Hi Philip,
I thought that might be the case. I guess
you take the optimistic view whilst I take the pessimistic view. Just because
there is more information about does not necessarily mean that correct identifications
will follow. In fact I wonder if the improved identification books may lead to
a greater number of ‘new’ bird observers which may well increase
the chances of misidentification. I appreciate your experience in the field
but I do not agree that it is easy to identify the Whistling Kite from the
Little Eagle and, assuming the proportion of ‘new’ bird observers
has increased, there is an increased probability of getting the identification
wrong.
All of this of course is pretty academic
except for the problem that we now have with the suggestion that the Little Eagle
be nominated as threatened species within the ACT. It will be interesting to
see what the data shows but I would not be surprised if it shows an increase.
We then have a problem to decide whether to include that data set in the
nomination. In fact even if it shows a decline it should not be used if we
have good reasons to think a large proportion of the observations are dodgy---
hence back to our problem!
I agree with Jerry that in the case of
this particular species the only data that can be used for the nomination is
the decline in breeding.
Chris Davey
-----Original Message-----
From: Philip Veerman
[
Sent: Thursday, 20 July 2006 2:37
PM
To: Chris Davey; 'Canberrabirds'
Subject: [canberrabirds] Little
eagles; a query for Philip V
Fair question. I guess it depends on
the meaning applied to the word "should". As in, does it have
tones of morality? Not really. In my use it suggests my estimate of
likelihood. It comes from a point I raised in my GBS report so it relates to
trends since 1981. Back in 1981 there was only one good generally available
field guide that included raptors. That was Slater's volume 1. Even so, many
people then would only have had Cayley's "What bird is that" (because
for decades that was the bird book of choice). So the information to help
observers wasn't so available. Now there are several good books. I think that
having more than one reference helps in identifying a bird, if it is not one
that the observer knows well. The range and choice of books has increased
progressively over the years. Also I suggest most COGites own at least two,
which helps a lot. Whilst given a good view, identification of Little Eagles
from other similar sized brown raptors is easy. On poor views it could be
described as not easy and sometimes just not possible. Also COG has run a
couple raptor id workshops over that time. It might help to copy here
the earlier messages from Jerry Olsen and Stephen Debus (author of one field
guide to raptors book) as well as my earlier message on the subject (that I had
forgotten about yesterday, so repeated my self a bit - sorry, it is not for the
first time). I hope they don't mind, I wouldn't think so.
I don't agree with Jerry's comment
below that "we need a photo, video, or a repeated visit
where we see the bird again to say with certainty what it was." It is just
my opinion and you can make your own, that Jerry was being overly pessimistic
in the abilities of people and I guess this attitude was carried forward
into his CBN article. Obviously I did not like that this seemed to extend
into a criticism of the GBS data (which just provided the information), within
a publication of COG's. I thought that the connection between the two sets of
data could have been better explored. Maybe Jerry is (obviously not talking
about himself) but dealing a lot with students, some of which may have good
academic levels but take on a bird project, never having had any interest in or
experience in bird observing and identification. For example, I am reminded of
Christine Cantor who did a project on W-w Choughs that I produced for
appearance in CBN in 1988. She did a quite good little study of the family of
birds on her family's property but I sat with her at the UC campus one lunch
time and explained to her that Magpie-larks were not young Magpies.
I am confident of my ability to
identify these birds and I am sure many other COGites are, too. I am also wise
enough to realise that there are some circumstances in which case the
conditions were not good enough to be sure of the id and that some remain as
unidentified. I trust most COG people to do the same. Maybe Jerry has a
different perception of COG people than I do.
Thanks Phillip
The thing about certainty in identification of these raptors is validation,
I mean, we need a photo, video, or a repeated visit where we see the bird
again to say with certainty what it was. For example, I would not have
published the plover paper in AFO 22: 1 2005 without photographs. It would
be pointless. Stephen and I are currently discussing a series of falcon
photos from Ashmore Reef, a discussion we could not have without photos or a
body. We can¹t validate sightings by saying people should know what they
look like, people often report back descriptions from books.
Secondly, I looked hardest for Little Eagles in the 2005 season, and found
ACT Whistling Kites and ACT Little Eagles in about the same numbers, but
found two successful ACT Whistling kite nests, and no successful Little
Eagle nests. The even numbers off Whistling Kites and Little Eagles should
show up in your 2005 data.
