The birds comprising the order of the Grallatores, or Waders, for the most part frequent the banks of rivers and lakes, the shores of estuaries, marshes, lagoons, and shallow pools, though some of them keep almost exclusively to dry land, preferring, however, moist and damp situations. In accordance with their semi-aquatic amphibious habits, the Waders are distinguished by the great length of their legs; the increase in length being mainly due to the great elongation of the tar so- metatarsus. The legs are also unfeathered from the lower end of the tibia downwards. The toes are elongated and straight (fig. 336, A), and are never completely palmate, though sometimes semi-palmate. There are three anterior toes, and usually a short hallux, but the latter may be wanting. The wings are long, and the power of flight usually considerable; but the tail is short, and the long legs are stretched out behind in flight to compensate for the brevity of the tail. The body is generally slender, and the neck and beak usually of considerable length (fig. 336, B). They are sometimes polygamous, sometimes monogamous, and the young of the former are able to run about as soon as they are hatched.
Fig. 336. - Grallatores. A, Leg and foot of the Curlew ; B, Head of Snipe ; C, Beak of the Avocet.
The most typical Waders - those, namely, which are semi-aquatic in their habits - spend most of their time wading about in shallow waters or marshes, feeding upon small fishes, worms, shell-fish, or insects. Others, such as the Storks, live mostly upon the land, and are more or less exclusively vegetable-feeders.
The Grallatores are divided into the four families of the Macrodactyli, the Cultirostres, the Longirostres, and the Pressi-rostres.
Fam. 1. Macrodactyli. - In this family the feet are furnished with four elongated, sometimes lobate, toes, and the wings are of moderate or less than average size. In many of their characters a considerable number of the birds of this family approach the Rasorial birds, and differ from the true Waders. The beak is mostly short, rarely longer than the head, and is compressed from side to side, or wedge-shaped. The legs are strong and not particularly lengthy; but the toes are often of great length, and are furnished with long claws. The neck is not very long, and the tail is very short. Some of them are strictly aquatic in their habits, and, like the Coots, approach in many respects to the Natatores; others, again, are exclusively terrestrial. The most familiar members of this family are the Rails (Rallus), Water-hens (Gallinula), the Coots (Fulica), and the Jacana (Parra jacana). The Water-hens and Coots are aquatic or semi-aquatic, swimming and diving with great ease. In the Coots the toes are semi-palmate, being bordered by membranous lobes, like the toes of the Grebes, but the toes are not fringed in the Gallinules. Amongst the Coots should probably be placed the Notornis (Owen), long supposed to be extinct, but recently proved to be still living in the Middle Island of New Zealand. The Notornis is much larger than the ordinary Coots, and is remarkable in the fact that, like many extinct and some living New Zealand birds, the wings are so rudimentary as to be useless for flight. The true Rails, comprising the common Water-rail (Rallus aquaticus), and the Land-rail or Corn-crake (Crex pratensis) of Britain, and the Marsh-hen (Rallus elegans), and Virginian Rail (R. Virginianus) of North America, live almost exclusively on land, though the first of these usually frequents damp or marshy places. In the Jacanas, lastly, the feet are furnished with excessively long and slender toes, which enable the bird to run about upon the leaves of aquatic plants; whilst the carpus is armed with formidable spurs. They are natives of South America, Africa, and India. Closely allied to the Jacanas are the Screamers (Palamedea) of South America, of which the Horned Screamer (P. cornuta) is the best known. It has a long frontal horn, and has spurs implanted on the edge of the wing.
Fam. 2. Cultirostres. - In this family of the Grallatores are some of the most typical and familiar forms contained in the entire order. The bill in this family is long - usually longer than the head - and is compressed from side to side; the legs are long and slender, having a considerable portion of the tibiae unfeathered; and the feet have four toes, which are usually connected to a greater or less extent at their bases by membrane. In this family are the Cranes, Herons, Stork, Ibis, Spoonbill, and others of less importance.
The Cranes (Gruidae) are large and elegant birds, and are chiefly remarkable for their long migrations, which were noticed by many classical authors. In these journeys the Cranes usually fly in large flocks, led by a single leader, so that the whole assemblage assumes a wedge-like form; or they fly in long lines. The common Crane (Grus cinerea) breeds in the north of Europe and Siberia, and migrates southwards at the approach of winter. The Numidian Crane or Demoiselle inhabits Asia and Africa, the Stanley Cranes (Anthropoides) are natives of the East Indies, and the Crowned Cranes (Balearica) are African. In many respects the Cranes are more nearly allied to the Rails than to the Herons. The Herons (Ardeidae) are familiarly known to every one in the person of the common Grey or Crested Heron (Ardea cinerea, fig. 337). It was one of the birds most generally pursued in the now almost extinct sport of falconry. Various species of Heron are found over the whole world, both in temperate and hot climates. Here, also, belong the various species of Night Heron (Nycticorax), the Bitterns (Botaurus), and the Boat-bills (Cancroma).
