I am trying to get an "ID" on this bird . The photo is by
John Judge - please respect his copyright.
The "history" is that John Judge took the picture
at Draycote, UK in August of 2003. He labeled it "Arctic Skua".
I put the picture into the BDI online field field guide as an immature
Parasitic Jaeger (based mostly on the photographer's initial ID and
secondly on my references). This ID has been challenged. I have asked
several knowledgeable birders for their input and I have placed their
comments below. The colors separate the remarks from different people.
The comments below are dated in the order I received them.
The authors are (in alphabetical order): Paul Buckley,
Bob
Budliger, Jack Dozier, Björn Johansson, John Judge, J Harry
Kreuger,
Tony Leukering, Todd McGrath, Klaus Olsen, Phil Pickering, Paul Sykes,
Noel Wamer, Cliff Weisse.
See comments (updated
11:00am Sept 26, 2004) below the picture - please send
YOUR thoughts to
<barbolink1@earthlink.net> THANKS
PS On Sept
25, the ID question was sent to Frontiers of Identification
http://birdingonthe.net/mailinglists/FRID.html#1096209814
Please check there for more comments.
copyrighted by John Judge
The comments that started this inquiry:
(Sept 4) There's a photo on
the BDI Feild guide on the Parasitic Jaeger page that I think
is of a light juvenile Long-tailed. It's by John Judge.
Points that I feel suggest Long-tailed include:
-bill structure; short thick bill with gonydeal angle closer to base of
bill than the nail;compare to the other birds
on the page, especially the one below it.
-cold tone of plumage with whitish feather edges
-undertail coverts barred black and white
-flanks barred black and white
-face appears concave in front of bill
and then he added this:
I just realized I didn't explain one point correctly regarding the
possible LT Jaeger on the Parasitic page. The gonydeal angle is
on the basal side of the end of the nail. On Parasitics it is on
the tip side of the end of the nail.
-bill structure; short thick bill with gonydeal angle closer to base of
bill than the nail;compare to the other birds
on the page, especially the one below it.
After sending the picture and the above comments to several
friends, this is what they had to say:
(Sept 13) Juv. Jaegers are really tough. This
bird looks to me like a Parasitic (Arctic Skua in British
parlance). I can't tell you why--it just doesn't have the small-headed,
delicate look of Long-tail, and I think the tips of the primaries
have too much white.
(Sept 22) I don't see much on this bird that
would be out of the range for Parasitic. The bill structure
looks like Parasitic to me. Although the bill is not in complete plan
view in the picture, it looks like the distance from
the proximal to the distal end of the nail is much less than the
distance
from the proximal end to the base of the culmen. Also, the dark
tip of the bill appears to be much less than 45 to 50 percent, as would
be expected in Long-tailed. Other points for Parasitic...
The overall impression of the mantle plumage is dark rusty, not dark
grayish that would indicate Long-tailed and the pale primary tips are
more prominent than I would expect in Long-tailed, which can lack them
entirely. Also, the bird looks to be to be rather bull-necked.
(Sept 22) ...my first impression was LTJA due to
the "whiteness" of the checkered back and the lateral and underneath
striping. The overhang of the hooked top mandible seems stronger
for LTJA in Sibley than that of PAJA, and it seems strongly hooked in
this photo. I'm looking at Sibley and Olsen & Larsson (SKUAS
AND JAEGARS), and I am even more confused. ...since last
night my thought processes are different. (Not that strange,
considering...). I feel it is a Parasitic Jaeger.
The streaking on the nape, the size (hard to judge), and its not so
dainty bill, head shape, not dove-rounded, lead me towards that
choice. I blew up some Internet photos to check it out again, and
came around to this decision. I remain a very uncertain amateur
concerning this family.
(Sept 23 ) Well, I think he was right in the
first place. Looks like a fine juv Parasitic to
me, for any number of reasons: head size and shape; bill size and
shape; light:dark ratio and position of bill color; heavy dorsal
streaks and scaling; overall coarse, contrasty brown color.
Another definitive fieldmark I would like to see but
can't is nicely pointed (Parasitic) vs rounded (Long-tail) central
rectrices, but it really isn't necessary here.
