Observations at a nest of Helmeted Hornbill Rhinoplax vigil in Borneo, Malaysia
Little is known about the nesting behaviour of the Helmeted Hornbill Rhinoplax vigil because it occurs in low numbers and nests are difficult to locate. The nest cavity is usually high and hidden amidst thick foliage and the cavity’s opening is inclined upwards, making it hard to see from the ground. A nesting pair of Helmeted Hornbills was observed in the Kinabatangan Wildlife Sanctuary between 2013 and 2017. We sought to determine the nesting period and associated behaviour, and to identify the type and amount of food provided to the female and chick over the nesting cycle. The nest was located inside the nub of a broken branch of a Shorea pauciflora tree, 37 m up on the trunk. The pair began nesting in May, in the drier months, and the single chick fledged in November the same year. The pair and the fledged young stayed together for at least six months. The male made a maximum of 11 visits per day to bring food to the nest midway through the breeding period. Food brought to the nest consisted of mainly figs, including Ficus stupenda, F. benjamina, F. stricta and F. crassiramea. The adult Helmeted Hornbills delivered stick insects, beetles and praying mantis, while the chick itself caught and consumed a giant millipede at the nest entrance. The specific fig diet and nest cavity preferences make the species extremely vulnerable to environmental changes caused by logging and agricultural expansion. The added pressure from hunting it for casques may be driving it to extinction. Therefore we recommend that their nests be located and offered protection by local authorities and communities through nest adoption schemes.