[NatureNS] Middlewood, Lun. Co. owl survey

Date: Fri, 15 May 2009 21:34:27 -0300
From: Susann Myers <myerss@eastlink.ca>
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Hi, Sylvia.

Great to hear your survey results.  I think it's my observation rather than 
Randy's that late-calling Saw-whets may be non-breeders - or those that have 
not managed to breed as yet, not for want of trying.  Randy appears to be 
saying that Saw-whets continue to call after breeding, in his experience.

As I understand it the main Saw-whet call, the on-going monotonous call that 
we pick up on roadside surveys, that continues for hours through the night, 
night after night, is an advertising call - a male advertising the 
availability of himself and a truly splendid nesting cavity.  It's described 
in the Birds of North America monograph on the Northern Saw-whet Owl written 
by Dick Cannings of BC, thus:

"Advertising song seems to be given almost exclusively to attract mates. 
After a female has completed her clutch, the production of and reaction to 
mate song falls off markedly.  The soft, rapid versions of the advertising 
song are apparently used in contact situations. ..."

Given the difficulties of understanding owl behaviour, "seems to" may be the 
best we can say at present.  It is very difficult to know what the Saw-whet 
calls we hear in roadside surveys mean in terms of population densities. 
Does a male calling the advertising song reflect a high density of owls that 
year (which once-yearly survey results tend to support), or a low density 
(that is, no female was present to respond to the male)?  I have done 
multiple surveys per year on my Cape Breton owl survey routes to try to 
understand these results better, but I think that observation at nesting 
sites is needed for a good understanding.

Randy? - it would be interesting to hear your experiences.

Cheers,
Susann
----- Original Message ----- 
From: <sfullert@dal.ca>
To: <naturens@chebucto.ns.ca>
Sent: Friday, May 15, 2009 6:45 PM
Subject: [NatureNS] Middlewood, Lun. Co. owl survey


> James Hirtle, Dorothy Poole, and I ran the Middlewood survey on
> May 11 in excellent conditions and had only four Barred and two
> Saw-whets. We had no Saw-whets last year. This is the latest this
> survey has been done and results may reflect Randy's observation
> that late calling  Saw-whets may be non-breeders.
>
> Sylvia Fullerton
> Broad Cove, Lun. Co.
> 


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