Meeting Abstract

S10.3  Friday, Jan. 7  Heterothermy in Afrotropical mammals and birds: a review MCKECHNIE, A.E.*; MZILIKAZI, N.; Univ. of Pretoria; Nelson Mandela Metropolitan Univ. aemckechnie@zoology.up.ac.za

Recent years have seen a rapid increase in the number of Afrotropical endotherms known to use daily torpor and/or hibernation to avoid mismatches between energy supply and demand. Among non-volant mammals, heterothermy has been observed in nineteen species representing eight families in five orders, namely Primates, Macroscelidea, Afrosoricida, Eulipotyphla and Rodentia. These species span a body mass range of 13 – 770 g, with heterothermic body temperatures ranging from 1 – 27°C and bout length varying from 1 hour to 8 days. Daily torpor was the most commonly observed form of heterothermy, with true hibernation observed in only three species, Graphiurus murinus, Atelerix frontalis and Cheirogaleus medius. Several species exhibit sun-basking behaviour when rewarming. The traditional distinction between daily torpor and heterothermy is blurred in some species, with free-ranging individuals exhibiting bouts of > 24 hrs and body temperatures < 16°C but none of the classical behaviours associated with hibernation. Heterothermy has been reported in Afrotropical bats representing four families, with at least one species (Tadarida aegyptiaca) exhibiting prolonged, multiday bouts similar to those of Australasian tree-roosting species. Among Afrotropical birds, heterothermy is known from six currently-recognized orders, including the Piciformes, Coliiformes, Strigiformes, and Passeriformes, and in species ranging in body mass from 7 – 150 g. Ecological correlates of heterothermy may vary within species; lunar phase was the strongest predictor of the depth of winter torpor bouts in Caprimulgus tristigma inhabiting a winter rainfall desert, whereas no such relationship was evident at a cooler, more mesic summer rainfall site.