Evaluating environmental drivers and synchrony of Arctic shorebird demographic rates to inform conservation management

Abstract

Many Arctic-breeding shorebirds are assumed to be declining, yet obtaining reliable estimates of species' demographic rates and trends is difficult because of challenges collecting data in remote breeding regions and throughout the annual cycle. For many vulnerable species, data limitations impede efforts to determine appropriate management actions in the face of ongoing environmental change. Integrated population models (IPMs) offer an approach to maximize the utility of available data by providing a framework for estimating demographic rates and environmental drivers of population change, while also accounting for sources of uncertainty. Here, we used an IPM to estimate demographic rates, synchrony, and population trends of Arctic-breeding shorebirds within the context of climatic and management-related changes. We estimated species-specific breeding population sizes, adult survival rates, number of adults gained into the breeding population through recruitment (i.e., the sum of immigration and reproduction), as well as the effects of environmental drivers on demographic traits for three shorebird species nesting near Utqiaġvik, Alaska, over an 18-year study period (2005–2022). We found that the annual number of adults recruiting into the breeding population was important for maintaining local populations, and that local environmental factors and management regimes had strong effects on demographic rates. The timing of snowmelt had a notable effect on (1) fecundity, (2) the number of adults recruited for two of the three species, and (3) adult survival during the following year for one species. Predator removal increased fecundity of all three species but had limited effects on subsequent local population sizes. The Pacific Decadal Oscillation, a broad-scale climate metric, affected adult survival differently across species, with a positive and negative effect for one species each, and a negligible effect for the other. Unlike adult recruitment and fecundity that varied synchronously among species, annual adult survival varied asynchronously. Our results suggest that differences in survival were likely related to conditions experienced during nonbreeding periods arising from dissimilar migratory routes, stopover sites, and nonbreeding season ranges. Future work should focus on incorporating additional environmental factors on the nonbreeding grounds to determine when and where these species could benefit most from management interventions.