Oystercatcher

The oystercatcher (Haematopus ostralegus) is unusual by being far from unusual! It is a species that is found practically worldwide, on virtually any coast that provides it with food. Needless to say, oysters do not feature frequently in its regular diet!

Distribution and habitat

In Europe the oystercatcher is resident on most coasts, although many birds over-winter in Britain from further north. In summer, oystercatchers are found inland in Scotland and northern England, where they feed on worms instead of marine life. In recent years they have started breeding inland as well as on the coast.

Oystercatchers are often seen in large groups on mudflats and river estuaries, especially where cockles are plentiful. However, cockle beds are often over-exploited for human consumption, and the oystercatcher populations then come under threat.

Appearance

The oystercatcher is a large bird at 43 centimetres (17 inches) in length and bulky in build. It is distinctive in appearance, with a black back and white underparts, a white rump, black tail (short) and a white wing-band that is noticeable in flight. The long, straight bill is orange-red and the legs pinkish-red. The colourings are duller in winter, and a white chinstrap appears across the throat. Males and females are very similar in appearance.

Behaviour

The flight is strong with shallow beats, but it is also a fast runner across mud or sand. It has a loud, shrill two-noted call that sometimes becomes a trill, especially during the courtship display when several birds run beside or behind one another. There is a video of the courtship display on this page of the RSPB website, together with other information.

As mentioned above, cockles and worms form much of their diet, plus mussels and insects. The long bill is used to probe the mud for food.

Breeding

When paired, couples stake out small nesting territories which they will defend against intruders. The nest, on the shore above the high-tide level, is a shallow scrape lined with pieces of shell, leaves and grass. The clutch, laid between April and July, is usually of three eggs, but can be two or four. Both partners incubate the eggs, which take around 27 days to hatch. Only one brood is raised per season. The young stay in the nest for one or two days, after which they follow their parents, being brought food at first but then finding their own.

Conservation status

The oystercatcher has amber conservation status, which means that its numbers are a cause for long-term concern in the British Isles although it is not in any immediate danger. The threats facing it are due to the over-fishing of cockles mentioned above and any coastal pollution that may occur.

© John Welford