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Wednesday, July 19, 2000

WILD WATCH

Hats on where the seabirds nest


Wheesh! Crack! Something furious hit me on the back of the head.

Even as I turned to see whom I had upset, the perpetrator was already hovering, brilliant white against the blue sky, ready for another attack as soon as I turned my back again. I made to move.

Crack! I was struck from the other side by something hard and sharp. Its partner in the attack was using its short sharp claws to make it clear that I was not wanted here.

I was wandering along a coastal salt-grass flat in northern Norway and had unwittingly strayed too close to the nesting grounds of a small flock of Arctic terns. This delicate, slim-winged member of the gull family is renowned for its determined defense of its nest, eggs and young.

I learned from that encounter that a hat is the minimum needed for self-protection. Better still, carry an umbrella, a staff or a walking stick raised above one's head so that they attack that instead!

My experience with the terns left me with a minor cut and served me well later when visiting gull and skua breeding grounds in various parts of the world. Parent birds cannot be blamed for defending their offspring; after all, we would do just the same in their situation.

What is astonishing is that such small birds have the determination to attack mammals so much larger than they. Even straying cattle are not too big for them to attack. The Arctic tern is unusual, perhaps, in that it so often presses its attacks home, whereas other members of its family tend to fail in their resolve at the very last moment. Nevertheless, it is a scary display if you haven't experienced it before.

Neither the Arctic tern, nor its close relative the common tern, breed in Japan, but other relatives do. The commonest of these is the black-tailed gull, or umineko. The umineko breeds in colonies from northern Hokkaido to western Kyushu. It favors islands, islets and even isolated rocks; there it builds a nest out of grasses growing nearby and lays its clutches, which are usually of two or three eggs, densely mottled olive-green and brown, beautifully camouflaged against the grasses of the nest when the adults are away.

The adults, of course, stand out like a sore thumb: bright white on their underparts, dark gray across their wings and mantle, with a black band near the tip of the tail which gives them their rather dull English name.

Their Japanese name, umineko, is far more attractive: "sea cat." This gull has a distinctive mewing call that one cannot fail to hear while visiting islands where they breed.

Watch out, though. They have a harsher, more aggressive call as well, and like those terns in Norway they are very willing to defend their own. Approach their nesting site too closely and they will soon begin to swoop and call. They don't press home their attacks, but because they nest in large colonies, the panic soon spreads to other pairs. When they all take to the wing their massed aerial presence is often sufficient to frighten off a potential egg or chick predator. Visiting humans trigger the same response even though they may only be there to watch rather than steal.

There is another behavior one should be aware of when visiting gull colonies. When birds fly up, panic peristalsis also takes over -- and splat! When you are standing beneath a swirling flock of outraged gulls it is not a good idea to spend too much time looking up admiring their plumage.

Better instead to retreat and admire them from a greater distance. They will soon settle, and treat you to views of their nesting behavior: changing over at the nest, carrying in food to their young and so on.

The umineko has a very distinctive long beak with a prominent black band and deep red tip. If there are young in the nest and the parents are busy visiting, watch the chicks closely. They will peck at the red part of their parent's bill. All of the larger gulls have either a red spot or a band, and the chicks use it as a pecking target. The pecking stimulates the parent to regurgitate the chick's next meal. It's as effective as pressing the button on a vending machine!

Almost all gulls are daytime hunters, but the swallow-tailed gull of the Galapagos Islands is an unusual exception. It has very large eyes and is most often seen flying away from the islands in the evening, setting off for nighttime hunting. Perhaps they hunt for those squid that rise to the surface at night, eerily flashing their luminous signals to each other.

Other gulls follow fishing boats. Most are rather generalist feeders, as willing to take a sandwich or ebisen thrown from a tourist boat as they are to snaffle the offal discarded by fishermen. The tide line is their scavenging ground, too, where just about any recently animate object is considered potential food.

Although they are essentially coastal, the term "sea gull" is not appropriate as a general name for this family. There are species that breed far inland, such as the Andean gull of the high mountains of South America and the great black-headed gull of Central Asia.

Certain species of gulls seem confident away from the coast, at least outside the breeding season, when they return to the shore. Some have quite easily extended their scavenging habits from the shoreline to our innumerable open landfill sites heaped with garbage.

There they vie for rotting and rancid morsels with each other, with other species of gulls, with crows and often with scavenging birds of prey such as kites, too. It is a noisome habit, and one that we humans have encouraged by our wastefulness and by our appalling habit of openly heaping garbage.

Despite the unappealing nature of their eateries, gulls do like to be clean, and invariably they soon head off to the nearest water to bathe. In Europe this has raised an interesting aspect of public health because some of the places where they bathe are storage reservoirs for water that is to be used as domestic water supply. The potential for transferring bacteria and disease organisms from garbage dump to water supply is real.

It is a problem caused by humans at both ends, of course; the birds are only taking advantage of an easy source of food and an equally available source of water. We cannot blame the birds. Like every other so-called "environmental problem," this is at root a human problem.

Black-tailed gulls seem bent on retaining their coastal character, or perhaps, because Japan is a rather narrow country, it is easy for birds that appear inland to quickly return to the coast. When approaching a coastal colony, be cautious, but not afraid, and you will have a chance to admire them in detail and to enjoy their behavior at close range.

Send e-mail messages to MarkBrazil@compuserve.com or by snail-mail c/o The Japan Times.


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