Advertisement

Archive for Sunday, December 20, 1998

S INLAND SEA, THE PRAIRIE SPECIAL TO THE JOURNAL-WORLD

December 20, 1998

Advertisement

Gulls are no stranger to Kansas. They often use the state's wetlands as a stopover during migratory flight.

Gulls, often called "seagulls," are regularly seen in Kansas. However, no less than 17 species of gulls are known to have occurred here in recent times, despite our current lack of a sea. Of all the 17, the Franklin's gull is probably the most familiar. Although one pair is known to have nested once at Cheyenne Bottoms, the species normally occurs here as a migrant in spring and fall, and may come in huge numbers over protracted periods. This year a migratory flock estimated at 100,000 was seen at Cheyenne Bottoms as late as the first week of November; one flock estimated at 2.5 million birds occurred in October in the 1960s at the Salt Plains Wildlife Refuge.

In spring migration, Franklin's gulls regularly feed in burned pasture or recently plowed fields, sometimes following farm machinery closely, picking up insects or earthworms. Later in the year, the birds nest in wetlands over northern reaches of the continent, and then include fishes and other aquatic animals in their diets. Especially in autumn, wheeling and darting rather gracefully, the birds can spend much time hawking flying insects. Overall, Franklin's gulls are dietary generalists, feeding on a variety of animals and sampling seeds and other vegetation.

Flock life

Migratory flocks loaf and sleep in or near wetlands and enter into some of the less complex food chains in Kansas. By day, the gulls are targets for larger falcons, which may course at speed close to the ground, coming upon the gulls before they can get well under way.

Peregrine (and probably prairie) falcons are effective gull hunters, at least at the edges of the flocks. As gulls at the edge lift off the ground to escape the falcons, slower birds are at risk, but the remainder of the flock is alerted in time to get under way before the falcons reach them. At places such as Cheyenne Bottoms, great clouds of gulls can be seen rising into the air, especially toward sunset, as falcons work them over.

By night, gulls are attractive to great horned owls, coyotes, foxes, raccoons and striped skunks. I have not seen nocturnal predators in action at gull dormitories, but suppose they are most effective by stealth at edges of the sleeping flocks. Flocks may be magnets to predators, but they lend a great deal of protection to most members.

Breeding colonies may number in the tens of thousands of pairs. Nests are built over water, in emergent vegetation, on floating debris, floating mats built by the birds, muskrat houses and similar sites. Pairs are single-brooded, and usually care for two- or three-egg clutches.

Citizen of the world

Of all the American gulls, Franklin's gulls probably hold the long-distance migration record. Some nest in northern Alberta, and winter in Peru or northern Chile. Occasionally migrants have gone even farther, as for example into the Pacific basin, at sites such as the Hawaiian Islands, Johnston Atoll and Japan, where they are not native. But this is only a vague indication of the capability of Franklin's gulls to move around the world. Recent sightings of the species exist for nine European countries (33 records); eight records are from Australia, four from Africa, two from south Atlantic islands and one from the Indian Ocean. For that matter, records for wintertime occurrence exist even for Kansas.

This capability for efficient and rapid movements over great distances points up one of the problems in the practice of bird conservation. Breeding areas may have problems different from migratory regions, and these can be different from those at wintering grounds. Conservation agreements among independent, sovereign nations are not always readily made and implemented. Developed and developing nations have different priorities, and funding is always a problem, regardless of relative wealth of a country. It's a wonder agreements on conservation are reached anywhere.

If Franklin's gulls are so abundant, should we be concerned about their conservation? It is probably a good idea. In the breeding season, for instance, entire colonies may desert their nests if humans disturb the birds more than a little. Even if desertion does not occur, parental care may be cursory, with mortality to the chicks; thousands of individuals can be involved as a result of careless intrusions. Other sources of mortality, such as from predation or hunting, are probably of little consequence to populations.

Wetlands of last resort

The most important problem for gulls is the wetlands used by the birds, especially in summer. Wetlands are at risk from ever-increasing human populations. You might think that if Franklin's gulls in migration occur in the hundreds of thousands at Cheyenne Bottoms that the species is in good shape. And, you might be right. But Cheyenne Bottoms is a case in point. It is, as you may know, the single most important wetland stopover site for migratory birds in the central United States. This is a status not casually to be denigrated, but one that is dependent on earlier conversions of many other lesser wetlands to farming in the Great Plains region.

A wetland in a dry part of the world probably has a limited functional life span. Under drought conditions, claims concerning water for environmental conservation might not take precedence over those concerning the human economy. We presently have no drought, of course, but I note that plans are being implemented that will require a doubling of the use of ground water for human use in the Great Bend region. This could affect availability of water for Cheyenne Bottoms. If Cheyenne Bottoms were dry, perhaps our gulls would simply fly over Kansas. That would, however, require a significant change in habits. A dry Bottoms could mean a drop in numbers of gulls, as well as of other species.

-- Richard Johnston is an emeritus professor at the Kansas University Natural History Museum and Biodiversity Research Center and a member of the Kansas Ornithological Society.

Commenting has been disabled for this item.