Justification of Red List Category
Some parts of this species's small and fragmented range are well-protected by reserves or by their remoteness. However, forests in the East Usambara Mountains, the only area in which it is common, are being rapidly altered or cleared. Its range and population are therefore suspected to be declining and it qualifies as Vulnerable (Collar and Stuart 1985).
The population in the Udzungwas might only number c.1,000 birds (L. Hansen in litt. 2007), with a more conservative guess being 'some hundred' individuals (Dinesen et al. 2001). The species is common in the Usambara and could number c. 1,000 individuals, maybe more (L. Borghesio in litt. 2016). Thus the total population is placed in the range band for 2,500-9,999 individuals. This equates to 1,667-6,666 mature individuals, rounded here to 1,500-7,000 mature individuals.
The species's population is suspected to be declining in line with the clearance and degradation of forest in the areas in which it occurs. The likely rate of decline, however, has not been estimated.
Anthreptes rubritorques is found in five areas of forest in eastern Tanzania: the Usambara, Nguu, Nguru, Uluguru and Udzungwa Mountains. It is only considered common in parts of the Usambaras (in the East Usambara it is widespread above 700m, both in the south - Amani Nature Reserve - and the north - Mt. Milo Nature Reserve [L. Borghesio in litt. 2016]), being elsewhere uncommon to rare (Evans 1997b, Cordeiro 1998, Seddon et al. 1999b). The population in the Udzungwas is guessed to number c.1,000 individuals (L. Hansen in litt. 2007), or more conservatively 'some hundred' individuals, and has been recorded at only three localities (Dinesen et al. 2001). The Uluguru population is known from only five specimens and any remaining population is likely to be found in the North Forest Reserve, since suitable habitat is generally absent elsewhere. The species was not located in the Ulugurus during surveys in 1999-2001 (Burgess et al. 2002). However, there are still areas in the south Ulugurus that are unexplored and there may be other sites within Ulu where the species occurs (L. Hansen in litt. 2007).
It has been recorded in rainforest at mid-altitudes (Zimmerman et al. 1996, Evans 1997b), in the canopy and (more frequently) in forest-edge habitats - e.g. large glades, disturbed or secondary forest with some surviving large trees, gardens and exotic plantations - perhaps because it is easier to see in such open areas (Cordeiro 1998), however surveys in 2006 in the East Usambaras found that the species showed a preference for edges and smallholder agriculture with sufficient large trees, including nesting by a roadside in open habitat, suggesting that it may be less dependent on primary forest than previously thought (Borghesio et al. 2008). The species is likely to show seasonal shifts in habitat preference, in reaction to changes in food abundance, probably showing a preference for forest edge habitats during the dry season and then moving to dense forest in the rainy season (L. Hansen in litt. 2007). The diet includes nectar, small berries and fruits (Cordeiro 1998, 2008, N. Baker in litt 1999). During the breeding season it will also take small insects and spiders to provide protein for nestlings (L. Hansen in litt. 2007). Breeding has been recorded from 300 to 1,200m (nest records from 900-1,200 in the Usambara [L. Borghesio in litt. 2016]), even though it occurs from 200 to 1,500 m. It is possible that the species undertakes altitudinal migrations, in which case habitat at lower elevations may be more vital to the species than previously thought (L. Hansen in litt. 2007). A nest was 15 m up in the crown of a leafless tree, deep in the forest (Evans 1997b), and further nest records have come from along forest edges and in Eucalyptus plantations near to forest (L. Borghesio in litt. 2016).
It is threatened over most of its range, by forest loss and degradation, as a result of clearance for agriculture, replacement of natural forest with plantations, and tree-cutting for timber and firewood (Evans 1997b). The fact that lower altitude forest is cleared first impacts the species (L. Dinesen in litt. 2007). In the Usambaras, the large human population is putting increasing pressure on land and the forests are highly fragmented (Evans 1997b). In the Ulugurus, inaccessible terrain protects the main montane forest block, but the lower slopes, around the species's optimal altitude, are being steadily cleared. Forest in the Ulugurus declined from c.300 km2 in 1955 to c.230 km2 in 2001, mostly due to clearance for cultivation below 1,600 m (Burgess et al. 2002). Thus, the population in the Ulugurus might be extirpated as a result of an increasing human population. Forests in Nguru are not currently considered threatened because of their precipitous terrain and the low human population. In the Udzungwas, some areas of potential forest habitat are under pressure and shrinking (L. Dinesen in litt. 2007).
Conservation Actions Underway
The East Usambara Catchment Forest Project has curbed much forest destruction and much of the remaining unprotected forest has been incorporated into reserves, e.g. Mt Nilo Forest Reserve now contains a significant area of mid-altitude forest, although lack of jurisdiction over the neighbouring Public Lands Forest threatens its long-term prospects. In the Udzungwas, it occurs in the Udzungwa Mountains National Park and West Kilombero Scarp Forest Reserve. In the Ulugurus, conservation projects are aiming to assist local initiatives and increase involvement of local communities in forest management (Buckley and Matilya 1998). Yearly surveys are carried out in the Usambara to monitor the population of this, and other, species (L. Borghesio in litt. 2016).
8.5-9 cm. Small sunbird of forest canopy and edges with short, gently-curved bill. Iridescent green upperparts contrasting with dark wings. Dull grey underparts. Male has inconspicuous, reddish breast-band (diagnostic). Female like male but with head more olive-green, greyish below and lacking breast band. Similar spp. Female Collared Sunbirds A. collaris also have iridescent upperparts, but bright yellow underparts. Voice Far-carrying shwerp. Hints In forest patches near Amani, East Usambara Mountains, Tanzania.
Text account compilers
Evans, M., Wheatley, H., Starkey, M., Taylor, J., Symes, A., Ekstrom, J., Shutes, S.
Hansen, L., Tye, A., Dinesen, L., Baker, N.
BirdLife International (2022) Species factsheet: Anthreptes rubritorques. Downloaded from http://www.birdlife.org on 13/08/2022. Recommended citation for factsheets for more than one species: BirdLife International (2022) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 13/08/2022.