Mauritius Bulbul Hypsipetes olivaceus Scientific name definitions

25–27 cm; male 69 g, female 76 g, unsexed 70 g and 79 g. A large bulbul with conspicuous pinkish-orange bill, loose and pointed erectile crown feathers. Forehead is olive grey-green, streaked darker, crown and nape very dark olive-green to blackish, slightly glossy; lores blackish, cheeks, ear-coverts and side of hindcrown above mid-point of eye greenish olive-grey; hindneck dull olive grey-green, streaked darker, upperparts dark greenish-olive, streaked brownish, rump slightly browner and warmer; tail and wings olive-brown, secondaries and tertials narrowly fringed greenish-grey; throat, breast and flanks dull dark greenish-grey, belly yellowish-grey, rear flanks pale cinnamon, undertail-coverts dirty yellowish with brownish feather centres; iris dark red-brown; bill pinkish-yellow or orangey, usually darker distally on distal culmen and on cutting edges; legs yellowish-orange or pinkish. Sexes alike, female on average smaller than male. Juvenile moults soon after fledging, then resembles adult but very dingy greyish-brown (lacking bright chestnut remiges of young H. crassirostris), with dark, dull bare parts.

Fruit, arthropods, small vertebrates; occasionally flowers and nectar. Diverse range of native and introduced fruits taken. Native species include Aphloia, Calophyllum, Protium, Syzygium, Warneckia and an unidentified palm; naturalized exotics include Apodytes, Artocarpus, Flacourtia, Lantana, Ligustrum, Litsea, Melia, Michelia, Ossaea, Psidium and Rubus. Also takes grapes, apples, papaya, mulberries, raspberries and cherries. Flower-feeding recorded on exotic Ipomoea and native Nuxia; one observation of nectar-feeding on exotic rose-apple (Syzygium jambos). Most animal items taken are arboreal insects: stick-insects (Phasmida), orthopterans (bush-crickets), cicadas (Cicadidae), lepidopterans (adults and caterpillars) and dragonflies (Odonata). Native diurnal geckoes (Phelsuma) account for 30% of animal items identified and may, because of large size, constitute a high proportion of biomass eaten. Usually found singly, in pairs, or in (probably family) groups; up to eight seen together. Strictly arboreal; extremely rarely collects food from ground. Animal prey caught by gleaning from leaf bases, twigs and branches, and clumsy flycatching; also crashes into dense foliage and sallies after small insects flushed. Larger items held in bill and immediately beaten against branches.

At least four types of call recognized, a “chuckle”, a “cat call”, a stress “kek” and soft notes of pair contact, similar to repertoire of H. borbonicus. The chuckle, “chuck chuck”, varies seasonally, sexually and with context, but forms basis of simple song, given morning and evening by territorial male, and used for recognition or greeting between pair-members, e.g. by female after a call sequence when rejoining mate or foraging group. Cat call a rather long, clearly defined, raucous “nyeer”; “kek” apparently given in situations of fear and aggression, as during interspecific and intraspecific interactions. Foraging pair utters soft, short chuckles, as do members of group at common food source, suggesting that pair-members maintain contact when in group; on rejoining after some time apart, both also chuckle jointly.

VULNERABLE. Restricted-range species: present in Mauritius EBA. In 1993, population estimated at 280 (225–340) pairs in simple census, and total area of occupancy 78 km². Densities extremely low compared with other Malagasy members of genus; generally fewer than 10 pairs/km², possibly reaching 15 pairs/km² in few localities; home range up to 50 ha. Dependent on woody vegetation that provides fruit and animal food; such vegetation currently largely native, and long-term decline caused by destruction of this habitat. Main threat is continued habitat degradation resulting from spread of exotic plants poor in food. This species’ populations may be limited by nest predation by non-native mammals and by resource competition with exotic birds, including Common Myna (Acridotheres tristis) and Pycnonotus jocosus, and mammals. Occurs in Black River Gorges National Park, as well as in number of nature reserves and mountain reserves, the latter aimed at watershed protection; some areas of critical habitat, however, are not included in any form of protected area. Introduced in Diego Garcia (Chagos Archipelago), but now extinct there.