Hello mystery lovers,
In spite of the obviously poor quality of the images provided, I have had some
very good responses to the second in my series of Mystery Birds.
I think I can say that the bird has been positively identified.
David Harper of Adelaide, South Australia has provided me with a very detailed
response and so with his permission I have reproduced a slightly edited version
of what he said.
---------------
David said:
The bird is obviously a sandpiper of sorts as opposed to a plover or dotterel
etc and it's obviously a member of the genus Calidris, I'm sure we're all agreed
about that. So what do we know about it? Well the photo was taken in January so
we're looking at a bird in non breeding plumage. It's overall background colour
is brown as opposed to grey thus eliminating several members of the genus
Calidris already such as: Great and Red Knot, Sanderling, Curlew Peep,
Red-necked and Little Stint. We can also eliminate Calidrids either not yet, or
not reliably, recorded in Oz such as Semi-p, Western, Temminck's, Least, Purple
or Rock (on the grounds these would have constituted a major twitch and I'm sure
you would have been onto that!) [Bob's note: In spite of a burning desire to
join the 600 club my list of suspects was much less creative than that!] Your
bird also clearly has olivey green legs as opposed to black, further eliminating
Dunlin, Baird's and White-rumped. So what does that leave us with?
And the nominees are (drum roll please)
1. Long-toed Stint
2. Pectoral Sandpiper
3. Sharp-tailed Sandpiper
4. Cox's Sandpiper
[Bob's note: That's more like it.]
So let's look at 'em. Size is difficult to judge when looking at photos of
single birds. Surely you could of had the presence of mind to ask it to
conveniently pose next to a box of matches for you, or better still a ruler!
Seriously the key to this is in the bird's overall proportions and for me the
legs are too long and the wrong colour for Long-toed Stint (LT Stints have
yellowish legs) One down three to go.
What about the beak? A good standard for estimating the length of a bird's bill
in the field is in proportion to the depth of its head, i.e. the depth of the
head is a measure from the base of the bill to the nape. Your bird's bill is
equal in length to the depth of its head. From the photos you can also see the
colour of the bill grading from blackish at the tip to olivey at the base. So
what does this mean? Cox's Sandpiper has a long black bill up to 1.5 times the
depth of the head, a gene character it inherits from it's Curlew Sandpiper
mummy. Note the illustration 201b of Cox's Sandpiper and the brief description
opposite in Hayman et al. is wrong. It's based on a miss identified Pectoral
Sandpiper. [Bob's note: My faith in 'Hayman' has been dealt a sharp blow!] Cox's
bills have never exhibited "sometimes with yellowish base". The head shots of
Cox's, Pec and Sharpie at the bottom left of plate 82 is more like it. Notice
how 201b and 199 are virtually identical! Compare this to the photos of Cox's in
the shorebirds photographic index series and you'll see what I mean.
That leaves a choice of Pec or Sharpie. So what's the difference and how do you
tell them apart? Lots of people struggle with them and there's no shame in that.
But it's not that hard honest! Note the photo of "juvenile Pec Botany Bay" at
the bottom of page 334 in the shorebirds photographic index series is in fact a
Sharpie. See what I mean?
Pecs always have yellowish legs and a yellowish base to the bill, although the
latter character is admittedly variable. The bill is also proportionately longer
than Sharpie by 3-4mm and sometimes longer in adult males. Pecs also have a dark
lore spot. This does not extend beyond the eye helping to make the supercilium
less distinct than that of Sharpie. The breast markings of Pec are also
distinctive. They are composed of dense wavy vertical lines always sharply
demarcated from the clean white feathers of the underparts in any plumage phase.
Pecs crown feathers are not as dark and rufous as Sharpie either, giving them a
less "cappy" appearance. Another distinction is in the shape of the feathers on
the back, wing coverts and mantle. Pecs feathers are rounder and broadly edged
paler brown, Sharpies being more pointed and darker centred.
So bearing all this in mind and carefully analysing the photos, the identity of
mystery bird No 2 can now be revealed.
And the winner is (major drum role please)
Sharp-tailed Sandpiper.
------------------
I have no reason to disagree with anything there but I would like to add a
couple
of notes:
Supercilium:
The bird in the photo appears to display a distinct supercilium that extends and
widens behind the eye.
This is a feature of Sharp-tailed whereas Pectoral has a far less obvious
supercilium that is faint or non-existent behind the eye.
Bill:
The bird in the photo appears to have a bill that is yellow-ish at the base, top
and bottom mandible.
I suggest that this is actually a trick of the light.
Sharp-tailed usually has paler colour (yellow-ish) confined to base of lower
mandible whereas Pectoral bill is often 'bi-coloured' with base of both
mandibles paler.
Cox's probably only ever has all black bill.
Legs:
Although Pectoral is usually a larger bird than Sharp-tailed, Pectoral has
shorter legs.
Other acknowledgements:
I think that Paul Walbridge would like to have made it a Pectoral Sandpiper to
add to my list.
But he wisely decided to stick with the truth.
Linda Cross (cautiously?) suggested Sharp-tailed while pointing out another
feature of that species: the rufous cap which can just be made out (imagined?)
in the photo.
Andy Burton felt quite confident it was a Sharp-tailed Sandpiper.
I'm sure it wasn't just a guess.
Maria Merkling Havens was extremely understanding when I advertised the new
mystery bird but failed to actually display it.
I have returned to taking the tablets, Maria, and I will be allowed out alone in
a couple of weeks.
I have decided not to embarrass anyone who guessed 'wrong'.
Images from other sources:
Once again, although not perfect, the volume 'The Shorebirds of Australia', John
Douglas Pringle, The National Photographic Index Of Australian Wildlife has some
worthwhile photos (but, as David points out, some are wrongly labelled).
The same photo (of Pectoral Sandpiper) that appears on page 333 of that
publication also appears in another Photographic Index publication,
'Encyclopedia of Australian Animals, Birds'. I would place this volume in the
same class as the 'Reader's Digest Complete Book of Australian Birds'; make of
that what you will!
'Reader's Digest Complete Birds' shows a Pectoral Sandpiper from the back!!! And
the main photo of Sharp-tailed is 'interesting'.
'Reader's Digest Photographic Field Guide Birds of Australia' has photos of the
two birds showing the differences in the supercilium.
Really, HANZAB is THE way to go.
Even if you can only afford Volume 3 you will have a very good reference for
waders.
[If anyone does follow my advice and order this volume or any other in the
series, would you please mention my name; maybe I will get a discount on the
future volumes. :-)]
On the Internet: a good image of Pectoral Sandpiper is available at:
http://www4.tpgi.com.au/users/kimbird/photo_gallery.htm
(This is a commercial web-page but I get no concessions for advertising it.
Actually I found out about it following-up a posting to Birding-Aus from Phil
Joy on the
10th Nov 2000, 'The next Best Thing'. Thanks Phil.)
-----------------
So ends Mystery Bird No 2.
Another one is pending but it may be a little while in the making.
In the meantime, keep looking at those BIRDS!
Bob Inglis
Woody point SEQld, Australia.
27 deg 15min S; 153 deg 5 min E
E-mail:
WWW: http://www.powerup.com.au/~inglisrc
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