Ectothermy And The Macroecology Of Home Range Scaling In Snakes

Aim A central question in ecology has been that of why animal home ranges scale more steeply with body size than do metabolic rates. Yet, the generality of this notion has scarcely been tested in non-model species like ectotherms, which have lower metabolic requirements than endotherms and which may, therefore, have different home range area requirements. Our aim was to examine how home range area scales with body size in snakes and to shed light on how other factors may shape home range area requirements in an understudied group of ectotherms.Location Global.Time period 1984-2018.Major taxon studied Serpents.Methods We compiled and analysed a dataset of snake home ranges from the literature to evaluate how body size, sex, climate, foraging ecology, and biogeographic factors shape home range area requirements.Results Home range area scaled more gradually with body size in snakes (log-linear slope of simple linear regression 0.72 with 95% confidence interval 0.48-0.96) than has been reported for mammals and birds, and instead more closely followed the scaling of metabolic rates with body size. Male snakes had larger home ranges than females and this difference increased as temperature increased at a study site, possibly from mate-searching behaviour of males and greater ease reaching optimal body temperatures in warmer areas. Finally, home range area scaled more steeply for snakes that forage actively than for those that rely on sit-and-wait ambush foraging, a reflection of their foraging ecology.Main conclusions Our results question the general notion that animal home range areas scale more steeply with body size than does metabolism. Key distinctions in the energy demands of endotherms and ectotherms and their responses to those demands give rise to differing home range area requirements. More attention to non-model species is needed when creating and evaluating ecological theory.