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Hi all,
I just ran the issue by Bernard Forsythe, who probably has more experience
with nesting owls than most other people in the Province - he tells me
that Barred and Gt. Horned Owls call when they're establishing territories
and attracting mates ( in Fall, when the young are dispersing) and
around Dec - April), the males call to announce to the female on the nest
that they have brought supper (about now) and sometimes the females reply,
and they can, but not always, respond to a taped call as if there were a
rival owl in the area at any time, but become less vocal for any reason
once the young have left the nest. I don't know about other species, but
Soren Bondrup-Nielsen in his book that discusses Boreal owls in the
Northern Ontario forests felt that that species basically stopped calling
once a pair bond had been established and mating had taken place.
My own limited experience is that on the owl survey that I do, Barred and
GH Owls are often heard during the waiting period at the beginning of the
tape, but Barred in particular will then come in closer to investigate once
the Barred Owl call has happened. Saw-whets seem to just toot away
regardless, and Gt.Horned take no notice. The Gt.Horned that are nesting
close to my home were quite vocal in Feb., but I haven't heard them since,
even though the nest is occupied. I don't think any conclusions can be
drawn from this, nor can owl behavior necessarily be applied to other
species.
Richard
On Wed, Apr 17, 2013 at 11:58 AM, Suzanne Borkowski <
suzanneborkowski@yahoo.ca> wrote:
> Hi Ron;
>
> Scott's comments/concerns have been expressed to me before in regards to
> the BBS data we gather. Cindy Staicer, from whom I took an Ornithology
> course at Dalhousie, believed that the birds singing on a BBS route in June
> were unpaired birds and therefore could not be used to give an indication
> of how many birds were breeding on that route. It certainly made sense -
> but raised a lot of questions in my mind, such as: if a lot of birds are
> singing on territory, does that mean they were attracted there because it
> was good breeding habitat? other birds of the same species are nesting
> fairly close by? the singing birds found an abandoned nest site and were
> hoping to use it? There's no sure way to answer these questions but it
> would seem that a lot of birds singing in one area would be an indication
> of a fair amount of breeding success even if it weren't those particular
> individuals who were doing the breeding.
>
> Since all these surveys are meant to show indications rather than exact
> results (there's no way to say exactly how many birds are present when you
> only spend a proscribed number of minutes at each stop) then perhaps BSC
> (and Cornell and Audubon) is way ahead of us on this?
>
> Cheers;
> Suzanne
>
>
>
>
>
>
> --- On *Wed, 4/17/13, Ronald Arsenault <rongarsenault@gmail.com>* wrote:
>
>
> From: Ronald Arsenault <rongarsenault@gmail.com>
> Subject: Re: [NatureNS] Lapland/Laconia Owl Monitoring Route
> To: naturens@chebucto.ns.ca
> Received: Wednesday, April 17, 2013, 9:10 AM
>
> Hello Patricia,
>
> Very interesting question and one to which I do not know the answer. I
> should also point out that the sentence which prompted your question was my
> interpretation of what Scott had said, so I will attempt to clarify.
> Please note that this is based on a conversation which happened three to
> four years ago.
>
> As I recall, Scott found during his monitoring that owls were less vocal
> when tending nests with eggs or young than was the case during years when
> they did not nest or the nesting was not successful. His concern was that
> the results of the owl survey were being (or would be) interpreted as "more
> calls = more birds", which his monitoring showed was not the case.
>
> At the time, his intent was to discuss his findings with Bird Studies
> Canada to make them aware of his concern. I do not know what eventually
> happened. Perhaps the "silent listening" was implemented as a result?
>
> I do not recall Scott going into detail re owl behaviours that would
> explain this. I would suggest though, that there are a number of factors
> which are likely to affect the calling rate, including the response rate to
> playback, of owls. However, I would not expect complete suppression except
> for cases of severe starvation. Some factors which likely affect the
> calling rate of owls (with or without stimulation by playback) are: timing
> - how far into the nesting season are the owls when the survey is done;
> whether or not the bird is paired - single birds would be more motivated to
> call; prey density - more time needed to catch enough prey = less time for
> calling; distance from nest - the closer the playback to the nest, the
> likelier the response; density of the owl population could even play a
> role; perhaps even the age of the birds could also be a factor - well
> established pair vs first time nesters?. These are just some of the factors
> which come to mind, and of course, these are not necessarily independent of
> each other. Perhaps others (Randy?) can add to or correct the above.
>
> Hope this helps,
>
> Ron
>
>
> On Tue, Apr 16, 2013 at 10:56 PM, P.L. Chalmers <
> plchalmers@ns.sympatico.ca<http://ca.mc1215.mail.yahoo.com/mc/compose?to=plchalmers@ns.sympatico.ca>
> > wrote:
>
> Hi Ron,
>
> ** **This is an interesting observation. But it leaves me with a
> question. Are "owls which have settled down with nesting duties" less
> likely to call AT ALL, or just less likely to respond to a recording? The
> ":silent listening" portion of the survey, which is the first part,
> preceding the broadcast of recorded calls, is considered the most
> significant part of the survey, I believe. {In some parts of the country
> the official survey protocol doesn't use broadcast calls at all.) So are
> owls which are freely calling, i.e. when unprovoked, more likely to be
> unsuccessful breeders than those who remain silent?
>
> ** ** Suzanne Borkowski and I usually detect many of the owls we
> find during those first two minutes of the survey; if they react to the
> broadcast calls later, it gives us more time to confirm distance and
> direction etc.
>
> ** **Cheers,
>
> ** **Patricia L. Chalmers
> ** **Halifax
>
> ** **
>
>
> At 02:16 PM 16/04/2013, you wrote:
>
> Hello Randy,
>
> This may in fact be good news. Scott Makepeace, NB Dept. Nat. Resources
> biologist who monitors owls, told me that his work has re