Factors Influencing Behavior and Success of Foraging Reddish Egrets (Egretta rufescens)

摘要

The Reddish Egret (Egretta rufescens) is the rarest and least studied species of heron in North America and is a species of conservation concern throughout its range. Foraging behavior and foraging success of the Reddish Egret were studied by focusing on whether their foraging behavior or success varied with age, color morph, group size, and habitat measures. Foraging individuals (n = 372) were video-recorded in the Laguna Madre of Texas, USA, from March 2008-April 2010. Adult Reddish Egrets were 30-250% more successful foragers than juveniles, and groups were 32-44% more successful foragers than solitary foragers. Foraging success was similar between color morphs. The more specialized foraging behaviors of canopy feeding, wing flicking, and foot-stirring had the highest success, but were employed infrequently. Four environmental variables (wind speed, light intensity, water depth, and percent seagrass coverage) were found to influence foraging success, but accounted for only 3% of the variation in foraging behavior. Our results suggest that environmental variables have little influence on foraging behavior of Reddish Egrets in the Laguna Madre, and we suggest that characteristics of the prey have a stronger influence. An understanding of how environmental variables influence foraging behavior and success may allow us to better assess habitat quality or possibly aid in identification of highly productive foraging sites and allow for more targeted conservation actions to those habitats that promote high foraging success