS ................................................................................................................................. 8

Study site delineation, plot establishment and setup .................................................................. 8

Nest discovery, nest monitoring, and fate assessment................................................................ 8

Potential predator abundance and lemming activity................................................................. 10

Landform, concealment, snow cover and temperature assessment .......................................... 10

Data analysis ............................................................................................................................. 10

RESULTS ................................................................................................................................. 11

Relative abundance and diversity of avifauna .......................................................................... 11

Nesting success, nest age, nest density, and nest initiation ...................................................... 12

Nest predator abundance........................................................................................................... 13

Microtine activity and abundance............................................................................................. 14

Landform, vegetation, and snow cover/temperature assessment.............................................. 14

Comparisons with results at the nearby Prudhoe Bay Oil field ................................................ 14

DISCUSSION........................................................................................................................... 15

ACKNOWLEDGEMENTS...................................................................................................... 18

LITERATURE CITED ............................................................................................................. 18

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LIST OF FIGURES

Figure 1. WCS study plots at the Teshekpuk Lake - Olak study site, Teshekpuk Lake Special

Area, NPR-A, Alaska, 2007.................................................................................................. 24

Figure 2. Pictures from the 2007 field season at the Teshekpuk Lake – Olak study site,

Teshekpuk Lake Special Area, National Petroleum Reserve – Alaska. ............................... 25

Figure 3. Nest densities (nests / km2) of the six common species that nested on study plots from

2005-07 at the Teshekpuk Lake - Olak study site, Teshekpuk Lake Special Area, NPR-A,

Alaska. .................................................................................................................................. 26

Figure 4. Daily survival rate summary (± 1SE) for the three most common nesters at both the

Teshekpuk Lake – Olak study site, Teshekpuk Lake Special Area, NPR-A and the Prudhoe

Bay Oilfield study site, Alaska, 2005-07. ............................................................................. 26

Figure 5. Daily survival rate summary (± 1SE) for combined “shorebirds” and “shorebirds +

passerines” at both the Teshekpuk Lake – Olak study site, Teshekpuk Lake Special Area,

NPR-A and the Prudhoe Bay Oilfield study site, Alaska, 2005-07. ..................................... 27

Figure 6. Mean nest initiation dates (± 1SE) for the three most common breeding birds from

2005 to 2007 at the Teshekpuk Lake – Olak study site, Teshekpuk Lake Special Area, NPR-

A, Alaska............................................................................................................................... 27

Figure 7. Average number of key potential nest predators detected per 30-min. period (± 1 SE)

during timed surveys at the Teshekpuk Lake – Olak study site, Teshekpuk Lake Special

Area, NPR-A, and the Prudhoe Bay Oilfield study site Alaska, 2005-07. ........................... 28

Figure 8. The average number of lemmings (sp.) and Pomarine Jaegers detected per 30-min

survey period (± 1SE) at the Teshekpuk Lake - Olak study site, Teshekpuk Lake Special

Area, NPR-A, and the Prudhoe Bay Oilfield study site, 2005-07. ....................................... 28

Figure 9. Number of nests found in each landform type within study plots at the Teshekpuk Lake

- Olak study site, Teshekpuk Lake Special Area, NPR-A, Alaska. ...................................... 29

Figure 10. Average snow cover for survey dates on all plot locations at the Teshekpuk Lake –

Olak study site, Teshekpuk Lake Special Area, NPR-A, Alaska and corresponding log-

transformed linear regressions for 2005-07. ......................................................................... 29

Figure 11. The average temperature (°C ± 1SE) during the core of the breeding season (20 May

to 30 June) at the Teshekpuk Lake – Olak study site, Teshekpuk Lake Special Area, NPR-

A, Alaska............................................................................................................................... 30

Figure 12. Overall nest densities (nests / km2) in 2005-07 at both the Teshekpuk Lake - Olak

study site, Teshekpuk Lake Special Area, NPR-A, and the Prudhoe Bay Oilfield study site,

Alaska. .................................................................................................................................. 30

Figure 13. Mean nest initiation dates (± 1SE) for the most common breeding birds (N > 10) in

2007 at the Teshekpuk Lake – Olak study site, Teshekpuk Lake Special Area, NPR-A and

the Prudhoe Bay Oilfield study site, Alaska. ........................................................................ 31

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LIST OF TABLES

Table 1. Bird diversity and relative abundance at the Teshekpuk Lake - Olak study site,

Teshekpuk Lake Special Area, NPR-A, Alaska, 2007. ........................................................ 32

Table 2. Number of discovered nests and nest density for each species from the Teshekpuk Lake

- Olak study site, Teshekpuk Lake Special Area, NPR-A, Alaska, 2007. ............................ 33

Table 3. Summary of Mayfield nesting success & daily survival rate estimates of tundra-breeding

birds at the Teshekpuk Lake - Olak study site, Teshekpuk Lake Special Area, NPR-A,

Alaska, 2007. ........................................................................................................................ 34

Table 4. Nest initiation dates of tundra-nesting birds at Teshekpuk Lake - Olak study site,

Teshekpuk Lake Special Area, NPR-A, Alaska, 2007 ......................................................... 35

Table 5. Average number (mean ± 1 SE / 30 min. count) of key potential nest predators recorded

during predator surveys for four time periods on and near study plots at the Teshekpuk Lake

- Olak study site, Teshekpuk Lake Special Area, NPR-A, Alaska, 2007. ............................ 36

Table 6. Summary of nest concealment for the most common species (N > 10) at the Teshekpuk

Lake - Olak study site, Teshekpuk Lake Special Area, NPR-A, Alaska, 2007. ................... 37

LIST OF APPENDICES

Appendix 1. Greater White-fronted Goose nesting success at the Teshekpuk Lake – Olak Study

site, Teshekpuk Lake Special Area, NPR-A, Alaska, 2007.................................................. 38

Appendix 2. Redpoll nest site habitat characteristics in 2007 ..................................................... 39

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INTRODUCTION & BACKGROUND

The North Slope of Alaska, encompassing the vast region north of the Brooks Range,

supports a significant proportion of western hemispheric breeding shorebirds and waterfowl

populations. In Alaska, 37 species of shorebirds are regular breeders, representing almost 20%

of all shorebird species worldwide (Alaska Shorebird Working Group 2000). In addition,

important populations of waterfowl and other waterbirds breed and stage in this region (Derksen

et al. 1979, Earnst et al. 2005). The North Slope is also a region of intense public interest, partly

because only 5% of it is protected from human and industrial developments, and partly because it

serves as a biological baseline upon which to gauge effects of anthropogenic disturbance and

climate change.

The North Slope also contains significant oil reserves. Currently, the oil-drilling

infrastructure is concentrated in the central portion of the North Slope near the Arctic Ocean in

the Prudhoe Bay region. The impetus for expanding oil and gas exploration is high because of

waning production in existing North Slope oil fields, improvements in oil exploration

technology, and the perceived need for greater domestic oil production. Plans for expansion of

oil exploration into the National Petroleum Reserve – Alaska (NPR-A) are currently underway.

The NPR-A, at over 23 million acres, is the largest piece of public land in the United States.

Although the NPR-A was originally set aside for oil exploration, there is a strong mandate from

the Department of the Interior for “maximum protection” of the wildlife in this region.

Presently, large tracts of breeding habitat in the Alaskan arctic remain largely unaffected by

human-development suggesting that habitat loss/degradation may currently not be a major factor

affecting breeding birds in this area. However, other sources of human disturbance may directly

affect nesting birds on the North Slope, including impoundments, vehicle traffic/noise, pollution,

dust, and thermokarst (NAS 2003). The effect of these disturbances at the population level is

understudied and still speculative. Currently, there is growing concern that increases in human-

subsidized nest predator populations due to a positive response to human activity may negatively

affect breeding bird productivity in some areas of subarctic/arctic Alaska (Day 1998, NAS 2003,

Bowman et al. 2004) and that cumulative impacts from a number of threats may negatively

impact wildlife and create population sinks in areas of disturbance (NAS 2003).

Nest predation is reported to be a significant cause of nest failure for shorebirds (Helmers

and Gratto-Trevor 1996), waterfowl (Pamplin 1986), and passerines (Custer and Pitelka 1977) in

many locations within the Alaskan subarctic/arctic. Troy (1996) found that three shorebird

species in the Prudhoe Bay region had nesting densities that fluctuated synchronously despite

wintering in different regions. These trends were correlated with hatching success two years

previously. Because hatching success or failure is primarily determined by predation, this

relationship suggests that population regulation occurs on breeding grounds and is mediated

largely through nest predation.

