“I was at Lake Kenyir, Trengganu [Malaysia] in October 2010. The lakeview chalet that we had was a real bonus. A wide variety of birds visited the trees that were in front of our balcony. From the Ashy Tailorbirds to Buff-necked Woodpeckers, a hunting Crested Serpent Eagle and even the hornbills (not to count the family of otters).
“But the strangest behaviour was exhibited by this Great Hornbill (Buceros bicronis). It flew in and spent some time in the middle of the tree. I think it was feeding because the behaviour didn’t look like it was excavating a nesting site (above and below).
“In the one week that we were there, this was the only occasion when its presence was observed. Assuming that it was feeding, its behaviour after that was even more of a mystery. It started chewing off a branch. At first I thought it was trying to break the branch off, for whatever reason. But then when it took its bill off the branch, I saw that it was the end of the branch and it stuck its bill into the tip of the branch several times.
“What was it doing? Was it using the branch like a toothpick to dislodge something from its bill? Seeing that it seemed to be part of a post-feeding grooming ritual (above), I can only conclude that it was somehow using the branch to ‘clean’ the inside of its bill (reminds me of the cleaning ritual that a cat goes through after a meal). But of course I could be completely wrong.
“Has such behaviour been observed before? Is there a more common explanation for it?”
Lim Poh Bee
31st January 2011
We have received two responses giving the reason for this behaviour:
1. Raju Kasambe of India: “I think this is the mandibulatory behaviour of the hornbills. This has been reported in many species. But I have never seen such lively pictures explaining the behaviour.” See HERE.
2. Dr. Pilai Poonswad of Thailand: “The behaviour of that female Great Hornbill can be interpreted as follows: 1) …using that branch as a toothpick as the photographer guessed, if she spits out that rotten piece of wood, or 2) if the female does this at the beginning of the breeding season, she may be using the wood as plastering material if she does not spit it out. This is evidenced from analysis of the [nest opening] plaster. I have seen this behaviour at Khao Yai National Park.”