Sociable Weaver
Encyclopedia
The Sociable Weaver or Social Weaver (Philetairus socius) is a species of bird
in the Ploceidae family endemic to Southern Africa. It is monotypic
within the genus Philetairus. It is found in Botswana
, Namibia
, and South Africa
. but their range is centred around Northern Cape Province
and southern Namibia. They build large compound community nests, a rarity among birds. These nests are perhaps the most spectacular structure built by any bird
in 1790. Four sub-species have been recognised. P. s. eremnus occurs around Orange River
valley, while the nominate P. s. socius around Northern Cape Province and Namibia. Both the others, P. s. xericus and P. s. geminus occur in Namibia, the latter found in Etosha National Park
and Owambo
. This is the only living species in the genus Philetairus.
, an important nesting material is an important determinant of its distribution. The taller grasses and the fire-prone nature of the Northern and Central Kalahari regions may be a factor for the absence of the bird in those regions. The area is semi-arid with low and unpredictable rainfall occurring mostly in the summer. The population has not been quantified but the birds are described as "common to abundant".
s in a single season in response to repeated predation of its young. Unlike northern temperate passerine birds which commence breeding within the first year of life, sociable weavers exhibit delayed onset of breeding, sometimes up to two years of age.
Sociable weavers construct permanent nests on trees and other tall objects. These nests are the largest built by any bird, and are large enough to house over a hundred pairs of birds, containing several generations at a time. The nests are highly structured and provide birds with a more advantageous temperature relative to the outside. The central chambers retain heat and are used for nighttime roosting. The outer rooms are used for daytime shade and maintain temperatures of 7-8 degrees Celsius inside while outside temperatures may range from 16-33 degrees Celsius. Sociable weaver nests are used commensally
by several other bird species, most commonly the Pygmy Falcon. Whereas this falcon is mostly believed to be a indifferent in most places, instances of predation of sociable weaver nestlings and animosity with the weavers has been reported from some sites in Kimberley
. Red-headed Finch
es and Rosy-faced Lovebird
use the nests for breeding while other bird species such as Pied Barbet
, Familiar Chat
and Ashy Tit
may use it for roosting. Larger birds like owls and vultures use the nest as a platform to build their nests.
The nests consist of separate chambers, each of which is occupied by a pair (sometimes with offspring) roost and breed. Nests are built around large and sturdy structures like Acacia trees or sometimes even telephone poles. The trees generally used for nest-building are Acacia erioloba
, Boscia albitrunca
and Aloe dichotoma
. The birds at Etosha National Park
also use Colophospermum mopane trees for nesting. Large nesting colonies can be active across several generations, sometimes over a hundred years. The nest appears like a large haystack in the tree. If seen from below, several entrances into the chambers may be seen, giving a honey-comb appearance. The entrances may be about 3 inches wide and can be up to 10 inches long. Sharp sticks may be placed to deter predators from entering. Snakes, especially Cape cobra
s are the most common nest predators, often consuming all the eggs in all the chambers of a large nest. Nest predation is often as high - in one study 70% of the clutches laid were depredated.
Nests built in electricity poles sometimes cause short circuits in the rainy season and can catch fire in the dry season.
, where standing water is scarce, the sociable weaver obtains all of its water from a diet of insects. They also feed on seed and other plant products. Foraging
is pre-dominantly on the ground, but also on bark and leaves of trees.
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
in the Ploceidae family endemic to Southern Africa. It is monotypic
Monotypic
In biology, a monotypic taxon is a taxonomic group with only one biological type. The term's usage differs slightly between botany and zoology. The term monotypic has a separate use in conservation biology, monotypic habitat, regarding species habitat conversion eliminating biodiversity and...
within the genus Philetairus. It is found in Botswana
Botswana
Botswana, officially the Republic of Botswana , is a landlocked country located in Southern Africa. The citizens are referred to as "Batswana" . Formerly the British protectorate of Bechuanaland, Botswana adopted its new name after becoming independent within the Commonwealth on 30 September 1966...
, Namibia
Namibia
Namibia, officially the Republic of Namibia , is a country in southern Africa whose western border is the Atlantic Ocean. It shares land borders with Angola and Zambia to the north, Botswana to the east and South Africa to the south and east. It gained independence from South Africa on 21 March...
, and South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...
