Gulls & Waders

Avocet

The pied avocet is a striking white wader with bold black markings. Adults have white plumageexcept for a black cap and black patches in the wings and on the back. They have long, upturned bills and long, bluish legs. It is approximately 16.5–17.75 inches (41.9–45.1 cm) in length of which the bill is approximately 2.95–3.35 inches (7.5–8.5 cm) and the legs are approximately 3–4 inches (7.6–10.2 cm). Its wing-span is approximately 30–31.5 inches (76–80 cm).^[4] Males and females look alike. The juvenile resembles the adult but with more greyish and sepia tones.

The call of the avocet is a far-carrying, liquid, melodious kluit kluit 

 Black-headed gull

This gull is 38–44 cm (15–17½ in) long with a 94–105 cm (37–41 in) wingspan. In flight, the white leading edge to the wing is a good field mark. The summer adult has a chocolate-brown head (not black, although does look black from a distance), pale grey body, black tips to the primary wing feathers, and red bill and legs. The hood is lost in winter, leaving just 2 dark spots. It breeds in colonies in large reedbeds or marshes, or on islands in lakes, nesting on the ground. Like most gulls, it is highly gregarious in winter, both when feeding or in evening roosts. It is not a pelagic species and is rarely seen at sea far from coasts.

The black-headed gull is a bold and opportunistic feeder and will eat insects, fish, seeds, worms, scraps and carrion in towns, or take invertebrates in ploughed fields with equal relish. This 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 regarded to be of dubious authenticity regarding a 63-year old bird

    Black-tailed godwit

The black-tailed godwit is a large wader with long bill (7.5 to 12 cm long), neck and legs. During the breeding season, the bill has a yellowish or orange-pink base and dark tip; the base is pink in winter. The legs are dark grey, brown or black. The sexes are similar,^[2] but in breeding plumage, they can be separated by the male's brighter, more extensive orange breast, neck and head. In winter, adult black-tailed godwits have a uniform brown-grey breast and upperparts (in contrast to the bar-tailed godwit's streaked back). Juveniles have a pale orange wash to the neck and breast.^[3]

In flight, its bold black and white wingbar and white rump can be seen readily. When on the ground it can be difficult to separate from the similar Bar-tailed Godwit, but the black-tailed godwit's longer, straighter bill and longer legs are diagnostic.^[3][4] Black-tailed godwits are similar in body size and shape to bar-taileds, but stand taller.^[2]

It measures 42 cm from bill to tail with a wingspan of 70–82 cm.^[2] Males weigh around 280 g and females 340 g.^[5] The female is around 5% larger than the male,^[2] with a bill 12-15% longer.^[6]

The most common call is a strident weeka weeka weeka. A study of black-tailed godwits in theNetherlands found a mortality rate of 37.6% in the first year of life, 32% in the second year, and 36.9% thereafter.^[2]

Common gull

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.^[

Common tern

The nominate subspecies of the common tern is 31–35 cm (12–14 in) long, including a 6–9 cm (2.4–3.5 in) fork in the tail, with a 77–98 cm (30–39 in) wingspan. It weighs 110–141 g (3.9–5.0 oz).^[16]Breeding adults have pale grey upperparts, very pale grey underparts, a black cap, orange-red legs, and a narrow pointed bill that can be mostly red with a black tip, or all black, depending on the subspecies.^[18] The common tern's upperwings are pale grey, but as the summer wears on, the dark feather shafts of the outerflight feathers become exposed, and a grey wedge appears on the wings. The rump and tail are white, and on a standing bird the long tail extends no further than the folded wingtips, unlike the Arctic and roseate terns in which the tail protrudes beyond the wings. There are no significant differences between the sexes.^[19] In non-breeding adults the forehead and underparts become white, the bill is all black or black with a red base, and the legs are dark red or black.^[19]The upperwings have an obvious dark area at the front edge of the wing, the carpal bar. Terns that have not bred successfully may start moulting into non-breeding adult plumage from June, but late July is more typical, with the moult suspended during migration. There is also some geographical variation, Californian birds often being in non-breeding plumage during migration.^[16]

Juvenile common terns have pale grey upperwings with a dark carpal bar. The crown andnape are brown, and the forehead is ginger, wearing to white by autumn. The upperparts are ginger with brown and white scaling, and the tail lacks the adult's long outer feathers.^[16] Birds in their first post-juvenile plumage, which normally remain in their wintering areas, resemble the non-breeding adult, but have a duskier crown, dark carpal bar, and often very worn plumage. By their second year, most young terns are either indistinguishable from adults, or show only minor differences such as a darker bill or white forehead.^[20]

