Increasing Shrubs Mean Changes for Some but Not All Arctic Birds

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Scientists can now predict which avian species are most sensitive to the increasingly dominant shrub habitat spreading across Alaska, a capability that will be useful for natural resource agencies in Alaska charged with managing these resources.

A small yellow bird being held in someone's hands.
(Credit: Rachel M. Richardson, U.S. Geological Survey, Public domain)

The U.S. Geological Survey research examines the tolerance of 17 tundra-breeding birds to climate-driven changes in ground covering shrubs.

“We found that increases in shrub cover and density will negatively affect abundance of only a few tundra-reliant species, but potentially benefit others,” said Sarah Thompson, a Research Wildlife Biologist with the USGS and lead author of the study. “However, the results also suggest that as shrub height increases further, tundra birds will likely find habitat increasingly unsuitable.”

The USGS conducted over 200 surveys of birds and their habitats on the Seward Peninsula of Alaska between 2012 and 2014. In total, over 10,000 birds of 68 species were counted and recorded. The study then examined which components of increasing shrub dominance might have the greatest effect on future distribution and abundance of tundra-breeding birds. 

“Although one might predict that more shrubs means more birds, our findings suggest that even species that prefer or rely on shrub habitats have limits,” said Colleen Handel, a USGS Research Wildlife Biologist and co-author of the study. “Our results suggest that we will see short-term increases in abundance of many bird species, but as shrubs become increasingly dominant, many shrub-tolerant species may eventually be displaced.”

Results of the new research suggest that increases in shrub height and density in some parts of the landscape will negatively affect the abundance of numerous species (e.g., bristle-thighed curlew and arctic warbler) and be beneficial for others (e.g., bluethroat and yellow warbler).

Arctic Warbler
(Credit: Rachel M. Richardson, U.S. Geological Survey, Public domain)

The new publication entitled, “When winners become losers: predicted nonlinear responses of Arctic birds to increasing woody vegetation” is published in the journal PLoS ONE. http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0164755

Additional information about wildlife and habitat research in Alaska