Black-tailed Waxbill

The black-tailed waxbill or grey waxbill (Glaucestrilda perreini) is a small estrildid finch found in patchy populations across central, eastern and southern Africa. Adults are about 10.5–11 cm long and weigh 6–9 g.

The plumage is predominantly soft grey, with a narrow black eye-stripe, black tail and bright red rump and upper-tail coverts. The bill is dark, and males and females look very similar. Juveniles are duller and lack the strong black eye-stripe.

It resembles the Cinderella waxbill (Glaucestrilda thomensis) of Angola and northern Namibia, but that species is paler, has a pinkish bill and shows more reddish colour on the lower flanks and belly.

Older sources usually placed the species in the large genus Estrilda. A genetic study published in 2020 supported separating the grey waxbill group into Glaucestrilda, giving the current name Glaucestrilda perreini.

Two subspecies are commonly recognised: G. p. perreini across the northern and western part of the range and G. p. incana from southern Malawi and Mozambique to eastern South Africa.

Black-tailed waxbills favour dense undergrowth and forest margins, including moist lowland and evergreen forest, coastal forest, sand forest, thicket, bamboo and open woodland with a well-developed shrub layer. They are often associated with clearings, streams and other places where seed-bearing grasses grow close to cover.

Small grass and herb seeds form most of the diet. Insects and other small invertebrates are also taken, especially during breeding.

The birds feed both on the ground and directly from vegetation, picking fallen seeds from open patches close to cover and clinging to grass and herb stems to remove seeds before they drop. Small invertebrates are gleaned from low vegetation.

Black-tailed waxbills are usually encountered in pairs or small groups and can be very inconspicuous in dense vegetation. Local groups may join other seed-eating finches at good feeding sites.

They are active by day and typically make short movements between feeding patches and cover rather than spending long periods in open ground.

Both adults build an oval or rounded grass nest with a side entrance, placed in a shrub, small tree or dense tangle. The inner chamber is lined with fine grass and grass seed heads. Instead of building from scratch, pairs may also renovate abandoned nests of dark-backed weavers (Ploceus bicolor), spectacled weavers (Ploceus ocularis) and village weavers (Ploceus cucullatus).

The clutch usually contains two to five eggs. Both parents incubate for around 12 days and feed the young. The chicks leave the nest after approximately 19–21 days and remain dependent for about another week.

The black-tailed waxbill is classified as least concern on the IUCN Red List. It has a broad but patchy range and is locally common in suitable habitat.

No current global population estimate is available. Loss or degradation of dense forest-edge and thicket habitat may affect populations locally, but no major range-wide threat has been identified.