Abstract
When approached by a parent to provide food, a nestling chick of the Japanese Night Heron Gorsachius goisagi twitched its wings and demanded food with its wings open and bent to the level of its head, and wing spurs raised (Fig. 1). The wing spur looked like a head, and the open wing looked like a second chick. Chicks usually opened a wing on one side, and sometimes opened both wings; these actions made the begging individual appear as two or three chicks demanding to be fed. Simultaneously with these actions it chattered intensely “gwaa gwaa”. The parent showed a marked tendency to give feeding priority to this chick. Although this behavior did not necessarily occur every time a provisioning parent visited a nest, it is considered that this behavior may bring two results. Firstly, by attracting the parent's attention, the chick would be able to get food earlier than other chicks in the nest, and secondly, by mimicking multiple hungry chicks, the behavior may stimulate the parent's food-providing activity. This behavior was documented at three nest locations, and was shown by chicks within the nest at from 29-days-old to fledging at 37 days, and thereafter for five days after fledging while receiving food outside the nest.
