Conservation and Management

Shooting And Trapping

Actively hunted for eggs and feathers during nineteenth century; now protected from both forms of exploitation. Exploitation all but stopped in U.S. and Canada as result of growth of conservation movement and protection of birds (Montevecchi and Tuck 1987, Dunlap 1988). Since 1991, individuals (71% adult, 29% subadult) have been shot to prevent collisions with aircraft at JFK International Airport, NY (Dolbeer and Bucknall 1997).

Pesticides And Other Contaminants/Toxics

Eggs collected from Appledore I., ME in 1977 contained PCB and DDE levels (mean 8.66 ppm ± 4.67 SD wet weight, range 4.0–27.00) 4 times those of Herring Gulls; all eggs examined (n = 28) contained PCBs and DDE, and 7 eggs contained DDT (Szaro et al. 1979). Eggshell thickness (mean 0.43 mm ± 0.25 SD, range 0.39–0.47) of same eggs similar to pre-DDT (pre-1947) measurements (mean 0.403, range 0.350–0.451) of eggs (n = 20) from Nova Scotia and Labrador. Because this species feeds at higher trophic levels, may accumulate higher levels of contaminants than Herring or Ring-billed gulls do (Ewins et al. 1992).

Oiled individuals are reported frequently, but usually are unaffected (Clapp et al. 1983). Oil-contaminated individuals found near Sable I., Nova Scotia, during winter of 1976–1977 from grounding and oil spill of Argo Merchant and Grand Zenith (Levy 1980). Vulnerability to oil higher in mid-Atlantic and n. Atlantic than in s. Atlantic and s. Florida; spills near colonies during breeding, or near roosts or loafing sites at any time of year, could have moderate effects on local populations (Hoopes et al. 1994). Eggs show reduced hatching success if contaminated with crude or fuel oil, particularly with higher or repeated doses at early stages of incubation; oil contamination of the plumage around brood patches also reduces hatching (Lewis and Malecki 1984).

Ingestion Of Plastics/Lead, Etc

No data.

Collision With Stationary/Moving Structures Or Objects

Collides with aircraft near airports; harassment is an effective preventive measure (Blodget 1988). Together with Herring and Ring-billed gulls, accounted for 34% of bird-aircraft collisions at JFK International Airport, NY, from 1988 to 1990; summer shooting program reduced collisions with aircraft by 64–89% from 1991 to 1996 (Dolbeer and Bucknall 1997).

Fishing Nets

No data for North America. Occasionally caught during fishing operations in Britain in stake nets or on long lines (Harris 1962).

Degradation Of Habitat

No data.

Disturbance At Nest And Roost Sites

Persistent presence of humans on colonies causes interruption of incubation, and subjects eggs to high or low temperatures and predation. Response to human intrusion on colony is influenced by prior disturbance, incubation stage, and ambient temperature (Burger and Gochfeld 1983).

Direct Human Research Impacts

Impact of research activity is minimized if nests are always visited in the same order (TPG). Velcro® leg tags are suitable for short-term studies, unsuitable for productivity studies; tag loss and tag-related injury to chicks can be prevented only through frequent colony visits (Cavanagh and Griffin 1993).

Measures Proposed And Taken

Nest and egg destruction, harassment, shooting, and avicides are used to reduce or eliminate breeding on islands. Needling eggs is ineffective, as eggs rot, burst, and are replaced (Drury 1973, Blodget 1988). Egg oiling and destruction program of early 1900s was thought to have harassed gulls from Maine and New Hampshire to s. New England (Drury 1973). Poisoning programs have been carried out by state agencies and private individuals to provide greater nesting opportunities for terns (Kress 1983, Blodget and Henze 1992, Cavanagh 1992), Atlantic Puffins, and even other gulls (Drury and Nisbet 1972, Blodget 1988).

Effectiveness Of Measures

Productivity on Ram I., MA, was completely suppressed in 1990–1991 after nests were baited with the avicide DRC-1339; population recovered from the skewed sex ratio (64 females:6 males; Blodget and Henze 1992). Limited use of DRC-1339 from 1980 to 1986 failed to control Herring and Great Black-backed gulls on Monomoy I., MA; colonywide application was proposed in 1988, but proposal was withdrawn because of overwhelmingly negative public response (Cavanagh 1992). Large-scale application of DRC-1339, combined with shooting on Monomoy I. in May 1996, was successful; sex ratio less skewed than in previous studies (Megyesi 1996). This approach was stopped after initial application because of negative public response; nondestructive methods prepared for 1997 and beyond.

Efforts often ineffective on large scale (“gull population control”), although small-scale efforts (“gull control”) have been successful in eliminating gulls from small colonies (Blodget 1988, Alpers 1991). Short-term culls and poisoning deal with symptoms, not causes (Howes and Montevecchi 1993). De facto gull population control possible if municipal refuse and commercial fishing waste are reduced (Blodget 1988), although these are likely less a factor for Great Black-backed Gulls than for Herring Gulls.