Some of the birds that frequent the Wirral are so distinctive that they can be recognised by anybody. One of these is the oystercatcher. This bird is present on our shore all year round, although the numbers are far higher in the winter. One of its old names is the ‘seapie’. If you think of a bird coloured like a magpie but living by the sea you have an idea of what this bird looks like – black and white. Unlike the magpie, it has a long, straight, bright orange or red bill and it does not have a long tail. This bold plumage and bill is so eye catching that you almost fail to notice the pink legs. In flight it has black wings with a bold white stripe running along its length and white lower back and base of the tail, again producing a very bold pattern.
As well as bold plumage, this bird has a strong, piping call that is constantly present on the Wirral shore. Some birds have a white collar over the throat. These are not a separate species.
Flocks of oystercatcher are commonly seen flying low across the beach and sea ahead of people and dogs in an attempt to find an undisturbed area. This causes the birds to use energy instead of feeding, and it is not unusual after hard weather to find dead oystercatcher on the shore.
The bill of oystercatchers varies in shape. Some birds have broad, chisel shaped bills with blunt tips. Others have slightly longer, narrower bills with pointed tips. These birds have been described as hammer’s or stabber’s and reflect the birds feeding habits. The shape is not fixed, though. Bird’s bills are composed of keratin, like our finger nails, and their shape is due to a balance between growth and wear. As the birds change food, either as a result of local prey abundance changing or moving habitat, the shape of their bills changes. This importance of wear on determining bill shape can also cause grotesque shapes when there is a slight misalignment between the mandibles. This weekend I saw an oystercatcher feeding in fields by the Wirral coastal park that had a bill almost twice as long as usual with narrow, crossed tips. It could only feed by putting its bill side on to the short, grazed grass and trying to pull small items into its mouth with its tongue. Sadly, the likelyhood of this bird surviving the winter are slim.
There has been a change in breeding behaviour by this species over the past century. The traditionally nesting area is a flat beach but increasing disturbance has caused declines in many areas. From the Liverpool area northwards birds started nesting in fields and by rivers beginning in the late 1800’s. Now inland breeding is widespread in Scotland and parts of Northwest England. This fundamental change in breeding habitat is not confined to England, but has been seen in many area of northern Europe.
The formation of large flocks of oystercatcher is a northern European phenomenon. Whilst several other species occur in the world, they rarely reach the abundance seen on the Wirral shores in winter. When Roger Tory Peterson (of field guide fame) visited Hilbre islands in the Dee estuary in the 1960’s, he was moved to write ‘the oystercatcher is the star of the show’. He simply was not used to seeing such large flocks of the American oystercatcher in comparable areas. It is easy to forget how special are common birds are. They are our legacy for the future and deserve our protection just as much as rarities.