Heat, Bushlarks and Crests

To: Philip Veerman <>
Subject: Heat, Bushlarks and Crests
From: Ricki Coughlan <>
Date: Wed, 13 Dec 2006 15:01:10 +1100
Hi Phillip

I might have misread your posting but I don't think that anyone is suggesting that the crest feathers on the bushlark (or any other species) were somehow acting as little conductors or "heat sinks". Feathers just don't work that way.

I don't think that anyone is saying that the crest feathers on the bushlarks are modified to form a longer crest in any way either. Rather, the suggestion is that by raising feathers, especially around apteria - feather free patches - that some heat transfer takes place, resulting in cooling (as long as the surrounding air is not hotter than the bird's body temperature, which is around 40 to as much as 44 degrees, as I recall). This is known as "ptilorection".

There appears to be evidence that crest raising in Singing Bushlarks takes place in hot weather in conjunction with "panting" and nobody has yet stated that they have witnessed this species raising its crest in cool weather. This may mean that they are raising their crest feathers as a type of ptiloerection.

At least that is my take on the discussion.

Happy birding

Belrose, Sydney

On 13/12/2006, at 12:21 PM, Philip Veerman wrote:

There is a curious thing about this discussion: Birds can raise or lower their feathers and do so to assist heat loss or transfer. I don't see how the issue of crests is relevant or helps (though it is lateral thinking and innovative). I agree with others that the issue is raising the feathers, rather than the feathers being modified (longer) into crests. Crests simply exist as the feathers at the top of the head are longer than usual, or longer than needed, to provide the ordinary layering required to insulate the bird's body (or head in this case). Crests exist for display or communication function (and are often coloured or shaped for the purpose). It is hard to conceive how, having longer feathers than usual, could assist in heat loss. If anything, shorter or less dense feathers would help.


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