Waders: Charadriiformes Charadrii

Generally plump shore birds, with long legs and bills and pointed wings. In most species males and females are alike. Flight is strong and swift. Most waders are highly migratory, traveling together in huge flocks sometimes many thousand strong.

Members of this sub-order are mostly small to moderately large birds with a long, slender beak and long, thin legs with the tibia bare of feathers; at all events, they include some of the most 'leggy' birds of all. Their legs are adapted for wading and the hind toe, if present, is short and situated higher up than the long front toes. The toes are sometimes joined together at the base by short webbing and in swimming species, such as phalaropes, they are bordered by lobed webbing. In keeping with their thin legs, waders also have a slim, lightly built body. The smallest species, the tiny Arctic stints of the genus alidris, weigh only 20 - 30 g and have a wingspan of around 30 cm, while the Curlew weighs over 800 g and has a wingspan of about 1 m. Waders have slim, pointed, angular wings and are all fast and enduring fliers. Most of them are strictly migrants, whose winter quarters are generally a long distance from their breeding sites. Their dense, tight-fitting feathers have an aftershaft and they also have a well-developed preen gland. Sexual colour dimorphism is gener­ally not very pronounced except in the case of the Ruff, the male of which has breeding plumage characterised by an expansible collar of long, brightly coloured neck feathers.

Another interesting feature is that, in many wader species in which the male cares for the offspring, the females are more brightly coloured than the males. Many species change their breeding plum­age for more plainly coloured winter plumage during a complete moult as soon as nesting is over and a subsequent partial moult. The breeding plumage is usually also quite plain, however, so that even experienced ornithologists have diffi­culty in identifying some waders from their appearance. Their voice is often a much better guide, since waders usually have very distinctive and clearly audible calls. Most waders live beside water and many species inhabiting wet meadows and woods move to flooded muddy or sandy localities or tidal shores when they have finished nesting. Some species, however, live in dry regions far from any water. Courtship is generally accompanied by loud vocal manifestations and striking nuptial flights. The nest is usually on the ground, sometimes unconcealed in the open, but general­ly hidden by grass, and is only very exceptionally built in a tree. There are in most cases usually four relatively large, speckled eggs, tapering markedly at one end and arranged in the nest with the pointed ends in the centre.

The nidi­fugous young leave the nest soon after they hatch and are almost immediately able to fend for themselves. They are covered with thick down with camouflage markings. When danger threatens they lie flat on the ground, while the parents attack the intruder to the accompaniment of loud cries, or try to lure it away by pretending to be lame. One curious feature of the family life of waders is that the females often abandon their family at a very early stage (in the case of phalaropes as soon as the eggs have been laid) and leave the care of the offspring entirely to the male. Waders live on animal food, which they look for in or on water or pick out of even deep mud with their long, thin beak. They have a special mechanism which allows them to open the tip of their beak a little way when they come across prey in soft soil, since the resistance of the soil would prevent them from opening the whole of their beak. When the bird makes contact with prey, the protractor muscles on its rotating quadrate contract and the bone moves, exerting pressure on the zygomatic arch from behind, so that the thin, flexible bones of the upper mandible are forced upwards and the beak opens at the tip. The bird is then able to seize its prey (which it feels by means of sensory cells at the tip of its beak) with these natural forceps.