I'd like to respond to Karen's comment, "One final opinion -- we talk so
much about the "native" species. How
many of us are native species to this area or to this continent."

Homo sapiens is native all over the world. From its presumed origin in east
Africa, our species has developed its geographic distribution on its
own--exactly as all species do. Species expand or retreat from the edges of
their range as a normal process. We had a period during which we spread
rather slowly around the world (over generations people walked from Siberia
to Tierra del Fuego, for example) and a long time of some geographic
isolation during which distinct genetic populations differentiated. At some
later period some of these semi-isolated populations developed ways (mostly
boats) by which they could again expand their range at a rather rapid rate.

Not surprising and probably not even noteworthy except that some (all?) of
those populations attempted to decimate, dominate, and/or dally with others
the range of which they entered, thus having some pretty profound effects
on history. But I emphasize that this was an entirely natural phenomenon,
just as the Mallard is reducing the numbers of some of its close relatives
in the world by genetic swamping as well as competition as it spreads.
Europeans were not any more evil than any other humans when they started
their expansion around the world a few centuries ago. If North Americans
or Africans or Australians had had the means, I think they would have done
exactly the same, although I suppose it's possible that more aggressive and
warlike populations were more likely to set out on voyages of discovery and
conquest.

In any case, it does no one any good to dwell on "native" vs. "non-native"
Americans. It may be politically correct to brand Europeans as non-native,
but it is biologically incorrect, as the Europeans who came here *on their
own* (sure, helped by boats) are entirely native by any criteria we have
for the spread of animal and plant populations. If one wanted to make a
distinction one might speak of "original" and "later-arriving" Americans or
Haitians or New Zealanders. I suspect there hasn't been a time since
humans evolved that "later arrivers" weren't on their way. For the most
part we aren't carried around; we choose to move from place to place, but
only in relatively recent times have we had the werewithal to move very far
very fast. It's a normal part of human behavior to jump in a plane and
move to the antipodes.

Now, as far as opossums in the Northwest, this is not a range expansion; I
don't think this tropical species would have ever made it here on its own
(except, of course, long ago when it was more tropical here). We brought
them here to hunt them, a purposeful introduction by our species that was
not by any means inevitable. Similar things could be said about other
non-native species, such as eastern gray squirrels that would never have
made it across the Rockies on their own. There are the possum-types that
we brought in to release in the woods, the squirrel-types that we brought
in to release in the cities, and the cat-types that every day we release in
our yards. When these sorts of things are done, there usually has been
little thought to the consequences. Like it or not, we are the stewards of
the earth, and only if we think a lot more clearly about what we are doing
than we have in the past is there any hope for it/us.

Dennis Paulson, Director phone: (206) 756-3798
Slater Museum of Natural History fax: (206) 756-3352
University of Puget Sound e-mail: dpaulson at ups.edu
Tacoma, WA 98416


-----------------------------

I agree, but I guess I still just think that all the problems in the
environment, including starlings and house sparrows, were due to man's meddling.
Stewards of the earth -- yes. And that entails a great responsibility to her
but I have to believe that until we learn to respect all of her creatures and
their right to live, mankind has no hope.


Dennis, I appreciate your thoughtful and thought-provoking answers to my
sometimes weird comments. Thank you.
Karen