Contrasting Fattening Strategies in Related Migratory Species: The Blackcap, Garden Warbler, Common Whitethroat and Lesser Whitethroat

Abstract

Related species showed different strategies when migrating south towards wintering grounds in the Sahel and southern Africa: the garden warbler steadily increased fuel reserves along the migration route, the blackcap showed mixed fattening strategy with high fat reserves just before the Sahara crossing, the common whitethroat accumulated large fat reserves well in advance (North Mediterranean) before crossing this barrier, while the lesser whitethroat starting from the northern part of the Mediterranean showed a stable level of fat reserves. Results of this study support the hypothesis that species-specific ecology, rather than phylogenetic relationships, plays the major role in the evolution and form of bird migration. There were also population-specific differences in the strategy of species based on migration distance (blackcap), as well as individual differences where some individuals of the same species were potentially able to cover larger distance than conspecifics (blackcap, common whitethroat).