The red-cockaded woodpecker (Picoides borealis) has been listed as an endangered species
since October, 1970. This species inhabits pine forests in the southeastern United
States where the majority of prime timberland is privately owned. Private ownership of
preferred habitat and historically destructive silvicultural practices create unique
problems for federal wildlife managers. This report analyzes three management techniques
being used to assess and augment red-cockaded woodpecker populations on federal lands in
the region, primarily military installations. Seeking cooperation between diverse
government agencies, wildlife managers attempt to accurately assess species abundance,
alter woodpecker nesting cavities, and construct nest sites in an effort to enhance
red-cockaded woodpecker habitat on limited federal holdings in the American southeast.
Key words: Picoides borealis, Global Positioning System, Geographic Information System,
cavity trees, cavity restrictors
The red-cockaded woodpecker (Picoides borealis) is an endangered species that inhabits
pine forests in an historical range from Texas to the Atlantic coast (Jackson, 1986;
Reed et al., 1988). Picoides borealis nest in clans or family groups that usually
consist of one breeding pair and 2 non-breeding male helpers (Jackson, 1986 ). This
group establishes and defends a territory that includes foraging habitat and nesting
"cavity trees" (Copeyon et al., 1991; Jackson et al., 1986; Rossell and Gorsira,
1996). Red-cockaded woodpecker clans excavate cavities in living pines, and have
established a living and foraging routine in conjunction with the southeastern pine
forests and the historical occurrence of fire, which reduces hardwood understory while
sparing fire-resistant pines (Jackson, 1986). Much of the prime nesting and foraging
habitat for this species has been systematically eliminated due to development, timber
harvest and intensive fire suppression (Jackson, 1986). The emergence of dense hardwood
understory and midstory as a result of fire suppression in red-cockaded woodpecker
habitat has resulted in the abandonment of many otherwise undisturbed areas (Jackson,
1986; Kelly et al., 1993).
The red-cockaded woodpecker has been listed as endangered since 1970 (Federal Register,
1970 as cited by Ertep and Lee, 1994). Four requirements for sustained red-cockaded
woodpecker populations that are lacking in the species historical range are identified as
critical to species stabilization and recovery: 1.) Open pine forests with shade
tolerant understory controlled by cyclical fire seasons; 2.) Old growth Pinus palustrus
aged > 95 years and Pinus taeda aged > 75 years; 3.) Approximately 200 acres for nesting
group or clan; 4.) Multiple clans per area to maintain genetic stability and variability
(Jackson, 1986). The opportunity to establish or preserve these habitat qualities on
private timberland is largely lost due to historical harvest practices and development,
and research on expanding populations on federal holdings is the most vital component in
red-cockaded woodpecker stabilization and recovery (Jackson et al., 1979a; Jackson,
1986).
Exacerbating the problem of habitat loss due to encroachment and fire-suppression are
natural hazards such as hurricanes, pine-beetle infestations and usurpation of
red-cockaded woodpecker cavities by other species (Carter et al., 1989; Rossell and
Gorsira, 1996). Effects of historically natural hazards are multiplied in the context
of a diminished species abundance (Carter et al., 1989; Jackson, 1986).
Land management for wildlife is subject to unique difficulties in the Southeast, as the
majority of forested land is privately owned (Jackson, 1986). In western states,
approximately 2/3 of undeveloped land is federally administered, making the enactment of
widespread management policies feasible, and controversies are apt to center around
questions of access and use, rather than the more difficult problems concerned with
private property rights.
MATERIALS AND METHODS
This report will focus on the current techniques being explored and enacted to stabilize
and increase red-cockaded woodpecker populations on federal lands throughout its previous
range. Three areas of concern regarding the red-cockaded woodpecker populations on
federal lands interact to define current management practices (Jackson, 1986). Wildlife
biologists, foresters, and the military have tested and combined specific techniques
involving habitat assessment and identification, cavity alteration, and cavity
construction to manage limited habitat for the red-cockaded woodpecker on federally
administered land (Carter et al., 1989; Copeyon, 1990; Ertep and Lee, 1994).
