Of the second or Pteroclo-Columbine group of Charadriiform Birds (p. [268]) the Old World Sub-Order Pterocles contains only–

Fam. IX. Pteroclidae, or the Sand-Grouse, equally interesting as regards their structure and their habits. Originally considered akin to Grouse, they have since given rise to much discussion; Dr. Gadow's view–here adopted–being that they are highly specialized forms, analogous to the Galli in their digestive organs, but homologically constituting a link between the Limicolae and the Columbae.[[205]] From the Pigeons they certainly differ remarkably in the condition of the chicks, which are covered with brown, creamy, and black down, and run almost immediately from the shell; yet they agree with them in most points of osteology, myology, and pterylosis, while the eggs recall those of Rails, and the flight resembles that of a Plover.

The body is compact; the bill short, arched, and fairly stout; the metatarsus abbreviated and feathered anteriorly, or entirely in Syrrhaptes. In this genus, moreover, the hallux, much reduced elsewhere, is totally absent; and the short front toes are enclosed in a sort of casing, which is covered as far as the thick claws with hairy plumage, the whole forming a padded foot unique among Birds. The long pointed wings have sixteen or seventeen secondaries, and eleven primaries, of which the outer has its shaft produced into a thin filament in Syrrhaptes paradoxus; the wedge-shaped tail has sixteen rectrices, the median pair being elongated and pointed in that genus and Pteroclurus (Pin-tailed Sand-Grouse), if the latter be allowed to stand. The furcula is U-shaped, the syrinx tracheo-bronchial, the tongue lanceolate; there is a small aftershaft, and a large crop; while the down of the adults is sparingly distributed.

Sand-Grouse are true desert-birds, affording excellent instances of protective coloration in their buff or brownish tints, slightly varied with grey, black, orange, and white; Pterocles fasciatus and P. lichtensteini, however, prefer bushy and rocky ground to bare, sandy, or stony plains. Gregarious yet monogamous, they are shy and wary, but very pugnacious among themselves; their flight is swift, strong, and noisy; their powers of walking and running good, though rather clumsy, owing to the extremely short legs. All the species lie closely until flushed, and are fond of basking in the sun on their sides, in holes scraped out for the purpose. Migration probably prevails to some extent throughout the Family, while the irruptions of Syrrhaptes paradoxus into Europe (p. [324]) are quite unparalleled. The cry, often uttered upon the wing, is a piercing whistle, or a twittering or clucking sound; though that of Syrrhaptes appears to be hoarser, and has been syllabled as "truck-turuck" and "caga-caga" in S. paradoxus and S. tibetanus respectively. The alarm-note is of a croaking nature. The food consists of seeds, tender shoots, bulbous grass-roots, and insects, or even of berries, peas, and beans; while the birds flock to drink at certain favourite spots, and are variously stated to take continuous or interrupted draughts. The nest is a mere hollow in the soil, frequently lined with a little grass; the three oval, but peculiarly cylindrical, eggs vary from whitish to buff, or greenish in Syrrhaptes, and are marked with brown, reddish, and violet. Both sexes assist in incubation, which lasts from twenty-five to twenty-eight days. Opinions vary as to the edible quality of the flesh.

Fig. 65.–Pallas's Sand-Grouse. Syrrhaptes paradoxus. × 3⁄10.

Pterocles arenarius, ranging from the Canary Islands, North Africa, and Madagascar to South Europe and Central Asia, has dark grey upper parts, with orange-yellow markings, except on the white-tipped primaries and tail; the chestnut throat surmounts a black patch, which is succeeded by a breast of the same dove-colour as the head, crossed by a black band; the belly being black also. The bill is horn-coloured, the feet are greyish. The female is buff, barred above and spotted below with black; her throat is yellowish-white, and the black areas on her lower surface are as in the male. P. decoratus of East Africa, P. bicinctus and P. variegatus of South Africa, P. coronatus and P. lichtensteini, extending from the Sahara and Kordofan respectively to North-West India, P. gutturalis of East Africa, P. personatus of Madagascar, P. fasciatus of India–the only species peculiar to Asia–and P. quadricinctus, found from Senegambia to Abyssinia, are fairly similar to the above, though chiefly sandy in some cases.

Pteroclurus alchata, absurdly termed "Perdrix d'Angleterre" in France, and Rock-Pigeon in India, is grey above, with yellow tips to the dorsal feathers; it has black, brown, and greyish-white wings, shewing chestnut and yellow on the coverts; yellowish rump and long median rectrices barred with black. The cheeks are orange, the throat is black with a little yellow beneath, the upper breast is chestnut-red, bordered by a black line above and below, the remaining under parts are white, the bill and feet brownish. The female differs in her white throat, and in her upper surface irregularly marked with buff, grey, and black. This species occurs in South Europe, North Africa, and South-West Asia; P. namaqua inhabits South Africa; P. exustus ranges from Senegal to the Pangani River in East Africa, and through Palestine to Central Asia and India; while P. senegallus extends from the Sahara to Palestine, Arabia, and North-West India.

Syrrhaptes paradoxus, Pallas's Sand-Grouse, has buff upper parts barred with black; mainly blue-grey wings and tail, with black and chestnut markings on the former, and white tips to the lateral rectrices; dull yellow crown and cheeks; orange nape and throat; greyish-buff neck and breast, white abdomen and metatarsal plumage, an interrupted black gorget, and a broader black band towards the belly. The female has less elongated median tail-feathers, black streaks on the buff head, a black bar across the throat, and is duller generally. S. tibetanus, with entirely white belly, the largest of the Family, extends from the Sutlej and South Kashmir to Koko-Nor; but its congener reaches from the Lower Volga or the Kirghiz Steppes to the north of Lake Baikal and North China, while some erratic impulse of uncertain origin causes it to invade the plains of China and the whole of Europe at irregular intervals. One specimen was obtained at Sarepta on the Volga in 1848, and again in 1860, when flocks visited Pekin; in 1859 a few examples occurred on the Continent, and between July and November three wandered to Britain; while in 1863 some 700 individuals reached our shores by May 21, straying as far as Ireland, but vanishing towards autumn. Several pairs bred on the sand-hills of Holland and Jutland. In 1872 and 1876 small parties visited us; and in 1888 another and incalculably larger invasion took place, which extended farther southward than that of 1863, and after entering Europe before the beginning of April, occupied Britain between May 6 and May 15, to remain there throughout that year and the succeeding. Besides breeding in Denmark, Holstein, and no doubt elsewhere on the Continent, two pairs nested in 1888 in the east of Yorkshire, and one or more on the Culbin Sands in Moray, whence in 1889 Professor Newton received on August 8 a chick of two or three days old. This was exhibited at the Newcastle Meeting of the British Association, and subsequently figured in The Ibis.[[206]] Doubtless the above were not the only cases of reproduction in England, and it was hoped that a protective Act, which came into force in February 1889, would lead to permanent colonization; but by 1890, or, according to some, 1892, all the birds had disappeared.

As a fossil, Pterocles occurs in the Eocene and Miocene of France.