Studying Arctic Shorebirds takes Collective Effort

Red-necked Phalarope hatchlings. USGS/Emily Weiser

The Arctic Shorebird Demographics Network was formed to bring together researchers across Arctic countries to study trends in shorebird populations. Data were collected from 16 sites across Alaska, Canada, and Russia, including a study site in Alaska's Cape Krusenstern National Monument. This recent paper presents the results of population models for six species: American Golden-Plover, Dunlin, Semipalmated Sandpiper, Western Sandpiper, Red-necked Phalarope, and Red Phalarope. The models predict population trajectories based on demographic rates from field research and documented in the literature. The power of the model is that it can evaluate which demographic variables have the strongest influence on changes in population size. They measured seasonal patterns in reproductive success, evaluated the effects of environmental and ecological conditions on reproduction, and estimated annual adult survival rates of breeding shorebirds.

The results of this study help identify species-specific trends as well as areas of uncertainty that need further exploration. Based on this information, more effective conservation actions and targeted study can be prioritized. For more information about the study findings and other contributions by the Arctic Shorebird Demographics Network, see this article from the American Ornithological Society.

Annual adult survival drives trends in Arctic-breeding shorebirds but knowledge gaps in other vital rates remain

Abstract

Conservation status and management priorities are often informed by population trends. Trend estimates can be derived from population surveys or models, but both methods are associated with sources of uncertainty. Many Arctic-breeding shorebirds are thought to be declining based on migration and/or overwintering population surveys, but data are lacking to estimate the trends of some shorebird species. In addition, for most species, little is known about the stage(s) at which population bottlenecks occur, such as breeding vs. nonbreeding periods. We used previously published and unpublished estimates of vital rates to develop the first large-scale population models for 6 species of Arctic-breeding shorebirds in North America, including separate estimates for 3 subspecies of Dunlin. We used the models to estimate population trends and identify life stages at which population growth may be limited. Our model for the arcticola subspecies of Dunlin agreed with previously published information that the subspecies is severely declining. Our results also linked the decline to the subspecies’ low annual adult survival rate, thus potentially implicating factors during the nonbreeding period in the East Asian–Australasian Flyway. However, our trend estimates for all species showed high uncertainty, highlighting the need for more accurate and precise estimates of vital rates. Of the vital rates, annual adult survival had the strongest influence on population trend in all taxa. Improving the accuracy, precision, and spatial and temporal coverage of estimates of vital rates, especially annual adult survival, would improve demographic model-based estimates of population trends and help direct management to regions or seasons where birds are subject to higher mortality.

Weiser, E. L., R. B. Lanctot, S. C. Brown, H. R. Gates, ... D. Payer, et al. 2020. Annual adult survival drives trends in Arctic-breeding shorebirds, but knowledge gaps in other vital rates remain. The Condor: Ornithological Applications 122: 1-14. DOI: 10.1093/condor/duaa026

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