. but their range is centred around Northern Cape Province
Northern Cape
The Northern Cape is the largest and most sparsely populated province of South Africa. It was created in 1994 when the Cape Province was split up. Its capital is Kimberley. It includes the Kalahari Gemsbok National Park, part of an international park shared with Botswana...
and southern Namibia. They build large compound community nests, a rarity among birds. These nests are perhaps the most spectacular structure built by any bird
Taxonomy and systematics
The Sociable Weaver was first described by ornithologist John LathamJohn Latham (ornithologist)
John Latham was an English physician, naturalist and author. He was born at Eltham in Kent, and was the eldest son of John Latham, a surgeon there, and his mother was a descendant of the Sothebys, in Yorkshire....
in 1790. Four sub-species have been recognised. P. s. eremnus occurs around Orange River
Orange River
The Orange River , Gariep River, Groote River or Senqu River is the longest river in South Africa. It rises in the Drakensberg mountains in Lesotho, flowing westwards through South Africa to the Atlantic Ocean...
valley, while the nominate P. s. socius around Northern Cape Province and Namibia. Both the others, P. s. xericus and P. s. geminus occur in Namibia, the latter found in Etosha National Park
Etosha National Park
Etosha National Park is a national park in the Kunene Region of northwestern Namibia. The park shares boundaries with the regions of Oshana, Oshikoto and Otjozondjupa....
and Owambo
Ovamboland
Ovamboland was the name given by English-speaking visitors to the land occupied by the Ovambo people in what is now northern Namibia and southern Angola...
. This is the only living species in the genus Philetairus.
Description and identification
Measuring around 14 cm (5.6 in) in length, the Sociable Weaver has a black chin, black barred flanks and a scalloped back. They weigh between 26-32 g and sexes are indistinguishable.Distribution and habitat
The species ranges across northwestern South Africa, southwest Botswana and extending northwards across Namibia. It is strongly associated with the arid savannahs characteristic of the southern Kalahari region. The presence of stiff grasses such as Aristida ciliata and StipagrostisStipagrostis
Stipagrostis is a genus of grass in the Poaceae family.-External links:*...
, an important nesting material is an important determinant of its distribution. The taller grasses and the fire-prone nature of the Northern and Central Kalahari regions may be a factor for the absence of the bird in those regions. The area is semi-arid with low and unpredictable rainfall occurring mostly in the summer. The population has not been quantified but the birds are described as "common to abundant".
Breeding
In the southern range of the weaver's habitat, breeding may occur any time of the year and is closely linked to rainfall. In the northern range, discrete breeding season between December to August has been noted. They may skip breeding during years when there is low rainfall and a substantial number (sometimes over half) of birds in the colony may never breed in a given season. Under typical conditions, weavers raise up to four broods per breeding cycle. Sociable weavers are known to assist in the care of younger siblings and unrelated hatchlings and nearly all pairs are assisted by helpers. A mating pair has been recorded as producing nine broodOffspring
In biology, offspring is the product of reproduction, of a new organism produced by one or more parents.Collective offspring may be known as a brood or progeny in a more general way...
s in a single season in response to repeated predation of its young. Unlike northern temperate passerine birds which commence breeding within the first year of life, sociable weavers exhibit delayed onset of breeding, sometimes up to two years of age.
Nesting
Commensalism
In ecology, commensalism is a class of relationship between two organisms where one organism benefits but the other is neutral...
by several other bird species, most commonly the Pygmy Falcon. Whereas this falcon is mostly believed to be a indifferent in most places, instances of predation of sociable weaver nestlings and animosity with the weavers has been reported from some sites in Kimberley
Kimberley, Northern Cape
Kimberley is a city in South Africa, and the capital of the Northern Cape. It is located near the confluence of the Vaal and Orange Rivers. The town has considerable historical significance due its diamond mining past and siege during the Second Boer War...
. Red-headed Finch
Red-headed Finch
The Red-headed Finch, Amadina erythrocephala, is a common species of estrildid finch found in Africa. It has an estimated global extent of occurrence of 1,600,000 km²...
es and Rosy-faced Lovebird
Rosy-faced Lovebird
The Rosy-faced Lovebird , also known as the Peach-faced Lovebird, is a species of lovebird native to arid regions in southwestern Africa such as the Namib Desert. A loud and constant chirper, these birds are very social animals and often congregate in small groups in the wild. They eat throughout...
use the nests for breeding while other bird species such as Pied Barbet
Pied Barbet
The Acacia Pied Barbet or Pied Barbet is a species of bird in the Lybiidae family. It is found in Angola, Botswana, Lesotho, Mozambique, Namibia, South Africa, Swaziland, Zambia, and Zimbabwe.-References:...
