White-throated Brown Hornbill (Ptilolaemus austeni)

Originally placed in genus Anorrhinus , together with its sister species Tickell’s Brown Hornbill with which it was also considered conspecific; the two differ in some details of plumage and bill color .

White-throated Brown Hornbill

Male 73-80 cm, female smaller. Male 710-900 g. Medium-sized hornbill
with generally dark brown plumage and rufous underparts, wings and tail
tipped white. Male has whitish cheeks and throat and creamy underparts
with dark cheeks and throat; ivory white bill and small casque.

Both have blue ring of naked skin around eyes. Juvenile resembles adult male,except for paler brown tips to feathers; short yellow bill and orange
skin around eyes; moults into adult plumage when around a year old.

The call is somewhat similar to Bushy-crested Hornbill but less harsh, a
loud series of repeated screams, croaks and chuckles.

Ecology and habits

Found in closed forest, both evergreen and deciduous, from the lowlands to the lower montane forest with pines and oaks,mainly in lower hills, It is recorded to 1,000 m elevation in India, 1,500 m in South-east Asia and 1,800 in Tibet and Yunnan province, China.

It is a social bird that lives in vocal and mobile group of 2-15 birds, up to 50 in one group have been reported. It moves through the forest at canopy level and feeds actively inside or just below the canopy.

The food in mainly fruits, 41 different varieties have been identified at Khao Yai NP. During a breeding survey in Thailand, recorded food by weight was 22% figs, 38% other fruits and 40% animals. It consumes animal prey as many as 41 species.

Prey included many arthropods, but also snails, earthworms and such vertebrate prey as bats, snakes, lizards and bird chicks and eggs. Sedentary and territorial, the mean home range of a breeding group in only 4.3-5.9 sq. km; there are no reports of movements apart from immatures dispersing.

In non-breeding season a number of up to 80 birds can be seen roosting together in Khao Yai NP.

White-throated Brown Hornbill
White-throated Brown Hornbill

Breeding ecology

The nesting season starts in the beginning of the year, in Thailand eggs are laid Feb-Mar and Chicks fledge May-Jun, in India Mar-Jun. This species is co-operative during nesting; the dominant pair in the group will breed, only males will help out.

The nest is a natural cavity or an old woodpecker hole at 5-27 m (avg 13 m) up in a large forest tree, often a Dipterocarpus or Cleistocalyx (formerly Syzygium). The clutch is 2-3 eggs, rarely up to 5. The incubation period is 27 days; the female will moult her flight feathers while incarcerated.

The female and the chicks are fed by 1-5 male nest helpers; a mean rate of food brought to the nest is 17 g per hour. The female leaves the nest together with the chicks; the nesting period is about 62 days .

The entire nesting cycle is 90 days on average (range 73-112 days).