Gulls, often colloquially known as “seagulls,” are a familiar sight in coastal and increasingly inland regions worldwide. While the term “seagull” is widely used, these birds are properly referred to as gulls. They belong to the family Laridae, which also includes terns and skimmers. Gulls are highly adaptable birds, known for their intelligence and widespread presence across diverse habitats, thriving in environments from oceans to urban centers.
The True Number of Gull Species
There are approximately 50 to 60 recognized gull species globally, though the exact number can vary depending on taxonomic classifications. Historically, most gulls were grouped under the single genus Larus. However, recent genetic research has led to a reclassification, resulting in the recognition of several distinct genera within the gull group. The Larus genus still represents a significant portion, containing about 25 to 49 species, depending on the authority.
Key Characteristics of Diverse Gull Species
Gull species exhibit a range of physical characteristics that allow for their differentiation, though identification can be challenging due to plumage variations. Size is a primary distinguishing feature, with gulls ranging from the small Little Gull, weighing about 120 grams and measuring 29 centimeters, to the large Great Black-backed Gull, which can weigh up to 1.75 kilograms and reach 76 centimeters in length. Plumage patterns vary significantly with age and season. Young birds typically display mottled brown coloration, gradually acquiring adult plumage over two to four years. Adult gulls generally have grey or white bodies with darker markings on their wings, and their heads can be entirely white, streaked, or feature dark hoods depending on the species and breeding season.
Differences extend to bill and leg coloration and shape. Gull bills are generally stout, heavy, and slightly hooked, with colors ranging from yellow, sometimes marked with a red spot, to red, dark red, or black. Leg colors also vary, appearing pink, yellow, greenish-yellow, or even black. The eye color, such as dark, yellow, or olive-yellow, and the presence or color of an orbital eye-ring, can also provide clues for identification. These subtle yet consistent differences in physical traits help scientists and birdwatchers distinguish between the many gull species.
Global Distribution and Common Species
Gulls demonstrate a global distribution, inhabiting every continent from the Arctic to Antarctica. While often associated with marine environments, many species thrive far from the sea, adapting to freshwater and terrestrial habitats, including urban areas. Many gull species are migratory, moving to warmer regions during winter, while others remain in their breeding areas year-round.
Well-known species found across various parts of the world include the Herring Gull (Larus argentatus), a widespread species in the North Atlantic, and the Lesser Black-backed Gull (Larus fuscus), known for its darker back and yellow legs. Other common examples include the Black-headed Gull (Chroicocephalus ridibundus), identifiable by its dark brown head in breeding plumage, and the Ring-billed Gull (Larus delawarensis), frequently encountered in North America. The Common Gull (Larus canus), despite its name, is less widespread than some other species but can be found across Europe and Asia.