The great curlew (Numenius arquata) is the largest among the birds we group into the large group of shorebirds. Including a downward-curved bill 9 to 15 cm long, it measures 48 to 57 cm. Females are somewhat larger than males and have a longer bill. Its wingspan ranges from 89 to 106 cm. It is an inconspicuously colored bird with long bluish-gray legs, which blends well with its surroundings thanks to a uniform pattern of dark bars and stripes on a gray-brown background. In flight it displays a white rump that extends onto the back and a white belly and dark, almost black wing tips. The shape of the bill is adapted to stabbing into soft ground, where it searches for its favorite food – earthworms. A large part of the great curlew's diet also includes insects, especially beetles and grasshoppers, but it does not shy away from crustaceans, mollusks, spiders and occasionally caught fish or some other small vertebrate. Occasionally it also treats itself to berries or seeds.
The great curlew is a migratory bird; the majority of them return from warm regions to breeding areas in April. From April to July, individual pairs mainly nest on marshes, open pastures and extensively managed, primarily wet and marshy grasslands. In a nest, which it lines in a shallow depression on the ground among grasses and reeds, it usually lays four eggs. It leaves for warmer regions, where it overwinters, between April and November. In winter it tends to stay near water, mainly by the sea, but is also found near lakes and rivers inland. During winter it forms small flocks that search for food there. It likes to roost at night in larger flocks at communal roosts. In our country it still nests in rare areas, but it is considered a critically endangered nesting bird.
It has been observed that the global population of the great curlew is declining. The causes of this are to be found mainly in the loss and fragmentation of wetlands due to encroachment by woody species and in the disappearance of wet and marshy grasslands due to regulation of waterways and the introduction of intensive agricultural practices. Premature mechanized mowing, which is possible on intensively cultivated meadows, does not spare eggs and chicks. In addition, surviving chicks on mown meadows are easy prey for predators. Human activities, for example construction in areas of communal roosts, construction of tidal barriers and thus flooding of muddy shallows in the bibavice belt and pollution, also threaten great curlew populations in wintering areas.
