Records Committee/Black-tailed Gull
Rick Blom (rblom@blazie.com)
Sat, 14 Feb 1998 13:07:47 -0500
Bob Mumford wrote, in part:
>Remember the BT Gull at Sandy Point a dozen or so years ago? It was concluded
>that this bird was ship or man assisted, based on the fact that there were few
>records outside the Pacific area. Thus, probability was used as the basis for
>judgement, as it often is.
I was a member of the records committee at the time of the
deliberation and it was somewhat more complicated than this. In fact, at
the time the committee did not conclude that the bird was ship- or
man-assisted. The bird was put in the Unknown Origin category, one created
because of that bird. There was considerable debate about the origin of the
bird, lasting several months. The unknown category was created to satisfy
the conflicting views of the members of the committee. It was not an
out-and-out rejection. Rather, it was an acknowledgement that at the time
of the deliberation we did not know and could not agree. One of the
purposes of the category was to flag records for which additional
information (such as new records) might become available over time and
might clarify the situation. I think, given the paucity of records at the
time, and information suggesting that the bird is not seen far from land in
its normal range, that the choice was a sound one. I do not know if the
category is still used or what other deliberations the committee has made
concerning the record.
>Yet:
> 1. Several BT Gulls have appeared on the East Coast since and
> 2. It is unlikely that a person would keep a gull in captivity (outside a
>zoo) and beyond comprehension that a gull would stay aboard a ship across
>the Pacific,through the Panama Canal and up the Atlantic coast.
Not beyond comprehension. At the time of the deliberations we
searched for evidence of ship assistance related to gulls and seabirds. I
no longer have the precise source, but W.R.P Bourne, the British seabird
expert, has published information on this subject. He noted that it was not
that unusual for crew members on some ships to capture gulls and other
seabirds and cage or tether them as pets for the duration of the journey,
hand feeding them. The birds were invariably released when the boat
appraoched port because of strict importation laws. He felt that this was
the explanation for a concentration of odd seabird records in the English
Channel, especially of Cape Pigeons, a bird not otherwise confirmed to have
occurred naturally north of the Equator at the time. Transit in the other
direction may also occur. Witness a Laughing Gull banded as a local
juvenile in New Jersey and recovered only a few months later in the
Hawaiian Islands. It is difficult to explain that record without invoking
ship assistance.
Although there have been a few additional records, note that most
of them are in the lower Chesapeake Bay region, one of the most important
shipping centers on the East Coast. It is also uncertain precisely how many
different birds were involved. I do not think the evidence is sufficient to
change the view that Black-tailed Gulls here may be ship-assisted. For that
to happen, one would like to see not only more reports, from a wider area,
but reports from sites between the natural range and the East Coast, of
which there are still precious few. Natural vagrancy usually (but not
always) appears as a pattern and no pattern is yet evident for this
species.
>As a person who has 640,000 miles at sea, my belief is that the term "ship
>assisted" is mostly in the minds of conservative birders, not derived from
>experience. Birds simply do not stay aboard ship for more than a few hours or
>a few days at most.
Admittedly, ship-assisted is a handy category for records that
appear otherwise inexplicable, but I am not as confident that it is not
valid. There are numerous published reocrds of birds coming aboard ship and
staying there: Most striking of the recent ones is the flock of 20+
Jackdaws that came aboard a French ore carrier in the English Channel and
did not leave until the boat was in sight of land in North America. Also
note that last year a wagtail came aboard a cruise ship off the Canary
Islands and did not disembark until the boat reached its port of call in
the Caribbean. Additional travelers of note can be found by reading the
back issues of the Sea Swallow, the journal of the Royal Naval Bird
Watching Society (only the British Navy would have its own bird watching
society and its own journal!).
Contrary to Bob's view, I think ship-assistance may be more, rather
than less, common than we recognize. It may not turn out to be the answer,
but it is certainly worth consideration in reviewing some records. It is an
issue relative to the Kelp Gulls in Texas and ought to at least be brought
up in any discussion of Yellow-legged (sp.) Gulls on the East Coast.
The source of Bourne's information may be "Long Distance Vagrancy
in the Petrels" published in 1967 in the Ibis, vol 109, pages 1414-167. It
is fascinating reading for anyone interested in seabirds. I made the
mistake of loaning it to someone half-a-dozen years ago and I cannot
remember who and it was not returned.
Rick
PS - At the time of the Maryland Black-tailed Gull there was only one
record for the West Coast south of Alaska, a bird collected at the naval
docks in San Diego at the time that it was the disembarcation point for
soldiers returning from the Korean War. The California Records committee
treated the bird as ship-assisted, noting other Asian birds found in the
immediate vicinity at the time. I do not know if they have reconsidred that
view.
"Everywhere I go I'm asked if the university stifles writers. My opinion is
that they don't stifle enough of them. There's many a bestseller that could
have been prevented by a good teacher." Flannery O'Connor
Rick Blom
rblom@blazie.com
Bel Air, Maryland