Mobbing birds

Mobbing in birds is an anti-predator activity in which smaller prey mob a larger predator by cooperatively attacking or harassing it. It is usually done to protect offspring. Behaviour includes flying about the predator, dive bombing, loud squawking and defecating on it. The smaller prey are usually quicker and more manoeuvrable than the larger predator, making it difficult for the mobbing bird to be captured. 

My blog postings are usually preceded by taking a picture of the event. Not on this occasion; I did not recently see any mobbing. Rather this posting was prompted by Bob McDonald’s C.B.C. programme, “Quirks and Quarks“. Mr. McDonald interviewed Madeleine Scott, an Oregon scientist, about mobbing of the Northern Pygmy Owl, and she observed that these mobbing events were more likely to happen during the spring and summer seasons, when food becomes more abundant for the songbirds.

Now, I have seen many Pygmy Owls but have never seen them mobbed. But I only see this owl during the winter in the valleys, apparently not the time when they are mobbed. During the breeding season around here, this owl heads high in the mountains. Apparently Ms. Scott conducted her experiments on the broad eastern Oregon plains where there was no opportunity of altitudinal migration. Presumably, the mobbing happens around here in the mountains.

Nevertheless, it seems a good time to give mobbing a brief, backward look.

This is a local Northern Pygmy Owl seen recently. OK it is not being mobbed but I do note that the first owl I ever saw in the wild was revealed by it being mobbed. 

A Tree Swallow is mobbing a Great Blue Heron who has chosen to park close to the swallow’s nest. Repeated fly-bys of the swallow and its partner finally drove the heron off. 

A Crow goes after a juvenile Bald Eagle. There was often more than one mobbing bird, but only one is usually caught in a picture.

A Tree Swallow harasses a juvenile Bald Eagle.

And again.

I don’t know if this standoff between the Black-billed Magpie and Bald Eagle is mobbing or not.

A raven goes after a Red-tailed Hawk.

Two Steller’s Jays harass a Red-tailed Hawk.

This Northern Goshawk was being actively harassed by some ravens. It was perhaps the only reason I was able to get close to it.