2013 July Nature News – Above and beyond the nest

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Fledgling red-tailed hawks remain near the nest, devouring fresh prey delivered by their parents for three weeks or so. Then the youngsters must begin making their own kills. Juveniles band together in small groups until individuals finally disperse in the fall.

Hummingbirds, finches and doves disperse fairly quickly after fledging, within a week or two. Barn owls and screech owls hang on with their parents for up to two months after leaving the nest. Condor young stay so attached for so long that the adults only breed every other year.

Raven youngsters are eager to leave the nest, but slow to learn to fly. The fledglings practice the use of their flight apparatus and receive handouts from mom and dad for several weeks. Then the whole family leaves the nest area together. Omnivores such as ravens eat a wide variety of foods, so these youngsters will rely on many sources of nutrition. Raven expert Bernd Heinrich believes there is a critical stage in a fledgling’s development when it learns from its parents about edible items and what to avoid. After the imprint period ends, ravens become naturally suspicious of anything new. In late summer, young ravens join up with other juveniles while they continue to study Survival 101. In a flock of ravens, it generally falls to the lowest guy on the totem pole (the omega bird) to venture out to inspect a new discovery. The others watch and wait to find out if this strange item is edible, or hazardous.

Great horned owls are among the slowest to mature. About six weeks after hatching, the owlets begin to branch, hopping to nearby perches and ledges. They gradually learn to fly over the next month, a process that’s not always elegant. But it takes the youngsters even longer to learn to kill their own food. Parents feed and protect their flighted young for three to four months. Next year’s breeding season is upon them when mom and dad finally boot their dependents out into the world.

At Liberty Wildlife, orphan owl nestlings are raised in small mews by foster parents and moved to flight cages when their feathers come in. Before the young are ready for release, mentor adult great horned owls will demonstrate where food comes from as they kill live mice provided them by the good folks at Liberty.

Liberty’s Animal Care Coordinator Jan Miller suspects that great horned owls are more instinct-driven than birds such as ravens that are known for their intelligence. She believes the instinct to kill for food is awakened in youngsters of a certain age when they observe adults hunting.

The length of time spent with parents after learning to fly demonstrates the magnitude of skills a bird needs to survive its first hazardous year of life. Often, birds that leave their parents’ care the earliest move immediately into flocks or small groups of juveniles. Perhaps mentors among these groups continue to guide the young. Certainly the foster birds at Liberty should qualify for sainthood, considering the sheer numbers of youngsters they have raised, tutored and prepared for a successful release into the wild.

Much of the information for this article came from Pinau Merlin’s excellent book A Guide to Southern Arizona Bird Nests & Eggs.

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