European Herring Gull (Larus argentatus)

The European herring gull (Larus argentatus) is a large gull (up to 26 in (66 cm) long). One of the best known of all gulls along the shores of western Europe, it was once abundant. It breeds across Northern Europe, Western Europe, Central Europe, Eastern Europe, Scandinavia and the Baltic states. Some European herring gulls, especially those resident in colder areas, migrate further south in winter, but many are permanent residents, e.g. in Ireland, Britain, Iceland, or on the North Sea shores. European herring gulls have a varied diet, including fish, crustaceans and dead animals as well as some plants.

Review made by Consordini team

While herring gull numbers appear to have been harmed in recent years, possibly by fish population declines and competition, they have proved able to survive in human-adapted areas and can often be seen in towns acting as scavengers.

Description
The male European herring gull is 60–67 cm (24–26 in) long and weighs 1,050–1,525 g (2.315–3.362 lb) while the female is 55–62 cm (22–24 in) and weighs 710–1,100 g (1.57–2.43 lb). The wingspan can range from 125 to 155 cm (49 to 61 in). Among standard measurements, the wing chord is 38.1 to 48 cm (15.0 to 18.9 in), the bill is 4.4 to 6.5 cm (1.7 to 2.6 in) and the tarsus is 5.3 to 7.5 cm (2.1 to 3.0 in). Adults in breeding plumage have a grey back upper wings and white head and underparts. The wingtips are black with white spots known as "mirrors". The bill is yellow with a red spot and there is a ring of bare yellow skin around the pale eye. The legs are normally pink at all ages but can be yellowish, particularly in the Baltic population which was formerly regarded as a separate subspecies "L. a. omissus". Non-breeding adults have brown streaks on the head and neck. Male and female plumage is identical at all stages of development, however adult males are often larger.

Juvenile and first-winter birds are mainly brown with darker streaks and have a dark bill and eyes. Second-winter birds have a whiter head and underparts with less streaking and the back is grey. Third-winter individuals are similar to adults but retain some of the features of immature birds such as brown feathers in the wings and dark markings on the bill. The European herring gull attains adult plumage and reaches sexual maturity at an average age of four years.

Yellow-legged variety
At least in the South-West part of the Baltic Sea and surrounding areas the European herring gull (Larus argentatus) actually can be seen with yellow legs. This is not considered as a subspecies, since they regularly breed with grey/flesh-coloured legged herring gulls. The offspring may get yellow or normal coloured legs. It must not be confused with the in general yellow-legged Larus michahellis, which are more common in the Mediterranean area but single birds may reach more northern seas.

Voice
The loud laughing call is well known in the Northern Hemisphere, and is often seen as a symbol of the seaside in countries such as the United Kingdom. The European herring gull also has a yelping alarm call and a low barking anxiety call.

European herring gull chicks and fledglings emit a distinctive, repetitive high-pitched 'peep', accompanied by a head-flicking gesture when begging for food from, or calling to their parents. It should also be noted that adult gulls in urban areas will also exhibit this behaviour when fed by humans.

Diet
These are omnivores and opportunists like most Larus gulls, and will scavenge from garbage dumps, landfill sites, and sewage outflows, with refuse comprising up to half of the bird's diet. It also steals the eggs and young of other birds (including those of other gulls), as well as seeking suitable small prey in fields, on the coast or in urban areas, or robbing plovers or lapwings of their catches. European herring gulls 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 of greater than 1–2 m (3.3–6.6 ft) due to their natural buoyancy. 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.[20] European herring gulls can frequently be seen to drop shelled prey from a height in order to break the shell. In addition, the European herring gull has been observed using pieces of bread as bait with which to catch goldfish. Vegetable matter such as roots, tubers, seeds, grains, nuts and fruit is also taken to an extent. It has been observed that captive European herring gulls will typically show aversion to spoiled meat or heavily salted food, unless they are very hungry. The gull may also rinse food items in water in an attempt to clean them or render them more palatable before swallowing.

European herring gulls may be observed rhythmically drumming their feet upon the ground for prolonged periods of time in a behaviour that superficially resembles Irish stepdancing. This is for the purpose of creating vibrations in the soil, driving earthworms to the surface, which are then consumed by the gull. It is believed that these vibrations mimic those of digging moles, eliciting a surface escape behaviour from the earthworm, beneficial in encounters with this particular predator, which the European herring gull then exploits to its own benefit in a similar manner to human worm charmers.

Whilst the European herring gull is fully capable (unlike humans) of consuming seawater, utilizing specialized glands located above the eyes to remove excess salt from the body (which is then excreted in solution through the nostrils and drips from the end of the bill), it will drink fresh water in preference, if available.

Courtship and reproduction
During courtship, the hen will approach the cock on his own territory with a hunched, submissive posture while making begging calls (similar to those emitted by young gulls). If the cock chooses not to attack her and drive her away, he will respond by assuming an upright posture and making a mewing call. This is followed by a period of synchronised head-tossing movements, after which the cock will then regurgitate some food for his prospective mate. If this is accepted, copulation will follow. A nesting site will then be chosen by both birds. European herring gulls are almost exclusively sexually monogamous and may pair up for life, provided that the couple are successful in hatching their eggs.

Two to four eggs, usually three, are laid on the ground or cliff ledges in colonies, and are defended vigorously by this large gull. The eggs are a dark blotched, olive colour. They are incubated for 28–30 days. Breeding colonies are predated by great black-backed gulls, harriers, corvids, herons and raccoons.

Juveniles use their beaks to "knock" on the red spot on the beaks of adults to indicate hunger. Parents typically disgorge food for their offspring when they are "knocked”. The young birds are able to fly 35–40 days after hatching and fledge at six weeks of age. Chicks are generally fed by their parents until they are 11–12 weeks old but the feeding may continue up to six months of age, if the young gulls continue to beg. The male feeds the chick more often than the female before fledging, the female more often post-fledging.

Like most gulls, European herring gulls are long lived, with a maximum age of 49 years recorded.[25] Raptors (especially owls, peregrine falcons and gyrfalcons) and seals (especially grey seals) occasionally prey on the non-nesting adults.
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https://en.wikipedia.org/wiki/European_herring_gull