Thirdly, I am constantly chasing reports, so I have a measure of validation
for people¹s sightings. I go out and try to locate the eagle, kite, falcon
reported, preferably with the person who reports it. Many Brown Falcons,
Brown Gos, Whistling Kites, Little Eagles and Wedgies are misidentified. No
good saying they should not be.
Lastly, the ACT Whistling Kite on the cover of AFO Vol 22, 3, 2005 is easy
to identify because you can sit and stare at it, but would not be easy if
you saw it in the distance, had a short glimpse in bad light. The ACT birds
we watch have no windows in the wings as such, so it is not helpful when
guides use this characteristic to separate them in the ACT.
Anyway, I hope you are correct about people not confusing these species. It
will lead to new pairs in 2006 I have missed.
Regards
Jerry
Message from Stephen Debus:
Hi Philip,
I take your points, and I think I queried Jerry's point about
misidentification, but he gave me some examples and I could certainly quote
some of my own. I have to agree with him that sometimes people do
misidentify raptors, though the better/more experienced birders are pretty good
these days.
Why not put your response in the next CBN? I think you should, because
the ACT Little Eagle issue needs more discussion.
Cheers,
Stephen
At 03:58 PM 6/03/2006, you wrote:
An interesting article in the CBN just
out CBN 30(4)141-145, about Little Eagle decline, provides evidence of reduced
breeding by the species locally. That may well be so and I would not doubt it.
It is concerning. However it mentions a comparison with GBS data that
supposedly doesn't support the same conclusion. I hasten to point out that they
are measuring different things. Reported abundance, as surveyed in the GBS, can
increase when suburbs encroach on or come closer to former nesting sites of the
species. The species can still be present in the area but suffer reduced
breeding. Indeed if they are spending less time at a nest, then they may well
be spending more time flying over the suburbs and so be seen more often by GBS
observers. So I don't see the results as conflicting at all. Indeed I suggest
that is what has happened. For a species that may live for many years, there
will easily be a delayed effect in breeding but not in presence. It is
disappointing to see the GBS data mentioned as data not in harmony, when this
approach was not at all necessary without explaining how the two sets of
information fit together. Besides the GBS Report only summarised what the data
shows.
As for the suggestion of misidentification, I don't agree at all. It can be
argued that almost any bird in any survey can be misidentified but that is
hardly helpful. In practise it is hard to confuse a Little Eagle for anything
else locally, apart from a Whistling Kite and Black Kite. People would not
record an ID on the GBS of something as different as the other species
mentioned, if they are that unsure. The culture of the GBS has always been to
be confident of the accuracy of your ID. In any case, it is obvious from the
figures given in the report that the numbers of GBS observations of the
Whistling Kites and Black Kites are so low, that even if every single Whistling
Kite and Black Kite GBS record in the history of the GBS was in fact a Little
Eagle (or indeed real Whistling Kites and Black Kites recorded as Little
Eagles), then the quantitative difference would be so low it would barely
impact on the statistics for the much more common Little Eagle. Besides the
misidentification issue only arises on assessing trends, if relative rates of
misidentification have changed over the years, (in particular in this case increased).
I doubt it. With the increased number and availability of several good field
guides and things like the couple of Raptor ID workshops that COG has run over
the years (to which Jerry Olsen, myself and others contributed), identification
accuracy rates should have improved since 1981, not decreased. This is another
factor consistent with the slight suggestion of increased status for the Little
Eagle in the GBS (more people able to identify them). However it is not at all
inconsistent with a reduced breeding status of the species. Fair opinion that
in the long term that is what is important.
Philip
|
Admin
The University of NSW School of Computer and Engineering
takes no responsibility for the contents of this archive. It is purely
a compilation of material sent by many people to the Canberra Ornithologists Group mailing list. It has not been checked for accuracy nor its content verified in any way.
If you wish to get material removed from the archive or
have other queries about the list contact David McDonald, list manager, phone (02) 6231 8904 or email
.
If you can not contact David McDonald e-mail
Andrew Taylor at this address:
andrewt@cse.unsw.EDU.AU
|
