Spent nearly an hour this morning watching what I
presume was the SIPO you saw the other day. Very short legs compared to the
other Oystercatchers it was with. As you observed, it was aggressive towards the
immature OZPOs, eventually chasing them off the sandbar.
After 45 minutes the bird spread its wings for me,
but the wingbar did not reach the edge of the wing, looking just like the OZPO's
wingbar. This was noted again when the bird flew off shortly after.
Other features noted were shorter, not longer,
bill; less prominent, not more obvious, white notch at shoulder; black on breast
came down at least as far, not less, than the OZPO; white on back looked
very similar to pattern on the OZPO (but I didn't get a great view of
this).
This bird was also slightly smaller and its
wingtips were equal in length to the tail, whereas on the OZPO present the
wingtips fell slightly short of the tail tip (don't know if this last point is
significant).
I didn't see the underwing pattern.
I think this bird I saw today needs further
investigation. It seems to lack important features of the SIPO, but the legs are
too short to overlook. Richard Baxter suggested it may be an OZPO/SIPO
hybrid. I've looked in Hayman et al and I can't see it being something
other than an OZPO or SIPO. Variable Oystercatcher doesn't fit nor does
American. Next closest was the Chatham Is. Oc, but that seems very
remote.
I did only see 4 birds, 2 A+2Imm, so it could be
that this is not the bird you saw. I think it is the bird I saw some time ago,
at which time I noted the same wingbar as today. I also saw that bird's
underwing, which looked the same as an OZPO.
Regards,
