Temperature Rhythms in African Montane Sunbirds

SUMMARY The thermoregulation of Nectarinia tacazze, N. famosa, N. mediocris and Anthreptes collaris was studied at three localities in the Cherangani mountains, Kenya. Most of the experiments were conducted at an altitude of 3,350 m. These sunbirds were found to have a diel temperature rhythm with ranges of 5o‐17oC, an adaptation for survival in the severe temperature regimes characteristic of high altitudes in Africa. The only other passerine birds in which regular temperature changes of this magnitude have been recorded are three members of the Hirundinidae. For Zosterops senegalensis and male N. mediocris a significant difference was found between the weights of birds caught at 2,690 m and those from 3,350 m.