Each owlet would eat up to a dozen mice per night if given the opportunity. With a normal nest containing six young, parent birds must capture up to 74 rodents nightly. To capture such a supply of food, adult owls may travel three miles. If they do not catch enough to eat at night, barn owls will hunt during daylight. Barn owls have learned to adapt to farms, which provide open lofts for nesting sites and an abundance of rodents.
Biologists examine the skulls in the pellets to identify the kinds of animals owls are eating.
The enormous quantity of pellets littering a nest area testifies to the amazing number of rodents a family of barn owls consumes. The presence of pellets is one of the first clues that barn owls are using a building. The staggered ages of barn owl nestlings increase the odds that at least one young will survive to adulthood. If the supply of small rodents is plentiful, all of the young owls may survive to fledging. However, if the parents are unable to find enough food for all of the youngsters, younger nestlings cannot compete with older, stronger siblings for food and will die.