Thick-billed Weaver
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The thick-billed weaver (''Amblyospiza albifrons''), or grosbeak weaver, is a distinctive and bold species of
weaver bird Ploceidae is a family of small passerine birds, many of which are called weavers, weaverbirds, weaver finches, or bishops. These names come from the nests of intricately woven vegetation created by birds in this family. In most recent classificat ...
that is native to the
Afrotropics The Afrotropical realm is one of the Earth's eight biogeographic realms. It includes Sub-Saharan Africa, the southern Arabian Peninsula, the island of Madagascar, and the islands of the western Indian Ocean. It was formerly known as the Ethiopi ...
. It belongs to the
monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unisp ...
genus ''Amblyospiza'' and subfamily Amblyospizinae. They have particularly strong mandibles, which are employed to extricate the seeds in nutlets and
drupe In botany, a drupe (or stone fruit) is a type of fruit in which an outer fleshy part (exocarp, or skin, and mesocarp, or flesh) surrounds a single shell (the ''pip'' (UK), ''pit'' (US), ''stone'', or ''pyrena'') of hardened endocarp with a seed ...
s, and their songs are comparatively unmusical and harsh. Their colonial nests are readily distinguishable from those of other weavers, due to their form and placement, and the fine strands used in their construction. They habitually fan and flick their tails.


Taxonomy and systematics

The generic name ''Amblyospiza'' was coined by
Carl Jakob Sundevall Carl Jakob Sundevall (22 October 1801 in Högestad – 2 February 1875) was a Sweden, Swedish zoologist. Sundevall studied at Lund University, where he received a Ph.D. in 1823. After traveling to East Asia, he studied medicine, graduating as a ...
in 1850 and means "blunt, finch", referencing the very large bill, while the specific name ''albifrons'' refers white forehead of the males. The thick-billed weaver was formally described as ''Pyrrhula albifrons'' in 1831 by the Irish zoologist and politician
Nicholas Aylward Vigors Nicholas Aylward Vigors (1785 – 26 October 1840) was an Ireland, Irish zoologist and politician. He popularized the classification of birds on the basis of the quinarian system. Early life Vigors was born at Old Leighlin, County Carlow, in 1 ...
from the collection of Henry Ellis, the specimens of which were attributed to Algoa Bay and environs in the
Eastern Cape The Eastern Cape ( ; ) is one of the nine provinces of South Africa. Its capital is Bhisho, and its largest city is Gqeberha (Port Elizabeth). Due to its climate and nineteenth-century towns, it is a common location for tourists. It is also kno ...
.


Subspecies

Ten subspecies are currently recognized: *''A. a. capitalba'' (Bonaparte, 1850) – discontinuously from south-eastern Guinea to southern Central African Republic and north-western Angola *''A. a. saturata'' Sharpe, 1908 – southern Nigeria to north-western Democratic Republic of Congo *''A. a. melanota'' (Heuglin, 1863) – South Sudan and southern Ethiopia, through the
rift valley A rift valley is a linear shaped lowland between several highlands or mountain ranges produced by the action of a geologic rift. Rifts are formed as a result of the pulling apart of the lithosphere due to extensional tectonics. The linear ...
and adjacent lowlands to north-western Tanzania *''A. a. montana'' van Someren, 1921 – Kenyan and Tanzanian interior, south-eastern Democratic Republic of the Congo to Malawi and
Okavango Basin The Kalahari Basin, also known as the Kalahari Depression, Okavango Basin or the Makgadikgadi Basin, is an endorheic basin and large lowland area covering approximately — mostly within Botswana and Namibia, but also parts of Angola, South A ...
*''A. a. unicolor'' (G.A.Fischer & Reichenow, 1878) – East coast littoral from southern Somalia to
Zanzibar Zanzibar is a Tanzanian archipelago off the coast of East Africa. It is located in the Indian Ocean, and consists of many small Island, islands and two large ones: Unguja (the main island, referred to informally as Zanzibar) and Pemba Island. ...
and
Pemba Pemba may refer to: __NOTOC__ Places * Pemba Island, in Tanzania * Pemba, Mozambique, the capital of Cabo Delgado Province * Pemba District, a district of Zambia * Pemba, Zambia Pemba is a small town (population about 4,000) located in Pemba ...
islands. *''A. a. tandae'' Bannerman, 1921 – north-western Angola and extreme western Democratic Republic of Congo *''A. a. kasaica'' Schouteden, 1953 – south-eastern Democratic Republic of Congo *''A. a. maxima'' Roberts, 1932 – south-eastern Angola, north-eastern Namibia, western Zambia, northern Botswana, extreme north-western Zimbabwe *''A. a. woltersi'' Clancey, 1956 – eastern Zimbabwe, southern Mozambique, north-eastern and eastern South Africa *''A. a. albifrons'' (Vigors, 1831) – eastern Zimbabwe and central Mozambique, southwards to eastern South Africa


