Recently, I came across the answer to a conundrum that had baffled me for some time. When the management of the Sanctuary at Roche Caiman changed hands about two years ago, I became aware of the lack of frogs in the wetland that makes up most of this site. Surely, I thought, such a relatively large standing body of water that is continuously fed by rain should have amphibians. Obviously, so many Tilapia fish in the wetland ate all the tadpoles. But areas that seasonally filled up with water and where there are no fish, never attracted frogs.  At first I thought the run-off from the road and the nearby sports complex car park was having an impact.