Although evidence indicates increasing nest predator populations in areas of human

development, few studies have attempted to determine if the nesting success of tundra-nesters

may be adversely affected by these reported increases. Attempts to understand the relationship

between bird productivity and the predator population is confounded by spatial and temporal

variation in weather conditions, cyclical predator-prey relationships, habitat differences, and

other sources of human-disturbance. However, the need to investigate this issue with greater

effort is prompted by the recognition of the North Slope as an important breeding area for

migratory shorebird and waterfowl species, some of which are experiencing population declines

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(Howe et al. 1989, Morrison et al. 2006), and because human-development in this region is

increasing. In 2005, with the help of the North Slope Borough (NSB), we began on-the-ground research

near Olak in the Teshekpuk Lake Special Area (TLSA) of the NPR-A allowing us to begin to

understand the breeding biology of shorebirds in the TLSA. There is a paucity of such

information in this region, yet it is especially important to understand the potential impact to the

nesting birds because of future plans for oil development in the TLSA, a region which had been

previously delineated by the Bureau of Land Management (BLM) as a “Special Area”

particularly important for wildlife and subsistence hunting (BLM 1998). WCS has now worked

at this site for three field seasons collecting a robust data set focused on reproductive biology of

all tundra-nesting birds and nest predators in this important region.

OBJECTIVES

The main objective of this effort is to:

1. Collect and assess baseline data on the nesting biology of all avifauna in the TLSA

focusing on nesting bird diversity and abundance, nest density, and nesting success.

2. Assess general activity levels and presence of potential nest predators.

3. Measure other characteristics that may influence nesting success including habitat

type, vegetative concealment, temperature, snow melt, and lemming abundance.

These results will be compared to other sites along the arctic coastal plain to help assess the

relative importance of this region as a breeding ground for nesting birds. In this report we

compare some of the results with a nearby site in the Prudhoe Bay oilfield.

In addition to our main objectives we conducted two other side projects1:

1. Assist the North Slope Borough (NSB) in assessing the nesting success of Greater

white-fronted Geese at nests found incidentally throughout the study area.

2. Determine nest microsite habitat features at Common (Carduelis flammea) and

Hoary Redpoll (C. hornemanni) nests.

We believe the data we collect in this study will be valuable to other institutions (e.g.

NSB, BLM, Alaska Audubon, etc.) involved in assessing the wildlife value of this region.

STUDY AREA

The WCS study site at Teshekpuk Lake - Olak is roughly 6.5 km due S of the SE shore of

Teshekpuk Lake. The study site covers an area of approximately 49 km2. The NW corner of

the study area is at N 70º 27.619′; W 147º 11.679′, and the SE corner is at 70º 24.174′; W 147º

00.936′. Kealok Creek forms the western boundary of the study site. No other landmarks

clearly delineate the boundaries of the study site although Wyoming Creek cuts through the

study plots in the eastern portion of the study area (Fig. 1).

The study site is within the Arctic Coastal Plain zone of the North Slope which is

characterized by a mosaic of tundra with a gradient of dry, upland tundra, often with high

densities of cotton grass tussocks, to wet and emergent vegetation in the lower areas. Compared

to the WCS study sites in the Kuparuk and Prudhoe Bay oilfields, the topography at Olak has

noticeably more relief with some rolling hills and cliffs generally associated with the drainages.

The tundra wetland complex is dominated by numerous ponds and lakes created by the thaw-lake

1 These side projects are included in separate Appendices at the end of this report

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cycle (Walker et al. 1980). Microrelief is characterized by the presence of high and low

polygons, hummocks, tussocks, and strangmoor/disjuct polygon ridges.

METHODS

Study site delineation, plot establishment and setup

We defined the study site as a 7 x 7 km square region with our camp location (Fig. 2)

positioned centrally. The size of this area was chosen based on the logistics of our daily work

load and maximum distance we could realistically cover on foot to our study plots. Plot

locations were selected by randomly choosing a point within a grid of points spaced 500 m apart

in all cardinal directions across the defined study area. The first point chosen (omitting points in

water bodies) was used as the first plot location. Subsequent plots were placed systematically in

relation to the first plot location. Our plots are spatially clustered in groups of four for safety and

logistic reasons. All told, we established 16 10-ha plots (Fig. 1). To determine plot orientation,

we first selected a random compass bearing. If the randomly selected orientation resulted in

open water covering greater than 20% of the plot area, we selected another random orientation

until a more appropriate region was selected.

Plots 1-16 were established in 2005. In 2006, we discontinued monitoring plots 9 & 12 and

established two new plots (17 & 18) because we were unable to access the former plots due to a

flooded Wyoming Creek. With the addition of plots 17 & 18, all of our plots are now on the

same side of Wyoming Creek and are easily accessible.

ArcView GIS software was used to aid plot site delineation. We followed plot design

methodology developed by Troy (1996) establishing 10-ha (100 m x 1000 m) plots. Plots were

marked at 50-m intervals along centerline axes using 1.2-m wooden survey stakes; thereby

subdividing the 10-ha plots into 40 50-m x 50-m units. For recording nest locations and

landform type, each unit was further subdivided into four 25-m x 25-m quadrats. Plots were

established on the ground 5 – 8 June 2005. Plots 17 & 18 were established on 9 June 2006.

Nest discovery, nest monitoring, and fate assessment

We searched for nests from 11 June to 3 July 2007 from approximately 0800 to 1830 Alaska

Standard Time (AST). We used two techniques to discover nests: rope-dragging and single-

person nest searches. The rope-drag technique consists of two observers stretching a 50-m rope

from the plot center to the outer edge and slowly walking while dragging the rope on the ground,

covering the entire plot. When a bird flushes, observers stop long enough to find and mark the

nest. The single-person nest searches are conducted by one observer per plot walking “W”

transects within each plot grid during which attention to bird behavior leads observers to nest

locations (Troy 1996). To be consistent with field efforts at the Prudhoe Bay study site, plots

were searched systematically by alternating two rope-drag sessions with two single-person nest

searches (order: rope-drag, single-person, rope-drag, single-person) following a systematic

schedule as defined in the standardized field protocol (Liebezeit 2007).

All nests were marked with a plain wooden tongue depressor on which was written the

species, nest identification number and coordinates to the nest. The tongue depressor was placed

approximately 1 m from the nest in the direction of the study plot centerline. A second

fluorescent orange tongue depressor (with the same information as the plain marker) was placed

at the plot centerline to further assist in relocating the nest. At each nest, information including

species, location of nest, nest identification number, observer, date, time, and method of

discovery were recorded onto a data form.

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We conducted nest monitoring visits systematically every 3-6 days until fates were

determined. Nest monitoring began on 15 June after the first rope-drag session and continued in

tandem with nest searches when necessary. After nest searches ended, we continued to monitor

nests until the end of the field season on 17 July.

We estimated nest fate based on criteria used by other researchers (Troy 1992, Mabee 1997,

Martin et al.1997). A “hatched” nest refers to one that is believed to have successfully hatched

at least one offspring of a nester with precocial young (e.g. shorebirds and waterfowl). A

“fledged” nest refers to one in which at least one nestling was successfully able to leave the nest.

This only applies to the Lapland Longspur (Calcarius lapponicus) since it was the only nester

that produced altricial young at this site. We assumed a nest hatched/fledged successfully if at

least two of the following conditions were met: the nest was empty within four days of the

expected hatch date (two days for longspurs), chicks were observed in the nest or nearby (within

10 m), egg pip holes were observed on the penultimate visit, and/or other evidence including

presence of egg pip fragments (~1-4 mm), and membranes that easily peel away from egg pieces

(waterfowl). We assumed predation if the nest contents were gone at least four days prior to the

expected hatch/fledge date and other evidence left at the nest indicated predation including large

egg-shell pieces with yolk or blood present, destroyed nest cup, and evidence of previous partial

predation. We did not assume predation if only one of the above conditions were met; in these

cases we conservatively determined the nest fate as “failure”. Other potential causes of nest

failure include inclement weather, abandonment due to infertile eggs, trampling by caribou, and

human-induced causes. Nest fate was classified as “unknown” if we did not have clear evidence

or had contradictory evidence as to nest fate. Nests that were still active when we left the field

were classified as “undetermined” fate.

