Comparative thermoregulatory adaptations of southern African tree squirrels from four different habitats

Abstract

Energy metabolism was investigated for Funisciurus congicus from arid savanna in north-western Namibia, Paraxerus cepapi cepapi from woodland savanna in central southern Africa, P. palliatus tongensis from mesic eastern coastal forest and P. p. omatus from evergreen subtropical forest. They are all adapted to hot regions and oxygen consumption was lower than the expected Brody-Proctor prediction. F. congicus had the highest thermal conductance. The two forest squirrel species showed heat stress at T_a 34°C contrary to the two savanna species. RMR for F. congicus was 0,85 ml O₂lg h, the same as for P. p. tongensis which is twice its mass, and it was 0,65 ml 0₂lg h and 0,71 ml O₂lg h for P. c. cepapi and P. p. omatus respectively. All four species maintained T_b ≤ 39°C at T_a from 12-32°C.