[Birdnet] Plover pictures

[Rick Fridell]

Hello Everyone,
Outstanding photos by Paul Higgins.  This is an intriguing bird, and at
first look I was almost sold on thinking it's an adult Pacific
Golden-Plover.
However....  Outside of typical breeding or (even non-breeding) plumages,
distinguishing these species should be based on structural / proportional
differences (rather than plumage differences). Therefore, I'm basing the
following on looking at Paul's photos for clues on relative proportions.

The difference in wing-length between the two species has been
well-discussed... American GP has relatively long wings projecting well
beyond the tip of tail and the Pacific GP has proportionally shorter wings,
projecting just past the tip of tail. In addition, American GP has a longer
primary projection with three to four primaries typically visible beyond the
longest tertial. Another key factor in distinguishing these species is the
length of the tertials relative to the tail tip; obviously shorter in
American GP and with tertials of the same length or projecting beyond the
tail in Pacific.

So looking at Paul's photos for these clues, reveals the primaries extending
just beyond the tip of the tail (photos 1,4,5,6 - a point leaning towards
Pacific GP) but the tertials are clearly shorter than the tail (photos
1,4,5,6,7 - a point leaning towards to American GP) ???? (And these
characteristics are supposed to be definitive!). Gauging actual primary
projection is tough from these photos, but looking closely reveals both the
primaries and the tertials to be very WORN. I think feather wear may be
reason for the discrepancy in these characteristics. First check out the
last photo of the obviously very worn primary tips, then check out the
outline of the right wing in Paul's third photo (of the plover with its
wings spread).  The wing outline clearly shows worn feathers, shortening the
tips of the outer primaries, and overall wing length. I believe this feather
wear accounts for the small difference between wing and tail tips, and
artificially (temporarily?) makes this trait appear to favor a Pacific GP.

Of course I haven't actually seen the bird, and perhaps one could argue the
tertials or even the tail are proportionally worn. The tertials do show a
lot of wear, particularly in photos 6 and 7, but even with this wear they
appear clearly shorter than the tail.

As to other structural differences, Pacific GP have a proportionally longer
bill and legs than American GP.  These characteristics are hard to
distinguish on a lone bird, but may be helpful in direct comparisons.  The
long legs of a Pacific GP typically project beyond the tail in flight, so
this may be something to watch for if this bird sticks around.  Also the
call notes of the two species are diagnostic, with a rising second syllable
in Pacific GP (opposite in American).

Very nice descriptions and photos from the Northern Birders. Well done. Keep
the observations and discussions going. You've inspired me to get out of the
house and go birding this afternoon.

Best Regards,

Rick Fridell
Hurricane, UT


-----Original Message-----
From: birdnet-bounces at utahbirds.org
[mailto:birdnet-bounces at utahbirds.org]On Behalf Of Utah Birds
Sent: Monday, September 04, 2006 10:50 AM
To: birdnet at utahbirds.org
Subject: [Birdnet] Plover pictures



Paul Higgin's photos have been posted on the Hotline Photo page along with a
picture of a Pacific Golden Plover taken in Hawaii by Pomera Fronce for
comparison.

Here's the link:
http://utahbirds.org/hotlinephotos/2006/PloverAug2006.htm

P.S.  The webmaster was out of state until last night resulting in the delay
in posting the photos.  Sorry about that.




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