Evolution of chain migration in an aerial insectivorous bird, the Common Swift Apus apus

Evolution of chain migration in an aerial insectivorous bird, the Common Swift Apus apus

Evolution, 2020

Citation

Åkesson, S., Atkinson, P.W., Bermejo, A., de la Puente, J., Ferri, M., Hewson, C.M., Holmgren, J., Kaiser, E., Kearsley, L., Klaassen, R.H.G., Kolunen, H., Matsson, G., Minelli, F., Norevik, G., Pietiäinen, H., Singh, N.J., Spina, F., Viktora, L. & Hedenström, A. 2020. Evolution of chain migration in an aerial insectivorous bird, the Common Swift Apus apus. Evolution 74: 2377–2391. doi:10.1111/evo.14093
Swifts, by Philip Croft / BTO

Overview

The highly aerial Common Swift Apus apus, which spends the non‐breeding period on the wing, has been found to exhibit a rarely‐found chain migration pattern.

In more detail

Abstract

Spectacular long-distance migration has evolved repeatedly in animals enabling exploration of resources separated in time and space. In birds, these patterns are largely driven by seasonality, cost of migration, and asymmetries in competition leading most often to leapfrog migration, where northern breeding populations winter furthest to the south. Here, we show that the highly aerial common swift Apus apus, spending the nonbreeding period on the wing, instead exhibits a rarely found chain migration pattern, where the most southern breeding populations in Europe migrate to wintering areas furthest to the south in Africa, whereas the northern populations winter to the north. The swifts concentrated in three major areas in sub-Saharan Africa during the nonbreeding period, with substantial overlap of nearby breeding populations. We found that the southern breeding swifts were larger, raised more young, and arrived to the wintering areas with higher seasonal variation in greenness (Normalized Difference Vegetation Index) earlier than the northern breeding swifts. This unusual chain migration pattern in common swifts is largely driven by differential annual timing and we suggest it evolves by prior occupancy and dominance by size in the breeding quarters and by prior occupancy combined with diffuse competition in the winter.

Funding for instrumentation and fieldwork was provided by research grants to (SÅ) from the Trygger's Foundation (CTS 12:563) and the Swedish Research Council (621-2007-5930; 621-2010-5584; 621-2013-4361). Cost for geolocators in the United Kingdom was financed by the British Thrust for Ornithology via a grant from Action to Swifts. Geolocators used in Belgium and the Netherlands (3 + 1) were covered by LK from Belora vzw. Geolocators and fieldwork were financed by Fundación Ibedrola España in Spain. The Government of the Basque Country financed the tagging with geolocators of 20 common swifts. This study received support from the Centre for Animal Movement Research (CAnMove) funded by a Linnaeus grant from the Swedish Research Council (349-2007-8690) and Lund University.