Green turtle (Chelonia mydas) hatching success at Raine and Heron Islands

Raine Island, the world's largest green turtle nesting location, has low nest hatching success. The main causes of this low hatching success are thought to be nest destruction by subsequent nesting females, and inundation of nests during high tides and storm surges. But even nests that are protected from nest destruction and inundation appear to have relatively low hatching success, with most of the embryo mortality occurring early in incubation. Here, I compare hatching success and developmental phase of embryo death of protected `dry' nests from Raine Island (RI) with similar nests from Heron Island (HI), a nesting location previously reported as having high hatching success. Nests at both sites were sampled close to the peak time of nesting (December). Twenty-eight nests were sampled at RI and 14 nests at HI. Nest temperatures were cooler during the first week of incubation at HI (median 26.9 degrees C) than at RI (median 30.1 degrees C), but three-days-in-a-row maximum nest temperatures were higher at HI (median 36.0 degrees C) than at RI (median 33.5 degrees C). I found the hatching success of sampled nests at both locations was similar, similar to 70%, but most embryo death occurred early in incubation at RI (median 16.5%) compared to HI (median 3.8%), but late in incubation at HI (median 4.9%) compared to RI (median 0.2%).