Divorce, Sea-Gull Style : Sometimes Two Birds Just Can't See Eye to Eye Over Brooding Privileges

William Jordan is a Long Beach-based science writer.

It's a nice day on the Farallon Islands, west of San Francisco. The sun is out. The 50-degree wind is not vicious, only relentless. And the local residents are soaking up the unusual ambiance.

They are Western gulls that have laid claim to little pieces of rocky real estate--nesting territories--spacing themselves out in a more-or-less even pattern, the subdivisions creating a neighborly regularity. A lazy chorus of mewlings, yelps, "laughs" and keks rises from the colony, and the sounds blend into a sort of 12-tone sea-gull Muzak. Nearby, a large male sits quietly on his grass-on-rock nest, his white head and neck contrasting smartly with his black tux of a back. Occasionally he nibbles at a stone or a stray blade of grass and nods off in the sun with his breast pressed warmly against three freckled, buff-brown eggs. This domestic bliss is not destined to last long.

A series of loud, almost catlike wails breaks forth overhead, and a second gull, his mate, glides in for a landing. Judging from her exuberance, she seems to be emphasizing the fact that " I have arrived."

While this is going on, a biologist named Judith Hand sits in a small shack about six feet away armed with a tape recorder, binoculars and a notebook. She wears a parka to endure the wind that is driving through the observation port, and she has been here since dawn and will remain until dusk--to record every action, every sound that the 17 pairs of gulls in her study make with regard to their nesting duties.

But the scene continues. The female gull picks up a few leaves of dried grass, walks toward her mate and stands there, grass in beak, all the while making a mewing sound that to human ears sounds plaintive. The male ignores her and keeps sitting on the eggs. This is not what the female wants. So she squats slightly, tilts up her rear, lowers her breast and head, pumps her neck up and down and emits a choking, pumping sound as if she's gagging. A feeling of domestic tension is in the air.

The male, too, assumes a slight crouch and, stern up, bow down, chokes back to his mate--but even more emphatically. He does not want to relinquish the eggs.

She stands there a moment, as if contemplating this turn of events, drops her beakful of grass, turns and walks away.

About six minutes later, here comes the female again, more grass dangling from her beak like a sarcastic offering. More mewing, but more urgent. Another episode of choking with the male again refusing to leave. Again the female drops her bouquet and walks away.

Six minutes later still, and again she comes back, beak bristling with the obligatory grass, mewing with evident determination. This time she chokes with fearsome intensity. And this time, as though he realizes the show is over, the male gets up without reply and walks away. The female stands over the nest, fluffs her breast feathers to expose a naked patch of skin called the brood patch--which provides warmth directly to the eggs--and carefully settles down. As her skin presses onto the warm, smooth eggs she shakes her tail and tilts her head up, giving the impression that there is nothing in this world so infinitely pleasurable as brooding one's eggs, which for a sea gull there probably is not. It is worth a confrontation with one's mate.

To Judith Hand, however, there is much more going on here than a simple squabble over who gets the eggs. In higher animals (including wolves, monkeys, antelopes, seals--and gulls), the interaction known as dominance/submission creates a system for dividing up resources. As they compete for food or territory or mates, the bigger and stronger usually win and eventually establish dominance. This leads to the classic peck order, in which the top individual is able to take what he wants, when he wants. It also leads to a system in which the strongest survive, especially when times are hard, and pass on their genes. In extreme situations, dominance can be a harsh, tyrannical system that leaves little hope for the weak. Not surprisingly, most humans find the notion repugnant. And it may seem like a long leap from the sea gulls' little nesting plot to the capitals of nations, but the principles of dominance may well underlie the whole issue of political ideologies. Despots are in fact highly dominant. Political systems based primarily on dominance/submission are sometimes called dictatorships. At which point we will now return to Judith Hand and her observations on mated gulls.

Most of the year, sea gulls use a system of male dominance. But when they pair off to mate, they switch over to an entirely different one in which they work out differences not on the basis of size or strength but on the basis of wants and needs. Rather than resort to aggression, they resolve their conflicts through communication: The gulls' choking is actually a ritualized display that showed, after three bouts, that the female would not be denied. Judith Hand terms it "egalitarian behavior." In contrast to pure dominance, in which the dominant individual wins 100% of the time, with egalitarian relationships each of the participants wins roughly 50% of the time. This is true for the two gulls. Choking works both ways, and there are times when the male "persuades" the female to relinquish the eggs so he too can get his share of the pleasure.

There is an intriguing aside to egalitarianism among the gulls, however, and it has to do with what can only be called divorce. Many gull species are described as monogamous; they're supposed to mate for life. So much for descriptions. It turns out that, depending on the species and the location, more than 25% of young, newly paired gulls split up after their first attempt at raising a family. These broken marriages often result from excessive squabbling. Enough energy is wasted on disagreements that it interferes with the purpose of mating in the first place, and the pair does not succeed in fledging their chicks. But life goes on, and the next year the divorcees show up with new mates, fully intent on giving it another go. And this time they often succeed. It probably comes down to temperament. "Both gulls," Hand says, "can have a high drive to incubate the eggs--say that each wants to do it 70% of the time--and in pairs like that it's probably not going to work. What you need is someone to complement your drives. If you want to incubate 70% of the time, then you'll probably get along pretty well with someone who wants to do it 30% of the time."

It's nice to know, though, that not everything is confrontational on the home front. It is now 4 1/2 hours later, and the female gull is still incubating. But it is no longer the pleasure it was at first. A normal sitting lasts about three hours, and she has already had to leave the nest briefly to relieve herself. Hunger is also making demands--and why doesn't the male get his brood patch back here so she can leave?

Finally, an obstreperous landing call blasts out overhead-- he has arrived--and this time there is no dawdling around with tufts of grass and emotional displays. The male, sassy and content after 4 1/2 hours of R&R;, wants nothing more than custody of the eggs. The female, hungry and frustrated after being forced to sit for an extra hour and a half, craves relief from domestic bondage. She gets up immediately and relinquishes the nest. Without pause, he walks over and prepares to settle down. For some reason, Oscar Wilde comes to mind: "If two people get along perfectly, one of them is . . . unnecessary." The male, whose eyes are closing in ecstasy as he sits on the warm, round eggs, would agree--for the next three hours. The female, who is flying off hungrily in search of food, would not.

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