Soil Type Impacts Macrohabitat Selection and Spatiotemporal Activity Patterns of Testudo graeca in an Eastern Mediterranean Ecosystem
Habitat preference is determined by complex interactions between biotic and abiotic habitat features and species-specific requirements. In many terrestrial organisms, studies of habitat preference emphasize the role of vegetation. Yet, in land-dwelling ectotherms, an often-overlooked characteristic that may have a strong effect on habitat preference is soil type. We followed 18 Spur-thighed Tortoises (Testudo graeca) mounted with radio transmitters to quantify their seasonal activity patterns, home-range sizes, and preferred habitats, including soil type. We used Maximum Entropy to quantify the spatial distribution of Testudo graeca in the study area based on species occurrence records and nine environmental variables derived from LiDAR. We describe for the first time a strong preference for soil type in Testudo graeca, as well as preference for flat terrain (avoidance of steep slopes). Individuals avoided areas with dense woody vegetation and chose habitats containing heterogeneous vegetation, including isolated trees, shrubs, and open patches. We further found that individuals in the study area do not hibernate but decrease activity in summer-autumn. Finally, home-range size was comparable between the sexes. The overlapping home ranges within and between the sexes throughout the year, including the mating season, suggest that this species is not territorial.

Number of observations of different individuals, males and females, throughout the study period.

Days of inactivity (average and standard deviation) for the radio-tagged tortoises during the radio-transmission period.

The average value ± standard error (across all ten models) of the percent contribution of different variables to the predictive power of MaxEnt models, which corresponds with their effect on tortoises' habitat preference.

A habitat-suitability map for tortoises in Ramat Hanadiv Nature Park, based on averaging MaxEnt suitability maps for a subset of ten tortoises mounted with radio transmitters (their occurrence locations are marked by circles, colored according to individual identity).

Home-range polygons of radio-tagged tortoises in the study area.
Contributor Notes
Associate Editor: D. S. Siegel.