We estimated nest age using one or more of the following methods (1) discovery of an

incomplete clutch during the laying stage and forward-calculating, (2) back-calculating from

hatch day, (3) nestling development (longspurs only), or (4) employing the egg flotation

technique (see Liebezeit 2007, field protocol – Appendix B, for the detailed egg flotation

methodology). For extrapolating age of the nest for methods (1) and (2) we used incubation and

nestling stage lengths based on published literature (Poole et al. 2003) and assumed birds laid

one egg per day. We defined nest age as beginning on the day the first egg was laid until the

date the nest was no longer active.

The egg flotation technique of estimating egg age is based on the premise that during the

course of incubation, evaporation of water and release of gases (e.g. expired CO2) by the

developing embryo causes a gradual loss of egg weight. Thus, newly laid eggs sink to the

bottom of a column of water. As egg age increases, eggs tip upward from the bottom and

eventually float at the surface. For most shorebird species, this technique can be reliably used to

age eggs within 2-4 days accuracy. We used flotation curves developed from data collected at a

number of site around the circumpolar arctic (Liebezeit et al. 2007).

We determined the nestling age of longspurs by taking detailed notes on longspur nestling

development at nests of known age and using this information to estimate age at nests found in

the nestling stage. We also used information in the literature on Lapland Longspur development

to assist in aging longspur nestlings (Hussell and Montgomerie 2002).

In order to minimize anthropogenic effects on predation rate we conducted nest checks from

a distance using binoculars (if possible), avoided creating dead-end paths when checking nests,

did not approach an active nest if predators were in the vicinity, did not eat or set equipment

down near active nests, and covered unattended waterfowl nests with down.

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After nests were no longer active, we determined if nests were within the plot using a tape

measure, and we used a Garmin

Legend Global Positioning System (GPS) receiver to obtain

geographic coordinates of the nest location (error ± 6 m). We set the GPS units to map datum

NAD 83 and decimal minutes for recording nest locations.

Potential predator abundance and lemming activity

We conducted nine sessions of timed point count surveys on all plots from 15 June to 13

July, between 0800 and 1900 AST. A point count session on each plot consisted of recording all

visual and aural detections of potential predators up to 300m from the observer during 6-12 2-

min surveys from fixed locations (centerline markers) within each study plot (for similar

methodology see Ralph et al. 1993). Each count was conducted at least 10 min. and 200m from

the previous one. We estimated predator distance from the observer (upon the initial sighting) by

using rangefinders, by judging the distance using the plot marker stakes as reference points, or

by pacing the distance on foot. We also noted general behavior and appearance of each predator

to assist in distinguishing individuals from one another to avoid recounting. During each point

count visit observers recorded date, time of arrival on plot, time of plot departure, % cloud cover,

precipitation, and wind speed.

We monitored plots for lemming activity by tallying all individual lemmings observed within

each plot during predator survey visits. We also assessed lemming activity by recording

incidental sightings of Pomarine Jaegers (Stercorarius pomarinus) and Snowy Owls (Nyctea

scandiaca). These species are known to nest much more prevalently in years of high lemming

abundance and thus can be an indirect measure of lemming abundance.

Landform, concealment, snow cover, and temperature assessment

We assigned the dominant landform type within the designated quadrat (25-m x 25-m

subdivision of plot) of each nest location. Landform type followed the designation of Walker et

al. (1980). These landforms are large-scale, geophysical features that may contain a variety of

vegetation types. For a thorough description of landform types and classification see Liebezeit

(2007) – Appendix J. For nests located outside of the plot boundaries, we estimated landform

type within a 12.5 m radius of a given nest.

We estimated % overhead vegetative concealment of all shorebird and passerine nests using

an ocular tube following methods described by James and Shugart (1970).

From 7 to 15 June, we estimated the percentage of tundra covered by snow to the nearest

10% within each 50-m x 50-m grid of each plot. We downloaded mean daily air temperature

information from publicly available data (http://www.wunderground.com) for Nuiqsut, Alaska

which is 80km from the study site.

Data analysis

We estimated nesting success using the constant survivorship model in Program MARK

which provides estimates of daily survival rate (DSR) and corresponding standard error estimates

(as in Johnson 1979). To calculate the number of days nests were active (exposure days), for

successful nests, we used the period between the estimated or known initiation date and hatch

date. For nests with uncertain fate we used the last observed active date as the final exposure

day to minimize downward bias (Manolis et al. 2000). For failed nests, Program MARK

incorporates probabilities of failure for each day between the last observed active date and first

observed inactive date thus no final exposure day is estimated. Unlike, with Mayfield estimates,

Program MARK does not assume fate day as the midpoint between the last observed active and

11

first observed inactive date. After DSR was calculated, we used incubation (and nestling stage)

durations reported in the literature (Poole et al. 2003, Ehrlich et al. 1988) to estimate Mayfield

nesting success (Mayfield 1975) for each species or species group if incubation durations were

the same (e.g. phalaropes)2. For all species, we assumed one egg was laid per day, and that

incubation started the day the last egg in the clutch was laid. We defined the beginning of the

nestling stage (for longspurs) as the day the first young hatched. Because of the paucity of nests

found in the laying stage for any species, we did not calculate nesting success estimates for this

nesting stage.

We calculated nest density by estimating the number of nests within plot boundaries per unit

area (km2). We estimated nest initiation day by back-calculating from nests of known age to the

date the first egg was laid. For both density and nest initiation estimates we omitted “re-nests”

from the analysis. A re-nest is a second nesting effort by a pair of birds that failed in a previous

nesting attempt. We assumed that a nest initiated shortly after another failed within

approximately 100 m of one another indicated a re-nest. We also assumed re-nesting took place

when nests were initiated > 14 days after that of comparable published mean initiation dates (at

other northern Alaska study sites). None of the species we monitored are believed to re-nest

after a successful nesting attempt with the possible exception of Lapland Longspurs (see Custer

and Pitelka 1977). We compared nest initiation dates for individual species between years and

sites (Teshekpuk and Prudhoe Bay) using analysis of variance and then compared pairwise

differences in means using Tukey-Kramer multiple comparison tests (Zar 1999).

We estimated the activity of potential nest predators across the study site by averaging the

number of predator species detections per 30-min time period per plot. We estimated activity

within four time periods defined as “early” (6/20 and before), “middle” (6/21 to 7/5), “late” (7/6

and after) and “season” (all periods). In order to standardize predator data collected in 2007 with

the two previous seasons, we used the first 30 minutes of count data from sessions 1 and 2 as the

“early” count data, the first five counts from sessions 3, 4, and 5 for the “middle” counts, and the

first five counts from sessions 7, 8, and 9 as the “late” count data. Unlike in previous year, we

did not record Artic Tern (Sterna paradisaea) or Sabine’s Gull (Xema sabini) as potential nest

predators.

We compared nest concealment for species with adequate sample sizes at successful versus

failed/depredated nests using a two-sample t-test. If the assumptions of normality or equal

variances were not met, we used the appropriate non-parametric analyses (Zar 1999). We also

compared the frequency of landform types for all within plot nests and displayed the results as a

histogram. We used log-transformed regressions of % snow cover per date to estimate snow

melt completion dates. We summarized mean air temperature across time periods of interest and

calculated corresponding standard errors.

We compared DSR among species, species groups, and between study sites with a χ2 test

using program CONTRAST (Sauer and Williams 1989). All other analyses were conducted

using Microsoft Access 2000, Microsoft Excel, or NCSS 2000 (Hintze 2000). Results are

reported as a mean ± SE, and were significant if P < 0.05.

RESULTS

Relative abundance and diversity of avifauna

From 7 June to 16 July we detected 48 species of birds within the boundaries of the study site

(Table 1). The estimates of relative abundance are based on casual, non-systematic observations

2 Mayfield estimates can not be calculated across different species when incubation lengths for individual species

differ.

12

of these species during our day-to-day activities at work in the field and at rest at our base camp.

Of these 48 species, 16 were known breeders, because we discovered their nests on our study

plots in 2007 (Table 2). In addition, we incidentally found nests of 10 additional species3 within

the study area. We suspect two other species were nesting in the area based on behavioral cues

or other evidence of nesting4. In 2005 and 2006 we detected four additional species that we did

not detect in 20075. In those previous years we documented nesting or probable nesting in 13

other species that we did not detect nesting in 20076. Thus, over the past two field seasons we

have detected 52 bird species within the study area and at least 41 of these species likely breed

here.

Nesting success, nest age, nest density, and nest initiation

We discovered and monitored 191 nests of 16 species from 11 June to 16 July, 2007. The

dominant nesting birds included the Lapland Longspur, Pectoral Sandpiper (Calidris melanotus),

Semipalmated Sandpiper (Calidris pusilla), Red Phalarope (Phalaropus fulicaria). These four

species accounted for 66% of the nests found within the study plots (Table 2). Most nests were

discovered during rope-drag nest search visits (88 of 191, 46%) and 83 nests were found during

the single-person searches. Twenty nests were found incidentally when we were carrying out

other field duties within our plots.

