Lots of beach-goers find seagulls annoying, but usually the only harm they do is snatching away poorly-guarded snacks. On one particular beach, though, scientists have found that some gulls have a much more aggressive and grisly way of getting their meals.
Biologist Austin Gallagher and his team have documented a startling behavior among kelp gulls in Dorob National Park on the Namibian coast. One of their collaborators, a local guide who’s led kayak and 4x4 tours of the park since 1999, has logged around 500 instances where gulls have approached Cape fur seal pups and “attacked the ocular region of the seal with its beak, and attempted to remove and consume the seals’ eyeballs.” After plucking out a seal’s eyes, which the birds successfully did about half the time, the first attacker was joined by other gulls who pecked at the blind and defenseless seal’s soft belly and began consuming it.
As far as Gallagher knows, this is the first record of this attack behavior and may be unique to the gulls living in the park. Why they do it isn’t exactly clear, but the researchers think the birds are just making the best of a bad situation. Both gull and seal populations in the area have grown in the last few decades and the two animals compete for the same food source: fish. With overfishing by humans making that competition stiffer, the gulls appear to to have turned their rivals into an alternate food source. Each new batch of pups “represents a dense and predictable pulse of energy” for the gulls, the researchers write, and plucking out their eye makes them easy pickings.
While seals getting their eyes plucked out may be hard to stomach, the researchers say that the gulls' odd, aggressive attacks deserve attention. Shifts in behavior like this can be indicators of ecological changes to come, helping us understand how pressures like overfishing are disrupting natural systems and alerting conservationists to areas and species that need protection.