Gulls And People
Because they are both omnivorous and opportunistic in their feeding habits, some species of gulls have benefitted greatly from certain human activities. In particular, gulls often feed on an amazing repertoire of foods at garbage dumps, especially if the daily refuse has not been covered over with a layer of dirt (as it would be in a sanitary landfill). Gulls also follow fishing boats, feeding on offal and by-catch as it is discarded overboard. In addition, gulls frequently patrol recently plowed agricultural land, where they feed on worms and other invertebrates that have been exposed by disturbance of the soil.
These and other opportunities provided to gulls by humans have allowed a tremendous increase in the populations and ranges of some species. Gulls whose populations in North America have shown especially large increases include the herring gull, great black-baked gull, ringed-bill gull, laughing gull, and glaucous-winged gull, among others.
In places where they are common, gulls are often considered to be a significant nuisance. Gulls are most commonly regarded as pests at and near solid-waste disposal sites, where they generally pick over the garbage. The can also be considered a problem in parks and stadiums, where they forage for left-over foods. In cities and towns where municipal drinking water is stored in open reservoirs, the presence of large numbers of gulls can result in fecal contamination of the water as a result of their copious defecations. Gulls are also a hazard to airplane navigation because of the risks of collisions. A single gull taken into a jet engine can easily ruin the machine and has resulted in airplane crashes. However, some species of gulls benefit humans by feeding on large numbers of insects that might otherwise damage crops.
The larger species of gulls, such as the herring and great black-backed gulls can be formidable predators of the young of smaller seabirds. The increased populations of these predatory gulls have severely affected the breeding success and populations of some smaller species, especially terns. This is a serious conservation problem in many areas, and it may only be resolved by killing adult gulls with guns or poisons. The alternative to this unsavory control strategy would likely be the local extirpation, and perhaps even global endangerment of, the prey species.
In many places gulls eggs are regarded as a delicacy and are collected as a subsistence food or to sell. To ensure freshness, all of the eggs in a colony are generally smashed on the first visit to the breeding site. Consequently, the age of any eggs that are collected on the second or subsequent visits is known. Adult or young gulls are also sometimes eaten by people, though this is not very common.
In spite of some of the problems with gulls, they are a favored group among bird-watchers. Numerous species of gulls can be seen in some places, especially during the non-breeding season. Birders often undertake field trips to those avian hot-spots, with the specific goal of identifying as many rare species of gulls as possible.
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