A silver gull (Chroicocephalus novaehollandiae), also known as a red-billed gull, is commonly found in coastal areas of Australia. The medium-sized white bird is 45 to 55 inches (about 114 to 140 centimeters) in length as an adult with a wing span of 37 inches (about 94 centimeters). The silver gull is known for its loud, raspy call and for its scavenger-like ability.
The head, neck, and body of an adult silver gull are white, the bill and legs are red, and its wings are silver with black markings. The color of the beak helps to indicate the age of the bird; the brighter the beak, the older the bird. Young gulls have brown markings on their wings and a dark-colored bill.
While the silver gull is commonly found along the coast, particularly on islands in Port Phillip Bay, the birds are also found in urban areas. Gulls are often found along beaches, near shopping centers, garbage dumps, and even airports. Flocks of the gulls may pose danger to Australian aircraft, as the birds fly unpredictably. If an aircraft hits a gull, there is a chance the bird can get stuck in the engine, resulting in mechanical failure.
Opportunistic in their feeding habits, gulls have been known to acquire some of their food at landfills and uncovered waste receptacles. The natural diet of the silver gull consists of fish, worms, plankton, and insects. Sometimes, gulls will feed on the young of other birds — even of other gulls. Predators of the gull include weasels and large mammals. The gulls often can ward off predators with their loud shrieks or by dive bombing their natural enemies.
By the age of two or three, the gulls are able to reproduce. Breeding typically occurs in July or August in large colonies, and the birds make their saucer-shaped nests out of seaweed, roots, and plant stems. Nests are often found on islets, rocks, and old boats, and in shrubs.
A female will lay anywhere from one to four eggs a season. Her eggs are light brown, blue, or green in color, with spots or stripes. Both the male and female share the feeding duties. Young gull wills stay in their next for about six weeks before wandering off on their own. If the birds leave the nest too early, they run the risk of being attacked or eaten by predators.