(Sept 23) The bird looks to
me like a light to intermediate morph Parasitic Jaeger (Arctic
Skua). The white tips to the primaries is pretty diagnostic (both LT
and Pom either lack these completely or or they are quite faint). The
bill seems OK for Parasitic, but the angle of the photo makes this hard
to judge. light LT jeagers often look gray rather than brown, and this
looks brown, although not as rusty brown as many Parasitics. The shape
also looks better for Parasitic, a LT jaeger would be slimmer and
slighter. I wouldn't have any trouble calling this a Parasitic, but it
is hard to judge jaegers from
one photo, but I think the primary tips are enough (when combined with
the shape and overall appearance) ot safely ID this bird.
(Sept 24) It's hard to be 100% confident based on
one photo but it definitely looks like a L-t to me. Contra
someone's comment, it does not look bull-necked at all to me. The
shoulders are quite narrow, and the body appears slight and quite
attenuated at
the rear. The head and eye appear too large in proportion to the body
for Parasitic. The overall jizz is like a small gull, while Parasitics
typically look more like fat chickens to me :)
I think I can see the distinctive L-t pinched look to the face in front
of the eyes, but would like a closer photo to feel more confident using
that as a mark. Forehead/bill angle is probably not as flat as
it appears at a glance because the head is turned away from the camera
slightly. Obviously a subjective statement, but to me the jizz of the
head shape and facial expression is all
L-t.
Bill appears quite stubby with black 1/3 or more along the culmen -
great for L-t. I haven't looked much at the nail/gonys
placement that you mention as a mark, will have to try that.
If the nape and neck are really as contrastingly pale as that
area appears that would be better for L-t. Also while parasitics can
have pale barring on the sides and undertail coverts, it's usually not
as clean and stark as it appears on this bird - more typical of
L-t. Cold plumage tones here do look more typical of L-t, although
often not safe to judge that in photos. Does not look
"rusty" at all on my monitor in any case.
Pale fringing to primary tips may be more typical of Parasitic, but L-t
can unquestionably at least show some pale tipping. In fact
the fringing on this bird really isn't that pronounced, probably less
so than you would expect on an average Parasitic. In any case that's
only a supportive mark at best, certainly not definitive either way.
As a side note since it was brought up, I also think the shape of the
central rect tips is a somewhat overrated mark. Perhaps it works for
juv's in fresh plumage in the hand, but in photos and in the field I've
more often than not found it misleading - far from
definitive, even with what I felt were good looks. I suspect it's at
least somewhat variable in both species.
The photographer (John
Judge) wrote this on 9/25/04:
Although we do not get many Skua's
inland at this site I have seen quite a few elsewhere. I first picked
up the bird as it flew in and the size shape and "jizz" of it made me
think it was either an Arctic or Pomarine Skua. Admitidly it does look
like
a very cold colour and I have not seen Arctic's as grey as this. Th
bill
of the bird is mentioned by one birder as short but the angle of the
picture makes this very hard to assume that. About 8 birders managed to
see the
bird before it flew off and all were
happy
with the ID that it was an Arctic. The pale edges to the
primaries point to Arctic and th bird was quite "heavy" as apposed to
the Tern like "jizz" of a Long-tailed. Hope this sheds a bit
more light on it
(Sept 25) Body, head, bill comparison give
the bird the delicate, yet still somewhat proportional look characteristic
of LTJA that at first glace is very similar to a mid-size larid
The feather edgings are very chrisp and light whitish, not buff as in
PAJA
The very neat, clear, crisp black and white barring on the tail coverts
is characteristic of light morph juvenile LTJA
Even on a light juvenile PAJA, the nape should be much more buffy and
streaked...this is good for LTJA
The tips to the primaries are very, almost imperceptibly narrow - very
charactereistic of LTJA
I super-enlarged the bill and the exact measurement of nail is half the
bill (realizing that it is an angled picture), as well as the gonydeal
angle being at about the beginning point (going left to right) of the
nail, or about half way on lower mandible
On Sept 25, the ID question was sent to
Frontiers of Identification
http://birdingonthe.net/mailinglists/FRID.html#1096209814
Please check there for more comments.
