Reproduction by great white herons Ardea herodias in Florida Bay as an indicator of habitat quality

Abstract

Reproduction parameters of great white herons Ardea herodias were used to evaluate the habitat quality of eastern Florida Bay. Clutch size and productivity of the herons during three breeding seasons were compared with similar data from 1923 which predated suspected human alteration of the Florida Bay ecosystem. In addition, since about 15% of the great white herons nesting in eastern Florida Bay supplemented their diet with food obtained from people, it was possible to evaluate the impact of food availability on reproduction. Herons that fed naturally in Florida Bay (unsupplemented) had significantly smaller clutches and produced significantly fewer fledglings than those of 1923. Herons that received supplemental food had reproductive parameters similar to those of 1923. We interpret these data as indicating that habitat quality is currently reduced from 1923 levels. These results support the prediction that wading bird reproduction can be sensitive to habitat quality and that these species should be useful as biological indicators for monitoring habitat quality.