The Curlew bird (Numenius arquata) is the largest European wader. It is resident, breeding in moorland, grassland, marshes, and dunes. In winters it is found on estuaries and coasts and its length is 53 to 58cm. The Whimbrel (Numenius phaeopus) is summer visitors, smaller than curlew. It breeds in dry moorland and grassland in north Scotland and Shetlands.
The curlew bird is a common wading bird. While it’s relative the whimbrel is scarce, mainly a bird of the Arctic. However, you may see whimbrels flying past on their migratory flights to Africa in autumn and on the way back in spring. The curlew is a truly unmistakable bird: a large, robust wader, common on estuaries in autumn and winter, and familiar in the west and north as a breeding bird of inland pastures and hayfields in spring and summer.
Its silhouette, with long legs, slightly hunched attitude, and the long, curved bill is unlike that of any other bird except for the whimbrel which, although it looks similar to the curlew, is rarely seen in Britain. Look closely at the curlew and you will see that its strong legs are a delicate pale grey, while the plumage is a warm ashy brown, paler below, and streaked with darker brown on the neck and upperparts.
Like other large waders, it has a long neck, but the most remarkable feature is the surprisingly long, downward curving bill. On the wing, curlews are bulky birds with strong, steady flight, less rapid than most other waders, and looking a little like gulls at a distance even in their habit of dropping down to their feeding grounds on estuaries in a long, planning glide. They are shy and wary birds, whose measured, dignified movements set them apart from the scuttling activity of the mass of other waders on the shore.
Introducing the Whimbrel
The much scarcer, but less timid, whimbrel is superficially similar to the curlew. But the main differences are a shorter and less curved bill, shorter legs, and a distinctive pattern of two dark bands of feathers on the crown. In general, it is a slightly darker and smaller bird than the curlew.
Although if it were not for the simple and distinctive call of the whimbrel, it is probably fair to say that a great number of individuals passing through on migration would go undetected. Whimbrels are essentially birds of passage in Britain, and so if you hear the sound of a whimbrel at all, it is likely to be flying overhead, giving its presence away by a call of about seven rapid, whinnying notes.
Whimbrels stay to breed only in small numbers, chiefly in the north of Scotland and the Shetland Islands. In their northerly habitat, they replace the curlew, which is a bird of the temperate zone. They breed chiefly in the Arctic zone all round the northern sphere. They nest on dry moors and old peat hags (mounds), and although much of this habitat exists in northern Scotland, the whimbrel remains a very scarce breeding bird in Britain, which lies at the southern limit of its breeding range.
The curlew in Spring
The return of the curlew to its nesting fields is one of the unfailing signs of spring. There are few sounds that are more welcome at the end of a long winter than the strident, bubbling song of the curlew.
The curlew bird song begins with a series of slow, graceful notes and then gains momentum, strengthening and rising in pitch to a rapid trill before descending again in a series of fewer than 350 pairs of low, single notes. This song is performed during a beautiful song flight in which the bird rises high with trembling wings and then descends in a shallow, gliding plane.
In the south of England, curlews begin to arrive in their nesting areas as early as the last days of February. But it is usually well into March before those that breed in Wales, northern England and Scot- land reach their strongholds in the hills and valleys. Often at this season, the birds can be heard calling at night, as they follow the river valleys up to the foothills.
At one time curlews were thought of exclusively as birds of upland moors, but in the last 50 years or so there has been a sharp increase in Britain’s curlew population, together with a marked spread into the lowlands. Now the curlew is as familiar in some lowland areas as in the uplands. There are probably about 60,000 pairs in Britain and Ireland.
Curlews are comparatively short-distance migrants: the main British population leaves the breeding areas in July but travels no further than our own coasts. Many of the curlews of Europe’s mainland, too, escape the Continental winter by flying across to Britain’s coasts. However, a particularly severe British winter is also a threat to the curlew, so that even here they may not be out of danger.
Whimbrels on the other hand, like many of the species which migrate to the Arctic to breed, are among the great long-distance travelers. At the end of the short breeding season, they journey south, stopping to find nourishment on the estuaries in Western Europe. Most travel in August, and by October the movement has finished except for a few stragglers.
They have far to go the majority seek the fertile tropical shores of West Africa, and some even go as far as South Africa. In spring the same movement occurs in reverse, most birds traveling up the coasts of western Europe in late April and May. However, relatively few touchdowns in Britain, but the bulk of those that do use the low wet meadows of the Somerset levels as their main staging post.
Following the tide outside the breeding season, both whimbrel and curlew share the mudflats and estuaries with hordes of other wading birds. Their activity is linked with the ebb and flow of the tides, both by day and by night. As the rising tide covers the feeding grounds they fly to the quiet of a safe roosting site; as the tide ebbs again, they rise and follow it down, feasting on the harvest left behind by the tide.
The curlew normally searches deeper than any of the other waders, and the whimbrel searches deeper than most. The tips of their bills are highly sensitive and enable them to feel the lugworms and ragworms in the sand. Both species also eat crabs and smaller crustaceans, and small shellfish.
Life in the Breeding Grounds
After flying inland to their breeding grounds, both whimbrel and curlew change to terrestrial habits of feeding. In this habitat of fields and moorland, they continue to use their bills to probe into the ground, where they find earth- worms-although there is less of these to find on the moors than in grassland. Most of their food is taken from the surface of the ground, in the form of insects and their larvae, spiders, woodlice, and other invertebrates. They also feed on the vegetation, including berries.
While the conspicuous song flight makes the curlew’s breeding territory easy enough to locate, the nest itself is much more elusive. The birds become very secretive once they have laid their eggs, slipping off the nest and moving away through the grass long before an intruder comes near. The eggs are laid in a scant nest of grasses, well concealed in a deep tussock or in other rough vegetation, such as standing hay.
In those areas where the breeding areas of the curlew and the whimbrel overlap, for example in the Shetland Islands, the separation between the two is clear: the curlews inhabit the hay meadows and water valley bottoms, and the whimbrels resort to the upper areas of dry moorland.
The picture becomes confused as the season advances, for then the whimbrels lead their young down to feed in the lower valleys. Once the eggs hatch, or towards the end of incubation, the adults become much more conspicuous and noisy if approached.
They defend their brood boldly against crows, birds of prey, foxes, dogs, or other ground predators. Parents often divide a brood between them and go separate ways- increasing the chance that at least one group will come safely through the vulnerable weeks of fledging. Once on the wing, the families reunite before leaving the breeding grounds.
Hopes of Protection
Until the passing of the Wildlife and Countryside Act (1981), curlews and whimbrels were both legitimate quarries for shooting. The Act gives total protection to both species at all times of the year, and the whimbrel, one of our scarcest breeding birds, is additionally protected by special penalties.
How Shore Birds Share their Prey
The many birds that feed on estuaries and mudflats do not all compete for the same food. The curlew and the whimbrel can locate deep-burrowing creatures with their long, sensitive bills. For shorter-billed species of birds, such as shelduck and oystercatcher, there are shallow burrowing shellfish, while turnstones and gulls feed on surface-dwelling crabs and mussels. Read More – The Spotted Sandpiper (Actitis macularia)