(Sept 26) Though identifiying a jaeger from only
one picture is difficult, if I were forced to identify this bird, I
would have to agree ... concerning the ID of the juvenile (not
immature) jaeger and call it a Long-tailed. Though I
realize that the picture was taken in the UK where Parasitic breeds,
the date is highly suggestive of Long-tailed and, in fact, would rule
out all other jaeger species in
the Lower 48, in my experience. I have a few additional comments:
Though the primary tips are nearly diagnostic for Parasitic, they are
not quite absolutely diagnostic -- I have seen one juv Long-tailed
(seen quite well and Klaus Olsen agreeing with the ID from perusing the
photos) with primary tips this broad;
The undertail coverts/vent barring is black and white, not dark brown
and buff as typical of Parasitic -- the coloration is typical of
Long-tailed;
The overall coloration is typical of Long-tailed -- I have never seen a
juvenile Parasitic this cold; and
The bill shape and pattern is that of Long-tailed and appears to me to
be too thick to be that of Parasitic.
(Sept 27) In my opinion (as earlier) the photo
attached is a rather pale juvenile Parasitic (Arctic) Jaeger
(Skua).
The bill structure and its color pattern alone ID's this
individual
(see Sibley 2000, p. 196; Jonsson 1993 Birds of Europe with
North Africa and the Middle East, Princeton Univ. Press, pp. 257,
260-261;
and Mullarney, Svensson, Zetterstrom, & Grant.
1999. Birds of Europe.----a Princeton Univ. Press Field Guide, pp.
166-167). Streaking on nape and head is characteristic of
of juv. Parasitics but
not juv. Long-tailed Jaegers. The bird in the photo is
atipical
of juv. Parasitic in that the feather edges are almost white
rather
than some shade of rusty; the juv. plumage coloration in jaegers
is
notoriously variable.
(Sept 28) Regarding that jaeger, when I first saw
that photo a couple of weeks ago my first reaction was: Why is that a
parsiticus? Compare bill and plumage with this bird in almost identical
angle of which there are other photos confirming ID as longicaudus
http://www.pbase.com/ol_coot/ltjarger_ky
The bill shape and marking is much better for longicaudus than for
parasitcus.
Here is a good view of a typical parasiticus
http://www.illinoisbirds.org/parasitic.jpg
This longicaudus shows pale edges to primaries, (if you look hard
enough)
http://www.scottspangenberg.com/Birds/LTJaeger1.htm
as does this one
http://www.surfbirds.com/media/Photos/ltjaeger.jpg
Finally, colour tones. As with all images and especially digital, many
things must be considered: time of day when photo was taken, low sun
makes
colours reddish, brand of film in camera, ISO setting of film or
camera,
normal, under- or overexporsure, white balance setting if digital
camera, if scanned slide setting of scanner and finally calibration of
computer
monitor.
As if that wasn't enough, here's a photo of a brown toned juvenile
longicaudus
http://www.surfbirds.com/cgi-bin/gallery/display.cgi?gallery=gallery9&start=61
2nd from bottom.
My view: until a photo shows up of that particular bird showing exact
shape of tail including central feathers or the upperside of the
primaries I'd
label it Long-tailed.
ID of jeagers are difficult and can be extremely difficult. There is
overlap in most of the characters for separation and ID must always be
based by
adding up as many characters as possible. If in photos of sitting or
standing
birds not enough are visible they will have to be left unidentified,
unfortunately not many birders today realise this.
For the record I have extensive experience of the three small
Stercorarius, (I saw 5 juv. Long-tailed yesterday)
The ID question
was sent to Frontiers of Identification
http://birdingonthe.net/mailinglists/FRID.html#1096209814
Please check there for more comments however, Klaus
Olsen added the following which will pretty
much end any further discussion: "Thanks for paying my attention to this bird, in my
eyes
a rather typical Long-tailed. I think the problem is, that many tries
to
identify the bird based on sole characters - in field ID as many
characters
as possible should fit each other."
Thanks for your help - Barb <barbolink1@earthlink.net>
This page:
http://home.earthlink.net/~barbolink1/BrdLnks/JaegerPage.html