Parental Care
Most birds are taken care of by at least one parent until they are able to fly and get their own food. The young of passerines are altricial (born naked, blind, and helpless) and require much more care and feeding than precocial young. For information on atricial vs precocial young, REVIEW Precocial and Altricial Young from Stanford University. One or both parents must bring food to altricial young until they are ready to leave the nest, and in most species the offspring are fed by the parents for a while after fledging. Most passerines are monogamous, and usually both parents help in rearing the young.
Often the male does more of the food gathering and the female more of the brooding, covering the young to keep them warm and protecting them from predators. Frequently, the male also feeds the female, and she in turn may pass food on to her helpless chicks. In some cases, however, those caretaking roles are reversed. female Red-eyed Vireos, for example, gather about three-quarters of the food their young receive. In cooperative breeders, such as Acorn Woodpeckers, nonbreeding adults or juveniles may help care for the young.
Although parent birds often feed their offspring a diet similar to their own, they may shift to a higher protein diet during the breeding season. Other parents swallow the food as they forage and then regurgitate it for the young when they return to the nest. As the young mature, the proportion of solid food in the regurgitant increases, perhaps an avian analogue to weaning. Some birds, such as pigeons, produce a special “crop milk,” which is also regurgitated for the young. Petrels regurgitate for their young an oil along with half-digested food from which the oil is derived. Raptors usually carry their prey back to the nest and tear it into bite-sized chunks for their chicks.
For more, refer to the following websites:
- Parental Care from Stanford University.
- The origin of parental care in birds: a reassessment from the Journal of Behavioral Ecology.
