John Pogacnik's post about finding hybrids, a male hooded merganser X
common goldeneye and herring X great black-backed gulls, at Lorain
yesterday stirred some speculative thoughts.
        A drake of the first cross was also reported at Medusa Marsh 11 March,
and another at Castalia Pond 16 Feb. Same bird, or different ones? I'm
guessing different ones. When these two species pulled off a mutual
nest, there would have been enough eggs to produce three drakes, and
they may have associated at least loosely in migration. The fact that
the three sightings were separated by more than a month argues further
for different parents. These species are thought to be closely related,
being separated only by Barrow's goldeneye and smew in the world
checklist, making them good candidates for hybridization.
        The gull hybrid has been increasingly noted in the Great Lakes over the
past few years, with a lot of sightings in NE Ohio. The two John noticed
could have been a product of one or more local nests, as we have records
of all age classes, and individuals of these two species have been
witnessed doing some possible courting in Cleveland. No proof yet. Great
black-backed gulls have established only a tiny toehold as breeders in
our neck of the woods, with no Ohio nesting pairs known, but the numbers
of adults seen here in summer are growing.  If it's true that pollution
has thus far prevented this top-of-the-food-chain predator from
expanding its nesting range this far west, then abatements, even local
or temporary, in contamination might permit successful nesting, and
maybe mixed pairs would have an advantage of some kind.
        As the glaciers retreated, gulls moved north and ended up colonizing
niches across the Arctic, probably evolving apart in appearance and
behavior and achieving full species status insofar as they remained
isolated. Some have speculated that garbage dumps and landfills have
encouraged gulls to overlap their ranges, serving to stir the gene pool
somewhat. As our garbage piles higher and the Arctic ice melts, perhaps
more and more gulls of mixed ancestry will blur species lines, and our
larger gulls will take the lumpy road back toward the single species
that may have spawned them all!
Bill Whan
Columbus

______________________________________________________________________

Ohio-birds mailing list, a service of the Ohio Ornithological Society.
Our thanks to Miami University for hosting this mailing list.
Additional discussions can be found in our forums, at www.ohiobirds.org/forum/.

You can join or leave the list, or change your options, at:
http://listserv.muohio.edu/scripts/wa.exe?LIST=OHIO-BIRDS
Send questions or comments about the list to: [log in to unmask]