Thursday, April 19, 2018

Farm Bulletin: Owlets Growing Up

An update on the great horned owl family at Ayers Creek Farm from contributor Anthony Boutard reveals the function of their striking facial disk in helping to locate prey.

Here are the young owls at day 73 minus (top photo; click for larger version). Notably, the adults are raising three young, so they are hunting over many long hours, leaving the young unguarded. You can see the difference in size reflecting the different ages of the birds.

They are developing their immature plumage, including that which defines their facial disk. The disk is important to the owls’ hearing, channelling and amplifying even the softest rustle made by their prey as it moves in the undergrowth and leaf litter. The ears are at the edge of the disk, in line with the eyes. Unlike the barn owl which mostly hunts on the wing over open ground, great horned owls employ a perch-and-pounce method. They will sit perfectly still on a branch, hunched over, “watching” the ground with their ears. The owl has the element of surprise as its prey can’t see the bird, and the soft plumage of the owl means it pounces without a sound.

Great horned owls are by nature nocturnal hunters, but when raising young they are hunting even when roosting during the day to avoid garnering the attention of crows and other noisy objectors to their presence. Late in the afternoon last week, [Carol's sister] Sylvia asked to see the young. I was a bit tired and grumpy, and opined sourly that she would see nothing so late in the day. As we looked at the snag trying to pick out the young, both adults returned to the redoubt with prey at the same time. So much for a promised dull moment.

Read the first owl post of 2018. Read more and see Anthony's fantastic photos from previous years.

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