Photo above by Shavez Cheema shows an adult male  Helmeted hornbill about to feed a Ficus forstenii fig to the female hornbill  inside the nesting cavity at Tawau.

Helmeted Hornbills are known to be fig specialists which feed largely on the fruit of strangling figs of many species supplemented with small mammals and birds and large insects. See Fig Ecology: Helmeted Hornbill

This article by Ravinder Kaur  describes the food fed to their single  offspring by a pair of nesting Helmeted hornbills on the Kinabatangan River between 2013-2017. 

Ravinder Kaur et al (2018) Helmeted nesting Kinabatangan

Food brought to the nest consisted mainly of figs, including Ficus stupenda, Ficus benjamina, Ficus stricta and Ficus crassiramea. The adult Helmeted hornbills delivered stick insects, beetles and praying mantis, whilst the chick itself caught and consumed a giant millipede.

Ravinder also notes that the patents fed unripe figs to the young bird. Due to the  way figs are pollinated by fig wasps, unripe figs often contain large numbers of fig wasps. These wasps all leave the fig before they ripen.  Thus unripe figs may contain higher levels of protein than ripe figs

As the fledging  of the chick approached  the male and female  brought unripe figs as noted elsewhere (Chong 2011).

Helmeted hornbill Shavez Cheema
Photo by Shavez Cheema: https://www.1stopborneo.org/about-us
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Ficus forstenii is a common fig of the Kinabatangan flood plain. Photo by Ravinder Kaur.

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Watching elephants Kinabtangan 3P7A7173.JPG