March 04, 2007

Mobbing

It is not uncommon to see a group of blackbirds or swallows chasing a hawk or eagle, or a group of songbirds fluttering and calling around a perched owl. Such "mobbing" behavior is probably the most frequently observed overt antipredator strategy. Nevertheless, the exact purpose of such noisy group demonstrations remains a matter of some debate.

Mobbing tends to occur most intensely on the breeding grounds. For instance, in April a tape recording of the cries of an Eastern Screech-Owl brought Prothonotary Warblers, Blue-gray Gnatcatchers, and other small songbirds swarming in from their newly established territories in the swamps of South Carolina. A week later the same tape had no discernible effect on warblers moving northward along a ridge in Nashville. Presumably the migrating warblers had less reason to mob, perhaps because they would be leaving the vicinity of the predator anyway. Mobbing may thus function to divert the predator from areas where there are fledglings, or simply to confuse and annoy the predator, in the hope of getting it to move away.


This "move-along" hypothesis, first put forth by E. Curio, a specialist in the biology of predation from Ruhr University in Germany, is supported by the research of ornithologist Douglas Shedd of Randolph-Macon Women's College. Shedd has shown that Black-capped Chickadees will respond to predators in fall and winter, even in January with the temperature 25 degrees below zero. The chickadees, which remain in residence all year long, still find it profitable to mob in winter. Migratory robins, in contrast, sometimes approached a stuffed screech-owl and tape combination outside the breeding season, but never mobbed.


Careful experiments have shown that birds can learn from each other which predators to mob (indeed, one bird in an experiment was taught by another to "mob" a many-colored plastic bottle, although the mobbing was halfhearted). Therefore one function of mobbing may be educational -- to teach young birds the identity of the enemy. Another may be to alert other birds to the presence of the predator, either getting them to join in the mobbing or protecting them, since a predator is unlikely to be able to sneak up on an alert victim. The original mobber may benefit directly by the predator being moved along, or indirectly if the protected birds are its kin.


Much is lacking in our understanding of mobbing. It is not clear why predators don't simply turn on their tormentors and snatch up one or two of the mobbing birds. If they did, presumably mobbing would quickly disappear; that it persists suggests that surprise is an essential element in raptor hunting
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By Paul R. Ehrlich, David S. Dobkin, and Darryl Wheye

3 comments:

Unsane said...

Surprise is an essential element of bullying. It gives the situation of being bullied a kind of aspect of religious ritual or rite of passage, since those who are bullying know what they are doing, but the target rarely does until much later. So there is a kind of esoteric, secret-society quality that is shared by the bullies, working as a collective group. They revel in their secretive knowledge of their shared designs, because it makes them feel powerful to know something that the target doesn't. The power is in this knowing, and not just in the domination they are trying to assert over the target's life and actions.

Anonymous said...

There is also an element of surprise when/if someone discoveres the extent to which an organisation/company/university are prepared to go to cover up the truth. There is huge surprise when one finds out that moral corruption permeates from top to bottom as everyone toes the line. There is also a painful surprise to find out that you have to deal with all of this alone as - surprise,surprise - your close friends and colleagues start to withdraw.

Anonymous said...

Yes this moral corruption is intriguing - where does this come from - why is it that former colleagues and friends move away - stay silent.

What is this power that surrounds bullying?

Why are people so fearful?

People who won't tolerate bullying generally leave - they won't fight bullying.

Where does the bully's power come from?

Why is it that something that is so common in the school playground is also found in universities?

Why are we more successful in addressing bullying amongst children than bullying amongst adults?

We feel safer talking about chn bullying... why?

Aphra Behn