Migration, moult and climate change in barn swallows Hirundo rustica in South Africa

Phenological change in long-distance migratory birds has responded less to climate change than that in short-distance migrants and residents. A general lack of information about the timing of migration in the winter quarters has prevented progress in interpreting the causes. Here we report long-term information on first arrival of barn swallows Hirundo rustica to-and last departure from-a major roost in South Africa during 1993-2010, a period when climate change at the breeding grounds was particularly pronounced. Although first arrival in autumn advanced by more than 2 wk, there was a tendency for a delay in last departure during spring, suggesting that cues for earlier spring departure from the winter quarters were missing. During 1999-2009, timing of moult was delayed, which may explain why spring migration by trans-Saharan migratory birds did not advance in this period.