Gulls are typically medium to large birds, usually grey or white, often with black markings on the head or wings. They typically have harsh wailing or squawking calls, stout, longish bills, and webbed feet. Most gulls, particularly Larus species, are ground-nesting carnivores, which will take live food or scavenge opportunistically. Live food often includes crabs and small fish. Gulls have unhinging jaws which allow them to consume large prey.
Gulls nest in large, densely packed noisy colonies. They lay two to three speckled eggs in nests composed of vegetation. The young are precocial, being born with dark mottled down, and mobile upon hatching.

Further Information: Wikipedia

Genus Larus

Great Black-backed Gull (Larus Marinus) Resident
Great Black-backed Gull (Larus marinus) Copyright Peter Drury

Great Black-backed Gull (Larus marinus) Copyright Peter Drury

The Great Black-backed Gull (Larus marinus) is the largest gull in the world, which breeds on the European and North American coasts and islands of the North Atlantic.
It is 71–79 cm (28–31 in) long with a 1.5–1.7 m (4 ft 10 in–5 ft 7 in) wingspan and a body weight of 1.3–2.3 kg (2.9–5.1 lb), though large males may exceed this weight

Where these can be seen: Usually in flight over the nature reserves

European herring gull (Larus argentatus) Resident
European Herring Gull (Larus argentatus) Copyright Peter Drury

European Herring Gull (Larus argentatus) Copyright Peter Drury

The European Herring Gull (Larus argentatus) is a large gull (up to 26 inches or 66 cm long), and is the most abundant and best known of all gulls along the shores of western Europe. It breeds across Northern Europe, Western 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 the British Isles, Iceland, or on the North Sea shores.

Where these can be seen: Common over much of the nature reserves.

Common Gull (Larus canus)
Common Gull (Larus canus) Copyright Peter Drury

Common Gull (Larus canus) Copyright Peter Drury

The common gull (European and Asian subspecies; see below) or mew gull (North American subspecies) Larus canus is a medium-sized gull which breeds in northern Asia, northern Europe and northwestern North America. It migrates further south in winter. Its name does not indicate that it is an abundant species, but that during the winter it feeds on common land, short pasture used for grazing.
Adult common gulls are 40–46 cm long, noticeably smaller than the herring gull, and slightly smaller than the ring-billed gull, also differing from the latter in its shorter, more tapered bill with a more greenish shade of yellow, as well as being unmarked during the breeding season. The body is grey above and white below. The legs are greenish-yellow. In winter, the head is streaked grey, and the bill often has a poorly defined blackish band near the tip (sometimes sufficiently obvious to cause confusion with ring-billed gull). They have black wingtips with large white “mirrors”. Young birds have scaly black-brown upperparts and a neat wing pattern, and grey legs. They take two to three years to reach maturity. The call is a high-pitched “laughing” cry.
Both common and mew gulls breed colonially near water or in marshes, making a lined nest on the ground or in a small tree; colony size varies from 2 to 320 or even more pairs. Usually three eggs are laid (sometimes just one or two); they hatch after 24–26 days, with the chicks fledging after a further 30–35 days. Like most gulls, they are omnivores and will scavenge as well as hunt small prey.

Where these can be seen: Anywhere along the coastline

Lesser Black-backed Gull (Larus fuscus) Winter Visitor
Lesser Black-backed Gull (Larus fuscus) Copyright Peter Drury

Lesser Black-backed Gull (Larus fuscus) Copyright Peter Drury

The lesser black-backed gull (Larus fuscus) is a large gull that breeds on the Atlantic coasts of Europe. It is migratory, wintering from the British Isles south to West Africa. It is a regular winter visitor to the east coast of North America, probably from the breeding population in Iceland.
This species breeds colonially on coasts and lakes, making a lined nest on the ground or a cliff. Normally, three eggs are laid. In some cities the species nests within the urban environment, often in association with herring gulls.
A confusable species in Europe is great black-backed gull. The lesser is a much smaller bird, with slimmer build, yellow rather than pinkish legs, and smaller white “mirrors” at the wing tips. The adults have black or dark grey wings (depending on race) and back. The bill is yellow with a red spot which young peck at, inducing feeding. The head is greyer in winter, unlike great black-backed.

