Low fitness at low latitudes: Wintering in the tropics increases migratory delays and mortality rates in an Arctic breeding shorebird
Loading...
Date
2019-10-04
Journal Title
Journal ISSN
Volume Title
Publisher
Journal of Animal Ecology
Abstract
1. Evolutionary theories of seasonal migration generally assume that the costs of
longer migrations are balanced by benefits at the non‐breeding destinations.
2. We tested, and rejected, the null hypothesis of equal survival and timing of spring
migration for High Arctic breeding sanderling Calidris alba using six and eight winter
destinations between 55°N and 25°S, respectively.
3. Annual apparent survival was considerably lower for adult birds wintering in tropical
West Africa (Mauritania: 0.74 and Ghana: 0.75) than in three European sites
(0.84, 0.84 and 0.87) and in subtropical Namibia (0.85). Moreover, compared with
adults, second calendar‐year sanderlings in the tropics, but not in Europe, often
refrained from migrating north during the first possible breeding season. During
northward migration, tropical‐wintering sanderlings occurred at their final staging
site in Iceland 5–15 days later than birds wintering further north or south.
Namibia‐wintering sanderlings tracked with solar geolocators only staged in West
Africa during southward migration.
4. The low annual survival, the later age of first northward migration and the later
passage through Iceland during northward migration of tropical‐wintering sanderlings,
in addition to the skipping of this area during northward but not southward migration by Namibia‐wintering sanderlings, all suggest they face issues during the
late non‐breeding season in West Africa.
5. Migrating sanderlings defy long distances but may end up in winter areas with
poor fitness prospects. We suggest that ecological conditions in tropical West
Africa make the fuelling prior to northward departure problematic.
Description
Research Article
Keywords
demography, fitness, migration, nutrient storage strategies, site fidelity, solar geolocation, survival, timing
Citation
Reneerkens J, Versluijs TSL, Piersma T, et al. Low fitness at low latitudes: Wintering in the tropics increases migratory delays and mortality rates in an Arctic breeding shorebird. J Anim Ecol. 2019;00:1–13. https ://doi. org/10.1111/1365-2656.13118