Are there too many hornbills on the main island of Singapore?

posted in: Hornbills, Nature Conservation | 0

The number of Oriental Pied Hornbills (Anthracoceros albirostris) in Singapore was once confined mainly to the offshore island of Pulau Ubin. As the island’s population increased, a few birds moved to nearby Changi on the main island. There they nested in natural cavities found in old trees and established a small natural population LINK. As such cavities are always in great demand by barbets, woodpeckers, kingfishers, dollarbirds, parakeets… as well as monitor lizards LINK, the number of hornbills increased at a slow pace. To this natural population was added limited releases of excess birds from Jurong Bird Park’s breeding programme. There were also occasional hornbills flying in from nearby Johor, Malaysia, especially when the forests there were disturbed by logging activities.

It was only when the Singapore Hornbill Project was initiated in 2006 that the hornbill population on mainland Singapore saw a sudden increase. Nest boxes were set up in many locations and the hornbills readily took to them. Within a few years the population of hornbills saw a sudden increase LINK.

Slowly, hornbills became a common sight when they moved into suburban Singapore LINK 1 and LINK 2. The hornbills then moved into urban areas including the Housing Development Board heartland LINK and also fed on plants grown along corridors LINK.

On the evening of 8th June 2019, a family of Oriental Pied Hornbills flew into my banana patch and ripped the young rolled up leaves LINK. They were obviously looking for the Whiskered Myotis (Myotis muricola) bats.

After all, Whiskered Myotis bats regularly roost inside the rolled-up young leaves of my banana plants LINK 1 and LINK 2.

Eleven days later the hornbills returned. This time I managed to photograph them eating the bats (above) LINK. I assumed the bats were Whiskered Myotis based on the fact that they move around the banana plants in the early evening. Cave Nectar Bats (Eonycteris spelaea) also visit the plants for the flower nectar but they only appear during the night LINK.

Then on 30th June I found two of my banana plants had their tightly rolled up young leaves badly ripped (above, below). I assume the hornbills were responsible. This time they were thorough in seeking out the bats. The young leaves were yet to unfold to allow for any bats to enter, let alone roost inside. The hornbills did a thorough job ripping them up.

Such aggressive behaviour by hornbills brings to mind earlier reports of these birds visiting the Housing Development Board’s heartlands LINK attacking caged birds. Also, see HERE.

Is it possible that the hornbills are facing a fierce competition for food, especially animal food, because of their high number? If so, is it time to do a study on the number of Oriental Pied Hornbills that Singapore can support, as suggested some years back LINK?

YC Wee
Singapore
16th August 2019

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