SREL Reprint #2109

 

 

 

 

Behavioural, thermal, and metabolic characteristics of a wintering lizard (Anolis carolinensis) from South Carolina

T. A. JENSSEN, J. D. CONGDON, R. U. FISCHER, R. ESTES, D. KLING, S. EDMANDS, and H. BERNA

Savannah River Ecology Laboratory, Drawer E, Aiken, SE 29802, USA

Summary

1. Anolis carolinensis, the most northerly distributed member of its neotropical genus, does not hibernate, but facultatively basks during days with direct sunlight throughout the December to March period.
2. Both sexes were primarily inactive (92% of emerged time), infrequently foraging (6.4%), interacting socially (1 .3%), or responding to predator threats (<0.1%).
3. Because subjects infrequently moved (averaging 2 cmh-1), apparent thermoregulatory behaviour (i.e. sun/shade shuttling) was rarely observed.
4. Body (Tb) and concurrent air (Ta) temperature relationships for emerged lizards maximum Tbs range of 33-34ºC, a mean Tb of 23ºC, and a mean Tb - Ta differential of 2.4ºC (ranging up to 15ºC).
5. Several criteria characterized winter A. carolinensis as being passive, thermal generalists.
6. Mean monthly oxygen uptake for wintering A. carolinensis was estimated at 0.924 (December), 0.686 (January), 0.884 (February), and 1.118 (March) M1 g-1 day-1.
7. The total estimated energy expenditure for the four months by the average male (3·8 g body mass) and female (2·9 g body mass) was 1·99 and 1·52 kcal, respectively, which is equivalent to 0·21 and 0·16 g of lipid metabolized, respectively (~6% of body mass).
8. Compared to metabolic rates at the species' 32-35 ºC preferred Tb range, the 23ºC average Tb of emerged lizards represented a 60% reduction in energy expenditure. We speculate that the observed basking Tbs reflect an adaptive trade-off between nonbasking Tbs for minimum metabolic costs and optimally high Tbs to facilitate physiological processes (e.g. gonadal recrudescence), but at a threat to lipid reserves.

Key-words: Energetics, seasonality, social behaviour, thermal regulation, time-budget profile

SREL Reprint #2109

Jenssen, T.A., J.D. Congdon, R.U. Fischer, R. Estes, D. Kling, S. Edmands, and H. Berna. 1996. Behavioural, thermal, and metabolic characteristics of a wintering lizard (Anolis carolinensis) from South Carolina. Functional Ecology 10:201-209.

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