Wednesday, 29 January 2014

Oystercatchers delight

It would be hard to miss these oystercatchers. Not only are they conspicuous because of their striking black and white plumage but their piping calls also serve to draw attention. At this time of the year I am well used to seeing them on the Norfolk coast but later in the year I will also be able to see and hear them well inland. In fact, there is a good chance that I will have them breeding within a mile or so of my house and I will occasionally hear them as they overfly the garden, shouting their familiar call.

The species was once something of a rare breeder within the county of Norfolk, its population checked by the collection of its eggs for food and the persecution of its adults to protect shell fisheries. Writing in the late 1800s, Stevenson commented that breeding oystercatchers only remained on the ‘wildest and most retired of their former haunts’. The establishment of nature reserves, coupled with a change in attitudes, saw numbers increase and then, quite suddenly, there was rapid colonisation of inland sites, including areas of lowland wet grassland, gravel pits and reservoir sites. It is an old gravel workings that supports my nearest pair.

Despite the name, oystercatchers do not feed on oysters, but instead take cockles, mussels and limpets at coastal sites, switching to earthworms and other invertebrates when occupying more inland areas. Oystercatchers are now so familiar that it is easy to overlook the significance of the UK population, which is of international importance. Perhaps a third of the East Atlantic Flyway population winters in Britain.

The shrill piping call of a pair of oystercatchers would, you think, draw attention to their nest but so beautifully camouflaged are the eggs that the merest scrape of nest is easily overlooked, even if you have a fair idea of where it is going to be. The resulting chicks are equally well camouflaged and the parents soon lead them away from the nest to find food. As with most wader chicks, the young are up and about very quickly and well able to respond to the alarm call of a parent bird by squatting down and freezing. Perhaps these birds are not as showy after all.

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