Integration of Long-Term Research into a GIS Based Landscape Habitat Model for the Red-Cockaded Woodpecker Page: 2 of 10
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STUDIES IN AVIAN BIOLOGY
knowledge of the Red-cockaded Woodpecker
into a landscape oriented assessment of potential
population growth and timber cutting options.
RESEARCH AND RELATED
MANAGEMENT ACTIONS AT THE
SAVANNAH RIVER SITE
Management activities at the SRS designed to
benefit the Red-cockaded Woodpecker have fo-
cused on improving habitat quality by control-
ling the encroachment of the hardwood midsto-
ry, by installing cavity inserts, and by minimiz-
ing use of Red-cockaded Woodpecker cavities
by southern flying squirrels (Glaucomys volans)
and other cavity users (Gaines et al. 1995). Re-
search has been directed at improving our un-
derstanding of the population status, genetics of
small populations, translocation protocols, for-
aging behavior, home range characteristics, and
the arthropod prey base.
Beginning in 1985, an active midstory control
program has included prescribed burning, com-
mercial thinning, and other mechanical means
that is essential to maintain or create suitable
nesting habitat by minimizing midstory devel-
opment. Without such midstory control, Red-
cockaded Woodpeckers will abandon cavities
once the midstory reaches a certain height or
basal area and the area is no longer characterized
as the open, mature pine forest that the species
prefers (Conner and Rudolph 1989, Costa and
Escano 1989, Hooper et al. 1991, Loeb et al.
1992). Although it is not known why Red-cock-
aded Woodpeckers abandon these clusters, Con-
ner and Rudolph (1991) speculate that the pres-
ence of an extensive hardwood midstory may
increase the number of nest competitors, reduce
the quality of foraging habitat near the nest trees
so that feeding young becomes more difficult, or
be counter to what the bird has become accus-
tomed to through its evolutionary history. The
cavity trees that are occupied by a given group
are referred to as a "cluster," and cavities are
used nightly throughout the year. From 1985-
1996, a total of 2,182 ha (f = 181.8 ha/yr) of
active clusters, inactive clusters, and recruitment
stands (a recruitment stand is an area that does
not contain a Red-cockaded Woodpecker group
but that has been treated for midstory control
and has been fitted with artificial cavities; see
below) at the site were treated with some form
of midstory control (W. Jarvis, pers. comm.). In-
termediate and co-dominant pines in the over-
story were treated mainly with commercial thin-
ning to reduce the remaining pine basal area to
13.8-18.3 m2 per ha. These treatments continue
to be employed as a method to improve foraging
and nesting habitat.
ARTIFICIAL CAVITY INSERTS
Red-cockaded Woodpeckers prefer older, live
pine trees for constructing their cavities (Steirly
1957, Jackson et al. 1979, Conner and
O'Hallaron 1987, Rudolph and Conner 1991).
The limited availability of live pine trees of suf-
ficient age to provide cavity trees was a major
concern in the management of the population, as
it precluded population expansion. After consid-
erable time and effort, an artificial cavity insert
was developed by David Allen at the SRS that
could be installed inside the trunk of younger
pine trees and was accepted by the birds (see
Allen 1991 for details on the design, construc-
tion, and installation). A drilled cavity technique
(Copeyon 1990) was developed, but was not
suitable for use at the SRS because the majority
of available pine trees were too young for this
procedure. Cavity restrictors, consisting of metal
plates that are fitted over the cavity entrances
(Carter et al. 1989), have been effective in pre-
venting other species, especially Red-bellied
(Melanerpes carolinus) and Pileated (Dryocopus
pileatus) woodpeckers, from enlarging cavity
entrances and usurping the cavities. From 1986-
1996, 305 artificial cavities were installed by
Forest Service personnel at the SRS, of which
292 are still usable for roosting and nesting.
Red-cockaded Woodpeckers readily accepted
the artificial cavities and successfully repro-
duced in them.
CONTROL OF SOUTHERN FLYING SQUIRRELS AND
SQUIRREL EXCLUDER DEVICES
Southern flying squirrels are known to use
Red-cockaded Woodpecker cavities extensively
at the Savannah River Site. To minimize the po-
tential adverse effects of squirrel cavity use on
the Red-cockaded Woodpecker population, a
squirrel monitoring program was initiated and
any flying squirrels encountered during the rou-
tine checks were destroyed. Active clusters, in-
active clusters, and recruitment stands were in-
cluded in the squirrel monitoring program.
Cavity inspections varied from a low of 282
in 1986 to a high of 4,594 in 1995 and resulted
in 2,304 southern flying squirrels being removed
and destroyed from artificial cavities, natural
cavities, and nest boxes (Table 1). Most of the
squirrels were taken from artificial cavities
(1,5 11 squirrels from artificial cavities, 652 from
natural cavities, and 141 from nest boxes).
To determine the necessity of continuing the
labor intensive squirrel removal program, an
evaluation was made to assess the possible im-
pact of squirrel removal on Red-cockaded
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Franzreb, K. & Lloyd, F.T. Integration of Long-Term Research into a GIS Based Landscape Habitat Model for the Red-Cockaded Woodpecker, article, October 1, 2000; New Ellenton, South Carolina. (digital.library.unt.edu/ark:/67531/metadc734002/m1/2/: accessed December 18, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.