Analysis of specific studies and practices in these three areas serve as a description of
the technique for managing limited federal lands for the enhancement and stabilization of
red-cockaded woodpecker populations.
DISCUSSION
HABITAT ASSESSMENT AND IDENTIFICATION
A significant problem associated with the management of red-cockaded woodpecker
populations is obtaining an accurate assessment of habitat availability and home range
estimates (Ertep and Lee, 1994; Reed et al., 1988). Differences in habitat quality
and availability throughout the range of the red-cockaded woodpecker affect population
density and the range of foraging and nesting activities within colonies, making general
application of population estimators difficult (Reed et al., 1988). This issue was
addressed in 1988 during a study to evaluate red-cockaded woodpecker population indices.
Reed et al. (1988) set out to evaluate studies concerning red-cockaded woodpecker
population indices and, if necessary, develop a new techniques to more accurately
estimate adult population size. Reed at al. (1988) researched the circular scale
technique (CST) as described by Harlow et al. (1983) and found that application of this
method of population estimation is limited. CST utilizes aerial identification of active
cavity tree groups, and encompasses said groups in a 460-m diameter circle that contains
as many of the active cavity trees as possible (Harlow et al., 1983 as cited by Reed et
al., 1988). While Harlow et al. (1983) and Lennartz and Matteaur (1986) used CST with
great accuracy in their study areas, estimating population sizes to between 92 and 95% of
the true number, the 1988 study by Reed et al. determined that the technique cannot be
used throughout the red-cockaded woodpecker range. Using CST in the Sandhills region of
North Carolina underestimated the number of groups in the Reed et al. study population
(Reed et al., 1988). In the Reed et al. (1988) study area, red-cockaded woodpecker
population density and the spatial arrangement of colonies was frequently influenced by
habitat fragmentation which led to the violation of assumptions held necessary in the CST
method of population estimation (Reed et al., 1988). Conclusions in the Reed et al.
(1988) study indicate that CST may be generally used as an index, but further research is
necessary to establish a universal technique to estimate red-cockaded woodpecker
populations.
The development of sophisticated computer programs and topographical analysis techniques
may make assessment of red-cockaded woodpecker habitat and species abundance more
accurate and less time consuming (Ertep and Lee, 1994; Reed et al., 1988). These
advancements in geographic analysis and terrain assessment technology have provided for
an unlikely union between wildlife managers and natural resource agencies on US military
installations throughout the southeast (Ertep and Lee, 1994; USMC, 1995). The
coordination of Geographic Information System programs (GIS) and Digital Multispectral
Videography (DMSV) at Fort Benning , Georgia adds a new technological advantage in the
search for red-cockaded woodpecker colonies and habitat by accurately identifying
longleaf pine stands (USACE, 1996). Image analysis and confirming Global Positioning
System information has been validated in initial tests by the confirmation of three GIS
and DMSV-identified red-cockaded woodpecker sites through direct ground observation in
the areas (USACE, 1996). Research is ongoing to examine the initial findings associated
with these new and highly technical habitat assessment techniques (Ertep and Lee,
1996).
CAVITY ALTERATION
A significant problem in the recovery of red-cockaded woodpecker populations involves
the usurpation of nesting cavities by other species, primarily southern flying squirrels
(Gloucomys volans), northern flickers (Colaptes auratus), European starlings (Sturnus
vulgaris), and other species of woodpeckers (Carter et al., 1989; Rossell and Gorsira,
1996). Invasive species occupy or significantly alter cavities, preventing their
continued use by red-cockaded woodpeckers (Carter et al., 1989). Many nesting locations
take months or years to construct, and adequate old-growth pines are now less frequent in
the red-cockaded woodpecker range (Walters, 1986). Wildlife managers and foresters have
experimented with altering or reinforcing red-cockaded woodpecker nesting cavities to
discourage these invaders. Carter et al. (1989) describe specific techniques for cavity
alteration. Three types of cavity restrictors alter the character of the cavity
entranceway, acting as a deterrent to enlargement or access by other species (Figure 1).
