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