Re-nesting of Great Horned Owlets

Some new spring arrivals are a family of Great Horned Owls from a pair that re- nested this past winter. Great Horned Owls will use nests previously built by other species, but usually only once and this family has three owlets that hatched in March, who are about 5-6 weeks old. These owlets hatched in March, so the owls likely started breeding and nesting in late January.  The eggs are laid on separate days and are immediately incubated by the mother, while the male brings food. Since each egg is laid individually, each owlet in a nest is a different size and age. The largest of these owlets was 1042 grams (2.2 lbs) and they eat about 4-6 mice each day on average, so they are growing quickly.

Great Horned Owl mothers have a brood patch on their abdomens, which is a featherless area with lots of blood vessels that keeps the skin warm and incubates the eggs by transferring heat to them directly. Even after the owlets hatch, the mother will still brood them to keep them warm until they grow feathers of their own and she will closely guard and protect them. Most owlets will leave the nest and walk around at about six weeks, so they will be venturing out on their own very soon, if they haven’t already. As of last week, two are still in the nest, although one was testing his wings, so by now they may have all left the nest.

After being out of the nest for about three weeks, most of the young owls will learn to fly, although the parents will continue to feed and care for them for several more months. The parents will leave the young alone for short periods, but will not stay away long enough for anything to harm the owlets. Approaching young owls or the nest is dangerous, as they are extremely protective and not afraid to attack if a potential threat to the family arises. Threatened or aggravated owls will “clack” with their beaks and young owls will shriek or scream for attention, so be aware of your surroundings. Mother owls can even knock a person out of a tree if they are too close to the nest, so be cautious if near a nest.

Great Horned Owls have strong numbers and are protected as a migratory bird, but they still face threats to their survival, which makes these owlets even more special. Great Horned Owls are losing habitat because of urban sprawl, which impacts nesting and hunting territories, and also from the use of insecticides and pesticides, especially agricultural uses, which reduce their food supply. Protecting their habitat is crucial to ensuring that future generations hear the mysterious and iconic “whoo hoo” of the Great Horned Owl.

*Article originally printed in Prairie Wildlife Rehabilitation Centre newsletter.

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