“Birds flock and roost together for many reasons. One reason I can think of is that as a collective unit, they are more alert with many pair of eyes that are able to look at different directions. Thus, the probability of spotting a predator will be increased significantly.
“A flock of birds consisting of Pink-necked Green Pigeons (Treron vernans) and Asian Glossy Starlings (Aplonis panayensis) was roosting peacefully in a tree one early morning (above). Suddenly, the birds screeched and took flight. Collectively, the birds must have spotted a predator and took evasive action. Sensing danger, the birds were reacting instantaneously. In a split second, all the birds were in the sky and the tree was barren of birds.
“The evasive action took less than two seconds. It was interesting to note that the fastest and first to react were the Asian Glossy Starlings. The Pink-necked Green Pigeons were noticeably slower in taking flight. What spooked the birds? No, it was not a bird of prey or raptor. It was a pair of Oriental Pied Hornbills (Anthracoceros albirostris) flying above (below left).
“The pigeons and starlings were probably alarmed by the large, odd looking hornbills, probably mistaking them for predators. The hornbills were later seen sharing the same tree. However, the smaller birds accorded due respect to the hornbills by perching on the opposite branches of the dead tree (above right).
“The hornbills did not bother the smaller birds but were indulging in preening and allopreening (below). It was observed that the female joined the male on the branch and initiated allopreening. There were occasions when she reached below the branch to delicately touch the male’s tail feathers, which she later raised with her bills and preened. Is this part of courtship behaviour?
“I believe that this pair of hornbills have made Pasir Ris Park their home and may be prospecting for a nest. I have spotted the couple on at least three different days over the past fortnight. To the officials of National Parks Board, please watch out for the hornbills at Pasir Ris Park when carrying out tree maintenance. The oriental pied hornbills, first originating from Pulau Ubin, then moved to Changi, could have started their highly awaited propagation on mainland Singapore. Lets all do our part to help conserve this majestic birds. ”
Kwong Wai Chong
16th December 2009