Black-tailed gull records
John O'Brien (johnobri@uic.edu)
Thu, 19 Feb 1998 10:07:07 -0600 (CST)
In response to Rick Blom's post regarding Black-tailed Gull
records, I can offer the following information:
1) The California records committee re-examined and accepted the
November 1954 San Diego record of a Black-tailed Gull in 1995,
based on an emerging pattern of vagrancy (Heindel and Patten, 1996,
Western Birds 27(1): 1-29). The July, 1984 Maryland record was
cited in this decision, though the Virginia, Rhode Island, and Nova
Scotia records had not occurred at the time of those deliberations.
Also cited were a number of Alaska records, one in Manitoba, and
records from Thailand and Australia.
2) Australia records (as of several years ago when I last looked at
this issue) include a bird in Darwin and one near Melbourne. The
latter is in southern Australia, approximately 60 degrees of
lattitude south of the normal wintering range of the species.
3) The most recent issue of Western Birds contains an article by
Kimball Garrett and Kathy Molina about a Black-tailed Gull they
observed at El Golfo de Santa Clara, Sonora, in June 1997
(WB 29(1): 49-54, 1998). This town is at the very northern end of the
Gulf of California. The authors cite probably all North American
records including 11 Alaska records (5 from southeastern Alaska),
a British Columbia record and a Belize record. They also
question the Manitoba record, saying the description did not
safely eliminate the Band-tailed Gull complex (Belcher's and
Olrog's Gulls).
While it is possible that all of these records refer to ship
assisted birds, the general consensus is that they do not. It
is relatively easy to argue that records along the Pacific rim
involve true vagrants and that those that make it to the
Atlantic must be assisted somehow. I can't pretend to know
the answer, but I would point out that records in southern
Australia and Gambell Is. Alaska suggest that the birds are
capable of coming pretty close to waterways that skirt around
the major continental barriers. Likewise, records on both sides
of Central America (forgive me for including Mexico in this
designation) suggest that they may be willing to fly over land.
John O'Brien