Hi all,
I've been reminded I had posted a query regarding the age/sex of the
Tufted Duck on ID Frontiers, seeking opinions from people with more
experience than most North Americans have. There wasn't a great deal of
response, as only two Europeans chimed in, Samuel Burkhardt of Switzerland
(via Matthew Winks of Illinois) & Lee Evans of the U.K.. Both, however,
said they felt it was a female and since there were no dissenting comments,
it's probably safe to say nobody disagreed with their opinion. Human nature
being what it is, I'm certain dissenters would have posted! In essence,
they said nothing precluded it being a female and at least one thing pointed
away from it being a young bird.
They both felt the bright yellow eye indicated it was an adult
(therefore female), in contrast to Pyle's assertion the eye color indicated
a male. One of them said he'd seen proven females with eyes that bright and
the other said young males should look much more obviously like males by
late January. Both felt the tuft length was within the range of females.
There was also a response from Tony Leukering, who is certainly known to
anyone who reads CoBirds. He was less inclined to say it was a female, but
also didn't necessarily rule it out. I'm somewhat surprised he didn't post
an opinion here. What he had to say was certainly informative.
To be sure I'm not taking anything out of context, and just so eveyone
can see their thoughts, all well stated, I'm going to post the responses of
all three below. I hope this is not in contravention of any etiquette of
either CoBirds or ID Frontiers. If it is considered wrong on CoBirds,
please let me know and I won't do so again. (And please forgive my
transgressions.) All the content is relevant. I'll also enclose the links
to all the photos I know of to refresh everyone's memory. On that note,
there are sure some great photographers in this state!
On a closing note, this is the *second* item I've posted to CoBirds
regarding waterfowl today, and they're not even a group of birds I get very
excited over. Blame it on the bitterly cold weather and high winds that
have made me forgo doing any birding of late!
----- Original Message -----
From: Matthew Winks
To: [email protected]
Sent: Wednesday, January 19, 2011 9:14 AM
Subject: Re: [BIRDWG01] Tufted Duck age/sex question
The following comments are from Samuel Burckhardt who has a lot of
experience with Tufted Ducks in his native Switzerland.
"thanks for the pictures of the Tufted Duck. I am not sure to whom I should
send my comments so I'm sending them to you. Feel free to forward them to
the appropriate people or post them.
The duck is an adult bird, with bright yellow eyes and a warm brown head. If
it were a juvenile, I would expect a duller eye color and a duller shade of
brown. I don't see anything that would go against an adult female. I don't
think the length of the tuft speaks against it, nor does the lack of any
white feathers around the bill. Both seem within the normal range of
variation.
I would expect a first year male to show a darker head color, something
towards a more purple/black sheen. I would also expect something like a
demarkation between the breast feathers and those of the flanks, more in
line with the adult male pattern.
I cannot rule out 1st year male complete, however, I think this bird is an
adult female.
An interesting variation is the white undertail which is not all that
common. Most Tufted Ducks I have seen have dark undertails."
Matthew Winks
Normal, IL
----- Original Message -----
From: Lee G R Evans
To: [email protected]
Sent: Wednesday, January 19, 2011 12:16 PM
Subject: [BIRDWG01] TUFTED DUCK sexing
http://www.pbase.com/hopko/image/131922024
The TUFTED DUCK in this image, as others have stated, is an apparent ADULT
FEMALE - based on the patterning of the bill and the brightness of the eye
colour.
The presence of white on the undertail-coverts is nothing unusual nor of
females with varying degrees of white 'scaup-like' blazeing on the forehead,
just above the bill. We get many such variants here in Britain.
Tufted Ducks are very variable though in appearance, and although
first-winter birds are generally uniformly darker billed (less contrast
between the pale blue upper mandible and the black nail) and much duller in
the eye (brown and then brownish-yellow), some individuals can be
inseparable from adults by December of their first year and it is only the
retained juvenile tertials that can differentiate them
Very best wishes
Lee Evans
----- Original Message -----
From: [email protected]
To: [email protected]
Sent: Thursday, January 20, 2011 10:42 AM
Subject: Re: [BIRDWG01] TUFTED DUCK sexing
Hi all:
The Boulder, Colorado, Tufted Duck and the questioning of its age and sex
has provided a venue to discuss ageing methods (as sex of this bird is
obvious if it can be proven to be an adult) of ducks in general and Aythya
more specifically. While both Europeans from whom we've heard agree with
each other that the bird is an adult female, I thought that I'd pass along
my thinking on the process and provide at least some niggling doubt as to
the bird's age (thus its sex).
