Seagulls, often associated with seaside holiday towns, are highly adaptable birds increasingly found inland, even in urban environments. While commonly called "seagulls," many of the approximately 50 gull species live far from the sea. Found on every continent, these hardy birds thrive in diverse habitats, from the coldest climates like Antarctica and the Arctic to warmer regions such as deserts and tropical islands like the Galapagos. In the UK, the Herring Gull, Lesser Black-backed Gull, and Greater Black-backed Gull are the most common species.
Adaptable Feeding Habits
As their name suggests, seagulls are often seen fishing in the ocean and nesting on coastal cliffs. However, many have moved inland, residing in urban areas and near landfills, where food is easily accessible. They are incredibly adaptable, traditionally consuming molluscs, small fish like sardines, crabs, shrimps, worms, and insects. However, they also eat chicks or eggs of other birds, roadside carrion, or discarded takeaway food when available.
One reason seagulls are considered pests is their penchant for feeding frenzies. They are habituated to humans and confidently approach them, begging for food. With few predators in urban environments, seagulls have become fearless. Hawks, eagles, and falcons may catch gulls in mid-air in the wild, and foxes and weasels may attack nests and chicks.
Breeding and Nesting
Seagulls typically mate for life, often exceeding 30 years. Once a breeding pair finds a suitable nesting site, they return to it annually. These intelligent birds often attract others, forming nesting communities. In the UK, nesting seagulls are protected by law, especially species like Herring Gulls and Kittiwakes, which are on the UK Red List due to declining coastal populations. Active nests, those in use or containing eggs or chicks, cannot be removed until abandoned and the chicks have fledged.
After the nesting season, from September to January, seagulls leave their nesting sites for winter homes. To prevent them from perching on rooftops, humane deterrents like spikes can be installed.
Read also: Feeding Ecology of Herring Gulls
Communication and Diet
Seagulls can drink both fresh and salt water, thanks to a special gland near their eye that removes salt from their system. They are strong communicators, using specific calls and body movements to signal each other. For example, the 'Mew' call is a high-pitched sound used in flight between flock members.
As omnivores, seagulls eat fish, eggs, insects, molluscs, small mammals, and even pigeons. They consume human refuse, happily feeding on chips, takeaways, and ice cream, timing their appearance with food availability, such as school lunchtimes or refuse deliveries at dumps. They may perch high up, waiting for food, and even steal ice cream by swooping in and startling people.
In early spring and autumn, taking action to install humane seagull spikes can prevent them from returning to nest the following year.
Gull Taxonomy and Characteristics
Gulls and seagulls belong to the seabird subfamily Larinae, closely related to terns and skimmers, and distantly related to auks and waders. Typically grey or white, they often have black markings on their head or wings. Their calls are harsh and wailing, and they possess stout bills and webbed feet. Most gulls are ground-nesting piscivores or carnivores, consuming live food or scavenging opportunistically, particularly among the Larus species. Live food includes crustaceans, molluscs, fish, and small birds. Their unhinging jaws allow them to consume large prey.
Gulls are generally coastal or inland species, rarely venturing far out to sea, except for kittiwakes and Sabine's gull. Larger species take up to four years to reach full adult plumage, while smaller gulls typically mature in two years. They nest in large, densely packed, noisy colonies, laying two or three speckled eggs in nests made of vegetation. Their young are precocial, born with dark mottled down and mobile upon hatching.
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Resourceful, inquisitive, and intelligent, larger gull species demonstrate complex communication methods and a highly developed social structure. Many colonies exhibit mobbing behavior, attacking and harassing predators and intruders. Some species, like the herring gull, use tools, such as bread as bait to catch goldfish. Many gull species coexist with humans and thrive in human habitats, while others rely on kleptoparasitism to obtain food.
