The effect of nest site orientation on the breeding success of blue swallows Hirundo atrocaerulea in South Africa

Abstract

The globally threatened blue swallow Hirundo atrocaerulea, with <1500 pairs remaining, is an intra-African migrant, breeding in eight countries in East Africa and Southern Africa, with nonbreeding birds in four countries in East Africa. Blue swallows build an open cup-shaped nest out of mud and straw in an existing hole in the ground. An updated description of a blue swallow's nest site is that it is a hole in the ground, that faces in a region-specific direction that maximizes reproductive success, with a roof or overhang or vegetation sufficient to keep the rain off the nest and its contents. Blue swallow breeding success was significantly different between KwaZulu-Natal and Mpumalanga but, within each province, not between natural and artificial nest sites. Based on the number of fledglings per egg, blue swallow breeding success in Mpumalanga was best in north- and west-facing nest sites, and in KwaZulu-Natal, breeding success was best in north- and east-facing nest sites. Artificial nest sites should continue to be created for blue swallows that are north to west facing in Mpumalanga (and possibly in Swaziland), and north to east facing in KwaZulu-Natal