Concept of critical habitat!


One would look at such as the book, "Placing Nature:
Culture and Landscape Ecology" Edited by Joan Iverson Nassuer.  Island
Press,
Washington, D.C. 1997.  In it William H. Romme has an article
entitled "Creating Pseudo-Rural Landscapes in the Mountain West." 

In this article, Mr. Romme studies the landscape ecology of
La Plata
County
in Colorado.  He had the help of Alan Andrews of the La Plata
County GIS Department.  Jim Garner of the Colorado Division of
Wildlife provided the wildlife data he uses and provides in the book.
He also list many others involved with development in
La Plata County
and others involved with landscape ecology and ecology itself.

He views the critical factor affecting wildlife as the limiting availability of winter forage versus
the relatively abundant summer forage.  He notes that although the
county has a large percentage of winter habitat for deer and elk, that
in reality the animals tend to concentrate in a few areas where forage
production and snow conditions are especially favorable.  These
concentration areas would include river valleys (major) and some
south-facing slopes where snow melts relatively quickly.  Other county
areas also provide habitat for deer and elk during severe winters.
These would be areas where forage is still available during severe
snow depths.  This would include steep south-facing slopes of middle
elevations and semi-desert lower elevations in the south county areas.
Many of these areas produce poor pant growth.  And the deer and elk
tend to feed elsewhere except in severe winters. These areas can
provide the difference between major die offs and the survival of a
large segment of the populations.
Now there is also a category of essential elk habitat which is defined
as the overlap of elk winter concentration areas and severe winter
range.

Charts are provided which give statistics on the total areas of this
needed winter habitat, the percentage of this habitat on private lands
and the percentage of this land which is developed.

For instance
Elk Winter Range - 157,827 public acres, Private - 414,229 acres,
Tribal - 167,707 acres
Elk severe winter range - 24,383 public, 162,720 private, 37,338
Tribal
Elk winter concentration areas - 22,883 public, 61,813 private, 2,907
tribal
Essential Elk habitat - 15,177 public, 47,702 private, 2,907 tribal
Acres occupied by Subdivisions
Elk Winter Range - 62,658 - 8% of 740,795 acres
Elk severe winter range - 28,095 - 13% of 224,460 acres
Elk winter concentration acres  - 14,645 - 17% of 87,580 acres
Essential Elk habitat - 10,598 - 16% of 65,786 acres

The statistics are much the same but more restricted in range, around
the private and critical habitat for deer, duck, black bear and bald
eagle populations.  The article does stress that there is much overlap
of effects by private areas occupied by subdivisions.  This would
include the effects of dogs and cats roaming around the yards.  It
would include fragmentation of habitats depending on how the
subdivisions are arranged.  Such as riding horses around the area can
disrupt wildlife.

Now
Colorado does have emergency winter feeding programs; but as one
can imagine this would not affect much of the other wildlife in the
area besides the deer and elk.  So it is viewed as a severe problem.
If the area is larger than 35 acres in
Colorado, it is exempt from any
usual regulations.  It can and does often disrupt critical habitat!