A large Gentoo Penguin jevenile running after its parent to beg for food.
This behavior occurs frequently with the larger chicks, partly as a way for adults to sort out young that are not their own. It may also serve to teach the juveniles to chase after food, a skill they will need when they lose their downy feathers and finally are able to enter the ocean themselves.
These chases often end with the growing chick tackling the adult, which finally relents and feeds it.