On Thu, 2006-09-07 at 18:30 -0400, Jim Stasz wrote:
> Hi Folks!
> 
> I just have to jump in.

Jim, I'm glad you responded.  It's always fun to hear the dissenting
opinion!

But first, there are three issues being discussed here.  One is whether
these birds should be counted.  The second is whether they used to
winter in the Chesapeake and by that I mean they were a regular part of
the ecosystem, and the third is whether the introductions were a good
idea.  I could be persuaded about the first two but the introductions
were an unambiguous mistake.

> Trumpeter Swans are historical in Maryland.  In addition to the specimen, I 
> seem to recall bones collected from Native American trash middens.  

Yes, I think we will all agree that if Maryland was birded around 1800
the way it is today, there would be well documented records of Trumpeter
Swans from Maryland.  But they were never common in this area -- just
look at how much trouble we're having coming up with evidence that they
were here.  This is the first I've heard of a specimen and that specimen
does not seem to have been considered evidence of Trumpeter Swans in
Maryland by the records committee.  The contents of trash middens cannot
be trusted because of the extensive trade between nations in those days.
The records committee seems to have accepted the species on at best
"flimsy" grounds.  I'm not saying that's a bad thing since it seems
reasonable they must have at some time passed through the state back
when they were "common" in the East, if indeed they were ever common in
the East.  I looked up the reference in my extensive library and I quote
from the minutes of the records committee's meeting of February 21, 1998

"Harvey Mudd presented the results of his research that provides
descriptive evidence of Trumpeter Swans in Maryland in historical times.
A 1835 account describes the presence of Trumpeter Swans on the Potomac
River 'at the mouth of the Occoquan River ... and for some 30 to 40
miles below.' "

That's it?  That's the best we can do?  The Occoquan is clearly in
Virginia as are a number of spots in the 30 to 40 miles downstream. 

There was discussion of exactly this point the following year.  Today
the SAV is mainly in the coves so the appropriate swan habitat is all in
Virginia.  But evidence was presented that at that time, the river
channel, which is in Maryland, had extensive SAV and was therefore also
good Trumpeter Swan habitat so the swans must have used it.  And even if
they didn't, they were close enough to Maryland that they must have
passed over Maryland at some time. (I paraphrase a little here).

I'm sorry folks; accepting this as evidence of Trumpeter Swans in
Maryland is a little like accepting a record of a Hobby based on two
reports -- one of a bird seen flying south past Cape Henlopen and a
second of a bird flying south past Chincoteague a few days later.  Sure,
we "know" it was here, but can you put it on the state list?

> 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.  

But you seem to be assuming that these introduced Trumpeter Swans are
migratory.  Where's the evidence?  Sure they wander around a bit but
where are the flocks that get up and fly south in the fall?  Where are
the flocks of adults flying north in the spring?  Don't many of the
introduced swans stay up north year round?  I don't know from where the
eggs came but *MANY* western Trumpeter Swans are non-migratory.  They
winter near Yellowstone.  They winter in interior Canada.

Remember the failed attempt from several years ago when they tried to
get these introduced swans to migrate by following light aircraft?  Why
would that have been needed if these birds are naturally migratory?

> They are at the very least second-generation offspring from a 
> re-established population.  

There is *absolutely* *no* *evidence* that the population is
self-sustaining.  It is not uncommon for the population of a species
introduced to a new area to grow wildly at first, then crash and either
disappear or stabilize at a much lower level.  That a couple birds are
breeding means nothing.  I don't understand biology but I think it has
something to do with the environment having to adapt to the new organism
as well as the new organism having to adapt to the environment.  One
such example would be a population that grows rapidly, then goes extinct
along with its host plant.  That doesn't happen to native species but
when you introduce a new species, it can take a very long time to reach
a new equilibrium.

> There are no subspecies of Trumpeter Swans...so 
> eastern/western has no meaning in this discussion [unlike the hybrid swarm Peregrines].

First. I didn't say subspecies.  I said population.  Let me give you a
local example.  The Eastern Bluebirds the breed in Maine winter in
Georgia.  The Eastern Bluebirds that breed in Maryland winter in ....
Maryland.  They are all the same subspecies but which population the
bird comes from sure does matter.  By the way, this is the kind of cool
stuff you learn from bird banding.

Second.  There may be no recognized subspecies of Trumpeter Swans today
and maybe there never were any but we don't know how much genetic
variation there was within Trumpeter Swans back before the great
population crash of the late 1800's.  And even without genetic
variation, we don't know how much difference in behavior there was back
then.

> 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.

Another truly sad story, but let's not go there.

> 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.

I simply don't see the relevance here.  The environment has changed so
much since the 1800's we can hardly claim that they will do fine now
since they did fine back then.

> Then there are European Starling, Rock Doves and House Sparrows.

Yes, these species are doing well, but I don't see how they are
relevant.  They are generalists and don't really fit the species-host
plant example I gave.  The other introduced species that went extinct
fit the example a bit better.  Trumpeter Swans (and Mute Swans) are
arguably intermediate but I claim they are a better fit the species-host
plant model than they are to the generalist model.  These two swans
(unlike Tundras) are strictly marsh critters.  Can the degraded wetlands
of today sustain their large populations?  Without wolves as predators,
will the population of Trumpeter Swans grow without bound until the
wetlands are gone?  If so the Swans will disappear soon afterwards.  And
if so, they cannot be considered established.  Regardless of the
decisions of the Ontario and Michigan records committees.

> 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!

Perhaps.  But you must wait at least until the population stabilizes.
The swan population is still growing.  They are not established.

And House Finches are a rotten example.  The population stayed confined
to a small area and small numbers for a very long time (> 20 years, if I
remember correctly).  Finally, because of the genetic bottleneck, the
population developed large bills.  Large enough to better handle
sunflower seeds.  It was only then that the population exploded.  

> 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 ,,,,,,

On all three of these points, I whole-heartedly agree.  And this is the
last I will say on the subject.

Good birding,

Dave
-- 
David Mozurkewich
Seabrook, PG MD
mozurk at bell atlantic dot net