Dave,

You have strayed farther from the point than these swans have from home. The 
point IS, these birds have been re-introduced into thier form range(in 
CANADA!), and if they are now considered re-established, then they should be 
countable.

Hans



Hans Holbrook

Baltimore, MD




>From: David Mozurkewich <>
>Reply-To: David Mozurkewich <>
>To: 
>Subject: Re: [MDOSPREY] Trumpeter Swan "countability" (was: Schoolhouse 
>Pond condition...
>Date: Thu, 7 Sep 2006 22:55:32 -0400
>
>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

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