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ring-billed gull

Larus delawarensis

What do they look like?

Ring-billed gulls are medium-sized birds. Males are slightly larger than females. They are about 50.2 cm long and weigh about 550 g. Females are about 46.9 cm long and weigh about 470 g. Males and females have a wingspan of about 127 cm.

The backs and shoulders of ring-billed gulls are pale bluish-gray, and the head is white. The wings are tipped in black with white spots. Underneath, ring-billed gulls are white. The legs and feet have a yellow or green color. There is a black ring around the bill.

Immature birds have different coloration. First year ring-billed gulls are white with brown flecks and very dark wing tips and tail. Second year gulls are more like the adults, but have a black-tipped tail. Nestlings have two color phases; some are smoky gray, while others are pink with white spots.

Ring-billed gulls may be confused with herring gulls. Herring gulls are larger and have thicker bills without the black ring. (Farrand, 1988; Palmer and Fowler, 1975; Peterson, 1967)

  • Sexual Dimorphism
  • male larger
  • Range mass
    300 to 700 g
    10.57 to 24.67 oz
  • Range length
    43 to 54 cm
    16.93 to 21.26 in
  • Average wingspan
    127 cm
    50.00 in
  • Average basal metabolic rate
    2.91742 W
    AnAge

Where do they live?

Ring-billed gulls are native to the Nearctic and Neotropical regions. They live across the northern United States and southern Canada. During winter they migrate to the southern United States, Mexico, and Central America. They are also found in Bermuda and Hawaii. (Farrand, 1988; Palmer and Fowler, 1975)

What kind of habitat do they need?

Ring-billed gulls are often found along inland waterways and in open landscapes. They typically occur on beaches, open grasslands, and wet meadows. Their preference for open areas makes them well-suited to urban and suburban landscapes and they are often found on large, grassy lawns, parking lots, and in vacant land. (Farrand, 1988; Palmer and Fowler, 1975; Ryder, 1993)

  • Aquatic Biomes
  • lakes and ponds
  • rivers and streams
  • coastal

How do they reproduce?

Ring-billed gulls are monogamous (one male mates with one female). Males and females for breeding pairs just before arriving on the breeding grounds, or just after arriving. Occasionally, two females mate with one male. This is called polygyny. (Ryder, 1993)

Ring-billed gulls nest in colonies on the ground, or sometimes in trees near lakes. They often nest near other water birds. The male and female work together to build the nest out of twigs, sticks, grasses, leaves, lichens and mosses.

The female lays three eggs. Each is about 6.4 cm long by 4.6 cm wide. The eggs are light blue, green or brownish and spotted. The male and female both incubate the eggs for about 20 to 31 days. After the chicks hatch, both parents brood and feed them. The chicks begin leaving the nest within days of hatching, and are able to fly at about 5 weeks old.

Ring-billed gulls breed between May and August. They probably do not begin breeding until they are at least 2 years old. (Farrand, 1988; Palmer and Fowler, 1975; Ryder, 1993)

  • How often does reproduction occur?
    Ring-billed gulls breed once per year.
  • Breeding season
    Ring-billed gulls breed between May and August.
  • Range eggs per season
    2 to 4
  • Average eggs per season
    3
    AnAge
  • Range time to hatching
    20 to 31 days

Both parents incubate the eggs and feed nestlings until they reach independence. The young remain in the nest until they are able to walk, at about 4 days old. Birds depart from the nesting area immediately upon fledging, at about 45 days old.

  • Parental Investment
  • precocial
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • protecting
      • male
      • female
  • pre-weaning/fledging
    • provisioning
      • male
      • female
    • protecting
      • male
      • female
  • pre-independence
    • provisioning
      • male
      • female

How long do they live?

Ring-billed gulls have been recorded living as long as 23 years in the wild. However, it is likely that the majority of these birds live much shorter lives than this, probably 3 to 10 years.

  • Range lifespan
    Status: wild
    23 (high) years
  • Typical lifespan
    Status: wild
    3 to 10 years

How do they behave?

Ring-billed gulls are active during the day. They migrate between breeding and wintering areas.

Ring-billed gulls are highly social, occupying large colonies especially during the breeding season. They defend small territories within nesting colonies. They engage in play, dropping objects while airborne, then swooping down to catch them. They may steal food from other gulls and European starlings as well as fending off other birds that may steal their food. (Farrand, 1988; Palmer and Fowler, 1975; Ryder, 1993)

  • Range territory size
    1 to 5 m^2

Home Range

How do they communicate with each other?

Ring-billed Gulls communicate using calls and body language. They have two alert calls; a screeching call that sounds like "kree, kree" and a shrill "kyow kyow kyow " call that sounds high-pitched and squealing. They use a "mew" call during breeding activities, such as courtship feeding and feeding chicks.

While being aggressive, ring-billed gulls lower their head to their feet and then toss their head backward at the end of a call. When they are being submissive, they hunch their head and neck and make short, high-pitched "klioo" calls while tossing their head. (Farrand, 1988; Palmer and Fowler, 1975; Ryder, 1993)

What do they eat?

