Demographic responses to climate change in a threatened Arctic species
Dunham, Kylee D. et al. (2022), Demographic responses to climate change in a threatened Arctic species, Dryad, Dataset, https://doi.org/10.5061/dryad.4qrfj6q88
The Arctic is undergoing rapid and accelerating change in response to global warming, altering biodiversity patterns and ecosystem function across the region. For Arctic endemic species, our understanding of the consequences of such change remains limited. Spectacled eiders (Somateria fischeri), a large Arctic sea duck, use remote regions in the Bering Sea, Arctic Russia, and Alaska throughout the annual cycle making it difficult to conduct comprehensive surveys or demographic studies. Listed as Threatened under the U.S. Endangered Species Act, understanding the species response to climate change is critical for effective conservation policy and planning. Here, we developed an integrated population model to describe spectacled eider population dynamics using capture-mark-recapture, breeding population survey, nest survey, and environmental data collected between 1992 and 2014. Our intent was to estimate abundance, population growth, and demographic rates, and quantify how changes in the environment influenced population dynamics. Abundance of spectacled eiders breeding in western Alaska has increased since listing in 1993 and responded more strongly to annual variation in first year survival than adult survival or productivity. We found both adult survival and nest success were highest in years following intermediate sea ice conditions during the wintering period, and both demographic rates declined when sea ice conditions were above or below average. In recent years sea ice extent has reached new record lows and has remained below average throughout the winter for multiple years in a row. Sea ice persistence is expected to further decline in the Bering Sea. Our results indicate spectacled eiders may be vulnerable to climate change and the increasingly variable sea ice conditions throughout their wintering range with potentially deleterious effects on population dynamics. Importantly, we identified that different demographic rates responded similarly to changes in sea ice conditions, emphasizing the need for integrated analyses to understand population dynamics.
Data were collected through a number of different methods and collated here for analysis in an integrated population model. Field collection methods include aerial survey data (waterfowl breeding pair survey), nest plot survey, and capture-mark-recapture. Details on processing are available in the "read_me" sheet within the "spei_data" excel file and in the forthcoming manuscript. Additional files include ".RDS" for the capture-history and multi-state m-array based on capture-mark-recapture data. Two R files are included with the code to load the data, the jags model, and the code to fit the jags model.
The ".RDS" files are ready to use as-is in an analysis of capture-mark-recapture data with state-assignment details in the accompanying code. Data in the excel files require minimal manipulation which is documented in the accompanying code.