Distribution and habitat

It has a patchy distribution in West, East and southern Africa, where it is present in marshes, uplands, suburban areas and artificial wetlands. Thick-billed weavers breed in reedy wetlands and can be found around forest edge outside the breeding season.


Behaviour and ecology


Breeding

Thick-billed weavers are
polygynous Polygyny () is a form of polygamy entailing the marriage of a man to several women. The term polygyny is from Neoclassical Greek πολυγυνία (); . Incidence Polygyny is more widespread in Africa than in any other continent. Some scholar ...
, in that a single male attempts to attract and mate with several females. A male may attract up to six females, and up to three nests may be active in any male's territory at once. When found at low density there are many apparently monogamous pairs, but they normally nest in small colonies. More than 100 nests have been counted in one South African colony. After mating the female normally will lay a clutch of 3 whitish pink eggs, spotted with red, purple and brown. The incubation of the eggs is carried out solely by the female. This lasts 14 to 16 days and the chicks are fed by regurgitation by the female until they fledge, though occasionally the male may also feed the young. The chicks fledge after about 18 to 20 days in the nest. The nests are vulnerable to predation and recorded nest predators include the white-browed coucal,
house crow The house crow (''Corvus splendens''), also known as the Indian, greynecked, Ceylon or Colombo crow, is a common bird of the crow family that is of Asian origin but now found in many parts of the world, where they arrived assisted by shipping. I ...
and the
Nile monitor The Nile monitor (''Varanus niloticus'') is a large member of the monitor family (Varanidae) found throughout most of Sub-Saharan Africa, particularly in drier regions, and along the Nile River and its tributaries in East Africa. Additionally, th ...
. After the nests have been used by the weavers they may be commandeered by climbing mice, or used for breeding by the
orange-breasted waxbill The orange-breasted waxbill (''Amandava subflava''), also known as the zebra waxbill, is a small (approximately 9 cm long) sparrow-like bird with a reddish iris, orange breast, red bill and dark olive-green plumage. The male has a red rump, ...
or
brown firefinch The brown firefinch (''Lagonosticta nitidula'') is a common species of estrildid finch found in Southern Africa. It has an estimated global extent of occurrence of 1,300,000 km2. It is found in Angola, The Democratic Republic of the Congo, ...
.


Nests

The thick-billed weaver constructs a distinctive nest which is compact, woven with thin strips of reeds and hung between the upright stems of reeds. It is globe-shaped with the entrance (unlike other weaver nests) near the top and facing to the side. The male weaves the nest with fine material leaving a neat impression, but the weave is in fact not as complex or developed as that of other weaver species. The initial entrance is large, but when a female has chosen the nest the entrance reduced to a narrow opening. Thick-billed weaver colonies may involve a single male, or may contain several males, and is usually established in a reed
swamp A swamp is a forested wetland.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p. Swamps are considered to be transition zones because both land and water play a role in ...
.


Gallery

File:Amblyospiza albifrons, nes, a, Manie van der Schijff BT.jpg, Nest built in an introduced
bamboo Bamboos are a diverse group of mostly evergreen perennial plant, perennial flowering plants making up the subfamily (biology), subfamily Bambusoideae of the grass family Poaceae. Giant bamboos are the largest members of the grass family, in th ...
species File:Thick-billed Weaver (Amblyospiza albifrons) juvenile (12929741175).jpg, Immature bird showing yellow mandibles File:Amblyospiza albifrons, w, vreet netel-dopvrugte, a, Skeerpoort.jpg, Female feeding on nettle nutlets in a mountain ravine File:Thick-billed Weaver (Amblyospiza albifrons) (6012173484).jpg, Male foraging on ground on a river bank


References


External links

* Thick-billed weaver
Species text in The Atlas of Southern African Birds

Thick-billed weaver
on Weaver Watch * {{Taxonbar, from=Q426384 thick-billed weaver Birds of Sub-Saharan Africa thick-billed weaver Taxonomy articles created by Polbot