Barn Owl Tyto alba
Case 3
Brood of orphaned Barn Owls fostered to adults whose own brood had all been killed
A
brood of five Barn Owls were killed by a fall from their nest in ceiling
insulation in a huge, open building at a steel fabricating plant near Vincent,
in Shelby County, Alabama. Apparently the insulation had torn because of the
increasing weight of the growing nestlings. As it happened, I was raising a
brood of five orphaned barn owls of roughly the same age from an adjacent
county, and I decided to try to foster these orphans to the adult birds who had
just lost their own brood at the steel plant.
Just
a few hours after the other nest had been destroyed, workmen from the plant
helped us to install a wooden nest box on a beam about 15 feet from the location
of the original nest. The adult owls had been roosting in another building, and
were not even aware yet that their own nestlings were dead. The nest box was in
place just before dark, and I settled down in my car in the open space in front
of the huge, open building to watch. This was one of my first efforts to
reunite, long before I began using the recorded calls. Without the calls, I had
to rely on the vocalizations of the orphans to attract the adult birds to their
nest box, and it turned out to be an all-night vigil.
The adult owls did not appear until well after dark, around 10 p.m. At first, they ignored the nest box, and spent several hours circling around the site of the damaged nest in the ceiling insulation. Finally, well after midnight, one of the adults flew over and perched on the flat top of the nest box, presumably attracted by the calls of the hungry nestlings. For about an hour the adult bird sat on top of the box, where it appeared to be listening to the sounds within. Finally, at about 2 p.m., the adult entered the box and remained inside for about five minutes. Then the adult owl’s head appeared in the doorway, and the bird appeared to survey the area, as if to orient itself, before taking off towards the open fields adjacent to the plant. When the bird returned about half an hour later, it was carrying a large rodent, and it flew straight to the nest box entrance. The other adult remained perched on top of the roof of the building, and did not approach the nest box at all that night. About 3 a.m. it flew off, and did not return. The first adult continued to bring food to the nest box at roughly half-hour intervals until dawn.
With only one owl hunting, and with such a late start, I was concerned that the young owls might not have had enough to eat. Early that morning I arranged to be hoisted up to the nest box, and placed 10 or 12 mice in the box. All of the juveniles looked healthy and contented. The following night I observed both adult birds bringing food to the nest box soon after dusk. By 11 p.m. the two birds had brought enough food to supply their adopted brood for the night, and I discontinued observation. The nest box continued to be monitored by the security guard, who reported that all five birds were successfully fledged.
This is the best demonstration I can offer of the very strong “urge to parent” which I have observed in so many raptor species. These two Barn Owls accepted a completely different brood of nestlings in a different location, and in a completely different type of nest. In this case, I had no recorded calls to use, and had to rely on the vocalizations of the five healthy juveniles to attract the adults. This is a good demonstration of the effectiveness of the juvenile’s calls in attracting nesting adults. The recordings just speed the process and contribute to the certainty of the contact.
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