, Familiar Chat
Familiar Chat
The Familiar Chat, Cercomela familiaris, is a small passerine bird of the Old World flycatcher family Muscicapidae. It is a common resident breeder in Africa south of the Sahara in rocky and mountainous habitat and around human habitation.-Description:...
and Ashy Tit
Ashy Tit
The Ashy Tit is a species of bird in the Paridae family.It is found in Angola, Botswana, Namibia, South Africa, and Zimbabwe.Its natural habitats are subtropical or tropical dry forests and dry savanna.-References:...
may use it for roosting. Larger birds like owls and vultures use the nest as a platform to build their nests.
The nests consist of separate chambers, each of which is occupied by a pair (sometimes with offspring) roost and breed. Nests are built around large and sturdy structures like Acacia trees or sometimes even telephone poles. The trees generally used for nest-building are Acacia erioloba
Acacia erioloba
Acacia erioloba is also commonly known as the Camel Thorn, Kameeldoring , Giraffe Thorn or Mokala . The Mokala National Park in the Northern Cape is named after this tree. The type specimen of Acacia giraffae, proved on closer examination to be a hybrid of A. haematoxylon and the species which...
, Boscia albitrunca
Boscia albitrunca
Boscia albitrunca, commonly called Witgatboom, Matoppie, or Shepherd's Tree, grows up to 10 metres tall but usually much smaller. It is an evergreen tree native to Southern and Tropical Africa, living in the hot, dry, and often brackish low-lying areas, sometimes on abundant lime and occasionally...
and Aloe dichotoma
Aloe dichotoma
Aloe dichotoma, also known as Quiver tree or Kokerboom, is a species of aloe indigenous to Southern Africa, specifically in the Northern Cape region, and Namibia....
. The birds at Etosha National Park
Etosha National Park
Etosha National Park is a national park in the Kunene Region of northwestern Namibia. The park shares boundaries with the regions of Oshana, Oshikoto and Otjozondjupa....
also use Colophospermum mopane trees for nesting. Large nesting colonies can be active across several generations, sometimes over a hundred years. The nest appears like a large haystack in the tree. If seen from below, several entrances into the chambers may be seen, giving a honey-comb appearance. The entrances may be about 3 inches wide and can be up to 10 inches long. Sharp sticks may be placed to deter predators from entering. Snakes, especially Cape cobra
Cape Cobra
The Cape Cobra or yellow cobra is a moderately sized, highly venomous cobra inhabiting a wide variety of biomes across Southern Africa...
s are the most common nest predators, often consuming all the eggs in all the chambers of a large nest. Nest predation is often as high - in one study 70% of the clutches laid were depredated.
Nests built in electricity poles sometimes cause short circuits in the rainy season and can catch fire in the dry season.
Food and feeding
The sociable weaver is insectivorous with insects comprising 80% of their diet. As an adaptation to living in the dry Kalahari DesertKalahari Desert
The Kalahari Desert is a large semi-arid sandy savannah in Southern Africa extending , covering much of Botswana and parts of Namibia and South Africa, as semi-desert, with huge tracts of excellent grazing after good rains. The Kalahari supports more animals and plants than a true desert...
, where standing water is scarce, the sociable weaver obtains all of its water from a diet of insects. They also feed on seed and other plant products. Foraging
Foraging
- Definitions and significance of foraging behavior :Foraging is the act of searching for and exploiting food resources. It affects an animal's fitness because it plays an important role in an animal's ability to survive and reproduce...
is pre-dominantly on the ground, but also on bark and leaves of trees.
Survival
The populations of this bird has increased in this century, perhaps due to increased availability of nesting structures such as electricity pylons and other man-made structures. Most of its present distribution is unlikely to see any major man-made alteration and its future in these areas is secure. However, a gap in its distribution in the Northern Cape Province, north of the ghaap plateau is probably due to habitat alteration by clearnance of Acacia. In other areas, encroachment due to overgrazing may also cause local extinction.External links
- Sociable Weaver videos on the Internet Bird Collection