THE FOOD OF THE HERON ARDEA CINEREA IN THE BREEDING SEASON.

Abstract

Summary. Food samples were collected from nestlings at three heronries by forcing them to regurgitate recent meals. Young Herons are fed about 3–4 times in 24 hours when one parent is feeding and about twice as often when both are feeding. Feeding is most frequent just after dawn and in the evening. It is estimated that a brood of Herons receives on the average 230 pounds of food during the nestling period. Herons select food between certain size limits, avoiding both very small and very large prey. The proportion of each species of prey was different at different heronries, correlated with the available feeding grounds. There were also some differences between years. The proportion of the various prey‐species varied with the season because some species changed their habits and were thus not always equally available to the Herons. At the peak of the breeding season food was more plentiful than either earlier or later. Certain Herons tended to specialize on certain species of prey, apparently because they often returned to the same feeding area. Many nestling Herons died of starvation and it is concluded that food is often short in the breeding season. The importance of asynchronous hatching is discussed. The breeding season of the Heron appears to be timed so that the young are in the nest when the chief species of prey are most available.