GULL INFORMATION (used with permission USDA Wildlife APHIS Services)
Cooperative Extension Division (1994)
Damage Prevention and Control Methods
By Victor E F Solman
Wildlife Biologist (Retired)
Canadian Wildlife Service
Gulls feed on land or water on aquatic animals, terrestrial invertebrates and small vertebrates, plant remains, carrion, and refuse. They frequently take the eggs and young of other nesting seabirds. Small species, including ring- billed, laughing, and Franklin’s gulls, may also feed in the air on flying insects.
Increasing gull populations in North America during the past century have led to a variety of problems for different segments of society. Gulls cause damage to agricultural crops and threaten human safety at and near air- ports. They are involved in more collisions with aircraft than any other bird group because they are numerous and widely distributed. The presence of gull roosts near reservoirs increases their potential for transmitting diseases to human populations. Gulls occasionally cause a nuisance when they nest on rooftops and seek food from people eating out-of-doors. Gulls are predators of several seabirds during the breeding season. Expanding and colonizing gull populations may have detrimental affects on the breed- ing performance of these other, often preferred, species.
Gulls are classified as migratory species and thus are protected by federal and, in most cases, state laws. In the United States, gulls may be taken only with a permit issued by the US Fish and Wildlife Service. Permits are issued only after frightening techniques, physical barriers, or both have been used correctly and qualified personnel certify that these methods have been ineffective. Some states may re- quire an additional permit to kill gulls. No federal permit is needed, however, to frighten or mechanically exclude gulls.
Damage Prevention and Control Methods
Exclusion of gulls from attractive areas (garbage dumps, sewage discharge areas, drive-in theaters, catering establishments) near airports can significantly reduce gull use of airport surfaces and flight-ways used by aircraft.
Exclude gulls from limited resting areas such as window ledges and roof tops by covering the surfaces with porcupine wires (see Pigeons). Exclude them from large areas such as water reservoirs, crop fields, and landfills, by installing wire or plastic netting or suspending parallel steel wire (28-gauge [0.36 mm]) or nylon monofilament line (50-pound [23-kg] test) over the area. Wire or monofilament spacing may be 40 feet (12 m) for large gulls to 15 feet (4.5 m) for smaller ones.
Birds have long been excluded from ponds in which fish are raised by using heavy, easily visible wires. Amling (1980) used strong, fine steel wires (28 gauge [0.036 cm]) on long, parallel spans up to 80 feet (25 m) apart to exclude gulls from a water reservoir. Wires have been used successfully to exclude most herring and ring-billed gulls from garbage dumps. McLaren et al. (1984) found that a wire spacing of 30 feet (9 m) worked if the food attraction was not too great. Fif- teen-foot (6-m) spacing worked even with very abundant food. Blokpoel and Tessier (1984) reported the successful exclusion of ring-billed gulls from food service areas in Toronto us- ing widely spaced nylon monofilament lines. They used more closely spaced lines to exclude the same species from part of a nesting area used by more than 70,000 pairs of gulls.
The reason that gulls rarely fly under or between fine parallel wires is not clearly understood. Other birds, including pigeons, regularly fly under and between the wires. The fine wires
The herring (Larus argentatus) and ring- billed (L. delawarensis) gulls are the most common and widespread of the species. They are distributed through- out North America, from coastal to inland areas, from unsettled areas to the downtown cores of large cities, from farmers’ fields to fast-food out- lets and drive-in theaters. Other com- mon species include the laughing gull (L atricilla), Franklin’s gull (L. pipixcan), great black-backed gull (L. marinus), and California gull (L. californicus). Some species are limited to coastal habitats, while others may occur inland seasonally, rarely, or in specialized habitats.
General Biology, Reproduction, and Behavior
Most gulls nest in colonies on sand- and gravel-covered shorelines and islands. They build nests on the ground and produce 3 to 5 eggs per nest. In the Great Lakes region, the number of ring-billed gulls has been increasing at about 10% per year since the early 1970s. Bent (1947) said of it, “the ring-billed gull yields readily to persecution, is easily driven from its breeding grounds and seems to prefer to breed in remote, unsettled regions far from the haunts of man.” However, a colony on Leslie Spit on the water- front of Toronto, Ontario, increased from 20 pairs in 1973 to 75,000 to 80,000 pairs in 1982 (Blokpoel 1983).
It appears that ring-billed gulls have changed some of their habits in recent years and have adapted to humans in their environment. A colony of laugh- ing gulls in the Jamaica Bay Unit of Gateway National Recreation Area, New York, increased from 15 pairs in 1979 to 7,600 pairs in 1990 (Richard A. Dolbeer, pers.commun.).