Physical Attributes
Gulls range in size from the little gull, weighing 120 grams and measuring 29 centimeters, to the great black-backed gull, weighing 1.75 kg and measuring 76 cm. They generally have heavy bodies, long wings, and moderately long necks. The tails of most species are rounded, except for Sabine's gull and swallow-tailed gulls, which have forked tails, and Ross's gull, which has a wedge-shaped tail. Their legs are moderately long with fully webbed feet, and their bills are generally heavy and slightly hooked.
Gulls are generalist species adept at swimming, flying, and walking. They are more proficient at walking on land than most other seabirds, with smaller gulls being more maneuverable. Their walking gait includes a slight side-to-side motion, often exaggerated in breeding displays.
Adult gulls typically have a white body with a darker mantle, ranging from pale grey to black. Some species, like the ivory gull, are entirely white, while others, such as the lava gull and Heermann's gull, have partly or entirely grey bodies. Most species have black wingtips, which improve resistance to wear and tear, often with diagnostic white markings. The head may be covered by a dark hood or be entirely white.
Global Distribution and Habitat
Gulls have a worldwide cosmopolitan distribution, breeding on every continent, including the margins of Antarctica and the high Arctic. They are less common in the tropics, though some species inhabit tropical islands like the Galapagos and New Caledonia. Many breed in coastal colonies, preferring islands, while the grey gull breeds in the interior of dry deserts far from water.
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Most gull species are migratory, moving to warmer habitats during winter, with varying migration distances. Some migrate long distances, such as Sabine's gull, which migrates from the Arctic coasts to wintering grounds off the west coasts of South America and southern Africa, and Franklin's gull, which migrates from Canada to winter off the west coast of South America. Food availability significantly influences non-breeding gull distribution, along with human activity and climate impacts.
Feeding Versatility
Gulls are highly adaptable feeders, consuming a wide range of prey, including fish, marine and freshwater invertebrates, terrestrial arthropods, rodents, eggs, carrion, offal, reptiles, amphibians, seeds, fruit, human refuse, and other birds. No gull species specializes in a single prey or foraging method. They catch prey in the air, on water, or on land. Some hooded species hawk insects on the wing, while others snatch items off the water or ground, and plunge-dive into water to catch prey. Smaller species are more maneuverable, hovering-dipping fish from the air. They may swim in tight circles or foot paddle to bring marine invertebrates to the surface. They also search the ground, often along the shore among sand, mud, or rocks.
Gulls may engage in foot paddling in shallow water for invertebrates or on wet grass for earthworms. They also drop heavy shells of clams and mussels onto hard surfaces to crack them open, learning the optimal height for dropping shells based on their weight. While overall feeding success increases with age, the diversity in prey and feeding methods does not.
Human Impact on Diet
Overfishing has caused a shift in gull diet, as seen in the yellow-legged gull (Larus michahellis), which has shifted from a sardine-based diet to one based on crustaceans due to sardine depletion. Closure of open-air landfills has also limited food availability, further stressing their diet.
From 1974 to 1994, yellow-legged gull populations on Berlenga Island, Portugal, increased significantly, relying on both natural prey and human refuse. They substantially consumed Henslow's swimming crab (Polybius henslowii) but shifted to human-related food when local prey was scarce.
Mating and Social Behavior
Gulls are monogamous and colonial breeders, displaying mate fidelity that typically lasts for life. Divorce can occur but carries a social cost. They exhibit high site fidelity, returning to the same colony and nesting location. Colonies range from a few pairs to over a hundred thousand pairs, sometimes shared with other seabird species. Some species nest singly, and single pairs of band-tailed gulls may breed in colonies of other bird species.
Within colonies, gull pairs are territorial, defending an area around their nesting site. Most gulls breed once a year, with breeding seasons lasting three to five months. They gather around the colony weeks before occupying it, re-establishing pair-bonds and courting. Nest building is crucial for pair-bonding, with most nests being mats of herbaceous matter with a central nest cup. Nests are usually built on the ground, but some species nest on cliffs or in trees.
