Pteroclidae – Sandgrouse
The Pteroclididae or Sandgrouse is a family of sixteen species of bird, members of the order Pteroclidiformes. They are traditionally placed in two genera. The two central Asian species are classified as Syrrhaptes and the other fourteen species, from Africa and Asia, are placed in the genus Pterocles. They are ground dwelling birds restricted to treeless, open country, such as plains, savannahs and semi-deserts. They are distributed across northern, southern and eastern Africa, Madagascar, the Middle East and India through to central Asia. The ranges of the Black-bellied Sandgrouse and the Pin-tailed Sandgrouse extend into the Iberian Peninsula and France, and Pallas’s Sandgrouse occasionally breaks out in large numbers from its normal range in Asia.
Sandgrouse have small, pigeon-like heads and necks and sturdy compact bodies. They range in size from 24cm to 40cm in length and from 150g to 500g in weight. The adults are sexually dimorphic with the males being slightly larger and more brightly coloured than the females. They have eleven strong primary feathers and long pointed wings giving them a fast direct flight. The muscles of the wings are powerful and the birds are capable of rapid take off and sustained flight. In some species, the central feathers in the tail are extended into long points. The legs are short and members of the genus Syrrhaptes have feathers growing on both the legs and toes and no hind toes, while members of the genus Pterocles have legs feathered just at the front, no feathers on the toes and rudimentary hind toes raised off the ground.
The plumage is cryptic, generally being in shades of sandy brown, grey and buff, variously mottled and barred, enabling the birds to merge into the dusty landscape. There is a dense layer of under down which helps insulate the bird from extremes of heat and cold. The feathers of the belly are specially adapted for absorbing water and retaining it, allowing adults, particularly males, to carry water to chicks that may be many miles away from watering holes. The amount of water that can be carried in this way is 15 to 20 millilitres.
Sandgrouse are principally seed eaters. Other food items eaten include green shoots and leaves, bulbs and berries. Insect food such as ants and termites may be eaten especially during the breeding season. The diet of many sandgrouse is highly specialised, with the seeds of a small number of plant species being dominant. This may depend on local availability but in other cases it reflects actual selection of favoured seeds over others by the sandgrouse. Seeds of leguminous plants are usually an important part of the diet. In agricultural areas oats and other grain are readily taken. Seeds are either collected from the ground or directly from the plants. Foraging techniques vary between species that coexist which reduces competition; in Namibia, Double-banded Sandgrouse feed slowly and methodically whilst Namaqua Sandgrouse feed rapidly, exploring loose soil with their beaks and flicking it away sideways. Grit is also swallowed to help grind up food in the gizzard. Sandgrouse are gregarious, feeding in flocks of up to 100 birds. As a consequence of their dry diet, they need to visit water sources regularly. Drinking times vary among the species.
Sandgrouse are monogamous. The breeding season usually coincides with a crop of seeds after the local rainy season and at this time, the feeding flocks tend to break up into pairs. The nesting site is a slight depression in the ground, sometimes lined with a few pieces of dry foliage. Most typically, three cryptic eggs are laid, though occasionally there may be two or four. Incubation duties are shared and in most species, the males incubate at night while the females sit on the eggs during the day. The eggs usually hatch after 20 to 25 days. The precocial chicks are covered with down and leave the nest as soon as the last hatchling has dried out. The parents do not provide them with food and they learn, with parental guidance, what is edible and what is not. The chicks obtain their water from the soaked downy feathers on the adults breasts. At first the chicks are too small and young to thermoregulate, and are provided with shade during the hottest part of the day and brooded at night. They remain with their parents, as a family group, for several months.
The IOC have agreed that there are 16 species in this family, which are:
Tibetan Sandgrouse Syrrhaptes tibetanus
Pallas’s Sandgrouse Syrrhaptes paradoxus
Pin-tailed Sandgrouse Pterocles alchata
Namaqua Sandgrouse Pterocles namaqua
Chestnut-bellied Sandgrouse Pterocles exustus
Spotted Sandgrouse Pterocles senegallus
Black-bellied Sandgrouse Pterocles orientalis
Yellow-throated Sandgrouse Pterocles gutturalis
Crowned Sandgrouse Pterocles coronatus
Black-faced Sandgrouse Pterocles decoratus
Madagascar Sandgrouse Pterocles personatus
Lichtenstein’s Sandgrouse Pterocles lichtensteinii
Painted Sandgrouse Pterocles indicus
Four-banded Sandgrouse Pterocles quadricinctus
Double-banded Sandgrouse Pterocles bicinctus
Burchell’s Sandgrouse Pterocles burchelli
Number of bird species: 16
Pheasants, Partridges & GrouseA Guide to the Pheasants, Partridges, Quails, Grouse, Guineafowl, Buttonquails and Sandgrouse of the World by Steve Madge & Phil McGowan Helm 2002 ISBN: 0713639660 Buy this book from NHBS.com