Feeding behaviour of Great Blue Herons at Creston, British Columbia

Abstract

Great Blue Herons (Ardea herodias) at Creston, British Columbia, used three feeding behaviours: standing, walking slowly, and feetfirst diving. The prey taken differed with each behaviour. Standing herons took a higher proportion of active prey than herons walking slowly did; herons walking slowly took more sedentary prey than standing herons did. Herons diving feetfirst took dead and dying fish made available by a summer kill. The diet range of herons diving feetfirst was narrower than that of herons standing and walking slowly. The sizes and species of prey taken by herons reflected in part the abundance of prey. The gross and net energetic return of feetfirst diving was higher than that of walking slowly, which in turn was higher than that of standing. The herons appeared to be constrained from using more profitable feeding behaviours.