[order] Charadriiformes | [family] Laridae | [latin] Larus argentatus | [UK] Herring Gull | [FR] Goéland argenté | [DE] Silbermöwe | [ES] Gaviota Argéntea | [IT] Gabbiano reale nordico | [NL] Zilvermeeuw

Zilvermeeuw determination

copyright: youtube

The adult Herring Gull is about 61 cm long from the tip of its bill to the tip of its tail. Its head, body, and tail are white, its bill is yellow with a red spot on the lower tip, and its legs are pink or flesh-coloured. The backs and upper wing surfaces of adult gulls are grey, and the tips of their outermost flight feathers are black with a white spot. In winter, the heads of adult gulls are streaked with brown. Immature birds are a mottled brown and take four years to develop full adult plumage.

In winter, Herring Gulls are most likely to congregate on beaches along the shores of oceans and other large water bodies. In other seasons, gulls may range inland and can be found beside lakes and rivers, in grassy meadows, or on garbage dumps, golf courses, islands, cliffs, and buildings. Their main habitat requirement is a dependable source of food nearby.
Herring Gulls can be quite useful, keeping our beaches clean by eating dead fish and other garbage and leading fishing boats to schools of herring, one of their favourite foods-hence the name "herring" gull. On the other hand, the gulls will steal any fish catch left unattended for any length of time, and their excrement, or bodily waste, often damages the roofs of buildings where the gulls roost, or settle for rest.
Herring Gulls will nest in a variety of sites, but always near a body of water. On offshore islands, they frequently occupy flat ground. On the mainland, however, they tend to nest on cliffs, probably to avoid predatory mammals. In some places where food from human activities is abundant, they have begun to nest on roofs and window ledges of buildings. On cliffs, Herring Gulls tend to nest on turf-covered ledges.
Herring Gulls are very social birds and prefer to nest in colonies. Once a colony is well established, they are faithful to it and reluctant to settle elsewhere. In the lower Great Lakes area, for example, older, experienced breeding birds usually stay close to their colonies and are the first to reoccupy nesting territories in early spring. Some may use the same nesting site for as long as 10 to 20 years.

The Herring Gull inhabits North America, north-eastern Asia and north-western Europe, from south-western France and the British Isles to north-western Russia. Most of these birds breed in coastal habitats, but in some regions the species also breeds far inland. Only the northern populations move to the south-west in winter. The population of the European Union is estimated at 450000 breeding pairs and the total European population at 800000 pairs. The species has strongly increased since the beginning of the century, so much that in many regions control programmes have been designed

Herring Gulls regurgitate, or bring up, food remains that they cannot digest. Analyses of these "pellets" and of their feces show that Herring Gulls, like most other gull species, will eat almost anything-clams, small fish, floating dead animals, small young and adults of other nesting birds, bread, french fries, and so on.
They have a knack for finding places where food is abundant, such as fish wharves and garbage dumps. Diet studies in the Great Lakes area showed that most pellets in colonies near large urban centres contained remains of garbage as well as various fish species. Pellets in colonies near agricultural areas often had the remains of small mammals, notably deer mice.
Individual Herring Gulls tend to specialize in particular types of food or feeding techniques. Within a large colony, some birds may regularly visit dumps, while others may feed entirely on fish and crabs found on the seashore. A few individuals take to cannibalism, watching their neighbours for an opportunity to sneak in and remove an egg or chick. These birds are often breeding birds that have lost their own brood. Although large numbers of Herring Gulls in North America are almost entirely dependent on human activities for their food, there are still populations breeding on offshore islands or in remote parts of the low Arctic that exist on a natural diet.
How far will Herring Gulls from a colony travel to get all the food they need to sustain themselves and raise their young? In one study, breeding gulls were caught and coloured several bright tints so that their daily trips for food could be traced. The vast majority of the gulls sought their food as close as possible to their breeding colony. If there was a fish pier within 8 km, few gulls went farther. If the nearest dump was 27 km away, commuting that far was regular. Even 40 km was not an unreasonable daily round, if there was nothing nearer and the rewards were attractive enough.

This species has a large range, with an estimated global Extent of Occurrence of 10,000,000 km². It has a large global population estimated to be 2,600,000-3,000,000 individuals (Wetlands International 2002). Global population trends have not been quantified, but the species is not believed to approach the thresholds for the population decline criterion of the IUCN Red List (i.e. declining more than 30% in ten years or three generations). For these reasons, the species is evaluated as Least Concern. [conservation status from birdlife.org]

Courtship begins as soon as birds arrive at the colony in the spring, usually mid-March. Once pairing has taken place, the birds build a nest or, more often, refurbish an old one. The nest is circular and lined with moss or grass, which is also used to build up the rim. In most areas, a group or clutch of three eggs will be laid by mid-May. Eggs are normally incubated, or kept warm until they hatch, for 26 to 28 days.
Females laying for the first time, usually in their third or fourth year, often lay only one or two eggs. They also tend to lay later in the season than more experienced birds, which generally make up about three-quarters of the breeding population.
Eggs are well looked after, but they can be lost. Some are eaten or stolen by other gulls, and others are washed away by storms. Birds that lose their eggs early in the season will usually lay additional eggs to replace the ones that were lost.
The greatest losses in the colony are usually of tiny chicks in the first few days after hatching, probably as a result of predation by neighbouring gulls. When they start to run about, chicks do not know the borders of their parents' territory, and the adults have to guard them against neighbours who would kill trespassers. Spots on the top and back of the chick's head identify each chick individually; the adults learn these markings in the first few days. These spots are the last of the downy plumage to be lost.
Mortality among older Herring Gull chicks is mainly caused by food shortages. In one study, each pair produced an average of one chick a year, which were ready to leave the colony at 40 to 60 days of age. However, about one-third of those chicks died before another month had passed because they could not fend for themselves.
When the Herring Gull population is dense, gulls will occupy all suitable places in their feeding area (as distinct from the colony). Adults on feeding areas drive away intruding gulls. If the fledglings (young Herring Gull chicks that have just started to fly, usually at about six weeks of age), already at a disadvantage because of their inexperience, were excluded from these feeding areas, their survival would obviously be endangered. However, chicks can lessen the adults' territorial aggressiveness on the feeding areas by assuming a hunched posture, pumping their heads, and voicing shrill calls. The same behaviour causes parents to feed their chicks on the breeding colonies. Such adaptations reduce the rate of death of chicks at the times when they are most vulnerable.

Mainly migratory in northern Norway, Gulf of Bothnia, Finland, Baltic States, and Russia; elsewhere either resident or dispersive to varying degree. In all populations, immatures remain widely distributed all summer (between colony and wintering area), though also evidence of partial return movement towards colony which is most marked in long-distance migrants.