INTRODUCTION. Sea gulls have long been associated with sea coasts. However, several species have extended their ranges significantly inland, with landfills and agricultural development being the attractions. Sea gulls are mainly nuisance pests around harbors, landfills, agricultural areas, and when begging for food. In addition, they foul residential and commercial buildings and public areas with their smelly droppings, and they account for 50% of documented aircraft-bird strikes. Sea gulls are worldwide in distribution, but are found mainly around sea coasts and large inland waterways.

RECOGNITION. Depending on the species, adults about 11-30" (27.9-76.2 cm) long. Large, mainly white water birds with slightly hooked bill, long pointed wings, usually short fan-shaped tail, and webbed feet; swim and feed at water surface. Color mainly white with no brown plumage, head feathers vary seasonally from dirty white/brown to pure white/black, and tail whitish with no dark bars.

Immature gulls often dirty white to brown.

SIMILAR GROUPS. (1) Terns (Laridae) with bill sharp-pointed and tail usually forked; typically in summer whitish with black caps (top of head) vs. in winter forehead replaced with white.

REPRESENTATIVE SPECIES.

1. Great black-backed gull, Larus marinus Linnaeus. Adults about 30" (76.2 cm) long; color white except back, wings (except tips), and tail black, eyes yellow, bill yellow with red spot on venter near tip, and legs and feet pinkish; 1st year immatures with head, breast, and rump whitish, back and wings mottled with brown and black, tail with black tip, and bill dark; breeds along Atlantic coast from Labrador south to Carolinas, rarely on Great Lakes; winters on Great Lakes and from Newfoundland south to Carolinas, rarely further south.
     
2. Herring gull, Larus argentatus Pontoppidan. Adults about 23-26" (58.4-66 cm) long; color white with gray back and wings, wing tip black with white spots, eyes yellow, bill yellow with red spot on venter near tip, legs and feet pinkish or flesh-colored; 1st year immatures mottled brownish with dark bill; breeds from Alaska and northern Canada south to British Columbia, western Saskatchewan, Montana, Great Lakes area, and northern New England, and or Atlantic Coast south to North Carolina, winters from southern Alaska, Great Lakes, and Labrador southwards, especially along coasts and open inland waters, such as Mississippi River basin.
    
3. Laughing gull, Larus atricilla Linnaeus. Adults about 15-17" (38-43 cm) long; color with white neck, breast, belly, and tail, dark gray back and wings, wing with hind edge white and tips solid black, legs dark, and eyes dark with white line above and below; in summer head black with red bill, in winter head whitish with gray on sides, bill black, and wings tipped with white; 1st year immatures brownish with gray back and breast, white rump, and black bill; breeds along Atlantic Coast from Maine to Texas and also at Salton Sea in southern California; winters from North Carolina southward, occasionally farther north.
     
4. Ring-billed gull, Larus delawarensis Ord. Adults about 18-20" (45.7-50.8 cm) long; color silvery gray on back, white on head, neck, tail, and beneath, with narrow black ring around yellow bill near tip, eyes yellow, and legs and feet yellowish; 1st year immatures mottled brown with blackish tail band, bill pinkish with black tip, and legs flesh-colored; breeds from Washington, central Saskatchewan, and central Manitoba south to northeastern California, Wyoming, and northeastern North Dakota, and also in Great Lakes area and Maritime Provinces; winters from southwestern British Columbia and Washington, Great Lakes area, and Nova Scotia southward, and also Mississippi River basin.

BIOLOGY. For the 4 representative species, this can be summarized as follows:

1. Great black-backed gull. The females lay 2-3 eggs that are olive with darker marks. The incubation period is 27-28 days. The immatures are feathered upon hatching and can generally feed themselves. They leave the nest in 49-56 days. There is 1 brood per year.
    
2. Herring gull. The females lay 3 eggs that are brownish with dark marks. The incubation period is 26 days. The immatures are feathered upon hatching and can generally feed themselves. They leave the nest in about 35 days. There is 1 brood per year.
    
3. Laughing gull. The females lay 3-4 eggs that are brownish with dark marks. The incubation period is 19-22 days. The immatures are feathered upon hatching and can generally feed themselves. They leave the nest in 35-40 days. There is 1 brood per year.
    
4. Ring-billed gull. The females lay 3 eggs that are light brown with dark markings. The incubation period is 21 days. The immatures are feathered upon hatching and can generally feed themselves. They leave the nest in several weeks. There is 1 brood per year.

HABITS. For the 4 representative species, these can be summarized as follows:

1. Great black-backed gull. They often nest in colonies mixed in with herring gulls. They nest on a mound of seaweed and other vegetation which is placed on the ground or on a ledge. Their habitat consists of the Great Lakes, coastal beaches, estuaries, lagoons, and refuse dumps. They are less common on inland lakes and rivers. This gull is an efficient predator on other birds and also eats small mammals and fish.
     
2. Herring gull. They nest in small colonies. Their nest is a scrape in the ground that is lined with grasses and seaweed. Their habitat consists of lakes, rivers, estuaries, and beaches, being common in all aquatic habitats; they are also found in fields but are very common in landfill areas. These gulls feed on mussels, clams, fish, garbage, rodents, insects, and the young of other gulls; steals food from other birds.
    
3. Laughing gull. They nest in colonies. The nest consists of grasses and sedges placed on the ground. Their habitat is coastal, including salt marches, bays, and estuaries; these gulls are very rarely found inland. These gulls eat fish, crabs, shrimp, aerial insects, and garbage.