Hi Folks!
I just have to jump in.
Trumpeter Swans are historical in Maryalnd. In addition to the specimen, I
seem to recall bones collected from Native American trash middens. The two
swans in question are both immatures. It is not at all uncommon for species that
take several years to reach breeding maturity to be south of the normal
breeding range [e.g. almost all immature Black Terns stay way south of the breeding
range]. The non-breeding-age Trumpeter Swans are not out of place for this
Season. They are at the very least second-generation offspring from a
re-established population. There are no subspecies of Trumpeter Swans...so
eastern/western has no meaning in this discussion [unlike the hybrid swarm Peregrines].
The Peregrine Falcons that we all(?) count are not even related to the
subspecies that used to breed in the East. They are a conglomeration of various
subspecies that never bred in Maryland.
The examples of species that were "established" but died out, or have nearly
so [i.e. Crested Mynah, Skylark, Black Frankolin] are all non-native. They
never occured naturally on this continent. Ring-necked Pheaseants in
Maryland...no; in the Dakotas...YES! Then there are European Starling, Rock Doves and
House Sparrows.
The "25 years rule" is apocraphal. There is, and probably should be no
fixed time. I believe Cattle Egrets in North American took less time. Eurasian
Collared Dove [or whatever it is called now] will easily break that record.
House Finches!
The distribution and abundance of species is not constant. Species get
introduced to a new area and survive or fail. Read the Maryland Atlas accounts.
Species adapt: look at breeding of Herring and Great Black-backed Gulls! Oh
where? oh where? have the nesting Laughing Gulls gone?
and finally: IT IS YOUR LIST! Enjoy the birds ,,,,,,
Good Birding!
Jim
Jim Stasz
North Beach MD
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