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More on quail?
- To: Carolina birds <carolinabirds@acpub.duke.edu>
- Subject: More on quail?
- From: Clyde Sorenson <clyde_sorenson@ncsu.edu>
- Date: Fri, 26 Jan 2001 13:31:43 -0500
- Organization: NCSU Dept. of Entomology
- Reply-To: clyde_sorenson@ncsu.edu
- Sender: carolinabirds-owner@acpub.duke.edu
All,
I encountered another piece of intriguing data the other day in my
reading that mighyt contribute to an understanding of quail decline. In
1990 62 % of North Carolina was forested; this compared to approximately
30 % in 1938. In ecology there is a subdiscipline called "island
biogeography," which essentially is the study of the dynamics of
populations of organisms in isolated patches of habitat. Generally, the
larger a patch of a habitat for a population, the more stable and
persistent is that population. Conversely, small populations in isolated
pockets of habitat, no matter how high the quality may be, are very
susceptible to extinction. (Of course, the definition of "large" and
"small" is very species dependent.) This theory is most apparent for
actual islands, isolated by water or other very apparent barriers, but
it also holds for less apparent "islands" like mountain-tops and patches
of grassland in large blocks of woods. Bobwhite quail are relatively
sedentary animals. One of the most significant things to happen to quail
in this state is this; they have gone from inhabiting the "ocean" of
disturbed, agricultural lands that existed in, say, the late 1930s, to
inhabiting, over much of the state, isolated (from a quail's
perspective) islands of habitat today. The few areas where quail
populations are still relatively healthy are also heavily agricultural;
in these areas, populations are not what they used to be due to changes
in how agriculture is done. Harry's observation of lower populations in
apparently good habitat may reflect the isolation of those patches from
other high quality patches which can supply recolonizers following
epsiodes of local extinction.
The bottom line is still this: the quantity and quality of habitat
that prevailed in the quail's heyday is not there.
Take care,
Clyde Sorenson
Clayton and Raleigh, NC
clyde_sorenson@ncsu.edu