In 2007, we discovered significantly fewer nests compared to 2006 (168 vs. 213 within-plot

nests) with overall nest density more similar to (but higher than) that of 2005 when overall nest

density was 90.7 nests / km2. Species-specific nest densities were similar across the past three

seasons although densities in 2006 were higher for most species. Two species had particularly

variable nest densities across some of the years. Red Phalaropes had noticeably higher densities

in 2006 versus 2005 and 2007 and Pectoral Sandpipers nest densities had noticeably lower nest

densities in 2007 compared to the previous two years (Fig. 3). Overall nest density was 100.1

nests / km2 with Lapland Longspurs, Pectoral Sandpipers, and Semipalmated Sandpipers having

the highest densities per species (Table 2). The average number of nests found in each study plot

was 10.5 with a range of 3 to 17.

For breeders with precocial young, most nests were found in the incubation stage (101 of

111, 90.9%), with the remainder found in the laying stage. Of the two species with semi-

precocial young (Arctic Tern and Willow Ptarmigan [Lagopus lagopus]) three nests were found

in the incubation stage and one ptarmigan nest was discovered in the laying stage. For the only

breeder with altricial young (Lapland Longspurs), most nests were found during incubation (n =

58; 76%), 15 were found during the nestling stage, and three nests were found during the laying

stage.

Among all species, 100 nests successfully hatched/fledged and 70 failed. We were unable to

reliably assess the fate of 10 nests because there was not enough evidence or because of

contradictory evidence at the nest sites. We were also unable to determine the fate of 11 nests

because they were still active at the end of the field season. It is likely one of these nests hatched

successfully since they were either star-cracked or pip holes were visible on the last visit to the

nest. For the five species with sample sizes >10, nesting success (assuming constant

3 Buff-breasted Sandpiper, Glaucous Gull, Northern Pintail, Long-tailed Jaeger, Parasitic Jaeger, Hoary/Common

Redpoll, Sabine’s Gull, Pacific Loon, Red-throated Loon, and Rock Ptarmigan 4 Spectacled Eider, Baird’s Sandpiper

5 Mew Gull, Semipalmated Plover, Bar-tailed Godwit, Ross’s Gull

6 Nesters: Greater Scaup, Pomarine Jaeger, Savannah Sparrow, Short-eared Owl, Snowy Owl; Likely nester: Red-

breasted Merganser, Ruddy Turnstone, Semipalmated Plover, Brant, Snow Goose, Cackling Goose, , Yellow

Wagtail, Sandhill Crane

13

survivorship) ranged from 0.29 (Long-billed Dowitcher; Limnodromus scolopaceus) to 0.71

(Semipalmated Sandpiper; Table 3). Overall daily survival rate for all shorebirds combined was

0.97 (Table 3).

We statistically compared nesting success for the species with sample sizes greater than 10

(Lapland Longspur, Pectoral Sandpiper, Red Phalarope, and Semipalmated Sandpiper, and Long-

billed Dowitcher)7. There was no significant difference in the daily survival rate comparisons

for these species for 2007 although Semipalmated Sandpiper nest survivorship was noticeably

higher than that of Long-billed Dowitcher and approached statistical significance ( 2

1χ = 2.85, P

= 0.09). We also compared nesting success (same-species comparison) across years (2005 to

2007) at the Teshekpuk study site for the three species with the most robust sample sizes

(Lapland Longspur, Pectoral Sandpiper, and Semipalmated Sandpiper). Although daily survival

rates were higher for all species in 2006 compared to the other two years (with the exception of

Semipalmated Sandpipers in 2005 vs. 2006), we found no significant difference (P > 0.05) in

daily survival rates for any of these comparisons.

As in previous years, nest predation was the most important cause of nest failure in 2007.

For eight nests we had direct evidence of predation and the 55 nests recorded as “failed” were

most likely taken by predators because the nest contents were gone more than four days prior to

the estimated hatch/fledge date. Thus, 63 of 70 nest failures, (90%) were likely due to

predation. Other sources of nest failure were abandonment for unknown reasons (n = 4) and

predation due to observers accidentally attracting predators to nests (n = 3).

We determined nest age for the majority of discovered nests (174 of 191; 91%) using the

following methods: back-calculation from known hatch and/or egg flotation (n = 111), nestling

age (longspur only; n = 49), incomplete clutch (n = 10) or a combination of more than one of

these methods (n = 4). Unlike previous years, we used flotation criteria to estimate the age of

Lapland Longspur eggs.

Mean nest initiation dates ranged from 7 June for Dunlin (Calidris alpina) and Lapland

Longspur to 17 June for Long-billed Dowitcher in 2007 (Table 4). Nest initiation dates for the

three most common species were significantly different between years with initiation dates

trending earlier from 2005-07 (Lapland Longspur: 214F = 12.02, P <0.001; Pectoral Sandpiper:

82F = 6.04, P = 0.004; Semipalmated Sandpiper: 49F

= 4.75, P = 0.013; Fig. 6). Nest initiation

dates in 2007 were 2-4 days earlier than in 2005 for these most common species.

Nest predator abundance

Eight species of potential nest predators were detected during timed point-count surveys. By far, the

most numerous detections were of the Parasitic Jaeger (Stercorarius parasiticus), Long-tailed Jaeger

(Stercorarius longicaudus) and Glaucous Gull (Larus hyperboreus;Table 5, footnoteb; Fig. 7). In 2007,

Pomarine Jaegers were not detected on timed predator counts (Table 5) and were only observed

incidentally in the study site until 11 June. In 2005, Pomarine Jaegers were similarly rare and were only

detected once during timed predator counts. These years contrast markedly with 2006, when Pomarine

Jaeger detection rate was high and, in fact, was the predator with the highest detection rate. This spike

in Pomarine Jaegers in 2006 is correlated with a boom in lemming abundance (Fig. 8).

7 A major difference between longspur and shorebird nesting success estimates is that longspur estimates include

both the incubation and nesting stage. However, the duration of these combined stages (22 d) is comparable to the

incubation stage length for most shorebirds, thus we felt justified in making these comparisons.

14

Microtine activity and abundance

Both brown lemmings (Lemmus sibiricus) and collared lemmings (Dicrostonyx torquatus)

were detected in the study area although we did not attempt to identify individuals to species in

most cases because identification can be difficult without close examination of animals in the

hand (Whitaker 1996). Lemmings were detected 26 times during approximately 444 hours of

observation time during plot visits (Table 6). After controlling for lemming observations per

unit time, it is clear that lemming abundances returned to relatively low levels similar to 2005

from the high numbers observed in 2006 (Fig. 8). We detected no Snowy Owls or Pomarine

Jaegers incidentally while on plot.

Landform, vegetation, and snow cover/temperature assessment

Nests were found in nine of 15 landform types. Most nests were located in the landform

types identified as Unit 7 (strangmoor and disjunct polygon rims) and Unit 2 (High-center

polygons, center-trough relief <0.5m; Fig. 9). This trend was also apparent in previous years

(Liebezeit 2005a, Liebezeit & Zack 2006a).

We compared overhead vegetative nest concealment between successful and depredated

nests for Lapland Longspurs; the one species with which we had adequate data. Nest

concealment was significantly higher at depredated nests compared to successful nests (mean

successful: 61.4%, mean predated: 71.0%; U = 1.77, P = 0.04). The previous two years, nest

concealment at longspur nests was higher at successful nests, significantly so in 2005 (Liebezeit

2005a).

Snow melt and subsequent exposure of the tundra occurred earlier in 2007 than in both 2005

and 2006 (Fig. 10). Mean snow cover was ~2.5% on 9 June (julian date: 160) compared to

16.1% in 2006 and 37.8% in 2005 on the same date. Likewise, snow melt was complete

approximately four days later in 2005 (16 June, julian date: 167) and two days later in 2006

compared to 2007 (Fig.10). Despite the earlier snow melt in 2007 versus 2006, the mean air

temperature during the core of the breeding season (20 May 20 to 30 June – covering the period

of bird arrival and main egg production) was lower than in 2006 (by approximately 3.5°C; Fig.

11).

Comparisons with results at the nearby Prudhoe Bay Oil field

During the same years we conducted research at Teshekpuk, we also sampled 12 10-ha plots

at the Prudhoe Bay Oilfield study site. At both sites we followed the same sampling

schedule/protocol and had roughly equal “person hours” per plot.

