Mobbing of a Barn Owl
This incident occurred about noon some two to three years ago around an old longan tree (Dimocarpus longan). The tree was planted from seed 37 years ago and at that time the branches had been pruned and new shoots were sprouting, producing 'bobs' of new leaves. It was the favourite of seven to eight House Crows (Corvus splendens) that used it to rest after feeding.
The tree was growing between our house and my uncle's who lived next door. He was gardening below the tree when he noticed a couple of crows circling above and calling loudly. Curious, he looked closely at the tree to find a Barn Owl (Tyto alba) resting on a branch, hidden by the one of the leaves bobs.
He called all of us out to see the owl. Naturally the bird ignored us as it was more concerned with the crows above. As long as my uncle was working below the tree, the crows kept their distance and the owl was left unmolested.
After a while, when my uncle finished his work and got further away from the tree, the crows came nearer to the tree, calling frequently. They did not land but I think their cries were too much for the resting owl. It took off soon after. It has not returned until today.
At present, the tree is no longer being used by crows. We have kept its branches pruned to the maximum and it is not as shady as before.
Contributed by Chew Ping Ting
Image of Barn Owl courtesy of Ashley Ng
This is a typical anti-predator behaviour and owls are popular targets, especially when caught resting during the daytime. Mobbing birds may include songbirds, crows, woodpeckers and those as small as hummingbirds. They make repeated dives as well as loud calls. They may or may not strike the predators. But cases have been known where owls were pecked on the eyes or the feathers. However, the owls are seldom hurt by these attacks and they seem to just ignore the mobbing birds, to eventually move away. It is possible that the mobbing birds know that it is safe to mob owls as these nocturnal birds are unable to attack the constantly moving mobbing birds.
Why birds mob predators? Probably to alert others of the presence of predator birds. Or to educate young birds on the identity of their enemies.
Comment by YC