Conservation and Management

Disturbance At Nest And Roost Sites

Native Americans in Maine used eggs for food (Gross 1945). Arrival of Europeans resulted in increase in egging, also in subsequent hunting for food and, in the nineteenth century, for the millinery trade. Reversal of decline, and increases in population in Northeast in first half of 1900s, due to protection (Gross 1948). Subsequent declines in Massachusetts and farther north in 1950–1970s partly due to hurricanes and sheep grazing, but mainly to competition and predatory interactions with Herring and Great Black-backed gulls (Nisbet 1971). In Texas, oil-drilling activities caused local decreases in number of breeding pairs; numbers increased when disturbance from drilling stopped (Mueller and Glass 1988).

Vulnerable to human intrusions at colonies: early in season, Laughing Gulls will abandon site; later, they mob and attack people entering colonies (JB). Effects of disturbance greater in small or new colonies than in large colonies. People still collect eggs for food (mainly in Caribbean), disturb nests, interrupt incubation, drive through sandy colonies with off-road vehicles, or allow dogs to chase and kill young chicks. Nesting Laughing Gulls relatively immune to human disturbance on salt-marsh colonies because people avoid this wet, mosquito-rich habitat. Dry land colonies more vulnerable to picnickers and other intruders.

Vulnerable to direct human disturbance on foraging grounds from sunbathers, joggers, swimmers, anglers, clammers, dog-walkers, and others (Burger and Galli 1987). Responds to these disturbances by flying away, remaining but stopping feeding, or by continuing to feed; percentage of birds that fly away inversely related to number of disturbances; Laughing Gulls thus habituate (Burger and Galli 1987, Burger and Gochfeld 1991).

Collisions With Stationary/Moving Structure Or Objects

Collisions with aircraft at Kennedy International Airport (JFK) in New York City (Belant and Dolbeer 1993a), at Atlantic City, NJ, airport (JB), and elsewhere have resulted in gull control, including direct killing of Laughing Gulls. Prior to 1980, few Laughing Gulls hit by aircraft at JFK (Burger 1985). In 1979, 15 pairs nested near JFK, in 1988 as many as 2,665; strikes with aircraft rose from 2 in 1979 to 180 in 1989 (56% of all strikes; Dolbeer et al. 1989). Control techniques at JFK failed (Sillings et al. 1992), and 14,191 (1991) and 11,847 (1992) Laughing Gulls were shot, resulting in 68% reduction in collisions with aircraft in 1991 (Belant and Dolbeer 1993a). Number of Laughing Gulls shot at JFK each year represents about 5–6% of annual nesting population from Maine to Virginia, and 2–3% of total U.S. nesting population (Belant and Dolbeer 1993a).

Pesticides And Other Contaminants/Toxics

All of 201 eggs analyzed in Texas (1978–1981) contained detectable levels of DDE, ranging from 0.3 to 91 parts per million (ppm) wet weight; residues of dieldrin, heptachlor epoxide, and toxaphene detected less frequently and usually <1 ppm (White et al. 1983a). DDE levels in Texas highest in agricultural drains at Port Mansfield (White et al. 1983a). Eggshell thinning detected at all colonies examined in Texas, ranging from 7 to 14% in Texas (White et al. 1983a).

Organochlorine compounds implicated in mortality that reduced fledging success by 33% in Texas in 1978–1981. Adults attracted to recently sprayed fields ate dead and dying insects; some adults died in fields, others brought contaminated insects to feed chicks which then died (White et al. 1979, 1983a). Parathion also altered incubation behavior of adults (White et al. 1983b).

Heavy metal levels in the feathers of Laughing Gulls nesting near Kennedy International Airport, New York City, are generally low, but lead and mercury are relatively high compared with other birds and other gulls (JB). Concentrations of lead, cadmium, mercury, manganese, selenium, and chromium in feathers, liver, kidney, heart, and muscle were examined in birds from the New York–New Jersey area. Generally, levels were within the normal range for most birds, although lead and mercury were at the high end for gulls. Significant age-related differences for lead, cadmium, selenium, and chromium were detected. Metal levels increased with age, except that selenium decreased with age (Gochfeld et al. in press).

Degradation Of Habitat: Breeding And Wintering

Nesting habitat is degraded when offshore sandy or rocky islands are developed, bringing increases in large gulls and mammalian predators. Foraging habitat is degraded when estuaries and coastal areas used for foraging are developed, when human activities increase, or when foods are overharvested.

Competition With Gulls And Other Species

Sheep on some offshore Maine islands denuded vegetation, making habitat unusable (Gross 1945). Competition for nesting habitat with Herring Gulls first noted in Maine in 1940s (Gross 1945); severe problem in New Jersey, the center of temperate nesting Laughing Gulls (Burger 1977b, 1979b). See Breeding: colony/nest site, above.

Research Impacts

Trapping breeders at nests for scientific research does not result in nest desertion as long as trapping occurs from mid- to late incubation and trapping time in any one area of colony is limited in duration (JB). Trapping should be avoided after hatching because chicks can be caught in traps or may wander and get pecked by neighbors, or adults may move young from the nest.

Not currently threatened anywhere in its range. No continentwide management programs other than protection afforded by Migratory Bird Treaty Act of 1918. No national breeding colony surveys, although many states conduct periodic monitoring of coastal colonial waterbirds. Considered a pest around landfills and airports, where a variety of methods are employed to scare Laughing Gulls away, including setting off noise-makers, running vehicles on the runways every few minutes, using trained raptors to scare birds, and implementing large-scale control programs that involve killing birds (Dolbeer et al. 1989, Belant and Dolbeer 1993a).