Interesting idea and is obviously logically true. But is that what happened? I wonder if a Koel is able to move with sufficient velocity so that it is the wave
shift that is sufficiently great for a human to detect the difference in pitch. I had thought it needs a greater speed for the Doppler shift to be noticeable to us. Or am I wrong? The mathematics is known but beyond me…… An internet search “Doppler shift”
provides the mathematics. Or was it coincidentally combined with an actual change of call? I can’t say I have noticed it for faster flying birds or is it just that I haven’t thought about it. For example a Peregrine Falcon flying circles around its nest site
is probably faster and gives repeated opportunity to detect this, whilst the observer is standing below. Does someone detect the change in sound as the bird moves towards and away from you? Yes the sound can change but is that the reason?
Philip
From: calyptorhynchus [
Sent: Sunday, 4 November, 2018 7:54 AM
To: Canberra Birds
Subject: [canberrabirds] Koel and the Doppler shift
Amusing incident just now at our place in Hughes. A calling Koel was chased out of a tree by a Red Wattlebird and pursued over our yard and into the distance, but the Koel still continued calling whilst being pursued. As it approached and
then receded the call changed in pitch noticeably.
:-)
--
John Leonard
Canberra
Australia
www.jleonard.net
‘There is kinship between people and all animals. Such is the Law.’ Kimberley lawmen (from Yorro Yorro)
