Distribution of the endemic Uluguru Bushshrike Malaconotus alius and Loveridge’s Sunbird Cinnyris loveridgei in the Uluguru Nature Forest Reserve, Tanzania

Abstract

The Uluguru Nature Forest Reserve (UNFR) in the Eastern Arc Mountains of Tanzania is a vital biodiversity hotspot housing unique flora and fauna. This study focused on two endangered bird species, the Uluguru Bushshrike (UBS) Malaconotus alius and Loveridge’s Sunbird (LS) Cinnyris loveridgei, which are endemic to the UNFR. During a 2006–2007 survey, 387 individual birds representing 31 species were recorded, of which 19% were classified as threatened. UBS and LS constituted significant proportions of the total observations. Within the surveyed area of 9 km², 59 UBS and 79 LS were recorded, and extrapolations to the entire UNFR (241 km²) return population sizes of ∼1 236 UBS and ∼1 935 LS individuals, underscoring their vulnerability. Altitude, canopy height and canopy cover influenced species distribution. UBS predominantly occupied altitudes between 1 200 and 1 800 metres, whereas the LS ranged from 1 200 to 2 400 m. Canopy height was positively correlated with UBS sightings in the 30–40 m range. LS was weakly correlated with canopy cover, indicating that it can occur across a gradient of canopy covers from open to closed. Because there is virtually no forest left in the lower montane region, the forested altitudinal range with its diverse canopy structures should be conserved to ensure the survival of endemic forest species in the UNFR.