Selective preservation of species
cmbb at sk.sympatico.ca
Sat Apr 27 15:42:02 EDT 2002
I deleted inadvertently your last post with copy to leplist. If my memory
serves me correctly, the question that you posed was should we try to stop a
species from disappearing if it appears to be at the end of its evolutionary
I do not know if that is an issue that we could realistically deal with.
Ideally, we should strive to ensure habitat for all that is out there.
In my area of the world little is known about what has actually happened to
most native butterfly and moth species. Not enough folks out there looking.
This area has been designated for butterflying as the "Weyburn Degree
Square." Its boundaries are latitude 49 to 50, longitude 103 to 104. An
arbitrary penciling of a map which for the most part reflects a homogeneous
27 butterflies species have been collected here. It is expected that
another 64 are also found in this region.
Since agricultural settlement there has been some interesting ebbs and
flows. Plains grizzlies and wolves were wiped out. The swift fox which was
also extirpated has been reintroduced and is holding its own. The habitat
change brought on by earlier agricultural practices has favoured
white-tailed deer and red fox. The destruction of the plains wolf has
eliminated the coyote's main competitor. Coyote numbers have increased
because they are no longer killed by wolves.
The treeing of the prairies - in this area - has brought in new settlers:
Red-tailed hawk, great-horned owl, merlin, raccoon and the fox squirrel.
As well, even more recently, mule deer are expanding their range. And there
is a chance that pronghorn antelope are returning.
The greater prairie chicken is an interesting footnote. With settlement, it
expanded into Saskatchewan. However, with continued clearly of brush for
farming the new environment that initially suited this bird was cut down and
the greater prairie chicken has receded back across the American border.
Northern boreal chorus frogs, at times, are ever present. Leopard frogs are
now few and far between.
How many of these observations are reflective of what is happening to
lepidoptera may only serve as tangential model. What matters is the
conditions of larval and food plants.
It is assumed that grassland skippers are in decline. On the other hand,
those species that have adapted to alfalfa and clover must be expanding in
number and location as these introduced fodder crops self-broadcast.
greetings from: Weyburn, SK., Canada.
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