The common tern is an agile flyer, capable of rapid turns and swoops, hovering, and vertical take-off. When commuting with fish, it flies close to the surface in a strong head wind, but 10–30 m (33–98 ft) above the water in a following wind. Unless migrating, normally it stays below 100 m (330 ft), and averages 30 km/h (19 mph) in the absence of a tail wind.^[5] Its average flight speed during the nocturnal migration flight is 43–54 km/h (27–34 mph)^[21] at a height of 1,000–3,000 m (3,300–9,800 ft)

Eurasian curlew

This is the largest wader in its range, at 50–60 cm (20–24 in) in length, with a 89–106 cm (35–42 in) wingspan and a body weight of 410–1,360 g (0.90–3.00 lb).^[2] It is mainly greyish brown, with a white back, and a very long curved bill. Males and females look identical, but the bill is longest in the adult female. It is generally not possible to recognize the sex of a single Eurasian Curlew, or even several ones as there is much variation; telling male and female of a mated pair apart is usually possible however.

The familiar call, from which this bird gets it name, is a loud curloo-oo.

The only similar species over most of the curlew's range is the whimbrel (N. phaeopus). The Whimbrel is smaller and has a shorter bill with a kink rather than a smooth curve. Flying curlews may also resemble, albeit not existing in the same area, bar-tailed godwits (Limosa lapponica) in their winter plumages; however, the latter have a smaller body, a slightly upturned beak, and legs that do not reach far beyond their tail tips. The Eurasian Curlew's feet are longer, forming a conspicuous "point".

The curlew exists as a migratory species over most of its range, wintering in Africa, southernEurope and south Asia. Occasionally a vagrant individual reaches places far from its normal range, such as Nova Scotia^[3] and the Marianas.^[4] It is present all year in the milder climates of the United Kingdom and its adjacent European coasts.

Black-legged kittiwake

The adult is 37–41 cm (15–16 in) in length with a wingspan of 91–105 cm (36–41 in) and a body mass of 305–525 g (10.8–18.5 oz).^[3] It has a white head and body, grey back, grey wings tipped solid black, and have black legs and a yellow bill. Occasional individuals have pinky-grey to reddish legs, inviting confusion with red-legged kittiwake. In winter, this species acquires a dark grey smudge behind the eye and a grey hind-neck collar. The name is derived from its call, a shrill 'kittee-wa-aaake, kitte-wa-aaake'.

It is a coastal breeding bird around the north Pacific and north Atlantic oceans, found most commonly in North America and Europe. It breeds in large colonies on cliffs and is very noisy on the breeding ground. Cliff nesting for gulls occurs only in the Rissa species, and the kittiwake is capable of utilizing the very sheerest of vertical cliffs, as is evident in their nesting sites on Staple Island in the outer Farne Islands (Hogan, 2005). One to two buff spotted eggs are laid in the nest lined with moss or seaweed. The downy young of kittiwakes are white, since they have no need of camouflage from predators, and do not wander from the nest like Larus gulls for obvious safety reasons.

At fledging, the juveniles differ from the adults in having a black 'W' band across the length of the wings and whiter secondary and primary feathers behind the black 'W', a black hind-neck collar and a black terminal band on the tail. The old fisherman's name of "tarrock" for juvenile kittiwakes is still occasionally used.

They are fish feeders, and are more pelagic than Larus gulls outside the breeding season. They do not scavenge at tips like some other gull species.

There are two races of black-legged kittiwake:

• Rissa tridactyla tridactyla – (Linnaeus, 1758) in the North Atlantic Ocean, which is unique among the Laridae in having only a very small or even no hind toe.
• Rissa tridactyla pollicaris – (Ridgway, 1884) in the North Pacific Ocean, which (as the namepollex, thumb, suggests) has a normally developed hind toe.

Common redshank

Common redshanks in breedingplumageare a marbled brown color, slightly lighter below. In winter plumage they become somewhat lighter-toned and less patterned, being rather plain greyish-brown above and whitish below. They have red legs and a black-tipped red bill, and show white up the back and on the wings in flight.

The spotted redshank (T. erythropus), which breeds in the Arctic, has a longer bill and legs; it is almost entirely black in breeding plumage and very pale in winter. It is not a particularly close relative of the common redshank, but rather belongs to a high-latitude lineage of largish shanks. T. totanus on the other hand is closely related to the marsh sandpiper (T. stagnatilis), and closer still to the small wood sandpiper (T. glareola). The ancestors of the latter and the common redshank seem to have diverged around the Miocene-Plioceneboundary, about 5-6 million years ago. These three subarctic- to temperate-region speciesform a group of smallish shanks with have red or yellowish legs, and in breeding plumage are generally a subdued light brown above with some darker mottling, and have somewhat diffuse small brownish spots on the breast and neck.^[2]