Hook-Billed Bulbul

The Hook-billed Bulbul is primarily diurnal, foraging actively from dawn until dusk within the shaded understory of lowland rainforests and swamp forests. Solitary or in loose pairs, these birds move through dense foliage with quick, short flights and deliberate hops along branches and fallen logs. Known for its soft, nasal calls and occasional rattling notes, it communicates at close range to maintain contact with mates or signal alarm. Unlike many songbirds, it often forages at middle and lower canopy levels, probing into clusters of fruit or leaf litter for insects. This species is non-migratory, maintaining small, stable territories year-round and showing adaptability to variations in rainfall and food abundance across eastern Sumatra and Borneo. They are shy and seldom seen in open gaps, preferring the protective cover of understory vegetation, yet may approach forest edges when fruiting shrubs or insect swarms offer feeding opportunities.

The diet of the Hook-billed Bulbul is varied, combining frugivory and insectivory to meet its nutritional requirements. It consumes a wide range of soft fruits such as figs, berries, and fleshy drupes, gleaned from tangled vines and low-hanging branches. Insects and their larvae—including beetles, caterpillars, and grasshoppers—supplement its diet, providing essential proteins. The bird's curved bill allows precise manipulation of berries and probing under bark and leaf litter for hidden prey. Seasonal shifts in fruiting and insect abundance drive dietary adjustments, with a higher reliance on protein-rich insects during the breeding season and greater fruit consumption during periods of fruit availability. This opportunistic feeding strategy supports its energy demands for flight, thermoregulation, and reproduction in humid tropical forests. Its flexible foraging behavior allows survival in both primary and secondary forests, where resource distribution can vary greatly.

Hook-billed Bulbuls form monogamous pairs that defend small nesting territories together. Courtship involves mutual vocal exchanges and subtle bill displays. Pairs construct shallow cup nests of grasses and twigs, often placed low in shrubs or small trees. After the female lays two to five eggs, she incubates them for about 13 to 14 days while the male brings food. Both parents feed and brood the hatchlings until fledging.

The global population size of the Hook-billed Bulbul is not precisely known, but experts estimate a declining trend as lowland forests are cleared or degraded. Major fragmentation of its range across eastern Sumatra and Borneo has isolated populations, increasing vulnerability to local extirpations. Conservation measures focus on habitat protection and restoration in protected areas and forest reserves. Continued monitoring aims to track population changes and guide land-use policies to mitigate ongoing habitat loss.