Fig. 337. - Crested Heron (Ardea cinerea). Europe.
The Ibises (Tantalinae) form a group of beautiful birds, species of which occur in all the warm countries of the world. They are distinguished by their metallic colours, long, cylindrical, curved bill, and more or less naked head. One, the Ibis religiosa, was regarded by the ancient Egyptians as a deity, and was treated with divine honours, being often embalmed along with their mummies, or figured on their monuments.
The Storks (Ciconinae) are large birds, of which one, the common Stork (Ciconia alba), is rarely found in Britain, but occurs commonly on the Continent, where it is often semi-domesticated. The Storks live in marshes, and feed on frogs, fishes, etc. Nearly related to the true Storks are the gigantic Marabout (Mycteria Marabou) and Adjutant (M. Argala) of Africa and India, which possess a sausage-shaped appendage in front of the neck.
The Spoonbills (Plataleadae) are also large birds, very like the Storks, but the bill is flattened out so as to form a broad spoon-like plate. The common White Spoonbill (Platalea leucorodia) is found commonly on the Continent, but is of very rare occurrence in Britain.
Fam. 3. Longirostres. - The third family of Waders is that of the Longirostres, characterised by the possession of long, slender, soft bills, grooved for the perforations of the nostrils (fig. 336, B). The legs are sometimes rather short, sometimes of great length; the toes are of moderate length, and the hallux is usually short, and is sometimes absent. The bill in these birds serves as an organ of touch, being used as a kind of probe to feel for food in mud or marshy soil. To fulfil this purpose, the tip of the bill is furnished with numerous filaments of the fifth nerve. They feed mostly upon insects and worms, and are not strictly aquatic in their habits, mostly frequenting marshy districts, moors, fens, the banks of rivers or lakes, or the shores of the sea.
In this family of the Long-billed Waders are the various species of Snipe and Woodcock (Scolopacidae), the Sandpipers (Tringa), the Curlews (Numenius), the Turnstones (Strepsilas), the Ruffs (Machetes), the Redshanks (Totanus), the Godwits (Limosa), and others which need no special notice.
Fam. 4. Pressirostres. - The members of this family are characterised by the moderate length of the bill, which is seldom longer than the head, and has a compressed tip. The legs are long, but the toes are short, and are almost always partially connected together at their bases by membrane. The hallux is short, and is often wanting. The wings are long, and they can both fly powerfully and run with great swiftness. In this section are two very distinct sub-families, the Charadriidae or Plovers, and the Otidae or Bustards. In the former of these the legs are long and slender, the toes are united at their bases by a small membrane, and the hind-toe is very small and raised above the ground, or is entirely wanting. In this group are the true Plovers and Lapwings (Charadrius and Vanellus), the Pratincoles (Glareola), the Long-shanks (Himantopus), the Oyster-catcher (Haematopus), and the Thick-knee (OEdicnemus). In the Otidae or Bustards, the legs are long, and the toes are short and furnished with stout claws. The hinder toe or hallux is entirely wanting; and these birds are chiefly interesting from the affinities which they exhibit to the Rasores on the one hand, and to the Cursores (Ostrich, etc.) on the other. The wings, however, are of ample size, and the tail is comparatively long, the reverse being the case in the Cursores. The Bustards are entirely confined to the Old World, and two species were formerly not uncommon in Britain. They are found in plains and downs, and rarely fly, but run with great swiftness, using the wings to accelerate their course. They are polygamous, and the males are generally brighter and more variegated in plumage than the females.
As regards their distribution in time, the earliest known remains of Grallatores have been found in the Cretaceous rocks of North America (Telmatornis and Palaeotringa). The Eocene Tertiary of both Europe and North America has yielded the remains of Waders, one of the most remarkable being a gigantic Rail (Gypsornis) from the Paris basin. The later Tertiaries also contain the remains of various Grallatorial birds allied to, or identical with, living types. In the Post-tertiary deposits of Mauritius are found the bones of the Aphanapteryx, a large Ralline bird, allied to the living Ocy-dromus, but incapable of flight. It survived into the human period, and was exterminated at a comparatively late date.