Ring-billed gulls are opportunistic feeders, or scavengers, meaning they will eat almost anything that they find. They eat fish, rodents, small aquatic animals, bird chicks and eggs, insects, and vegetable matter such as fruits, though they prefer animal foods.

This kind of feeding behavior has made them very successful in areas around humans where they take advantage of land fills, garbage dumps, and ships that dump garbage overboard. They also scavenge from plowed fields, parks, and parking lots. In fact, these gulls might be seen squabbling over discarded items from fast-food restaurants. Ring-billed gulls are able to snatch food from the water's surface while in flight. (Farrand, 1988; Fisher and Chartier, 1997; Palmer and Fowler, 1975)

  • Animal Foods
  • birds
  • mammals
  • fish
  • insects
  • terrestrial worms
  • Plant Foods
  • seeds, grains, and nuts
  • fruit

What eats them and how do they avoid being eaten?

Predators of ring-billed gulls include red fox, coyote, striped skunk, raccoons, long-tailed weasel, mink, California gulls, herring gulls, great horned owls, snowy owls, American crows and common ravens.

Ring-billed gulls swoop and soar above predators to drive them away. They also mob predators by attacking them in groups. Because ring-billed gulls nest and feed in large colonies, they depend on each other to detect predators. The alarm calls and panic flights of neighbors let other birds in colony know that a predator is nearby. (Ryder, 1993)

What roles do they have in the ecosystem?

Ring-billed Gulls are scavengers, so they often consume foods that would otherwise go to waste. They affect the populations of the animals they prey upon. They also support the populations of small predators that prey on them.

Ring-billed gulls compete with other gull species for food and have been observed stealing food from starlings. (Ryder, 1993)

Do they cause problems?

Some people consider large groups of these birds to be pests due to their droppings, garbage stealing, and the noise that they create.

How do they interact with us?

Ring-billed gulls often eat garbage created by humans, which helps reduce waste. (Farrand, 1988; Palmer and Fowler, 1975)

Are they endangered?

Ring-billed Gull populations are not threatened. Population sizes may have increased in recent historical times because ring-billed gulls benefit from human activities, such as landfills and fishing practices.

They are protected under the U.S. Migratory Bird Treaty Act as migratory birds.

Contributors

Tanya Dewey (author), Animal Diversity Web.

Kari Kirschbaum (editor), Animal Diversity Web.

Janice Pappas (author), University of Michigan-Ann Arbor.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

acoustic

uses sound to communicate

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends.

chemical

uses smells or other chemicals to communicate

coastal

the nearshore aquatic habitats near a coast, or shoreline.

colonial

used loosely to describe any group of organisms living together or in close proximity to each other - for example nesting shorebirds that live in large colonies. More specifically refers to a group of organisms in which members act as specialized subunits (a continuous, modular society) - as in clonal organisms.

desert or dunes

in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.

diurnal
  1. active during the day, 2. lasting for one day.
endothermic

animals that generate their own body heat through metabolic processes.

freshwater

mainly lives in water that is not salty.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

migratory

makes seasonal movements between breeding and wintering grounds

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

omnivore

an animal that mainly eats all kinds of things, including plants and animals

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

polygynous

having more than one female as a mate at one time

saltwater or marine

mainly lives in oceans, seas, or other bodies of salt water.

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

suburban

living in residential areas on the outskirts of large cities or towns.

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

urban

living in cities and large towns, landscapes dominated by human structures and activity.

visual

uses sight to communicate

young precocial

young are relatively well-developed when born

References

Farrand, J. 1988. Eastern Birds; An Audubon Handbook. New York: McGraw-Hill, Inc.

Fisher, C., A. Chartier. 1997. Birds of Detroit. Canada: Lone Pine Publishing.

Palmer, E., H. Fowler. 1975. Fieldbook of Natural History, 2nd ed. New York: McGraw-Hill, Inc.

Peterson, R. 1967. A Field Guide to the Birds: Eastern Land and Water Birds, 2nd ed. Boston: Houghton Mifflin Company.

Ryder, J. 1993. Ring-billed Gull. Pp. 1-28 in A Poole, P Stettenheim, F Gill, eds. The Birds of North America, Vol. 33. Philadelphia: The Academy of Natural Sciences; Washington, D.C.: The American Ornithologists' Union.

 
University of Michigan Museum of ZoologyNational Science Foundation

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Pappas, J. 2001. "Larus delawarensis" (On-line), Animal Diversity Web. Accessed April 24, 2014 at http://www.biokids.umich.edu/accounts/Larus_delawarensis/

BioKIDS is sponsored in part by the Interagency Education Research Initiative. It is a partnership of the University of Michigan School of Education, University of Michigan Museum of Zoology, and the Detroit Public Schools. This material is based upon work supported by the National Science Foundation under Grant DRL-0628151.
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