Clutch size is typically three eggs, although some smaller gulls lay two, and the swallow-tailed gull lays a single egg. Birds synchronize their laying within colonies, with higher synchronization in larger colonies. Gull eggs are usually dark tan to brown or dark olive with dark splotches and scrawl markings, providing camouflage. Incubation lasts 22 to 26 days, beginning after the first egg is laid but becoming continuous after the second egg, resulting in the first two chicks hatching around the same time. Young chicks are brooded by their parents for one or two weeks, with at least one parent guarding them until they fledge.
Scientific Classification
The family Laridae was introduced by Constantine Samuel Rafinesque in 1815. The taxonomy of gulls is complex due to their widespread distribution and zones of hybridization, leading to gene flow. In common usage, members of various gull species are referred to as 'sea gulls' or 'seagulls,' a layperson's term not used by most ornithologists and biologists.
Fossil evidence suggests the Laridae family dates back to the Early Oligocene, approximately 30â33 million years ago.
The Diverse Diet of Opportunistic Omnivores
Seagulls are consummate opportunists with a varied diet, including live fish, marine invertebrates, terrestrial arthropods, small rodents, eggs, berries, seeds, agricultural crops, and human food waste. This dietary flexibility allows them to thrive in diverse environments.
Natural Feeding Behaviors
Along coastlines, gulls exhibit fascinating natural feeding behaviors:
- Plunge diving: Hovering above the water, gulls dive bill-first to catch fish swimming near the surface.
- Tide-following: Gulls patrol the wet sand, probing for sand crabs, marine worms, and small clams.
- Shell-breaking: Gulls drop hard-shelled prey onto hard surfaces to crack them open.
- Water dancing: Gulls perform foot-stomping dances in shallow water to startle prey.
- Food washing: Gulls carry food items to water for washing before consumption.
Urban Adaptation and Human Interaction
Urban gull populations often rely heavily on human food waste, with up to 80% of their diet consisting of it. They quickly learn to associate humans with easy meals and develop specialized techniques for opening food packaging. They communicate food sources through specific calls and behavior patterns. Kleptoparasitism, or stealing food, is also common.
Seasonal Diet Variations
Gull diets shift dramatically with the seasons. During spring and summer, breeding gulls focus on protein-rich natural food sources. In fall and winter, they move inland and rely on human food waste.
Feeding the Next Generation
Seagull parenting involves feeding adaptations to ensure chick survival. Adults emphasize protein-rich foods and regurgitate partially digested food for their young. Chicks communicate hunger through begging calls and pecking at a red spot on the parent's bill, stimulating regurgitation.
The Impact of Feeding Gulls
Human food isn't always beneficial for gulls. Regular consumption of processed foods can lead to nutritional deficiencies and health problems. Unnaturally large congregations can increase disease transmission, and dependence on anthropogenic food makes gulls vulnerable to changes in human practices. Wildlife experts generally discourage feeding gulls.
Seagull Attacks
In Scotland, a series of seagull attacks has raised public safety concerns, with politicians issuing warnings about "dive-bombing gulls" after elderly residents were injured.
Seagull Intelligence and Adaptations
Seagulls find food using intelligence, a keen sense of smell, and great vision. Their hooked bill is ideal for hunting and eating fish, and they can drink saltwater. They hunt in groups, but it's every bird for itself once food is found. Baby seagulls eat regurgitated food from their parents for the first two weeks of life, gradually transitioning to an adult diet a few months after fledging.
Winter Diet
Seagulls eat mainly the same foods during winter, traveling to obtain them. Some that live in crowded human areas continue to feast on human food and garbage.
Predators of Seagulls
Sharks and other larger creatures will eat seagulls that stop to drink, but seagulls are rarely alone, making them difficult to catch.
What Seagulls Should Not Eat
Certain foods have high levels of toxins and can lead to serious issues and even death for seagulls.
