Seasonal Shifts in Habitat Choice of Birds in the Sahel and the Importance of ‘Refuge Trees’ for Surviving the Dry Season

Every year, hundreds of millions migratory birds cross the Sahara to spend northern winter in Sahel. After their arrival September region does not receive any rainfall until June while temperatures increase. Birds inhabiting Sahel have several strategies cope with this seasonal advent drought. Most ground-foraging and arboreal migrants actually remain desiccating Sahel, although Northern Wheatear Oenanthe oenanthe remains arid zone only a wet but moves from semi-arid dry year. Some stay for 1–2 months during early season, move on more humid further south rest winter. Common Redstart Phoenicurus phoenicurus is Sahelian migrant that southward period. Counter-intuitively, Curruca species northward after season where they concentrate woody plant whose attractiveness increases later season. This either because those plants then gain berries (Toothbrush Tree Salvadora persica) or develop flowers (six desert species). In zone, tree-dwelling bird disappear tree when these lose leaves. However, which do shed leaves, numbers constant (those using Desert Date Balanites aegyptiaca) increase Winter Thorn Faidherbia albida, foliates season). On floodplains acacia trees As consequence, become concentrated fewer shrub rainy seasons, leaves them later, giving foraging space. At end Africa number half suggesting higher mortality years. Clearly, such years would be even without what can seen as ‘refuge trees’: acacias floodplains, lesser degree