Lapland Longspur, Pectoral Sandpiper, and Semipalmated Sandpiper were the most common

nesting species at both sites. Nest densities were noticeably lower at both study sites compared

to 2006 and approached densities observed at these respective sites in 2005. Overall nest

densities have been higher at Teshekpuk compared to Prudhoe Bay from 2005-07 (mean, all

years combined = 108.2 vs. 79.1 nests / km2; Fig. 12).

Nest predation has, by far, been the most important cause of nest failure at both Prudhoe Bay

and Teshekpuk in all years sampled (>80% of all failed nests). Daily survival rates for nests for

two of the three most common species, Lapland Longspurs and Pectoral Sandpipers, were

significantly higher at Teshekpuk compared to Prudhoe Bay in 2007 ( 2

1χ = 4.13, P = 0.04; 2

1χ =

3.77, P = 0.05; Fig. 4). Overall, combined shorebird daily survival rate has been slightly lower at

Prudhoe Bay for the past three seasons compared to Teshekpuk although none of these

differences are significant (Fig. 5). However, the combined daily survival rate of shorebirds

combined with passerines (i.e. longspurs) was significantly lower at Prudhoe Bay in 2007 ( 2

1χ =

15

4.15, P = 0.04) and nearly significantly lower in 2005 and 2006 ( 2

1χ = 3.00, P = 0.08; 2

1χ = 2.62,

P = 0.11; Fig. 5).

Nest initiation dates were slightly earlier at Prudhoe Bay compared to Teshekpuk (by <1 day)

for the four of the five species most common species (N>5). Only Pectoral Sandpipers had a

later average initiation date at Prudhoe Bay. For the three most common species (N>10)

differences in nest initiation dates between sites were not statistically significant (Fig. 13). Nest

initiation dates also tended to be earlier at Prudhoe Bay versus Teshekpuk in the two previous

years, though these differences were rarely statistically significant (Liebezeit 2005d, Liebezeit &

Zack 2006b).

Based on the predator count surveys, at both sites the most important potential nest predators

were Glaucous Gulls and jaegers in 2007 (Fig. 7). Glaucous Gulls and jaegers have been the

most commonly detected predators at both sites for all years sampled. Glaucous Gulls were

detected significantly more at Prudhoe Bay compared to Teshekpuk in 2007 ( 133T = -2.26, P

=0.025; Fig. 7). No other differences for each species between sites were significant in 2007.

Pomarine Jaegers were notably absent at both sites compared to their common occurrence at the

sites in 2006. Slightly more arctic fox (Alopex lagopus) were detected in Prudhoe Bay in 2007

although were in low numbers at both sites. During timed counts, Common Ravens (Corvus

corax) were only detected at Prudhoe Bay in low numbers in 2007 (Fig. 7).

DISCUSSION

We found a relatively high diversity of breeding birds at the Teshekpuk Lake – Olak study site

with 41 species that breed or are likely breeders. In 2007, nest densities at Teshekpuk were

noticeably lower than in 2006 and returned to levels similar to 2005. 2006 was also a year of

high lemming abundance. These observations suggest that 2007, in the scheme of cyclical

patterns in the arctic, was a return to a more “typical” year and that 2006 was a peak year in nest

densities, nest survivorship, and in lemming abundance. In 2006, early season air temperatures

were noticeably higher than in 2005 or 2007. Warmer June temperatures have been shown to be

correlated with higher breeding productivity in arctic waterfowl (Barry 1962, Summers and

Underhill 1987). This relationship is typically explained by reduced clutch sizes or lack of

nesting due to late thaw in cooler years. Our air temperature data appears to support this

hypothesis since there is a positive correlation between nest survivorship (DSR) and temperature.

Nesting densities at other sites, such as at our Prudhoe Bay site and at a U.S. Fish and Wildlife

run site near Barrow (R. Lanctot, pers. comm.) returned to lower levels suggesting this was a

region-wide trend across a significant portion of the Alaskan Arctic coastal plain.

Overall, nest densities at this site were comparatively higher than at other study sites

sampled in recent years on the arctic coastal plain to the east (Liebezeit 2003, 2004a-b, 2005b-d,

Kendall et al. 2003, Kendall and Brackney 2004, Rodrigues 2002, Burgess et al. 2003, Johnson

et al. 2004, 2005) and compared to an inland site in the eastern NPR-A (Cotter and Andres

2000). This pattern fits the trend that shorebirds diversity and abundance on the Alaskan arctic

coastal plain generally increases with latitude (nearer the Arctic Ocean coast) and longitudinally

to the west (Johnson et al. 2007). At the U.S. Fish and Wildlife site near Barrow, nest densities

have been higher than at Teshekpuk, however, 17 arctic fox were removed from the area in 2006,

potentially influencing nest densities and survivorship (R. Lanctot, pers. comm.).

This year lemming abundance returned from the high levels observed in 2006 to low levels

similar to that observed in 2005. Correspondingly, lemming numbers also were lower at

Prudhoe Bay this season. Cyclical lemming population booms are a known phenomenon in the

16

Arctic (Krebs 1964). The first apparent lemming population boom in this region since at least

2002 occurred in 2006 (Soloviev and Tomkovich 2002-04). Pomarine Jaegers, a species that

nests only in high lemming years (Wiley and Lee 2000) were observed briefly during the first

week at the site, and then were absent for the rest of the season. Snowy Owls, another species

that relies heavily on lemmings, were detected less frequently in 2007 compared to 2006. Unlike

in 2006, neither of these species was observed nesting this season. Long-tailed Jaegers, another

species that is believed to be highly dependent on lemmings (Wiley and Lee 1998) were detected

in similar numbers to 2006 and we did find at least three nests incidentally within the study area.

When omitting the “lemming obligate” Pomarine Jaegers from predator detection totals

across years, overall predator numbers were relatively high in 2007 compared to the two

previous years. Much of this is due to the increased observations of Parasitic Jaegers. Arctic fox

detections were also noticeably higher in 2007; however, part of this increase is due to the

observation of at least four fox pups on a den in one of our study plots (plot 13). This den was

also active in 2006 with pups present but they were not detected on predator counts in 2006. It is

important to note that the daytime predator surveys we conduct may be biased toward detecting

avian predators, because arctic fox have been found to be most active nocturnally (Eberhardt et

al. 1982).

There is a possibility that we overestimated nest predator number in 2007 because of changes

in our data collection methodology since we visited the sites more frequently (but conducted

shorter timed counts per visit). This change in methodology was done so that Program

DISTANCE can be used in the future to make more accurate density estimates (Thomas et al.

2006). However, we believe this error is negligible since we continued to minimize recounting

error and, for this analysis, we standardized our 2007 data to our previous methods.

We found nest predation to be the most important cause of nest failure at this site. This result

is in accord with other nesting success studies, including those conducted at the Prudhoe Bay

Oilfield (Troy 2000, Liebezeit 2004b, 2005b,d, Liebezeit & Zack 2006b), Kuparuk Oilfield

(Liebezeit 2003, 2004a, 2005c), and other North Slope sites (Kendall et al. 2003, Kendall and

Brackney 2004, Rodrigues 2002, Burgess et al. 2003, Johnson et al. 2004,2005). Nest predation

has also been reported to be the most significant cause of nest failure for passerines, shorebirds,

and waterfowl at many other locations within the arctic coastal plain (Custer and Pitelka 1977,

Quinlan and Lehnhausen 1982, Helmers and Gratto-Trevor 1996). As in previous seasons, we

found other causes of nest failure to be minimal. However, other researchers have found

inclement weather to cause large-scale nest failure in some years (Barry 1962). Caribou

trampling has also been suspected to be an important cause of nest failure in the Prudhoe Bay

region (D. Troy pers. comm.).

We observed the lowest overall nest survivorship at Teshekpuk in 2007. It is possible that

the predators may have “switched” from preying on lemmings the previous year when lemming

numbers were high to preying on nests more often this year when lemmings were less abundant.

This phenomenon of “prey switching” in response to cyclical population booms in lemmings has

been documented in other parts of the arctic (Summers 1986, Summers and Underhill 1987). At

Prudhoe Bay nest survivorship was even lower compared to both Teshekpuk in all years and to

Prudhoe Bay the previous year.

Over the past three seasons we have detected fewer human-subsidized predators (i.e.

Glaucous Gulls, arctic fox, and ravens) at Teshekpuk compared to Prudhoe Bay. These

predators are known generalists and are often attracted to human-altered areas including arctic

oilfields (Day 1998, NAS 2003). Conversely, jaegers are not known to be attracted to human-

disturbed areas so it is not surprising that their numbers did not reflect this trend.

