Herring gulls, known for their opportunistic feeding habits, are a common sight across North America, Europe, and Asia. These birds, scientifically classified within the Laridae family, exhibit a highly adaptable diet, allowing them to thrive in diverse environments. This article delves into the specifics of their dietary habits, exploring the variety of food sources they exploit and the unique behaviors associated with their feeding strategies.
Distribution and Habitat
The herring gull, including the American herring gull (Larus smithsonianus), is native to North America, Europe, and Asia. It lives along coastal shorelines as far north as Eastern Russia and Alaska and as far south as Central America and China. This species can be found in at least 70 countries, including Canada, the United States, Mexico, China, Germany, and Japan. Their habitats are varied but are all associated with water. These gulls can be found along shores, beaches, bays, marshes, lakes, piers, islands, and docks. Occasionally, they will venture out to farmlands and dumps.
These birds are short to medium-distance migrants. Most populations breed throughout Canada and Alaska and migrate to the United States and Mexico coasts. Those living in New England, the Great Lakes region, and the Southern Alaskan coast remain in their environments year-round. In Asia, those inhabiting areas of Eastern Russia may stay in their habitat all year, while others will migrate as far south as Viet Nam.
General Feeding Behavior
The herring gull is a feisty scavenger, always looking for a quick and easy meal. You will find them at garbage dumps, fisheries, or anywhere humans are likely to leave food and trash. They also have no problem stealing food from others or robbing the nests of their own species. Herring gulls are all about food and spend much of their time perched near food sources, coasting along the shoreline, and gathering around fishing boats.
The American Herring Gull forages while walking, swimming, or flying, dipping down to take items from the surface of water or land, sometimes plunge-diving into water. It may steal food from other birds. It may also carry hard-shelled items (such as crabs and mollusks) high in the air and drop them on rocks to break them open.
Read also: The Hoxsey Diet
European herring gulls feed by day, seeking suitable small prey in fields, on the coast, or in urban areas, or robbing plovers or lapwings of their catches. They may also dive from the surface of the water or engage in plunge diving in the pursuit of aquatic prey, though they are typically unable to reach depths greater than 1-2 m (3.3-6.6 ft) due to their natural buoyancy.
Dietary Components
Herring gulls exhibit an omnivorous diet, consuming a wide range of food items depending on availability and location. Their varied diet includes marine invertebrates like mussels, squid, sea urchins, and crabs. They also eat fish, insects, carrion, human trash, and other birds.
Specifically, the American Herring Gull's diet varies with place and season and includes fish, crustaceans, mollusks, sea urchins, marine worms, birds, eggs, and insects. They scavenge refuse and carrion. At sea, they may feed on schools of fish driven to the surface by foraging whales.
European herring gulls are omnivores and opportunists and scavenge from garbage dumps, landfill sites, and sewage outflows. They eat fish, crustaceans, chips, and dead animals, as well as some plants. They also steal the eggs and young of other birds. Despite their name, they have no special preference for herrings - in fact, examinations have shown that echinoderms and crustaceans comprised a greater portion of these gulls' stomach contents than fish, although fish is the principal element of regurgitations for nestlings. Vegetable matter, such as roots, tubers, seeds, grains, nuts, and fruit, is also taken to an extent.
Individual gulls often specialize on a food type. Most choose marine invertebrates like crabs, sea urchins, or clams, even though fresh-caught fish make their most calorie-, protein-, and fat-rich meals by far. In spite of this apparently poor choice, these gulls have the largest, heaviest eggs and the highest hatching success rates.
Read also: Walnut Keto Guide
Unique Feeding Behaviors
Herring gulls have developed several unique behaviors to access and consume their food. One notable behavior is their technique for eating clams and mussels: they drop them from a height onto a hard surface, like a rock, to break the shell. European herring gulls frequently drop shelled prey from a height to break the shell.
In addition, the European herring gull has been observed using pieces of bread as bait with which to catch goldfish. European herring gulls may rhythmically drum their feet upon the ground for prolonged periods of time in behavior that superficially resembles Irish step dancing.
Impact of Diet on Egg Traits
The opportunistic diet of the herring gull has consequences for egg traits. A study found that larger eggs were laid in colonies where females consumed either a higher proportion of marine resources or terrestrial resources; smaller eggs were laid in colonies where females had an intermediate diet.
Interactions with Humans
European herring gulls are not always appreciated by mankind due to their droppings and screaming, but they must be regarded as a "natural cleaner", and just as with crows, they help by keeping rats away from the surface in the urban environment, not by killing rats, but by eating the potential rat food before the rats get the chance. They are found all year round in the streets and gardens of Britain, due to the presence of street lighting (which allows the gulls to forage at night), discarded food in streets, food waste contained in easy-to-tear plastic bin bags, food intentionally left out for other birds (or the gulls themselves), the relative lack of predators, and readily available, convenient, warm and undisturbed rooftop nesting space in towns and cities.
Once familiar with humans, urban European herring gulls show little hesitation in swooping down to steal food from the hands of humans, although a study conducted in 2019 demonstrated that some gulls are more averse to snatching food in proximity to humans if the experimenter made eye contact with the bird. During the breeding season, the gulls also aggressively 'dive bomb' and attempt to strike with claws and wings (sometimes spraying faeces or vomit at the same time) at humans that they perceive to be a threat to their eggs and chicks-often innocent passers-by or residents of the buildings on which they have constructed their nests.
Read also: Weight Loss with Low-FODMAP
Conservation Status and Threats
The IUCN lists the herring gull as LC or “least concern.” Due to its extensive range and substantial population, this species does not meet the qualifications for “threatened” status. The global herring gull population is estimated to number 430,000 to 520,000 individuals.
However, their numbers have slightly decreased over the last several decades, primarily due to the reduction in discards from fisheries. Their other threats include wind turbine collisions, hunting, trapping, and habitat shift from climate change. American Herring Gull populations declined by approximately 3.0% per year between 1966 and 2021, resulting in a cumulative decline of about 82% according to the North American Breeding Bird Survey.