Dark-rumped Petrel


David Vander Pluym
 

Sorry about this third post but I have no idea why the text of the message
isn't being forwarded so here it is (I hope) cut and pasted out of the
e-mail. Once again here is the message that Ryan Shaw asked me to post


David, could you possibly forward this to CALBIRD, Thanks!
Ryan

Greetings everyone, sorry for the delay in details, but after the research
cruise, I did some birding in Arizona and Mexico and just now got back to a
computer.  Here is my write-up on the DR Petrel.


DARK-RUMPED PETREL
Pterodroma phaeopygia

Observer:  Ryan T. Shaw
Location:  Approximately 100 miles west of Point Conception, Santa Barbara
County, California.
34.195 Latitude  122.687 Longitude
Time and Duration:  13:02PST.  on July 25, 2001;  45 second duration.
Weather:  Completely overcast, viewing conditions were great as visibility
was about 10 kilometers.
Wind:  5 knots, from the north
Swell:  2-4 feet.
Optics:  Bausch and Lomb Elite 8x42 binoculars.

While on transect with a heading of 01 degrees, I was seeing very few birds.
A Black-footed Albatross here, some Leach's Storm-Petrels there, but for the
most part, it was a slow day.  Then my eyes perked up when I saw a
pterodroma flying from the north closing in on the bow of the 160 foot
research vessel, New Horizon.  I thought to myself, "Great, my ABA Area
Cook's Petrel"  ( I had seen 2 Cook's Petrels on some previous transects,
but in Mexican and International waters).  Then the size of the bird hit me.
This was not a Cook's Petrel, it was quite a bit larger than the Cook's I
had seen earlier in the week.  I would say almost twice the size.  The bird
was flying with languid arcs, and it was about 30 meters off the bow when it
displayed its ventral side.  Nearly all white underwings and belly with
black on the primary tips and trailing edge.  A black "wrist patch" at the
carpal joint was noted, and it extended to the primary coverts one way, and
a lateral dark line extended into the secondary coverts the other way.  The
bird then banked again, showing me its dorsal surface.  My response to
seeing this was "Holy ****, Dark-rumped Petrel!"  The wings, mantle, rump,
and tail were solid black-brown, as was the head from just abouve the eye,
down the side of the neck giving the bird a partial colar.  I could detect
no contrast at all from the upperparts, besides the contrast of the dark
upperparts and the gleaming white forehead.  The bird's size was comparable
to that of a Sooty Shearwater, though more elegant and graceful looking.
Slim and trim and very long winged.  The bird arced a few more times as it
continued on its course southward.

I do have previous experience with this species, though only on one other
occasion.  Off Kauai, Hawaii on April 1, 2001.  But this sighting I have to
say, was much better, closer, and way more satisfying as it left no doubt in
my mind of possible confusion with other Pterodromas.

Elimination of similar species was easy, as Juan Fernandez Petrel would be
the only one in this region that could possibly be confused with Dark-rump
(and boy did I ever hope to see a JF Petrel on this trip, but luck only goes
so far).  JF Petrel can be eliminated by my bird having solid dark
upperparts, where Juan has a more contrastin and paler dorsal surface, paler
rump, and some individuals have white necks. Also the white forehead is more
extensive in DR Petrel than JF.  As is the partial dark colar.

Sources used was Harrison's SEABIRDS,
Notes written after the sighting while on research station.

Ryan T. Shaw
4670 Barrington Lane SE
Lacey, Washington 98503
rtshaw80@...



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