17

The nesting success results from 2005-07 at both study sites suggest that the Teshekpuk nest

survivorship is robust whether in a lemming boom year or not. On the other hand, nest

survivorship evidence at Prudhoe Bay suggests higher predation rates in low lemming years

(except in 2004 when both predation and lemming numbers were low), perhaps due to more

abundant human-subsidized predators, but then comparable nest survivorship to Teshekpuk in

high lemming years, perhaps due to predation relief as a result of prey switching behavior by

nest predators.

We did not detect any advantage in nesting success due to vegetative concealment for the

most common nesting species. However, Lapland Longspur nest concealment is typically much

higher compared to most shorebird nesters. This may be due to their differing nest site selection

strategies. Longspurs tend to nest at the base of grass tussocks, on the side of ridges, or abutting

polygon rims (see Rodrigues 1994) while many sandpipers nest in open scrapes. Because

longspurs rear altricial young at the nest, it may be more important for them to have greater

overhead concealment. In contrast, precocial sandpipers have cryptically marked eggs and

quickly leave the nest upon hatching and may not require as much vegetative cover.

Snow melt and subsequent exposure of tundra has occurred successively earlier at Teshekpuk

over the past three years. Surprisingly, air temperature in the late spring/early summer was

colder this year than in 2006. Despite the cooler temperatures, snow cover may have dissipated

sooner this year largely because mean snow depth was apparently lower at this site in 2007

compared to previous years (S. Oppel, pers. comm.)8. Correspondingly, nest initiation dates for

most species were earlier this year as well. This correlation between nest initiation and snow

cover has been documented by other researchers including Meltofte (1985) at a site in Greenland

and Troy (1992) who found that snowmelt was strongly correlated with Dunlin and Lapland

Longspur nest initiation at Prudhoe Bay from 1981-91. During the short arctic breeding season,

most species tend to initiate nesting as early as possible, thus the main limiting factor at this time

is believed to be snow cover. A delayed snowmelt may preclude breeding at high latitudes

(Barry 1962, Cartar and Montgomerie 1985) or have a negative impact on nest survivorship

(Byrkjedal 1989). In support of this, at both Prudhoe Bay and Teshekpuk, air temperature during

the early season appears to be strongly correlated with nest survivorship. In years of relatively

higher temperatures, nest productivity has also been relatively high. Degree of snow cover may

also influence predation rates. Byrkjedal (1989) found greater predation of artificial nests earlier

in the season when nest predators could systematically search snow-free areas. We have been

unable to evaluate this hypothesis during our years monitoring at this site because most snow has

melted by the time we begin nest searches.

Snow melt at Prudhoe Bay has been consistently earlier than at Teshekpuk for the past three

years. Accordingly, initiation dates for most species have been earlier at Prudhoe Bay as well.

Despite this trend, we expected to observe earlier snowmelt at Teshekpuk compared to Prudhoe

Bay since it is located more inland and summer temperatures on the North Slope are typically

lower near the coast on the North Slope. We do not have temperature or snowfall data to help

explain this seemingly contradictory trend, although we suggest two possible explanations: 1.

the immediate climatic conditions near Teshekpuk Lake are typically colder and/or have greater

snow cover than at Prudhoe Bay in early June due to local geography and weather patterns;

8 Snow machine riders (in March 2007) reported much less snow depth than in other years with more tundra

exposed. River water levels receded earlier at this site in 2007 than the two previous years suggesting less snow

melt.

18

and/or 2. The Prudhoe Bay site is “warmer” due to the elevated level of human emissions in this

area (e.g. excess gas burnoff, road dust, etc.).

ACKNOWLEDGEMENTS

We would like to thank the U.S. Fish and Wildlife Service – Neotropical Migratory Bird

Conservation Act Grant, the Liz Claiborne/Art Ortenberg Foundation, and the Wildlife

Conservation Society for providing funding for this project. We thank the North Slope Borough,

in particular Robert Suydam, for providing support and guidance during our March 2007 supply

run from Barrow. We also thank, Brian Person of the North Slope Borough, Steffen Oppel, and

Heather Vukelic for additional help on the April supply run. We thank Steve Kendall and Philip

Martin at U.S. Fish and Wildlife – Fairbanks for allowing storage space at the Fairbanks office as

well as the use of the Galbraith Lake camp. We thank Steve Kendall, Bob Rodrigues, Rick

Johnson, Philip Martin, Rick Lanctot and others who reviewed the field protocols and provided

helpful suggestions. At BP we thank Bill Streever, Wilson Cullor, and Brian Collver for logistic

support at the Prudhoe Bay site. We thank Patagonia

and Salomon

for generously donating

field clothing for the field crews. We thank UAF graduate student Steffen Oppel for his

assistance in the field. Finally, we thank Ian Ausprey, Ruby Hammond, and Megan Jones for

their hard work in the field.

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_______, J.R. 2005a. Breeding bird diversity, density, nesting success and nest predators in the

Olak region of the Teshekpuk Lake Special Area – 2005. Annual report. Prepared by the

Wildlife Conservation Society for the North Slope Borough and the Tundra-bird

Productivity Studies collaborative group. 32 p.

_______, J.R. 2005b. Nesting success and nest predators of tundra-nesting birds in the

Prudhoe Bay Oilfield – 2005 annual report. Prepared by the Wildlife Conservation

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_______, J.R. 2005c. Nesting success and nest predators of tundra-nesting birds in the

Kuparuk Oilfield – 2004 annual report. Prepared by the Wildlife Conservation Society

for the Tundra-bird Productivity Studies collaborative group. 33 p.

_______, J.R. 2005d. Nesting success and nest predators of tundra-nesting birds in the

Prudhoe Bay Oilfield – 2004 annual report. Prepared by the Wildlife Conservation

Society for the Tundra-bird Productivity Studies collaborative group. 34 p.

_______, J.R. 2004a. Nesting success and nest predators of tundra-nesting birds in the

Kuparuk Oilfield – 2003 annual report. Prepared by the Wildlife Conservation Society

for the Tundra-bird Productivity Studies collaborative group. 37 p.

21

_______, J.R. 2004b. Nesting success and nest predators of tundra-nesting birds in the

Prudhoe Bay Oilfield – 2003 annual report. Prepared by the Wildlife Conservation

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Kuparuk Oilfield – 2002 annual report. Prepared by the Wildlife Conservation Society

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predators in the Olak region of the Teshekpuk Lake Special Area – 2006. Annual report.

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U.S. Fish and Wildlife Service (Arctic NWR). 37 p.

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the Prudhoe Bay Oilfield – long-term monitoring – 2006 report. Prepared by the Wildlife

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24

Figure 1. WCS study plots at the Teshekpuk Lake - Olak study site, Teshekpuk Lake Special

Area, NPR-A, Alaska, 2007.

25

Figure 2. Pictures from the 2007 field season at the Teshekpuk Lake – Olak study site,

Teshekpuk Lake Special Area, National Petroleum Reserve – Alaska.

WCS field crew (from left): Ian Ausprey, Ruby

Hammond, Joe Liebezeit, Megan Jones (Photo

credit: S. Zack).

Freshly hatched Stilt Sandpiper (Photo credit: K. Pietrzak).

Long-tailed Jaeger (Photo credit: M. Jones).

WCS field camp from the air (Photo credit: S. Zack).

26

0

5

10

15

20

25

30

35

40

45

2005 2006 2007

Ne

st d

en

sity (

ne

sts

/ k

m2)

GWFG

LALO

PESA

REPH

RNPH

SESA

Figure 3. Nest densities (nests / km

2) of the six common species that nested on study

plots from 2005-07 at the Teshekpuk Lake - Olak study site, Teshekpuk Lake Special

Area, NPR-A, Alaska.

0.9

0.91

0.92

0.93

0.94

0.95

0.96

0.97

0.98

0.99

1

PB 2005 PB 2006 PB 2007 TESH 2005 TESH 2006 TESH 2007

Study Site / Year

Dail

y s

urv

ival

rate

Lapland Longspur

Pectoral Sandpiper

Semipalmated Sandpiper

Figure 4. Daily survival rate summary (± 1SE) for the three most common nesters at both the

Teshekpuk Lake – Olak study site, Teshekpuk Lake Special Area, NPR-A and the Prudhoe

Bay Oilfield study site, Alaska, 2005-07. Sample sizes range from 12 to 67.

