Thanks and nice to have that extra insight, that the second peak in the
monthly GBS graph has a good basis. This species is one of the few that some
/ several observers in the early years of the GBS had the habit of recording
a H (heard) on the GBS chart, rather than a number. I don't know the origin
of that. It gave me some hints as to comments to make in the text of The GBS
Report. This H stopped with the issue of my clearer instructions with the
version 3 of the chart in 1993. A choice was made that any H went into the
database as 1 unless there was a reason to be a higher number. If they were
calling, it is likely there was more than one, but no way of the person
typing in the data to know. Unfortunately now there is no way to segregate
out the seen counts from the heard counts. Clearly both are included, each
with their own separate set of biases as to observability. Clearly they both
call and move around at different rates at different times of year. Unless
Jerry or others know differently, apart from the time of new young most
years, I would expect the actual number of birds in our area to be fairly
stable through the year.
Philip
-----Original Message-----
From: Geoffrey Dabb
Sent: Monday, 24 February 2014 7:32 AM
To:
Subject: FW: [canberrabirds] Boobooks calling actively
>From Jerry Olsen -
Well, not quite. Yes, there is a spike of autumn calling now, and males can
be quite aggressive with each other, even physically fight. Many females
have left for their winter home range and none we watched participated in
this autumn territoriality, except that some watched. There is a much bigger
pulse in calling around 1 September that peaks maybe in November/December.
The attached is nights heard calling but there is a good graph in Taylor and
COG (1992), the ACT Atlas, that shows calling frequency in cells in the ACT
for Boobooks. It shows a nice peak in November, then a little spike in
March, but autumn isn't the major time of calling no matter how you gather
the data, spring is.
Jerry
PS - Veerman (2002) page 95 has a similar graph for Boobooks, with a peak
Oct to Dec, then a smaller spike in March. This data seems to link more to
calling than sightings because main sightings would be are around January
when broods are out.
jerry
-----Original Message-----
From: Stuart Rae
Sent: Sunday, 23 February 2014 1:40 PM
To: Denis Wilson
Cc: COG bird discussions
Subject: Boobooks calling actively
Hi Denis,
Sedentary owl species such as tawny owl, typically sort out their
territorial boundaries post breeding season, during the dispersal period of
the young birds of the year. Peak calling is actually during this time,
which is generally autumn. They do call again at onset of nesting but much
less. So as various local birds here are now in their autumn/winter mixed
flocks, the magpies are singing and the wattle-birds are making their
autumn/winter calls, I would regard your owl calling as part of autumn
territorial behaviour. I have heard them calling at this time before, I
heard one the other night, and thought nothing of it as it seemed normal,
familiar owl behaviour to me. Many species sort out their territories then,
even if they leave for winter quarters and come back they still have
dominance in spring. And any that can will remain throughout for as far as
territories are concerned, the holder usually has the advantage over
intruders.
We need to get out at night more.
Stuart
On 23 February 2014 09:29, Denis Wilson <> wrote:
> I live on the edge of the village of Robertson, surrounded by mostly
> cleared farmland, with Rainforest remnants around.
> Boobooks are not uncommon. I hear the occasional call, and would not
> normally comment upon it.
>
> However, last night, in light misting rain, at 10:30 PM a Boobook was
> calling actively. That was unusual.
>
> I wondered if this is possible breeding season activity?. It seemed
> early in the season, (to my ears).
>
> Denis Wilson
>
> Are you amongst Greg Hunt's "increasingly hysterical environmental
> activists"?
> If not, why not?
> The Great Barrier Reef decision of 31 January 2014 is a travesty.
>
> "The Nature of Robertson"
> www.peonyden.blogspot.com.au
--
Stuart Rae
http://sites.stuartrae.com/
http://stuartrae.blogspot.com/
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