Another interesting feature of a number of bird species is that they will feed their babies in the nest by the regurgitation of food that they have caught and stored in their bodies.
In some species, the adult needs some form of stimulation before it can regurgitate the food from its stomach back in to the nest for the young to eat.
One such form of stimulus, as depicted in the illustration, shows a young Little Black Cormorant, rubbing its head up and down on the neck of its parent. This massaging will continue till the young bird has successfully caused its parent to bring up its food and provide early morning sustenance for the nestling.
Members of the pigeon and dove family which are seed eaters, are able to store the seeds they collect in its neck in what is called its ‘Crop’.
The babies can reach in to the food by placing their own beaks in through the open beak of the parent. The Doves usually have two young, sometimes called a ‘Pigeon Pair’ and it is said that one of the pair can enter its parent’s beak from one side while its sibling can go in from the other side, both at the same time.
The penguin has to travel great distances out to sea to find fish, swallow them, then return to feed its young. By bringing the food back up, it is able to keep its young one nourished.
Baby pelicans feed in a similar way by putting their heads into the large bill of the adult. Although I haven’t seen it myself, I’ve heard that, as the young gets larger, they often jump up when entering the bill to the extent that their feet are off the ground.