27

0.9

0.91

0.92

0.93

0.94

0.95

0.96

0.97

0.98

0.99

1

PB 2005 PB 2006 PB 2007 TESH 2005 TESH 2006 TESH 2007

Study Site / Year

Dail

y s

urv

ival

rate

shorebirds

shorebirds + passerines

Figure 5. Daily survival rate summary (± 1SE) for combined “shorebirds” and “shorebirds +

passerines” at both the Teshekpuk Lake – Olak study site, Teshekpuk Lake Special Area,

NPR-A and the Prudhoe Bay Oilfield study site, Alaska, 2005-07. Sample sizes range from

54 to 183.

155

157

159

161

163

165

167

169

171

2005 2006 2007

Ju

lian

date

Pectoral Sandpiper

Semipalmated Sandpiper

Lapland Longspur

Figure 6. Mean nest initiation dates (± 1SE) for the three most common breeding birds from

2005 to 2007 at the Teshekpuk Lake – Olak study site, Teshekpuk Lake Special Area, NPR-

A, Alaska.

28

0

1

2

3

4

5

6

Tesh 2005 Prud Bay

2005

Tesh 2006 Prud Bay

2006

Tesh 2007 Prud Bay

2007

Most common potential nest predators

Av

g. #

Pre

ds

. d

ete

cte

d / 3

0m

in

Common Raven

Arctic Fox

Pomarine Jaeger

Parasitic Jaeger

Long-tailed Jaeger

Glaucous Gull

Figure 7. Average number of key potential nest predators detected per 30-min. period (± 1

SE) during timed surveys at the Teshekpuk Lake – Olak study site, Teshekpuk Lake Special

Area, NPR-A, and the Prudhoe Bay Oilfield study site Alaska, 2005-07.

0

0.1

0.2

0.3

0.4

0.5

0.6

2005 2006 2007

Avg

. # d

ete

cte

d /

30 m

inu

tes

Lemmings -PB

Lemmings - Tesh

Pomarine Jaegers -Tesh

Pomarine Jaegers -PB

Figure 8. The average number of lemmings (sp.) and Pomarine Jaegers detected per 30-min

survey period (± 1SE) at the Teshekpuk Lake - Olak study site, Teshekpuk Lake Special

Area, NPR-A, and the Prudhoe Bay Oilfield study site, 2005-07.

29

0

10

20

30

40

50

60

Unit 0 Unit 1 Unit 2 Unit 3 Unit 4 Unit 5 Unit 6 Unit 7 Unit 8

Landform type

Nu

mb

er

of

Nests

Figure 9. Number of nests found in each landform type within study plots at the Teshekpuk

Lake - Olak study site, Teshekpuk Lake Special Area, NPR-A, Alaska.

.

0

10

20

30

40

50

60

70

155 160 165 170 175

Julian date

Avera

ge p

erc

en

t sn

ow

co

ver

Teshekpuk 2005

Teshekpuk 2006

Teshekpuk 2007

Log. (Teshekpuk 2005)

Log. (Teshekpuk 2006)

Log. (Teshekpuk 2007)

Figure 10. Average snow cover for survey dates on all plot locations at the Teshekpuk Lake

– Olak study site, Teshekpuk Lake Special Area, NPR-A, Alaska and corresponding log-

transformed linear regressions for 2005-07.

30

0

1

2

3

4

5

6

7

8

9

2005 2006 2007

Year

Me

an

te

mp

era

ture

- M

ay

20

-Ju

ne

30

(oC

)

Figure 11. The average temperature (°C ± 1SE) during the core of the breeding season (20

May to 30 June) at the Teshekpuk Lake – Olak study site, Teshekpuk Lake Special Area,

NPR-A, Alaska.

133.8

100.1101.6

60.0

90.6

75.8

0

20

40

60

80

100

120

140

160

2005 2006 2007

Year

Overa

ll n

est

den

sit

y (

nests

/ k

m2)

Teshekpuk

Prudhoe Bay

Figure 12. Overall nest densities (nests / km

2) in 2005-07 at both the Teshekpuk Lake - Olak

study site, Teshekpuk Lake Special Area, NPR-A, and the Prudhoe Bay Oilfield study site,

Alaska.

31

150

152

154

156

158

160

162

164

166

168

Pectoral Sandpiper Semipalmated

Sandpiper

Lapland Longspur

Ju

lian

Date

Teshekpuk 2007

Prudhoe Bay 2007

Figure 13. Mean nest initiation dates (± 1SE) for the most common breeding birds (N > 10)

in 2007 at the Teshekpuk Lake – Olak study site, Teshekpuk Lake Special Area, NPR-A and

the Prudhoe Bay Oilfield study site, Alaska.

.

32

Table 1. Bird diversity and relative abundance at the Teshekpuk Lake - Olak study site,

Teshekpuk Lake Special Area, NPR-A, Alaska, 2007.

Species Abundance* Species Abundance*

American Golden-plover (Pluvialis dominica)

C Parasitic Jaeger (Stercorarius parasiticus)

Arctic tern (Sterna paradisaea)

A Pectoral Sandpiper (Calidris melanotos)

A

Baird’s Sandpiper (Calidris bairdii)

X Peregrine Falcon (Falco peregrinus)

U

Black-bellied Plover (Pluvialis squatarola)

C Pomarine Jaeger (Stercorarius pomarinus)

R

Buff-breasted Sandpiper (Tryngites subruficollis)

U Red Phalarope (Phalaropus fulicaria)

A

Brant (Branta bernicla)

U Red-breasted Merganser (Mergus serrator)

U

Cackling Goose (Branta hutchinsii)

R Red-necked Phalarope (Phalaropus lobatus)

A

Common Raven (Corvus corax)

A Red-throated Loon (Gavia stellata)

U

Dunlin (Calidris alpina)

A Rock Ptarmigan (Lagopus mutus)

C

Glaucous Gull (Larus hyperboreus)

U Rough-legged Hawk (Buteo lagopus)

R

Golden Eagle (Aquila chrysaetos)

F Ruddy Turnstone (Arenaria interpres)

R

Greater Scaup (Aythya marila)

A Sabine’s Gull (Xema sabini)

C

Greater White-fronted Goose (Anser albifrons)

C Sandhill Crane (Grus canadensis)

R

King Eider (Somateria spectabilis)

R Savannah Sparrow (Passerculus sandwichensis)

F

Gyr falcon (Falco rusticolus)

F Semipalmated Sandpiper (Calidris pusilla)

A

Hoary & Common Redpoll (Carduelis hornemanni & flammea)

A Short-eared Owl (Asio flammeus)

U

Lapland Longspur (Calcarius lapponicus)

C Snow Goose (Chen caerulescens)

R

Long-billed Dowitcher (Limnodromus scolopaceus)

F Snowy Owl (Nyctea scandiaca)

R

Long-tailed Duck (Clangula hyemalis)

C Spectacled Eider (Somateria fischeri)

U

Long-tailed Jaeger (Stercorarius longicaudus)

Stilt Sandpiper (Calidris himanotpus)

C

Merlin (Falco columbarius)

U Tundra Swan (Cygnus columbianus)

C

Northern Harrier (Circus cyaneus)

C Willow Ptarmigan (Lagopus lagopus)

A

Northern Pintail (Anas acuta)

C Yellow-billed Loon (Gavia adamsii)

R

Pacific Loon (Gavia pacifica)

A Yellow Wagtail (Motacilla flava)

U

*(A) Abundant: Easy to find in large numbers on any given day in a variety of habitats; (C) Common: Easy to find in good numbers on any

given day in suitable habitat; (F) Fairly common: Likely to find in small numbers on most days in suitable habitat; (U) Uncommon: Possible

to find in small numbers on one in four days in suitable habitat; (R) Rare: Seldom found in any numbers even in suitable habitat.

(X) Extremely rare: Found only in some years and only one or two occurrences in the season.

33

Table 2. Number of discovered nests and nest density for each species from the Teshekpuk Lake

- Olak study site, Teshekpuk Lake Special Area, NPR-A, Alaska, 2007.

