Seagulls are highly adaptable birds found in diverse environments, from coastlines to urban areas. Their widespread presence is largely due to their varied and opportunistic diet, allowing them to thrive.
The Diverse Natural Diet
Seagulls are omnivores and opportunistic feeders. In marine habitats, their diet primarily includes live fish and marine invertebrates like crustaceans, mollusks, and worms, caught from the water’s surface. They also consume fish eggs and carrion found along shorelines. Some species employ specific foraging techniques, such as plunge diving for fish or foot-stomping in shallow water to stir up prey.
Beyond marine sources, seagulls forage in terrestrial environments. They consume insects, earthworms, and small rodents. Bird eggs and chicks, along with reptiles and amphibians, can also be part of their diet. Additionally, plant items like berries and seeds are eaten when available. This broad diet showcases their scavenging nature.
Adapting to Human Environments
Seagulls successfully adapt their feeding strategies to human-populated areas. Their opportunistic scavenging extends to readily available human food sources like discarded food in landfills, trash bins, and picnic areas. Fishing vessels also provide opportunities for discarded catch, which gulls readily consume.
Studies indicate that in some urban gull populations, human food waste can constitute a significant portion (up to 80%) of their diet. This provides calorie-dense food with less effort, and gulls quickly learn to associate humans with easy meals. Their intelligence allows them to observe human behavior, such as handling food, and even develop techniques for opening food packaging. While adaptable, this shift alters their diet’s nutritional composition from natural sources.
Foods to Avoid Giving Seagulls
Feeding seagulls human food is generally detrimental to their health and natural behaviors. Foods like bread, crackers, and french fries offer poor nutritional value, leading to deficiencies and long-term health problems. Such an artificial diet may cause issues like “Angel Wing” syndrome, a deformity that impairs flight. These easy food sources can make gulls dependent on humans, discouraging natural foraging.
Certain human foods are toxic to seagulls. Salty foods can cause dehydration and kidney issues. Fried or greasy foods can lead to digestive problems. Chocolate is particularly toxic due to theobromine and caffeine, causing hyperactivity, tremors, seizures, and even death. Avocado contains persin, a toxin harmful to birds; feeding gulls can also lead to unnaturally large congregations, increasing disease transmission risk among birds and potentially to humans.