Environmental and ecological conditions at Arctic breeding sites have limited effects on true survival rates of adult shorebirds
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Full Publication: https://doi.org/10.1642/AUK-17-107.1Product Type: Journal Article
Year: 2018
Authors: Weiser, E. L., R. B. Lanctot, S. C. Brown, H. R. Gates, R. L. Bentzen, J. Bêty, M. L. Boldenow, W. B. English, S. E. Franks, L. Koloski, E. Kwon, J-F. Lamarre, D. B. Lank, J. R. Liebezeit, L. McKinnon, E. Nol, J. Rausch, S. T. Saalfeld, N. R. Senner, D. H. Ward, P. F. Woodard, and B. K. Sandercock
Suggested Citation:
Weiser, E. L., R. B. Lanctot, S. C. Brown, H. R. Gates, R. L. Bentzen, J. Bêty, M. L. Boldenow, W. B. English, S. E. Franks, L. Koloski, E. Kwon, J-F. Lamarre, D. B. Lank, J. R. Liebezeit, L. McKinnon, E. Nol, J. Rausch, S. T. Saalfeld, N. R. Senner, D. H. Ward, P. F. Woodard, and B. K. Sandercock. 2018. Environmental and ecological conditions at Arctic breeding sites have limited effects on true survival rates of adult shorebirds. The Auk 135(1):29-43. doi:10.1642/AUK-17-107.1
Abstract
Many Arctic shorebird populations are declining, and quantifying adult survival and the effects of anthropogenic factors is a crucial step toward a better understanding of population dynamics. We used a recently developed, spatially explicit Cormack-Jolly-Seber model in a Bayesian framework to obtain broad-scale estimates of true annual survival rates for 6 species of shorebirds at 9 breeding sites across the North American Arctic in 2010-2014. We tested for effects of environmental and ecological variables, study site, nest fate, and sex on annual survival rates of each species in the spatially explicit framework, which allowed us to distinguish between effects of variables on site fidelity versus true survival. Our spatially explicit analysis produced estimates of true survival rates that were substantially higher than previously published estimates of apparent survival for most species, ranging from S = 0.72 to 0.98 across 5 species. However, survival was lower for the arcticola subspecies of Dunlin (Calidris alpina arcticola; S = 0.54), our only study taxon that migrates through the East Asian-Australasian Flyway. Like other species that use that flyway, arcticola Dunlin could be experiencing unsustainably low survival rates as a result of loss of migratory stopover habitat. Survival rates of our study species were not affected by timing of snowmelt or summer temperature, and only 2 species showed minor variation among study sites. Furthermore, although previous reproductive success, predator abundance, and the availability of alternative prey each affected survival of one species, no factors broadly affected survival across species. Overall, our findings of few effects of environmental or ecological variables suggest that annual survival rates of adult shorebirds are generally robust to conditions at Arctic breeding sites. Instead, conditions at migratory stopovers or overwintering sites might be driving adult survival rates and should be the focus of future studies.
Keywords: shorebirds, survival, climate change
Annotation
Estimates of adult shorebird annual survival were generally high after accounting for imperfect detection and permanent emigration. Survival was affected by local conditions in only a few cases, suggesting that either conditions elsewhere in the annual cycle are more influential, or other variables such as food availability, habitat quality, or disease might be more important than previously thought. However, as conditions continue changing in the Arctic, it is possible that the variables we tested may become more influential as conditions are pushed past the climatic niche in which our study species evolved. More extreme conditions than those we measured, including conditions expected to arise as a result of climate change, could still affect adult survival rates.