Mesangat Lake

For my MSc by Research, I provided information on the ecology and habitat use of juvenile endangered crocodilians in a disturbed wetland habitat, which can be used in preparation of a management plan for the area.

Using spotlight surveys and stomach contents analysis I examined ecological niche partitioning between juvenile Tomistoma schlegelii and Crocodylus siamensis in Mesangat Lake (Indonesia). The two species present in Mesangat Lake appear to use different habitats and nesting seasons, but share similar dietary niches.The overlap in diet suggests that, similar to many Crocodylus spp., juvenile T. schlegelii are generalist feeders. Conservation efforts need to focus on both of these endangered crocodilians and account for their interaction. Together the animals could act as flagship and umbrella species for large-scale habitat conservation in Mesangat Lake, an important site for crocodilians that is threatened by habitat change, especially the planting of oil palm.

I also experimentally investigated the ecological factors triggering ventral colour change observed in 23 wild juvenile T. schlegelii in Mesangat Lake, comparing greyscale values on ventral scale images of 5 captive crocodiles held under different light,temperature and background colour conditions. Ventral colour darkening in juvenile T. schlegelii is a response to increased levels of ambient light. This constitutes the first documented instance of physiological colour change in a crocodilian, and the first account of colour change in the ventral scales, yet the underlying evolutionary adaptive reason for this process is not clear.