Nesting of Common Iora

posted in: Nesting | 0

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“Noon is a bad time for birding – most birds would be hiding from the hot weather. However, I decided to go to the Japanese Gardens as I had not been there for a while.

“A male Common Iora (Aegithina tiphia) was found sitting on its nest (left top). The nest was built at the fork of some branches around 4m above the ground and covered with spiderweb. When the female returned with food, the male would leave and the chicks could be seen gaping for food (left middle). The food item was fed whole to one chick.

“After that, the female looked a while to see if the chick would excrete any faecal matter. One chick did and sure enough the female picked it up (left bottom). The faecal sac looked watery, unlike the sunbirds’, which looked compact. I expected the female to fly away to dispose of it, just like the sunbirds that I’ve seen, but to my surprise, she ate the faecal sac! Then the female settled down to brood the chicks, or should I say shelter them from the hot sun.

“One parent was always on the nest, except for one occasion when the female flew off and caught a spider on the same tree. She whacked the spider for about 30 seconds, severing some of the spider’s legs before feeding it to one of the chicks.

“While brooding the chicks, both parents left their beaks open most of the time (below: female left, male right) – this led me to think that these birds don’t sweat, that’s why they have to ‘pant’ like dogs to cool down! Even the chicks popped their heads out of the nest, maybe it is cooler that way.

“Later, the male returned with food. After feeding one chick, he also looked to see if the chick would defecate, sure enough the chick did and the male promptly picked it up and ate it as well before settling down to brood the chicks. In contrast, I’ve observed that with the Olive-backed Sunbirds (Cinnyris jugularis), it is usually the female that wait to see if the chicks defecate and then she’ll dispose the faecal sac, while the male would feed and leave. At least four feedings were observed.”

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Note: (1) The excrement of young chicks contains undigested food that the adults can benefit, thus they swallow the faecal sacs. As the chicks grow older, their digestive system becomes more efficient and the adults stop eating the faecal sacs. (2) Birds lose heat by opening their mouths and pant, as seen above. (3) The masses of white on the surface of the nest is probably more of spider cocoon silk than spider silk. Cocoon silk is spun by the spider to protect its eggs until they are hatched.

Date of observation: 1st April 2008

Tan Gim Cheong
Singapore
May 2008

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