Survival fluctuation is linked to precipitation variation during staging in a migratory shorebird

Abstract

Understanding how weather conditions affect animal populations is essential to foresee population changes in times of global climate shifts. However, assessing year-round weather impacts on demographic parameters is hampered in migratory animals due to often unknown occurrence in space and time. We addressed this by coupling tracking and weather data to explain extensive variation in apparent survival across 19 years in a northern European population of little ringed plovers (Charadrius dubius). Over 90% (n = 21) of tracked individuals followed migration routes along the Indo-European flyway to south India. Building on capture-recapture histories of nearly 1400 individuals, we found that between-year variation in precipitation during post-breeding staging in northern South Asia explained 47% of variation in apparent adult survival. Overall, the intensity of the monsoon in South Asia explained 31-33% of variability in apparent survival. In contrast, weather conditions in breeding, final non-breeding and pre-breeding quarters appeared less important in this species. The integration of multi-source data seems essential for identifying key regions and periods limiting population growth, for forecasting future changes and targeting conservation efforts.

Figure 1

Distribution range of the little ringed plover (Charadrius dubius; light-coloured polygons) and the main regions (kernel density estimates; polygons) where tracked individuals (n = 21; dots and triangles) occurred during the main annual cycle periods (Table 1). Coordinates of the geographic positions (dots and triangles) represent modus of daily positions derived from geolocators. Lines connect geographic positions and do not reflect migratory routes.

Figure 2

Between-year variation in amount of precipitation (A) and near-surface mean air temperature (B) during four main annual cycle periods of little ringed plovers (Charadrius dubius). (C) Between-year variation in the amount of precipitation during monsoon period (July–September; relative values presented). (D) Between-year variation in apparent survival estimates of adult little ringed plovers (mean ± SE) estimated from the time dependent model (Table 2).

Figure 3

Apparent survival (with 95% confidence intervals) of little ringed plovers (Charadrius dubius) in relation to precipitation in the post-breeding staging region in South Asia (model ‘Precipitation post-breeding’ from Table 2). The annual estimates from the time dependent model are shown as dots.