Why do they harass? Jay vs. Hawk

[Linwood Ferguson]

A red shouldered hawk (at least I believe it was one) was being harassed for quite some time by a mocking bird, a blue jay, and a crow.

One shot is below. Two others via links are here and here. As photographs go they are not very good -- the attacking bird is never sharp, the light is bad. But it was fascinating to watch.

But why? I realize that they CAN, they are more manuevarable than the hawk, and not in much danger. But why do they harass? Does the hawk prey on these birds (or their young)? Do they actually succeed in driving them away? (In this case he pretty regally just sat there).

[John Chardine]

Raptorial and predatory birds provide a universal threat to most other bird species, either because of the chance of being eaten or even greater chance of having your eggs or chicks eaten. At this time of year, male passerines such as robins, kingbirds, jays, grackles et al., are in nest protection mode and will see off any crow, raven, hawk, eagle etc that ventures too close. The behaviour they exhibit is called "mobbing" and is done singly or in groups, depending on the species. The mobbing birds do not appear to be in any danger of the predator turning on them, although I think this is partly because they choose who they mob pretty carefully. I have never personally seen a fast flying falcon or accipiter mobbed (anyone seen this?); both of these are bird predators and have high flight performance so would present a real threat to the mobbed bird.

Any other thoughts ladies and gentlemen?

[Axel Hildebrandt]

I have never seen that smaller birds mob highly-maneuverable predators such as Cooper's Hawks, either. I remember reading that some species are especially intolerant of intruders, particularly those that tend to live in flocks such as Blue Jays and Crows.

Once I saw a Bald Eagle hover above a pond and there was quite a commotion because a pair of Canada Geese were there with their goslings. One of the parents went up and viciously attacked the eagle and he was supported by crows and Blue Jays. I had never seen several species attack a predator in teamwork before. The eagle didn't even try to get one of the goslings.

[Joerg Rockenberger]

Saw just yesterday a pair of Red-Shouldered Hawks mobbing a Crow flying by. Seemed unusual. Guess they have a nest nearby... JR

[Patti Edens]

I was in a raptor blind at the Martin Refuge in south Texas and watched this behavior for quite some time. A Mockingbird was mobbing a Harris Hawk repeatedly. The mocker would get right next to the hawk and screech at him. He would fly under him and then slam up into the hawks chest with his back. Then he started flying at him from the rear and biting the hawks backside. It finally escalated to the point that the hawk flew off and found another perch to wait his turn at the buffet outside the blind. Another hawk took the first hawk's perch and it started all over. That was one fiesty Mockingbird.

Patti

[Declan Troy]

John, I've seen Parasitic Jaegers mob Peregrine Falcons. The jaegers are be quite effective at it.

[Daniel Cadieux]

A couple of years back there was a well known Great Horned Owl's nest here in Ottawa. The parents were continuously being mobbed by numerous crows. One day, one of the GHOs actually caught one of the mobbing crows and fed it to one of the just-fledged young ones. A colleague of mine was there and captured the whole sequence with his camera:eek:. Very gruesome, with the last pictures having only the crow's leg and foot sticking out of the bill....I'll try to dig out the link to the images when I'm back home....

[John Chardine]

John, I've seen Parasitic Jaegers mob Peregrine Falcons. The jaegers are be quite effective at it.

Interesting example Declan in that jaegers have high flight performance and are relatively big-bodied mobbers so perhaps a Peregrine does not pose a real threat?

[Declan Troy]

Parasitic Jaeger has turned up on a Peregrine dinner plate or two but I think the falcon would need to catch a jaeger napping or ill to capture one. They are both incredible fliers (I'd give the jaeger the edge on maneuverability). The incident most vivid in my memory involved a peregrine that erred by settling on the tundra not far from a jaeger nest. Both jaegers just dive-bombed the falcon until it took the hint and moved on to a more peaceful area.

[Rene A]

Interesting,
I just got back trying to find some "feet". But not luck. But I saw an osprey being chased by a crow & the crow being chased by 2 crackles. I was a spectacle & very noisy.
Looked like a triple decker.
I looked up & also saw far off vultures being chased by crows.