Preliminary Insights on the Spatial Ecology, Population Demography, and Sexual Dimorphism of the Critically Endangered Sulawesi Forest Turtle (Leucocephalon yuwonoi)

Abstract. Sulawesi Forest Turtles (Leucocephalon yuwonoi) are critically endangered and endemic to the island of Sulawesi. We conducted radiotelemetry and capture–mark–recapture to study their spatial ecology, habitat selection, activity patterns, and demography in February–April and June–July, 2019. The average area occupied by 14 turtles using the minimum convex polygon (MCP) method was 0.49 ± 0.42 ha (standard deviation [SD]), whereas using the fixed 50% kernel density method averaged 0.076 ± 0.061 ha (SD). Males (mean = 0.53 ± 0.40 ha, N = 7) occupied a larger area (MCP method) than females (mean = 0.44 ± 0.46 ha, N = 7) but the difference was not statistically significant. Turtles took refuge in habitat containing significantly more canopy cover, broadleaf plant cover, and more and deeper ground cover than that in random plots. Males were predominantly active at night and females were exclusively so. We caught 25 adult females, 16 adult males, and 38 unsexed juveniles in two stream sections. Estimated population size (95% confidence intervals) in the lower stream was 17 turtles (15–28) in the wet season and 10 turtles (8–21) in the dry season. The population estimate in the upper stream was 25 (24–33) and 13 (9–28) turtles in the wet and dry seasons, respectively. Our study provides important baseline ecological data that can be used to inform future conservation and recovery programs for the species.