Noteworthy 72% of the 83 arctic and alpine species have medium or high vulnerability to climate change. Temperature increases in the arctic in the last 50 years are twice that of the rest of the globe. Increases in temperature will result in major alterations to the abundance and distribution of surface water in the arctic and major vegetation changes in arctic and alpine regions, which will affect bird abundance and distribution. Timing of long distance migrations and food availability at migration stopovers and on breeding grounds may become mismatched.
	Image: Arctic National Wildlife Refuge courtesy USFWS

Observations and Predictions

Average annual temperatures will continue to rise over the next century. However, these increases are not uniform across the arctic. There is a greater temperature rise in Alaska (3-4°F in summer) than in the eastern Canadian arctic. As average annual temperatures rise and the permafrost thaws, the active soil layer becomes deeper. This allows the spread of trees and shrubs into tundra now composed of sedges, grasses, and dwarf shrubs, and will affect bird abundance and distribution.

Although highly variable, precipitation is increasing at a greater rate in the arctic than elsewhere around the globe and it is occurring primarily as rain. Precipitation will probably increase and warmer temperatures will result in higher evaporation, which will reduce soil moisture and reduce tundra wetlands in the western and central arctic. An increase in the number and extent of tundra fires will also alter these drier habitats.

Long-tailed Jaeger courtesy USFWS

Vulnerability of arctic and alpine birds is primarily due to their long-distance migrations, their obligatory use of these biomes, and the exposure of many arctic and alpine habitats to effects of climate change. Shorebirds, in particular, are dependent on arctic and alpine habitats for breeding. Habitat exposure was highest for alpine breeding species and those using low-elevation wet tundra. Simple interactions among bird species and their food resources increased sensitivity for some species. Because many arctic birds are long-distance migrants, these species could also experience climate change-induced alterations to the habitats they use at other times of the year, which might increase their overall exposure and vulnerability.

Of 83 arctic and alpine species, 72% are moderately or highly vulnerable to climate change.

Spectacled Eider courtesy USFWS

Melting permafrost may result in changes to surface water and plant communities, changing the distribution and abundance of waterfowl, shorebirds, and gulls. Melting permafrost may also release contaminants, such as mercury and organic pollutants, into the aquatic environment, exposing species such as the Spectacled Eider, Yellow-billed Loon, and Sabine’s Gull to new threats. Advancement of trees and shrubs will have dramatic effects on arctic and alpine breeding birds by narrowing or eliminating tundra and alpine breeding habitats used by species such as Surfbird, Black Turnstone, and Brown-capped Rosy-finch. As boreal forest birds expand into the arctic, new avian communities will develop. 

The earlier onset of spring might initially increase productivity of nesting shorebirds, although migration schedules of long-distance migrants would have to change so they raise their young at the time when the most insects are available. Changes in weather and tundra habitats could decrease the abundance of lemmings and their predators, such as jaegers and Snowy Owls. A decrease in lemmings could also cause predators to switch to eating other birds and their eggs. 

Ptarmigan by David Benson

Because of the exposure of low-elevation tundra and alpine zones to climate change effects, minimizing additional human-induced stresses on these habitats is necessary. Increasing the network of protected areas in the arctic should keep pace with any further industrial development there. 

Few monitoring systems are in place to understand the status of arctic and alpine birds and how they are responding to climate change during their annual cycle. Monitoring systems should be deployed to understand how arctic and alpine birds are responding to changing climatic conditions and what steps could be taken to offset negative effects. Reducing atmospheric carbon will be necessary to maintain arctic and alpine biodiversity. 

Conservation in Action
 

Arctic and alpine birds that rely on shrubs for breeding habitat will increase in these regions. Research and monitoring programs are being initiated in arctic regions to increase our understanding of how birds will respond to a changing climate and to develop effective conservation strategies. 

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