Eye color -- As eye color changes in Aythya (and other ducks) from juv to
adult, the feature can be used to age individual birds. However, after late
fall, eye color is only truly reliable on the young end of the spectrum.
So, while the Boulder bird has distinctly bright yellow eyes, that feature
should in no way be considered definitive. Witness the male Lesser Scaup
presented here (http://www.flickr.com/photos/tony_leukering/5373075160/),
which is obviously an immature, yet has a bright yellow eye by 28 December.
Tertials -- While retained juvenal tertials are a good indication of
immaturity, the fact that at least some individuals of most Aythya species
(if not all) replace from one to all three tertials in their pre-formative
molt belies the usefulness of this feature in ageing, very much in the same
vein as eye color: we can determine the ones with juvenal tertials as
youngsters, but not those with all tertials replaced. Additionally, Pyle
(2008) states that Tufted Duck tends to have a fairly extensive
pre-formative and writes that "most males and many females replace 1-3
tert[ial]s and tert[ial] cov[ert]s." If one can be sure that the individual
in question has any adult-like tertials, then the color of such would be
useful in sexing that bird. However, determining in the field whether a
block of unicolored tertials is juvenal or not can be problematic.
Rectrices -- Tail color and wear is just about the single best feature to
age ducks in the field, though even that feature is not always definitive.
I first started research into the age of the Boulder bird because many pix
of the beast suggest that its tail is paler than the upperparts, a feature
typical of worn juvenal tails in ducks. Rachel Hopper sent me one picture
of the Boulder bird that shows the tail well enough to see that the bird
lacks the notches out of the tips of the rectrices that are typical of
juvenal Aythya tail feathers (Pyle 2008, fig. 67, pg. 105). However, it is
not unheard of for immature Aythya to replace all 14 rectrices in the
pre-formative, so, again, this feature is not definitive by itself.
Body plumage -- The Boulder bird seems to exhibit two generations of
feathers on the head, with the presumably newer feathers being darker (the
older, browner feathers seem to be concentrated on the rear and lower
portions of the head). The pictures I've looked at do not have the
resolution to assess the wear of these feathers or even to be certain that
this apparent color difference represents reality, rather than photographic
appearance. In some pictures, there appears to be two generations of flank
feathers, some with creamy fringes, some with pearl-gray fringes.
Obviously, if the bird does have two generations of flank feathers with none
of them white, then it's nearly a slam-dunk for the bird to be a female.
Finally, among the scapulars, there are some with wide pale fringes and
others lacking that distinction. How these might relate to age assessment,
I have no good idea. Someone with more experience with the species than I
have (I've seen two adult males) and/or more knowledge of Aythya plumage
patterns might chime in on this.
With all this, it seems unlikely for the Boulder Tufted Duck to be a male,
as it would have had to be among the minority in each of a large number of
plumage and molt aspects:
-- undertail coverts color,
-- tertial replacement in pre-formative,
-- pre-formative replacement of all rectrices,
-- hormone shift delayed such that the bird did not get white flank feathers
in pre-formative, and (at least)
-- advanced bill-color change with concurrent female-like bill pattern.
However, as I often say, "this is biology" and virtually anything is
possible, including that the Boulder Tufted Duck -- despite all its
female-like characters -- is a young male.
Sincerely,
Tony Leukering
Villas, NJ
http://www.pbase.com/hopko/tufted_duck
www.flickr.com/photos/lochkilpatrick
http://sweatysanderlings.blogspot.com/2011/01/perfect-storm.html
http://brdpics.blogspot.com/2011/01/right-place-at-right-time.html
Cheers,
Rob Parsons
Winnipeg, MB
CANADA
[email protected]
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