Predicting breeding shorebird distributions on the Arctic Coastal Plain of Alaska

Sarah T Saalfeld,Stephen C Brown,James A Johnson,Jonathan R Bart,David T Saalfeld,Brad A Andres,Richard B Lanctot

doi:10.1890/es12-00292.1

Abstract

The Arctic Coastal Plain (ACP) of Alaska is an important region for millions of migrating and nesting shorebirds. However, this region is threatened by climate change and increased human development (e.g., oil and gas production) that have the potential to greatly impact shorebird populations and breeding habitat in the near future. Because historic data on shorebird distributions in the ACP are very coarse and incomplete, we sought to develop detailed, contemporary distribution maps so that the potential impacts of climate‐mediated changes and development could be ascertained. To do this, we developed and mapped habitat suitability indices for eight species of shorebirds (Black‐bellied Plover [Pluvialis squatarola], American Golden‐Plover [Pluvialis dominica], Semipalmated Sandpiper [Calidris pusilla], Pectoral Sandpiper [Calidris melanotos], Dunlin [Calidris alpina], Long‐billed Dowitcher [Limnodromus scolopaceus], Red‐necked Phalarope [Phalaropus lobatus], and Red Phalarope [Phalaropus fulicarius]) that commonly breed within the ACP of Alaska. These habitat suitability models were based on 767 plots surveyed during nine years between 1998 and 2008 (surveys were not conducted in 2003 and 2005), using single‐visit rapid area searches during territory establishment and incubation (8 June–1 July). Species‐specific habitat suitability indices were developed and mapped using presence‐only modeling techniques (partitioned Mahalanobis distance) and landscape environmental variables. For most species, habitat suitability increased at lower elevations (i.e., near the coast and river deltas) and decreased within upland habitats. Accuracy of models was high for all species, ranging from 65–98%. Our models predicted that the largest fraction of suitable habitat for the majority of species occurred within the National Petroleum Reserve‐Alaska, with highly suitable habitat also occurring within coastal areas of the Arctic National Wildlife Refuge west to Prudhoe Bay.

Highlights

The Arctic Coastal Plain (ACP) of Alaska encompasses several diverse landholdings including state and native corporation lands, the Arctic National Wildlife Refuge (ANWR), and the National Petroleum Reserve-Alaska (NPR-A), as well as the largest oil field in North America SAALFELD ET AL.(Prudhoe Bay Oil Field)
Summer temperatures on the ACP of Alaska usually range between 5–158C (National Research Council 2003, Martin et al 2009), with maximum summer temperatures averaging 88C (Gallant et al 1995)
We evaluated the accuracy of the habitat suitability maps by selecting threshold values so that we maximized predictive gain (Browning et al 2005)

Summary

Introduction

The Arctic Coastal Plain (ACP) of Alaska encompasses several diverse landholdings including state and native corporation lands, the Arctic National Wildlife Refuge (ANWR), and the National Petroleum Reserve-Alaska (NPR-A), as well as the largest oil field in North America SAALFELD ET AL.(Prudhoe Bay Oil Field). Current projection models based on a moderate emissions scenario (scenario A1B) for the ACP of Alaska predict a 1.68C increase in summer temperatures and 12% increase in summer precipitation by mid-century (i.e., 2051–2060) as compared to historic values (Martin et al 2009) These climate changes are likely to have profound impacts on physical and ecological variables (e.g., surface water, vegetation community, and insect community), which will in turn affect both shorebird habitats and populations on the ACP of Alaska. Development may enhance predator populations by providing denning and nesting sites, perch sites, and supplemental food (e.g., human garbage; National Research Council 2003, Liebezeit et al 2009)

Methods

Results

Conclusion