Foraging ecology of the Grey Heron (Ardea cinerea), Great Egret (Ardea alba) and Little Egret (Egretta garzetta) in response to habitat, at 2 Greek wetlands

We studied the responses of 3 heron species, Grey Heron (Ardea cinerea), Great Egret (A. alba) and Little Egret (Egretta garzetta) to different foraging habitats in 2 Greek wetlands of international importance, Lakes Mikri Prespa and Kerkini. These lakes are different in their hydrology, productivity and vegetation cover. Parameters of foraging tactics-such as strike rate, foraging effort expended per min and effort expended per strike-as well as parameters of foraging efficiency-such as striking efficiency, captures per unit effort and biomass intake per unit effort-were analyzed in relation to habitat and lake. Each species adopted different tactics and achieved variable efficiencies in response to the particular lake, habitat conditions and prey characteristics. Little Egrets revealed the greatest plasticity in their foraging repertoire, especially with regard to their mobility and prey preference. Great Egrets and Grey Herons consumed larger amounts of biomass per unit effort than did Little Egrets, with Great Egrets achieving the highest striking efficiency. Riverine habitats proved to be more profitable than marshes for all 3 species, while wet meadows seemed to play a complementary role for herons' foraging.