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by Jim Parry
In college, my Mammalogy professor (How many
of us took a class with that name?) told me that
the range of the opossum expands northward several
miles per decade.
Even though I took the class
quite a while ago, that little piece of information
has left a real impression on me. How remarkable
that some living things are changing their habitats
in our lifetime! Some other examples of this
phenomenon:
- It is likely that there are
more whitetail deer in America now than there
ever have been.
- Armadillos and fire ants
are moving northward as well.
- The Audubon
Society reports say that many kinds of birds — such
as robins and hawks — are migrating later
in the season or even staying through the winter
in some places.
- Ranges of many plants
and trees are changing in our lifetime.
- The
ranges of many birds, for example several species
of warblers, are decreasing.
- There are
examples of changes in the range for many insects,
frogs, reptiles, and more.
Contrary to what you
might expect, I am not about to rant about global
warming. Rather, I want to talk about adaptations
of living things. Isn't it fascinating
that some living things do better, while at the
same time others don't?!? Biology tells
us that adaptations are anatomical or physiological
aspects of a living thing that enable it to live
better. Animals that have very general food or
shelter requirements (adapted to a broader range
of conditions) have a seeming advantage over
those with more specific needs. What is it about
some birds (or any other organism) that makes
them successful generalists, while others are
literally losing ground?
American crows eat all
kinds of things and live nearly everywhere in
the U.S. Their familiar caws often are simply
an annoyance to many. Warblers are insect-eating
birds; some have very specific dietary or shelter
requirements. The snail kite is a bird whose
diet is largely restricted to the apple snail,
both of whom are confined to the Florida Everglades.
Serious birders are very excited to see them!
And what role do humans have in this drama?
Cowbirds eat insects and thrive in civilized
places. Cowbirds also lay their quick-hatching
eggs in the nests of Kirtland's warblers, decreasing the
survival chances of the warbler chicks.
First
of all, here is a marvelous metaphor and lesson
from nature, which tells us something about our
lives among our human peers, I daresay. As we
humans make the natural world more accommodating
to us with parking lots, soccer fields, housing
and general urban sprawl, certain wild things
follow. What shall we think about aggressive
generalists, and the more susceptible specialists?
It also should inspire us to take a closer look
at living things around us to see what else we
can learn. Many camps act as wildlife refuges,
on a small or large scale, and offer easy glimpses
of both crows and warblers. Have their proportions
changed at your camp in your memory?
There is
probably some case to be made about global warming.
Humans change circumstances for other living
things in more direct ways, too. Consider that
there are fewer predators (cougars, wolves) of
deer around now. And opossums, as omnivores and
scavengers, may find food a little easier near
dumpsters and city parks. Crows love to eat corn.
Let us remember that from the point of view
of wildlife, the whole world is the natural world.
To a wild creature, a resource is a resource!
We may not want a cockroach in our cabin, so
we must make it a poor habitat for them there.
Brooms and pesticides are not good habitats for
those bugs!
How about the plants and animals
that thrive in our human world? Dandelions, sparrows,
starlings, crows, seagulls, raccoons, opossums,
mosquitoes. Is our destiny to live in a world
of pigeons and house mice? Will rare wildlife
become rarer?
Are there some generalists that
do not find an advantage? Probably . . . .
So,
we are witnesses to changes occurring in the
natural world during our lifetime. What opportunities
will you have to share these observations with
campers, even casually? We might prepare our
campers to observe more change as they grow up.
Originally published
in the 2008 July/August issue of Camping Magazine.
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