A week ago I witnessed a wonderful sound and light show in Capertee Valley NSW. About 200 Noisy Friarbirds held a session of "sunset chorussing" and I was lucky enough to be there! The effect was visually and aurally spectacular. Just as the last of the sun was raking the ridgetops and lighting up the distant cliffs with an orange glow, the friarbirds began to sing. They gathered in small groups, perched in sunlit tree tops, and spread out across 3 or 4 adjoining ridges adjacent to Coco Creek.
The chorus ebbed and flowed, beginning as a duet on one ridge, then taken up by others on that ridge, and then continuing to the next ridge, and the next, as if in reply. Birds sometimes flew and re-grouped, then sang some more. It seemed much more than a random cacophony, with some special communication processes involved perhaps. To my mind the whole event seemed like a celebration, but I guess that's unscientific! I did manage to tape record some of this, but only in mono, when what I really needed was quadrophonic monitoring!
A couple of years back I saw something similar with Noisy Friarbirds, same area, same time of year, but the group was only about 50 birds. They called at sunset each evening for about a week.
I asked David Geering about this. He hadn't heard that happen with Noisy Friarbirds, but he had once seen and heard 150 Regent Honeyeaters chorussing at sunset in winter 1997, Capertee Valley, in a manner similar to the Noisy Friarbirds that I've just described.
Carol Probets has heard Noisy Friarbirds chorussing at sunset on the rim of Kanimbla Valley near Mt. Victoria NSW. She said the whole hillside seemed alive with singing friarbirds just as the sun was going down. That was about 10 years ago, I don't know the time of year.
Another recollection was from Kakadu National Park, NT. I was trying to record the calls of Helmeted Friarbirds. They only gave one-note calls at dawn, but at sunset (winter) about a dozen of them would chorus in a call-and-answer routine.
There's been lots written about dawn chorussing, but does anyone know any more about the phenomenon of sunset chorussing? And more particularly, what are the Noisy Friarbirds communicating to one another? How big do their flocks get? Is this a winter farewell gathering? Are they pairing up for the spring, checking out the song quality of potential mates? Or what?
All ideas to Birding-Aus! Thanks!