Nonchalant neighbors: Space use and overlap of the critically endangered Elongated Tortoise

To prevent population extirpations, we need to understand a species' requirements, especially for critically endangered species inhabiting biodiversity hotspots. Studying animal movement provides necessary insights and gauges protected area effectiveness. Southeast Asian protected areas are becoming isolated, stressing the need for maintaining population viability. We used radio-telemetry with the critically endangered Elongated Tortoise (Indotestudo elongata) to assess: movements, space use, and conspecific overlap in a small protected area-Sakaerat Biosphere Reserve, Thailand. Movements were weakly seasonal, higher in hot and wet seasons than the dry season, and annual space use varied (4.24-55.57 ha), with conspecifics frequently overlapping. Conspecific comparisons revealed males (n = 5) moved similarly to females (n = 12) but used larger areas. Despite more instances of conspecific attraction over avoidance (20:8), avoidance/attraction behavior appeared disconnected from individual size; therefore, interaction patterns may result from resources locations (mates or food) rather than competition (i.e., no evidence of smaller individuals avoiding larger individuals). Female-female attraction suggests no resource exclusion tactics at our temporal resolution. Male-female attraction may indicate seasonal reproductive movements, but we could not detect significant interactive effects linking conspecific attraction or step length to breeding activity. Our observations of annual space use and overlap present critical components when designing robust population assessments underlining any successful I. elongata conservation effort. In the context of previous work connecting space overlap with population viability, our results suggest the biosphere population of I. elongata to be reproductive, with enough resources to be viable, emphasizing the importance of relatively small protected natural areas.

Automated summary

In order to prevent population extirpations, it is crucial to understand the requirements of species, especially those critically endangered species in biodiversity hotspots. Studying animal movement can provide important insights for assessing the effectiveness of protected areas. Our study of Elongated Tortoises in a small protected area in Thailand revealed weakly seasonal movements, varying space use, and frequent conspecific overlap, with attraction among individuals potentially influenced by resource locations.