Gulls are familiar birds often seen near coastlines, large bodies of water, and human settlements. These adaptable birds belong to the family Laridae, encompassing over 50 recognized species worldwide. While commonly referred to as “seagulls,” this is a colloquialism, as no single species is scientifically named a seagull. Gulls exhibit diverse behaviors, including varying migratory patterns.
Not All Seagulls Migrate
The migratory habits of gulls vary significantly among species and even within populations. Some gulls are truly migratory, undertaking long journeys between their breeding and wintering grounds, while others remain in the same general area year-round. This phenomenon is known as partial migration, where some individuals within a species migrate, while others do not. For instance, certain European Herring Gull populations are sedentary, while northern and eastern populations migrate longer distances. Long-distance migrants include Franklin’s Gull, traveling from North America to Argentina, and Sabine’s Gull, covering thousands of kilometers from Arctic breeding grounds to wintering areas off South America and southern Africa. In contrast, species like the Lava Gull of the Galapagos are largely non-migratory, as are many gulls in the Southern Hemisphere or closer to the equator.
Why Seagulls Migrate
Gulls migrate primarily in response to environmental and biological factors that influence their survival and reproduction. A significant driver is food availability, as gulls follow changing food sources throughout the seasons; for example, frozen water bodies limit access to fish, prompting gulls to move where food remains accessible. The presence of human fisheries and refuse dumps can also influence gull distribution by providing abundant food resources. Migration also allows gulls to access optimal breeding grounds, which are often remote locations offering abundant resources and fewer predators for raising young. Furthermore, gulls migrate to escape harsh winter climates, seeking more temperate conditions conducive to survival, and moving to new areas can also help them avoid predators, especially during nesting.
The Journey and Its Challenges
The migratory journeys undertaken by gulls vary greatly in distance and complexity; some species, like Franklin’s Gull, travel thousands of miles, while others may only move short distances to coastal areas or open waters. Migratory routes often involve north-south movements, with North American gulls typically migrating to South America and European gulls heading towards Africa or the Middle East; Brown-headed Gulls, for instance, travel between China and Thailand, covering an estimated 2,400 kilometers in about 12 days. Gulls employ various methods to navigate these long distances, including using the sun, stars, Earth’s magnetic field, and their sense of smell, which helps them correct for displacement and stay on course. These journeys demand considerable energy expenditure, imposing physical stress on the birds. Migrating gulls face numerous challenges, including extreme weather conditions, the scarcity of suitable food and rest stops along their routes, and various human-made obstacles, yet despite these hardships, migration is an adaptive strategy that provides advantages for their survival and reproductive success.