Great Horned Owl (Case History #4)

Much younger nestling owlet fostered to family with a single brancher.

In 2005, a homeowner in Prattville, Alabama, reported a brancher Great Horned Owl that had been found in his fenced back yard, where he kept a large mixed-breed dog.  Although both adult birds could be seen roosting in an adjacent strip of trees and underbrush, the homeowner was unwilling to allow us to move the brancher to the other side of the fence for fear the bird would return to the yard. Reluctantly, we agreed to take custody of the bird for a week or so, until the bird gained enough strength and agility to perch well. The homeowner agreed in return that as soon as the bird could stay out of trouble, we could reunite the bird with its parents.

 

About a week later, we received a much smaller nestling that had been found by fishermen on the banks of the Tennessee River.  We had no way of locating the owlet’s nest, as we did not even have the finder’s names. The young nestling was healthy, and eating well, but it called almost incessantly, even after being fed. Normally, nestlings only vocalize until their hunger is satisfied, and I concluded that the trauma of being separated from its mother and of being handled by so many people had conditioned the young bird to a state of anxiety that could not be satisfied just by feeding. I decided to see if the Prattville owls would care for the nestling, even though it was at least a month younger than their own juvenile. The homeowner gave us permission to have our volunteer tree climber, Tim Leopard, install a nest basket containing the nestling in a large shade tree in their back yard. We played the recorded call for about an hour without seeing the adults. However, we had left enough mice in the nest basket to keep the owlet fed overnight, and I was confident that the nestling’s own calls would eventually summon the adults.  We left the nestling to spend the night in the basket and drove back to Birmingham about 11 p.m.  The next morning the homeowner reported that our owlet was no longer calling, and one of the adult owls could be seen perching above it in a nearby tree. About a week later, the brancher from Prattville began perching well.  The bird had been living on the ground in a flight cage containing an injured adult Horned Owl and a slightly older brancher that was already perching.  I took the brancher back down to Prattville and put it in the thicket outside the fence, on a sloping tree trunk that led upwards into the canopy.

As soon as the two adult owls saw the brancher, they flew in and stationed themselves overhead, clucking anxiously. I left the area, stopping only to check on the Tennessee River nestling.  The younger bird was now conspicuously silent, and obviously healthy.

The younger nestling could not have been fostered to a family with a juvenile that was so much larger and more developed if the older juvenile had been present in or near the nest.  Competition from older juveniles is a real concern. However, the same concern does not extend to the adult birds. This case supports my belief that nesting adults are not disturbed by an age difference in a fostered chick, any more than they are disturbed by a change of nest type and location. As long as they have an adequate food supply, they will accept a foster nestling of almost any age.

 

 

 

Adult owl in Prattville watches
the return of the fledgling

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