U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2013–3054

July 2013 PrPrinted on recycled paper inted on recycled paper

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Arctic and boreal ecosystems provide important breeding habitat 

for more than half of North America’s migratory birds as well 

as many resident species. Northern landscapes are projected to 

experience more pronounced climate-related changes in habitat 

than most other regions. These changes include increases in shrub 

growth, conversion of tundra to forest, alteration of wetlands, shifts 

in species’ composition, and changes in the frequency and scale 

of fires and insect outbreaks. Changing habitat conditions, in turn, 

may have significant effects on the distribution and abundance of 

wildlife in these critical northern ecosystems. The U.S. Geological 

Survey (USGS) is conducting studies in the Boreal–Arctic 

transition zone of Alaska, an environment of accelerated change in 

this sensitive margin between Arctic tundra and boreal forest. 

Through the Changing Arctic Ecosystems initiative, USGS 

strives to inform key resource decisions by providing scientific 

information on current and potential future ecosystem responses 

to a changing climate. As part of this initiative, the USGS is 

conducting a suite of studies in the Boreal–Arctic transition zone 

to evaluate (1) how the distribution, abundance, and community 

structure of breeding birds are related to climate-driven habitat 

conditions; (2) how rapidly the distributions of birds and their 

habitats are changing in this transition zone; and (3) how avian 

recruitment and survival are affected by climate and climatedriven habitat conditions. Results from these studies will be used 

to forecast which avian species, communities, habitats, and core 

geographic areas are likely to be most vulnerable to projected 

climate changes. This information will guide decisions for 

conserving biodiversity and help to discern the potential future of 

the Arctic tundra region.

Transition zone between boreal forest and Arctic and subarctic tundra 

in Alaska.

Example of long-term increase of shrubs in Arctic ecosystems. 

Photographs of the Nimiuktuk River watershed in 1950 and 

2008. Photographs provided by Ken Tape, University of Alaska 

Fairbanks.

Pacific Golden-Plover. 

Photograph taken by 

Ken Archer.

Changing Arctic Ecosystems

The Role of Ecosystem Changes Across the Boreal–Arctic Transition Zone on the Distribution and 

Abundance of Wildlife Populations

Nimiuktuk River watershed 1950

Nimiuktuk River watershed 2008

Photograph taken by Ken Tape

Photograph taken by U.S. Navy
Theme III - The Boreal–Arctic Transition Zone

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Alaska

Study area

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Proportion of survey locations

1988 2012

Non-shrub species (n = 4)

Low-medium shrub species (n = 4)

Tall shrub species (n = 11)

Changes in Distribution and Abundance of Terrestrial Birds 

Related to Climate-Driven Habitat Changes

Climatic changes already are causing significant shifts in 

vegetation and wildlife habitat across boreal and Arctic 

landscapes. In boreal forests, tree line is shifting northward and 

wildfires are increasing due to changes in seasonal weather. In 

tundra systems, shrub growth is accelerating due to changes 

in temperature and precipitation, increases in frequency and 

intensity of tundra fires, thawing of permafrost, changes in snow 

conditions, and increases in microbial activity due to increased 

soil temperatures. 

The USGS conducted surveys of landbirds and shorebirds over 

gradients of habitat conditions in the western Boreal–Arctic 

transition zone during 1988–92 and again in 2000. During 

2012–13, USGS scientists replicated these multispecies bird and 

habitat surveys, and will complete the surveys again in 2014. 

Historical and modern surveys will be used to quantify rates of 

change in occurrence of birds relative to changes in vegetation, 

identify key habitats for sensitive species, and build historical 

and contemporary distribution maps for species with varying 

habitat requirements and migration patterns.

Changes in Recruitment and Survival in Avian Populations 

Across the Boreal–Arctic Transition Zone

Wildlife populations are influenced by environmental factors 

through effects on their abilities to survive and reproduce, which 

ultimately determine their patterns of occurrence and abundance. 

Knowledge of these demographic processes is required to 

understand how well wildlife populations can adapt to changing 

environmental conditions. The USGS is evaluating relationships 

between environmental and ecological drivers, such as weather 

and vegetation, and the demographic responses of birds with 

diverse life histories. These data will be used to understand the 

ecological processes that govern patterns of avian abundance 

relative to climate change.

Forecasting Future Wildlife Communities and Distributions

Through the Changing Arctic Ecosystems initiative, the USGS is 

building new expertise in several novel analytical techniques to 

combine relevant climate 

data, scientific information, 

and expert knowledge to 

forecast future responses 

of wildlife populations 

to ecosystem change. 

Bayesian networks are 

being used to identify 

what information is most 

critically needed to predict 

how wildlife populations 

will respond to climate 

change. By combining 

spatially explicit ecosystem 

models with climate 

projections, the USGS is identifying key environmental variables 

that determine important wildlife habitat and is modeling 

predicted future distributions of wildlife populations.

During the past 25 years (1988–2012), songbirds associated with shrub 

habitats have increased across tundra on the Seward Peninsula, 

Alaska, based on a comparison of surveys completed during 1988 and 

repeated in 2012.

Authors: Lance McNew, Colleen Handel, John Pearce, 

Tony DeGange, Leslie Holland-Bartels, and Mary Whalen

For more information:

U.S. Geological Survey

4210 University Drive, Anchorage, AK 99508

http://alaska.usgs.gov

Publishing support provided by the U.S. Geological Survey

Tacoma Publishing Service Center

Lapland Longspur. 

Photograph taken by 

Ken Archer.

Predicted distribution and abundance of Lapland Longspur on the 

Seward Peninsula, Alaska, based on surveys completed during 2012.

Arctic Warbler. 

Photograph

taken by 

Ken Archer.