Hi all,
Judith L-A's kind comments about my email to her on how I would approach the
task of deciding
between Black or Brown falcon appear to have generated some interest.
I didn't post that info to Birding-Aus for personal reasons (I would rather not
explain that) but I
have now decided to do so.
Please note that the following are my own personal opinions and ideas on this
subject.
These concepts have been developed from my own experiences and research.
Other people may have differing views and opinions which is their right and I
respect that.
I present this information in the genuine interest of hoping to provide
assistance to those birders
who may be having difficulty with such identification.
---------Start------
It is my opinion that identifying Black Falcon in flight is not as easy as some
may think.
Admittedly I say that from the position of having seen and positively
identifying Black Falcon
only twice, both times in far south west Qld.
BROWN FALCON plumage is enormously variable, from very pale to very dark with
rufous in between.
The pale phase can be similar to Grey Falcon (but without the G F's long
trousers, see below) and
the dark
phase can be almost as dark as Black Falcon.
In spite of the intentions of the producers of HANZAB the illustrations in that
publication do not
cover all of the Brown Falcon plumages. I believe the lightest possible plumage
phase has not been
depicted.
Similarly, the field guides have a limited range of plumage examples and the
colours in the
illustrations can not be trusted.
I believe the best way to confirm the identification of Black Falcon is the
method you appear to be
using, the flight characteristics.
Additionally note the noticeably long, pointed and very 'falcon-like' wings
compared to the shorter
and less pointed wings of the Brown Falcon.
Black Falcon has a most peculiar flight characteristic which it may not always
display.
It may be necessary to observe the potential Black Falcon in flight for some
time to be sure.
I don't think the Black Falcon hovers but it has a wing-beat style at times
which could be an
attempt to hover.
At times during flight the Black Falcon adopts a very rapid but shallow
wing-beat which is more like
a 'flutter' than a full, heavy beat.
The Brown falcon never does that but always has a deep, heavy wing-beat action.
This 'fluttering' action of the Black falcon is most peculiar and obvious and
is unique to that
species.
I had read about it before I observed it but I was absolutely amazed when I saw
it the first time.
To tell the truth, it was one of those 'birding moments' I cherish.
When identifying BOPs it is always advisable to observe the length of the
'trousers', i.e., how
much of the leg (particularly the tarsus) is exposed when the bird is perched.
Brown Falcons have short trousers exposing the full tarsus while Black and Grey
Falcons have long
trousers covering most of the tarsus. This is always the case regardless of
plumage phase or morph.
Hope that helps.
Do you have the abridged version of the HANZAB section of the birds of prey
published as "The Birds
of Prey of Australia, A Field Guide" (Stephen Debus 1998, Oxford University
Press in association
with Birds Australia)?
It contains the gist of the HANZAB text and the HANZAB illustrations in reduced
size, 21.5 cm x 13.5
cm.
---------End--------
A comment was made by one birder having this ID dilemma:
".....and of course I was keen to decide on Black Falcon!"
I suspect that happens quite often, and not just with Black Falcons.
I definitely had the same experience when I sighted a 'Grey Falcon' in far NW
Qld a few years ago.
Fortunately (?) I took some photos which revealed that the bird was a very
pale-phase Brown Falcon.
(The trousers clinched it.)
The field guides did not show that particular plumage type and nor does HANZAB.
I still have to find a Grey Falcon!! (I am sure they don't really exist but are
simple figments of
some peoples' imaginations!!)
Cheers
Bob Inglis
Woody Point
Queensland
Australia
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