(reprinted by request)
This column was written a few winters ago as we watched small birds mobbing a bald eagle.
The same idea applies to our summer birds. But instead of eagles, the small birds mob the larger birds such as our hawks and ravens.
We climb the hill east of Hart's Basin. There's movement in the sky to my right. We slow down ... and there are at least 15 dark birds against the stormy, gray sky. Allen pulls off to the edge of the road so that I can watch the bird show ... there's a much larger bird in the midst of smaller ones ... they're about half the size of the big one. The large bird has a black body, white tail ... white head. It's a bald eagle! And it's trying to gain altitude. But the smaller, black birds are attacking it. One of the smaller birds dives at the eagle's right wing ... the eagle dips to avoid it. But there's another one diving at the left wing. The eagle is being mobbed! He struggles to avoid contact and still tries to get higher ... he's slowly managing to climb. But there are at least 10 smaller birds above him. Despite his powerful flying ability, the eagle is having a difficult time. A car is coming behind us, so we have to move on. By the time we find a place to stop, the aerial display is over. I know that a bald eagle is about 30 inches long but the crow is only about 15 inches. The smaller birds seemed to be about half the size of the eagle, so I'd guess them to be American crows.
As we drive along, I try to recall information about small birds mobbing larger birds. First of all, the larger bird represents a threat to the fledglings: but this is mid-winter, so no fledglings. But if the smaller birds are resident, as these crows could be, it might be good to just get the eagle out of this territory. The bald eagles are winter visitors here and the American crows are resident. So this argument fits the situation. The "Birders Handbook" mentioned that the mobbing may be educational: to teach the young birds who the enemy is, and how to chase it. I recall that the handbook mentioned that there was much to be learned about mobbing behavior. Certainly seems to be the case to me.
Long ago, my instructor was asked, "Do little birds ride on the backs of big birds?" His answer involved the misinterpretation of this mobbing behavior. The smaller ones manage to out maneuver the larger bird, so it appears that they are in control. I've seen sparrows, finches and such mobbing crows and ravens during nesting season. So our leisurely drive brings an opportunity to see bird behavior.blog comments powered by Disqus