Species Species Code Discovered Nests a Nest density b

(nests/km2)

Lapland Longspur LALO 76 (68) 40.0

Semipalmated Sandpiper SESA 20 (18) 10.6

Pectoral Sandpiper PESA 17 (16) 9.4

Red Phalarope REPH 13 (13) 7.5

Long-billed Dowitcher LBDO 12 (12) 7.5

Red-necked Phalarope RNPH 9 (9) 5.0

King Eider KIEI 7 (7) 4.4

Stilt Sandpiper STSA 6 (6) 3.8

Dunlin DUNL 5 (5) 3.1

Greater White-fronted Goose GWFG 15 (5) 3.1

Black-bellied Plover BBPL 4 (2) 1.3

Arctic Tern ARTE 2 (2) 1.3

Willow Ptarmigan WIPT 2 (2) 1.3

American Golden-Plover AMGP 1 (1) 0.6

Long-tailed Duck LTDU 1 (1) 0.6

Tundra Swan GLGU 1 (1) 0.6

Total 191 (168) 100.1

a ( ) = Nests found within the plot boundaries

b Nest density calculated from nests within plot only and excludes probable second nesting attempts (Lapland

Longspur: 07RLH044, 07IJA042, 07MAJ048, 07RLH041; Pectoral Sandpiper: 07IJA043; Red-necked Phalarope:

07RLH043; Semipalmated Sandpiper: 07MAJ058; Red Phalarope: 07MAJ050).

34

Table 3. Summary of Mayfield nesting success & daily survival rate estimates of tundra-breeding

birds at the Teshekpuk Lake - Olak study site, Teshekpuk Lake Special Area, NPR-A, Alaska,

2007.

Species Na Mayfield

b Daily

survival

ratec

SE

Lapland Longspur 67 0.568 0.975 0.006

Semipalmated Sandpiper 18

0.707 0.983 0.009

Pectoral Sandpiper 15 0.646 0.980 0.010

Red Phalarope

13 0.504 0.966 0.015

Long-billed Dowitcher 12 0.293 0.946 0.020

Red-necked Phalarope 9 0.601 0.975 0.014

Stilt Sandpiper 6 0.335 0.947 0.030

Dunlin 5 0.707 0.986 0.016

Phalaropes 22 0.545 0.970 0.010

Shorebirds 81 - 0.970 0.005

Shorebirds + longspurs 148 - 0.972 0.004

a This estimate excludes nests outside of the study plots and nests that failed due to human disturbance. Only

included individual species estimates if N≥5. b All estimates are for incubation period only except Lapland Longspur (includes both incubation and nestling

periods). C Program MARK constant daily survivorship model used to calculate daily survival rate and corresponding

standard error estimates.

35

Table 4. Nest initiation dates of tundra-nesting birds at Teshekpuk Lake - Olak study site,

Teshekpuk Lake Special Area, NPR-A, Alaska, 2007. This estimate excludes nests of unknown

age or probable second nesting attempts.

Species

N Mean initiation date ± 1 SE Minimum Maximum

Lapland Longspur 72 7 June ± 0.30 3 June 17 June

Pectoral Sandpiper 16 12 June ± 1.52 3 June 23 June

Red Phalarope 12 15 June ± 1.93 6 June 26 June

Semipalmated Sandpiper 19 11 June ± 0.92 4 June 20 June

Long-billed Dowitcher 12 17 June ± 2.05 7 June 29 June

Red-necked Phalarope 8 15 June ± 1.10 8 June 18 June

Greater White-fronted Goose 8 9 June ± 0.91 6 June 13 June

Dunlin 5 7 June ± 0.68 5 June 9 June

Black-bellied Plover 4 13 June ± 1.19 11 June 16 June

American Golden-plover 1 8 June - -

Stilt Sandpiper 6 10 June ± 1.95 6 June 19 June

Tundra Swan 1 2 June - -

Arctic Tern 1 10 June - -

Willow Ptarmigan 1 9 June - -

36

Table 5. Average number (mean ± 1 SE / 30 min. count) of key potential nest predators recorded

during predator surveys for four time periods on and near study plots at the Teshekpuk Lake -

Olak study site, Teshekpuk Lake Special Area, NPR-A, Alaska, 2007.

Speciesb Early

a Middle Late Season

Glaucous Gull 0.56 ± 0.27 0.81± 0.50 1.0 ± 0.39 0.79 ± 0.35

Parasitic Jaeger 1.0 ± 0.34 2.0 ± 0.37 1.38 ± 0.41 1.46 ± 0.24

Pomarine Jaeger 0 0 0 0

Long-tailed

Jaeger

0.69 ± 0.24 0.94 ± 0.44 0.31 ± 0.15 0.65 ± 0.24

Jaegerc 1.69 ± 0.42 2.94 ± 0.40 1.69 ± 0.43 2.10 ± 0.24

Arctic fox 0.44 ± 0.26 0.56 ± 0.27 0.06 ± 0.06 0.35 ± 0.19

Common Raven 0 0 0 0

a Early = 6/20 and before, Middle = 6/21 to 7/5, Late = 7/6 and after, Season = all time periods. Total sample size

for each period = 16. b Total detections: Parasitic Jaeger (n = 70), Long-tailed Jaeger (n = 31), Glaucous Gull (n = 38), Arctic Fox (n =

17), Arctic Ground Squirrel (n = 12),

Peregrine Falcon (n = 3), lemming sp. (n = 2), Red Fox (n = 2). c Combines all jaeger species

34

37

Table 6. Summary of nest concealment for the most common species (N > 10) at the Teshekpuk

Lake - Olak study site, Teshekpuk Lake Special Area, NPR-A, Alaska, 2007.

Species N Mean concealment ± 1 SE

Lapland Longspur 76 61.84 ± 3.00

Semipalmated Sandpiper 20 19.00 ± 3.55

Pectoral Sandpiper 17 14.12 ± 2.98

Red Phalarope 13 12.31 ± 4.69

Long-billed Dowitcher 12 17.50 ± 4.94

38

Appendix 1. Greater White-fronted Goose nesting success at the Teshekpuk Lake – Olak Study

site, Teshekpuk Lake Special Area, NPR-A, Alaska, 2007.

Objective: To provide the North Slope Borough with an estimate of Greater White-fronted

Goose nesting success at the Teshekpuk Lake - Olak study site in 2007.

Summary: We discovered and monitored 15 Greater White-fronted Goose nests within our study

area in June/July of 2007 following the methodology described in this report (see pgs. 8-10).

Most nests (n = 10) were discovered incidentally off of our study plots. At nine nests, chicks

successfully hatched while eggs at six nests were likely depredated. Two of the depredated nests

were believed to have failed because observers inadvertently led avian predators (in all cases,

Parasitic Jaegers) to the nests during nest monitoring visits. Including all nests, the Mayfield

estimate of nest success was 0.39 with a daily survival rate of 0.963 ± 0.015 SE. Excluding nest

that failed due to observers, the Mayfield and daily survival rate estimates are: 0.51 and 0.973 ±

0.0135 SE.

Map of nest locations:

Please contact Joe Liebezeit (jliebezeit@wcs.org) if you would like a copy of the raw data for

these nests. The raw data includes: nest location coordinates, nest discovery date, nest visit

dates, number of eggs/young, fate, and nest initiation date.

39

Appendix 2. Redpoll nest site habitat characteristics in 2007

Objective: To increase our knowledge of the breeding biology life history characteristics of

Hoary and Common Redpolls (Carduelis spp.) on the arctic coastal plain of Alaska.

Summary: In addition to our main

project objectives, we also

assessed redpoll nest microsite

habitat characteristics. We

conducted nest searches for redpoll

nests along both banks of

Wyoming Creek in riparian habitat

on 14 July of 2007 (See map). We

discovered five nests that were

believed to be active in 2007 but

were inactive when found. All

nests were in willows (Salix spp).

We were unable to assess nest fate

or estimate nest survivorship since

all nests found were discovered

when inactive.

We collected information

on both vegetative and physical characteristics at each nest location (nest site scale). This

information is summarized in the table below. For a more detailed description of the field

methodology contact Joe Liebezeit (jliebezeit@wcs.org).

Summary of nest & habitat characteristics at redpoll nests (mean ± SE). Teshekpuk Lake - Olak

study site, Teshekpuk Lake Special Area, NPR-A, Alaska, 2007.

Variable

N Metric

Nest height (m) 5 0.44 ± 0.15

Cup diameter - exterior (cm) 5 11.70 ± 1.22

Cup diameter – interior (cm) 5 5.90 ± 0.46

Cup height (cm) 5 6.20 ± 0.86

Cup depth (cm) 5 3.74 ± 0.37

Overhead nest concealment (%) 5 46.00 ± 12.08

Lateral nest concealment (%) 5 61.50 ± 9.37

Nest substrate height (m) 5 0.99 ± 0.16

Nest patch area (m2) 4 144.88 ± 138.40

Distance to Wyoming Creek (m) 5 8.16 ± 2.83

Aspect (º) 5 138.80 ± 44.19

Slope (º) 5 55.60 ± 32.04