[mou] Alert: Pomarine Jaeger - LaCrosse, WI

[Dan Jackson]

I apologize for not sending this to the Minnesota lists yesterday.  I
intended to, but got distracted.  I am posting in case anyone is interested
in a bird on the border.  A few of us will be trying to relocate the bird
today.  If we are successful, I will post that sighting on a more timely
basis.

Yesterday's Message:

I went Jaeger hunting (Jaeger Jaegering?) over the lunch hour and was able
to relocate the Jaeger that Fred Lesher found and reported yesterday.  When
I found it, the bird was loafing on Lake Onalaska straight west of the
observation deck at Nelson Park on the north end of French Island in the
area where Fred found it yesterday.  In total, I was able to watch the bird
for nearly 1 1/2 hours.

When I spotted the bird, I tried to call several area birders.  I did reach
Jean Ruhser and she was able to join me.  After she arrived, we were able to
leisurely compare the bird to the Sibley and National Geographic field
guides and we are positive that this bird is in fact a Pomarine Jaeger and
not a Parasitic Jaeger.

The bird is a light morph adult that is close to breeding plumage.  We were
able to get definitive looks at the bird's black cap, bill, wings and tail.
All of the field marks as well as the bird's size and bulk point to an ID of
Pomarine Jaeger.

On this bird, the black cap extends well below the lower mandible of the
bird's bill.  This extension was not as obvious as the mutton chop sideburns
of a Peregrine Falcon but was definitely well below the gape and lower
mandible and gave some of that same appearance when the bird was viewed from
head on.  The bird's bill was two-toned and was relatively heavy - more like
that of a Herring Gull than the more pointed, slender bill of a Parasitic
Jaeger.

Both Jean and I were able to get good looks at the top and bottom of the
bird's wings.  The top of the wings were a uniform dark brown with an
indistinct white crescent at the base of the primary flight feathers.  The
underside of the wings showed a very distinct white crescent at the base of
the primaries and a less distinct white crescent at the base of the first
row of coverts of the primary and secondary flight feathers that connected
to an extended indistinct white line at the margin of the secondaries and
their coverts.  There was also a great deal of other white mottling on the
other coverts toward the leading edge of the underside of the wing.

The bird is all white below from the dark breast band to the under tail
coverts.  According to the Sibley field guide, this is a feature of some
adult male light morph Pomarine Jaegers.

The bird's central tail feathers were not fully developed but did extend at
least 2 inches past the end of the other tail feathers.  These central
feathers were broad and rounded and when the bird flew parallel to our
viewing location showed the 90 degree twist of a Pomarine Jaeger.  They gave
the end of the tail a thick and almost rudder-like look.

I have seen several Parasitic Jaegers at Duluth and Wisconsin Point.  This
bird was much larger and bulkier, with a thicker neck, broader wings, and
more of a pot-bellied look when it was flying.  Although we did not get to
see it in close proximity to a Ring-billed Gull, there were gulls in the
area.  This bird was definitely larger and bulkier than the gulls.  In
general, the bird did not appear as agile in flight as the Parasitic Jaegers
that I have seen.  The wings were much wider and did not have the relatively
thin, pointed aspect of those of a Parasitic Jaeger.

Thanks Fred for alerting us to this great bird.  It gave Jean and I
wonderful looks.  Hopefully, others can share it as well.  Since it is so
early in the fall migration, perhaps it will stick around for awhile.

Good Birding,

Dan Jackson
Chaseburg, Vernon County, Wisconsin
(Near LaCrosse)
http://community.webshots.com/user/danielejackson


-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://moumn.org/pipermail/mou-net_moumn.org/attachments/20070816/2e767934/attachment.html