Gulls Eating Stuff Project
A University of Salford ecologist, Dr. Alice Risely, initiated a project called "Gulls Eating Stuff," asking the public to send pictures of seagulls eating. The project revealed that gulls eat a varied diet, from sandwiches to profiteroles and starfish to coot chicks. One person even submitted an image of a gull eating a mole. Gulls have also been seen suckling milk from seals and eating the flesh of sleeping whales in South America.
Gulls have increasingly shifted from natural habitats to urban areas, and understanding their eating habits can provide insights into this shift. The project has shown that gulls are not just scavengers but also predators, eating worms, chicks, and small mammals. Earthworms are a particularly important food item for all gulls.
Additional Gull Facts
- Gulls have been seen using tools, such as bread to bait fish.
- They know to drop heavy clams and mussels from lower heights and lighter ones from higher heights to crack them open.
- They use a complex system of communication with different sounds and body movements.
- They can drink seawater, flushing excess salt out through their nostrils.
- They eat almost anything, using brain power to figure out what is edible.
- They have a highly developed social structure and nest in large colonies, working together to mob predators and intruders.
- While seagulls are monogamous, pairs sometimes split, and divorcees may suffer social costs.
Seagull Characteristics
Seagulls are seabirds with around 50 different species worldwide, existing for at least 30 to 33 million years. They are frequently seen around coasts, shorelines, lakes, ponds, and farms.
Physical Characteristics
- Average length: 22.1 to 26.0 inches (55 to 67 cm)
- Average weight: 28.2 to 44.1 ounces (800 to 1270 g)
- Wingspan: 53.9 to 57.5 inches (135 to 147 cm)
- Small head with a long, thick beak that ends with a hook and has a red spot on the tip
- Two ear holes and two eyes with nictitating membranes for extra protection
- Relatively large bodies covered with white plumage
- Small claws halfway up their lower leg
- Broad wings that may be grey or white, typically with black or dark-colored tips
- Thin but elongated legs colored black, brownish, or orange to dark red
- Webbed feet for swimming and walking
- A tail that is squared off or rounded
Habitat and Location
Seagulls are found all over the world, including Antarctica, and are frequently linked with coastal areas, beach towns, fishing villages, inland rivers, and certain inland sites, particularly coastal ecosystems. They are also common in cities, circling garbage cans, docks, and parks in search of food. Seagulls dwell in colonies ranging from a few pairs to thousands of birds.
Mating and Reproduction
Seagulls are monogamous, gathering to reproduce and care for their offspring annually. Each breeding couple occupies and protects its territory. They share responsibilities in incubating eggs, feeding, and protecting babies. Females lay one, two, or three dark brown or olive-green eggs, depending on the species, and the incubation phase lasts between 22 and 26 days. Young gulls form nursery flocks supervised by adult males until they are old enough to reproduce. They have a strong social structure that works well against predators in their breeding colonies.
Food and Diet
Gulls are primarily carnivorous and adaptive feeders, consuming a wide variety of prey, including fish, marine and freshwater invertebrates, arthropods, insects, rodents, smaller birds, eggs, carrion, offal, reptiles, and amphibians, as well as seeds, fruit, and leftovers from human meals. They are versatile in both what they eat and the method they use, grazing in the air, water, and on land. They steal food from other birds, animals, and even humans, and occasionally devour young members of their species (cannibalism). Each day, seagulls can consume up to 20% of their body weight in food.
Amazing Features and Traits
- Seagulls can drink salt water, thanks to unique salt glands that remove excess salt from the body.
- They have a rich and highly developed communication vocabulary.
- They have amazing vision and can see clearly from up to two kilometers away.
- They have an incredible sense of smell, detecting even the smallest amount of food from over 3 miles away.
- They have sophisticated facial recognition abilities.
- They have a lifespan of 10 to 15 years in the wild, but they have been known to live up to 30 years.
- They can achieve flying speeds of about 23 to 25 mph in headwind and 29 to 30 mph in tailwind situations.
- To defend themselves from predators, they fly in an unpredictable pattern known as âjinkingâ.