The Ornithology Department of the National Museum is calling upon members of the public to look out for the Red- Billed Buffalo- weaver in the Free State and to report any sightings. From the distribution data available, this weaver is now extinct to the Free State. Deforestation of large tracks of camel thorn savannah for agriculture and firewood has been identified as the likely cause of the local extinction of this weaver.
The Red-billed Buffalo-weaver is a large, heavy-billed weaver that has a red to orange coloured bill. The male has black plumage and its flank feathers are mottled with white. The female’s plumage is more brownish black and the feathers on the belly are slightly scaled.
They usually occur in small flocks often associated with starling species in savannah areas that are dominated by Vachellia and Baobab trees, located in the northern parts of southern Africa (North West Province, Limpopo and Botswana and Zimbabwe). They also occur further north, as far as southern Sudan, Kenya and Tanzania. They breed colonially in these Vachellia species and other trees and their nests are constructed mainly by the males using large thorny twigs.
They also have adapted to build nests on manmade structures such as windmills, power pylons and telegraph poles. Each nest has more than one nest chamber with short tunnel entrances. Nests clutch size ranges from 2 to 4 eggs and the egg incubation period is about 14 days (Vernon & Dean 2005).
Red-billed Buffalo-weavers used to occur in the Vachellia erioloba (Camel Thorn) savannas near the Bloemhof Dam area in the Hoopstad District. Specimens of this species were collected in Bloemfontein by Kotie Herholdt in August 1985 and November 1986. This species was reported in the First Atlas of bird distribution in the Orange Free State (Earle & Grobler 1987). This distribution data was incorporated into the first South African Bird Atlas Project (SABAP1) that was initiated in 1987.
This species is currently extinct in the Free State and was not recorded during the SABAP1 or more recently during the SABAP2 project (from July 2007). However, during the Birds in Reserves Project in the 1990s (http://birp.adu.org.za) they were recorded between the months of March and May at Sandveld Nature Reserve near the Bloemhof Dam. The current SABAP2 distribution map (http://sabap2.adu.org.za/species) shows their distribution mainly in the Northern Cape and western North West and Limpopo areas. Apart from observations made during field work by the National Museum during the past 30 years in the Hoopstad/Bloemhof areas, no other observations have been made of this species in suitable habitat.
Deforestation identified as the likely cause of the extinction
The skin and skeletal specimens of the weaver is the only current evidence of the occurrence of this species in the Free State (Fig 2). A possible reason for the local extinction of the Free State population was established as the short period during which conditions were favourable for breeding. A more likely scenario is the deforestation of large tracts of camel thorn savannah for the purpose of agriculture and collection of firewood.
Other species that are also dependant on this habitat and which are endemic to the Hoopstad/Bloemhof area of the Free State include Pygmy Falcon (Kimberley area also), Magpie Shrike, Southern Yellow-billed Hornbill, Groundscraper Thrush, Yellow-throated Petronia, Lilac-breasted Roller and others which have a wider distribution range (e.g. Sociable Weaver and others). All these species occur mostly in association with these camel thorn savannah areas that have large trees for nesting and foraging sites.
The value of museum specimens is illustrated by current distribution data of birds as well as historical distribution records from regions where they are currently extinct. In our study skin collection there are several examples of specimens collected (e.g. Brimstone Canaries from the Zastron District) from certain areas in the Free State and rarely reported today by the birding community or citizen scientists.
The Ornithology Department regularly undertakes field trips in the Free State to collect distribution data of birds and to expand their study skin and skeletal collections. These collections are widely used by scientists for genetic, avian distribution and morphological studies. If any members of the public are interested to participate in the SABAP2 or any citizen scientist projects they are welcome to contact the National Museum in Bloemfontein.
Earle, R. A & Grobler, N. J. 1987. First atlas of bird distribution in the Orange Free State. Bloemfontein: National Museum.
Vernon, C. J & Dean, W. R. J. 2005. Red-billed Buffalo-weaver Bubalornis niger. In: Hockey, P. A. R.; Dean, W. R. J & Ryan, P. G. (eds.). Roberts – Birds of Southern Africa (VIIth Ed). Cape Town: The Trustees of the John Voelcker Bird Book Fund. pp. 1003-1005.
- A Red-billed Buffalo-weaver male photographed in the Limpopo Province (note the black plumage of the male and red bill) (photo credit: Derek Engelbrecht)
- The Free State Buffalo-weaver specimen collected near the Vaal river west of Bloemhof Dam, Hoopstad District on 28 November 1986. This species is locally extinct in the Free State and last observations were made during the 1990s at Sandveld Nature Reserve (similar area than specimens). Historical distribution data again shows the value of Museum specimens.
- Camel thorn tree. Photo by Harald Süpfle – photo taken by Harald Süpfle, CC BY-SA 2.5, https://commons.wikimedia.org/w/index.php?curid=399826.