Where these can be seen: At the lagoon and shoreline.

Iceland Gull (Larus glaucoides) Rare Winter Visitor
Iceland Gull (Larus glaucoides) Copyright Peter Drury

Iceland Gull (Larus glaucoides) Copyright Peter Drury

The Iceland gull (Larus glaucoides) is a large gull which breeds in the Arctic regions of Canada and Greenland, but not Iceland, where it is only seen in the winter. It is migratory, wintering from in the North Atlantic as far south as the British Isles and northernmost states of the eastern USA, as well as in the interior of North America as far west as the western Great Lakes. It is much scarcer in Europe than the similar glaucous gull.
These are omnivores like most Larus gulls, eating fish, molluscs, offal, scraps, and eggs. These birds forage while flying, picking up food at or just below the water’s surface, also feeds while walking or swimming. Their scavenging habits lead them to frequent garbage dumps, sewage outlets, and places where fish are cleaned.

Where these can be seen: A rare visitor, blown off course whilst on migration. A vagrant in birding terminology.

Genus Ichthyaetus

Mediterranean gull (Ichthyaetus melanocephalus) Resident
Mediterranean gull (Ichthyaetus melanocephalus) Copyright Peter Drury

Mediterranean gull (Ichthyaetus melanocephalus) Copyright Peter Drury

The Mediterranean gull (Ichthyaetus melanocephalus) is a small gull which breeds almost entirely in the Western Palearctic, mainly in the south east, especially around the Black Sea, and in central Turkey. There are colonies elsewhere in southern Europe, and this species has undergone a dramatic range expansion in recent decades. Birders often abbreviate its name to “Med gull”. Formerly restricted to the Black Sea and the eastern Mediterranean this species has now expanded over most of Europe as far as the Great Britain and Ireland, with 37 sites: 543–592 pairs in the United Kingdom in 2008.
The Mediterranean gull is slightly larger and bulkier than the black-headed gull with a heavier bill and longer, darker legs. The breeding plumage adult is a distinctive white gull, with a very pale grey mantle and wings with whiteprimary feathers without black tips. The black hood extends down the nape and shows a distinct white eye crescents.[1] The blunt tipped, parallel sided, dark red bill has a black subterminal band. The non breeding adult is similar but the hood is reduced to an extensive dusky “bandit” mask through the eye. This bird takes two years to reach maturity. First year birds have a black terminal tail band and more black areas in the upperwings, but have pale underwings.

Where these can be seen: anywhere over the nature reserve. Limited use of the oysterbed islands in the breeding season.

Genus Chroicocephalus

Black-headed Gull (Chroicocephalus ridibundus) Resident
Black-headed Gull (Chroicocephalus ridibundus) Copyright Peter Drury

Black-headed Gull (Chroicocephalus ridibundus) Copyright Peter Drury

The black-headed gull (Chroicocephalus ridibundus) is a small gull that breeds in much of Europe and Asia, and also in coastal eastern Canada. Most of the population migratory, winters further south, but some birdsreside in the milder westernmost areas of Europe. Some black-headed gulls also spend the winter in northeastern North America, where it was formerly known as the common black-headed gull. As is the case with many gulls, it was previously placed in the genus Larus.
The black-headed gull is a bold and opportunistic feeder. It eats insects, fish, seeds, worms, scraps, and carrion in towns, or invertebrates in ploughed fields with equal relish. It is a noisy species, especially in colonies, with a familiar “kree-ar” call. Its scientific name means laughing gull.
This species takes two years to reach maturity. First-year birds have a black terminal tail band, more dark areas in the wings, and, in summer, a less fully developed dark hood. Like most gulls, black-headed gulls are long-lived birds, with a maximum age of at least 32.9 years recorded in the wild, in addition to an anecdote now believed of dubious authenticity regarding a 63-year old bird
A large number of these birds breed on the islands in the oysterbed lagoon.

Where these can be seen: Very common in the area with signicant pairs forming a breeding colony on the Oysterbed islands.