Justification of Red List Category
This species is listed as Vulnerable because it has a very small population. Although it may be at risk from the effects of introduced species, its population is presumed to have remained stable.
In 1993, there were estimated to be 280 pairs (=560 mature individuals). This equates to roughly 840 individuals in total.
The species's range and population were probably stable between 1975 and 1993 (Safford 1997c), and it is presumed that they have remained stable since; the species is believed to be increasing in some areas and declining in others (V. Tatayah in litt. 2012).
Hypsipetes olivaceus is endemic to Mauritius, and is widespread. It is found in areas including Black River Gorges and adjacent forest areas, the Fouge and Bambous Mountain ranges, slopes between Bel Ombre and Combo, and forest patches in the central plateau (Safford 2013). It was judged to have been reduced to c.200 pairs in the mid-1970s. In 1993, there were estimated to be 280 pairs, with the range and population probably stable since 1975 (Safford 1997c).
It occurs in nearly all native forests, favouring evergreen broadleaved forest (Cheke 1987b, Safford 1997c). It also forages in forest margins, degraded forest remnants with exotic trees, secondary scrub and exotic plantations (Safford 1996b). It is largely frugivorous but also takes some insects and geckos (Cheke 1987b). Territorial and monogamous, breeding takes place between November and February, with clutches consisting of 3 eggs (Safford 2013), but as of yet fledged brood sizes of 3 young have never been observed (Safford 2013). Nests have been found in low bushes (Cheke 1987b) and, more recently, 6-9 m up in Japanese red cedar Cryptomeria japonica (Safford 1996b). Densities are low (rarely over 10 pairs/km2), and are highest between Mt Cocotte and Combo (Safford 1997c), and down into lower Bel Ombre (C. Jones in litt. 2000). This is explained by the presence of wet, evergreen forest (C. Jones in litt. 2000). Usually found in pairs or alone, it can also be seen in groups of up to 8 individuals (presumed to be made up of family members) (Safford 2013).
Habitat degradation, through invasion by exotic plants, is the major threat in the long term (R. Safford in litt. 1999). Nest-predation and competition from introduced rats, crab-eating macaque Macaca fascicularis, P. jocosus and Common Mynah Acridotheres tristis are also threats. Competition may restrict H. olivaceus to native forest (Jones 1996).
Conservation Actions Underway
The Black River National Park partly covers its range (Jones and Hartley 1995). It has also responded well to rehabilitation of native ecosystems in Conservation Management Areas, which has included exclusion of introduced animals and replacement of exotic plants with native species (Safford and Jones 1998, C. Jones in litt. 2000).
22-23 cm. Large, black-capped bulbul. Greyish body, with pink bill and legs. Similar spp. Red-whiskered Bulbul Pycnonotus jocosus has obvious crest and white cheek patch. Voice Various nasal and wheezy calls. Hints Noisy, arboreal bird, usually seen in pairs or small parties (Cheke 1987b).
Text account compilers
Benstead, P., Ekstrom, J., McClellan, R., Pilgrim, J., Shutes, S., Symes, A., Taylor, J., Warren, B. & Westrip, J.
Jones, C., Safford, R. & Tatayah, V.
BirdLife International (2020) Species factsheet: Hypsipetes olivaceus. Downloaded from http://www.birdlife.org on 31/05/2020. Recommended citation for factsheets for more than one species: BirdLife International (2020) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 31/05/2020.