Once the young are able to fly, some parents show their young how to hunt. Cooper's hawk and peregrine falcon parents have been observed leading their young on rapid chases before giving up their prey. These same parents may also release still-living prey for their young to catch and kill. I. Chick growth and development. Because chicks of the same clutch hatch over several days, the older, larger chicks are better able to compete for food.
Scientists believe asynchronous hatching is an adaptation to unpredictable food supplies.
If food is plentiful, all the chicks survive. If food is scarce, the brood is rapidly reduced. As with incubation, large species have proportionately longer nestling periods than small species. Small species grow more rapidly than large species. Small species may reach adult weight by fledging, while large species may not reach adult weight until sometime after leaving the nest.