Choo Teik Ju’s studies of a Barn Swallow ( Hirundo rustica ) fledgling show the changing mood of the young bird as it waits for the adults to arrive with food. It sits quietly when the adults are not nowhere in sight (above left). Note the yellow flanges lining the mandibles. The moment it senses an adult coming, it gapes widely to highlight the yellow-red bottomless pit of a throat lined by the flanges (above right). At the same time screeching loudly. All these help guide the adult on where to deposit the food. Once the adult is in sight, the wings will unfold, probably to make itself conspicuous (below left).
Once fed, the fledgling may indulge in comfort behaviour, stretching its wings one at a time (above right) or both together and scratching its head.
The photographs were documented by Choo Teik Ju at the Mai Po Marshes, Hongkong.
This post is a cooperative effort between NaturePixels.org and BESG to bring the study of bird behaviour through photography to a wider audience.