The Ability of Arctic Shorebirds to Adapt to a Warming Climate

The cover of Ecological Monographs featuring a Semipalmated Sandpiper from Utqiaġvik.

Phenological mismatch occurs when the timing of life-cycle events in interacting species (such as an animal and its food source) change at different rates. These changes can occur for a variety of reasons, including climate change. As the Arctic warms, and places across the Arctic are warming at different rates, vegetation and insects are sometimes growing at a different time of year than what other animals expect. Shorebirds come to the Arctic to nest and raise their chicks, in part because of the plentiful insects there. The arrival of migratory shorebirds in the Arctic and hatching of chicks has evolved to coincide with snowmelt and insect emergence, respectively. But what if the timing of the insect boom changes, and it no longer coincides with when the chicks hatch?

This study looked at sites distributed across the North American Arctic, from Nome and Cape Krusenstern in the west to East Bay and Churchill on Hudson Bay, and examined six species of Arctic-nesting shorebirds. We found that, in some cases, populations of insects that shorebirds adults and chicks eat peaked before the chicks hatched, resulting in a reduction in food availability for these birds. The degree to which the insect availability and demand for insects by chicks were offset varied by location and species. In general, shorebirds in the eastern Arctic regions and higher latitudes experienced the most change. If the degree of mismatch is small, birds may be able to adapt, but if the mismatch is too large or occurs too rapidly, the birds may not be able to respond and their population may decline. Our results suggest that Arctic-breeding shorebirds may be inherently limited in their ability to adapt to climate change, and some species in the eastern North American Arctic are already experiencing regional declines related to environmental change.

Geographic variation in the intensity of warming and phenological mismatch between Arctic shorebirds and invertebrates

Abstract

Responses to climate change can vary across functional groups and trophic levels, leading to a temporal decoupling of trophic interactions or phenological mismatches. Despite a growing number of single‐species studies that identified phenological mismatches as a nearly universal consequence of climate change, we have a limited understanding of the spatial variation in the intensity of this phenomenon and what influences this variation. In this study, we tested for geographic patterns in phenological mismatches between six species of shorebirds and their invertebrate prey at 10 sites spread across ~13° latitude and ~84° longitude in the Arctic over three years. At each site, we quantified the phenological mismatch between shorebirds and their invertebrate prey at (1) an individual‐nest level, as the difference in days between the seasonal peak in food and the peak demand by chicks, and (2) a population level, as the overlapped area under fitted curves for total daily biomass of invertebrates and dates of the peak demand by chicks. We tested whether the intensity of past climatic change observed at each site corresponded with the extent of phenological mismatch and used structural equation modeling to test for causal relationships among (1) environmental factors, including geographic location and current climatic conditions, (2) the timing of invertebrate emergence and the breeding phenology of shorebirds, and (3) the phenological mismatch between the two trophic levels. The extent of phenological mismatch varied more among different sites than among different species within each site. A greater extent of phenological mismatch at both the individual‐nest and population levels coincided with changes in the timing of snowmelt as well as the potential dissociation of long‐term snow phenology from changes in temperature. The timing of snowmelt also affected the shape of the food and demand curves, which determined the extent of phenological mismatch at the population level. Finally, we found larger mismatches at more easterly longitudes, which may be affecting the population dynamics of shorebirds, as two of our study species show regional population declines in only the eastern part of their range. This suggests that phenological mismatches may be resulting in demographic consequences for Arctic‐nesting birds.

Kwon, E., E. L. Weiser, R. B. Lanctot, S. C. Brown, H. R. Gates, G. Gilchrist, S. J. Kendall, D. B. Lank, J. R. Leibezeit, L. McKinnon, E. Nol, D.C. Payer, J. Rausch, D. J. Rinella, S. T. Saalfeld, N. R. Senner, P. A. Smith, D. Ward, R. W. Wisseman, and B. K. Sandercock. 2019. Geographic variation in the intensity of warming and phenological mismatch between Arctic shorebirds and invertebrates. Ecological Monographs 89(4):e01383. 10.1002/ecm.1383