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 analyzed 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 following 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 behavior 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 Conclusion: 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.

Database of Snake Home Range Sizes

Database of snake home ranges compiled by the authors from the literature through 2018 in CSV format. The database also includes body masses, home range estimates (by sex, where available), the number of IUCN habitats recorded for each species, the proportion of IUCN habitats that are aquatic, and the following information for each study site: location coordinates, elevation, Net Primary Productivity, total annual precipitation, and mean annual temperature. The metadata describing the values and their units as well as the full list of references for the database are provided in the README.txt file.

File Names:
'todd_and_nowakowski_snake_home_range_full_dataset.csv'
'README.txt'

Subsets of Data and R Code for Re-creating the Analyses and Results

Three subsets of the main database were created in CSV format for analysis depending on the response metric of interest as described in the associated paper. The R code provided here references the three CSV files as named and will recreate the results reported in the associated manuscript published at Global Ecology and Biogeography.

File Names:
'Snake_HR_Ratios.csv'
'Snake_HR_woSex.csv'
'Snake_HR_wSex.csv'
'SnakeHR_LMM_PLMM.R'