Ring-billed+Gull

toc // Larus delawarensis //

Order: Charadriiformes =**__Husbandry Information__**=

Diet Requirements

 * In the wild, ring-billed gulls eat fish, insects, earthworms, rodents, grain, and garbage.
 * In captivity, they are fed chicks and dog food.
 * Gulls forage while walking on land, dipping for food on the surface of the water, skimming shallow water for small fish, and hawking for flying insects.

Notes on Enrichment & Training


=__Programmatic Information__=

Potential Messaging


=__Acquisition Information__=

=__Comments from the Rating System__=
 * Philadelphia Zoo: Our experiment with one individual did not go well; it was very wary, which made training difficult. It could not even successfully crate train. This was a rehab bird.

=__Natural History Information__=

Range and Habitat
Ring-billed gulls can be found in North America and Europe. They are migratory, wintering in the south and breeding the in the north.

Physical Description
Ring-billed gulls are a medium-sized gull, and the smallest of the “white-headed gulls.” Adults have a yellow bill with a black ring near the tip, and yellow legs. Plumage colors of gulls change with age. Juvenile birds tend to be very brown, while adults tend to have white heads – except in the winter when they may regain some brown coloration. Subadults take three full years to gain their adult plumage. Adults have white heads and underparts, light grey along the back, and the wingtips are black with white spots. Fully grown, they are 14 to 16 inches long with a 49 inch wingspan. They typically weigh about 1.5 pounds, with males being slightly larger than females.

Life Cycle
Many if not most ring-billed gulls return to breed at the colony where they hatched. Once they have bred, they are likely to return to the same breeding spot each year, often nesting within a few meters of the last year’s nest site. Females lay 2 to 4 light-blue to greenish-brown spotted eggs in a scrape nest with grass, twigs, sticks, leaves, and lichens. Young gulls are semi-precocial, and may leave the nest cup a day after hatching. Hatchlings are covered in cryptically colored down. The average lifespan of this species is not known, but some birds have been documented to live 32 years.

Behavior
Ring-billed gulls play by dropping object while in flight, and then swooping down to catch them again. This playful behavior may be practice for catching and retrieving prey. The call is a shrill “oooww” and a seires of short “a-a-a-a-a-a-a-a.”

Threats and Conservation Status
Ring-billed gulls were almost exterminated by human persecution and development from 1850 to 1920. Their plumage was used for millinery trade (hats), eggs were used for food, and nesting habitat was developed. Today, however, this species is common and wide-spread. In fact, it is expanding its breeding range. Natural predators include foxes, owls, and larger gulls.

=__Did you know…__=
 * Young ring-billed gulls tested at only two days of age showed a preference for magnetic bearings that would take them in the appropriate direction for their fall migration.

=__Photographs__=

=__Contributors and Citations__=
 * The Philadelphia Zoo