Breeding biology and success of the Western Reef Heron Egretta gularis on Nakhiloo Island, Persian Gulf

A study of the breeding performance of the Western Reef Heron Egretta gulariswas carried out on Nakhiloo Island in the Persian Gulf from March to September 2008. Atotal of 92 pairs nested on the island in four colonies. The breeding success during theincubation, nestling and post-nestling stages was 62.1%, 46.4% and 39.2%, respectively.Overall breeding success (the proportion of eggs laid that were successfully reared tofledging) was 39.2%, for 60 fledglings (N=153 eggs). Predation on eggs by Black RatsRattus rattus, high temperatures and desertion due to unknown reasons were the mostimportant causes of breeding failure. The average weight of the chicks was 22.19±0.61 g at hatching and 590±10 g at fledging.