Rusty-cheeked Hornbill is a recent split from Brown Hornbill and this taxon has been adopted by the BCST on their latest checklist of the birds of Thailand; formerly it was known as the tickelli subspecies of Brown Hornbill. At Kaeng Krachan this species is fairly easy to see with most sightings being between the Bang Krang campsite and stream 3. Sometimes this species can be quite unobtrosive but often gives itself away with its manic screeching.
The bird in the photos below was part of a flock of 9 birds and was checking out a nest hole beside the road at Kaeng Krachan in late February 2009. This was a nest hole which had been used the previous year by a pair which had successfully reared chicks and I have a vivid memory of them passing lizards to the young birds.
The BCST issued accompanying notes with their checklist and these make interesting reading; here I reproduce the notes on Rusty-cheeked Hornbill.
Rusty-cheeked Hornbill Anorrhinus tickelli and Brown Hornbill A. austeni
P. Poonswad (Hornbill Project Thailand; unpubl. data) has suggested that the genetic distance between these two taxa is at least as great as that between Great Hornbill Buceros bicornis and Rhinoceros Hornbill B. rhinoceros, and on this basis we tentatively treat them as distinct species following some earlier authors (e.g., Kemp 1988). It should be noted, however, that the vocalisations of the two “brown hornbill” taxa are very similar. In addition, although the females are highly distinctive, A. tickelli being dark-billed and A. austeni being pale billed, occasional whitish-throated male A. tickelli that appear inseparable from typical male austeni have been observed in tickelli groups (Anak Pattanavibool, in litt.).