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Black-headed gull

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The black-headed gull, known scientifically as Chroicocephalus ridibundus, is a small and highly adaptable bird.

Skrattmås - (Larus ridibudus) - Ystad-2026
Skrattmås - (Larus ridibudus) - Ystad-2026

These birds are found across much of the Palearctic, which includes large parts of Europe and Asia. They also exist in smaller numbers in coastal eastern Canada. Most of the population is migratory, meaning they fly to warmer regions during the winter. However, some birds stay in the milder areas of northwestern Europe. They are important members of their ecosystems because they are opportunistic feeders. They can eat insects, fish, seeds, worms, and even human food scraps.

Understanding the physical appearance of this gull requires looking at its seasonal plumage. The term plumage refers to the bird's feathers, which change depending on the time of year. During the summer, an adult gull has a chocolate-brown head. While it looks black from a distance, it is actually brown. These adults also have white necks, white underparts, and red bills and legs. In the winter, the gull loses this dark head. It instead shows only two dark spots located above and behind the eyes.

This transition is a natural cycle that helps them adapt to different seasons.

These gulls have complex life cycles and take two years to reach maturity. Juvenile birds look very different from adults when they first leave the nest. For the first two months, they have a mottled pattern of brown spots across their bodies. They also feature a black band on their tail. As they enter their first winter, they undergo a moult, which is the process of shedding old feathers to grow new ones. By their first summer, they develop a partial brown hood. The size of this hood varies greatly between individual birds.

The history of how we classify this bird has changed over time. In 1766, the Swedish naturalist Carl Linnaeus formally described the species. He originally placed it in the genus Larus and named it Larus ridibundus. The name ridibundus is Latin for "laughing."

Black-headed gull vocalizing (05604)
Black-headed gull vocalizing (05604)

Later, genetic studies in the early 21st century changed how scientists group gulls. They discovered that the genus Larus was paraphyletic, meaning it did not include all descendants of a common ancestor. Consequently, the black-headed gull was moved to the genus Chroicocephalus. This name comes from Greek words meaning "colored head."

Black-headed gulls are incredibly successful and numerous. There are an estimated 2 to 3 million pairs living globally. The largest concentrations are found in Europe. For example, Great Britain has up to 300,000 pairs, and Poland has about 250,000 pairs.

Their range is also expanding westward. They colonized Iceland in 1911 and Greenland in 1969. In 1977, they reached Newfoundland in Canada. These birds are also quite long-lived. One wild black-headed gull was recorded living for at least 32.9 years.

Behavior in the colony is often driven by survival and efficiency. One notable behavior is eggshell removal. Once chicks hatch, both parents carry eggshells away from the nest. This acts as a form of camouflage to hide the nest from predators like foxes or stoats. The parents can tell the difference between an egg and a shell by feeling the thin, serrated edges.

Another interesting behavior is begging coordination. Siblings learn to synchronize their begging signals to get food more efficiently. This coordination helps increase the rate of food regurgitation from the parents.

Social structures within the colonies can also be quite complex. Some females practice conspecific brood parasitism. This is when a female lays her eggs in the nest of another female of the same species. This can reduce the cost of raising young for the parasitic bird. Additionally, the species shows sexual size dimorphism. This means males and females are different sizes, with males averaging between 186 and 400 grams. Females are generally lighter, averaging between 166 and 350 grams. These various behaviors and traits allow the black-headed gull to thrive in many different environments.

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🖼️ Images & Media (5)
Black-headed Gulls (Larus ridibundus)...
Chroicocephalus ridibundus - winter...
Skrattmås (Chroicocephalus ridibundus) -...
File:Skrattmås - (Larus ridibudus) - Ystad-2026.jpg
Skrattmås - (Larus ridibudus) - Ystad-2026.jpg
File:Black-headed gull vocalizing (05604).jpg
Black-headed gull vocalizing (05604).jpg
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