Cavity restrictors generally consist of a camouflaged metal plate fastened over the
cavity entrance (Carter et al., 1989).
A study by Rossell and Gorsira (1996) demonstrates the importance of specific cavity
parameters in assessing the availability of nesting and roosting cavities for
red-cockaded woodpeckers. The results of their study showed that red cockaded
woodpeckers nested only in cavities with normal entrances (Rossell and Gorsira, 1996).
Even if cavities with enlarged entrances contained normal chambers and were not occupied
by competing species, red-cockaded woodpeckers avoided them (Table 1).
TABLE 1?Diurnal occupants versus entrance (ent.) and chamber (ch.) characteristics of
active red-cockaded woodpecker (Picoides borealis) cavities in the Northeast Management
Area, Fort Bragg, North Carolina, May, 1993. (Rossell and Gorsira, 1996)
Use among entrance and chamber categories
Normal ent. Enlarged ent.
Occupant or Contents Norm. ch. Enlarged ch. Norm ch. Enlarged ch.
Red cockaded-woodpecker 21 0 0 0
Southern flying squirrel 7 4 1 7
Red-bellied woodpecker 0 0 1 0
Red-headed woodpecker 2 0 0 0
Screech owl 0 0 0 2
Northern flicker 0 0 0 2
Nest material 1 1 1 1
Unoccupied 29 3 3 4
CAVITY CONSTRUCTION
Techniques to artificially create red-cockaded woodpecker cavities have been initially
successful on federal holdings such as Fort Bragg, North Carolina, which holds one of the
largest red-cockaded woodpecker populations on federally administered lands (Copeyon et
al., 1991; Rossell and Gorsira, 1996). The technique and effectiveness of artificial
cavity construction is best examined by analyzing the physical characteristics of
artificial red-cockaded woodpecker cavities, and reviewing studies wherein the cavities
are used as a management tool (Copeyon, 1990; Copeyon, et al., 1991; Rossell and
Gorsira, 1996).
Perhaps the most comprehensive study concerning artificial cavity construction for the
benefit of the red-cockaded woodpecker was conducted by Copeyon, Walters and Carter as
part of a ten year study of red-cockaded woodpecker populations in the Sandhills region
of North Carolina (1991). Their work, Induction of Red-Cockaded Woodpecker Group
Formation by Artificial Cavity Construction, (Copeyon et al., 1991) represents the most
practical and valuable guide to red-cockaded woodpecker population enhancement techniques
to date (Conner and Rudolph, 1995).
In 1990, Carole Copeyon published an article describing a technique for constructing
artificial cavities for red-cockaded woodpeckers. Explaining that excavation of suitable
living
cavities takes a minimum of ten months and normally much longer to complete, Copeyon
(1990) surmised that construction of artificial cavities may be an effective management
tool that would encourage colonization of abandoned areas and reduce energy expenditure
associated with nesting cavity construction.
After making the decision to use artificial nesting cavities as a management tool,
wildlife managers should attempt to select older trees in their respective areas of
responsibility (Copeyon, 1990; Copeyon et al., 1991). Selection of older trees mimics
the natural inclination of the red cockaded woodpecker and that older trees have
sufficient heartwood development to support large nesting and roosting cavities without
sustaining damage (Copeyon, 1990). As indicated previously, red-cockaded woodpeckers
generally select trees between 80 and 100 years old depending on species availability.
Copeyon (1990) reveals that an adequate artificial nesting cavity requires an entrance
approximately 4.4cm.-6.4cm. in diameter placed at 1-24 meters above ground level. An
entrance tunnel should be excavated into the heartwood with the nesting chamber extending
down at a right angle to the entrance tunnel to a depth between 20.3 and 27.3cm. (Figure
2) (Copeyon, 1990). Small resin wells are drilled around the tree above and below the
entrance site (Copeyon 1990; Rossell and Gorsira, 1996). Seepage from these wells act
to discourage competitors and predators (Copeyon, 1990).
The results of Copeyon's initial study concerning red-cockaded woodpecker cavity
construction are contained in (Table 2).
TABLE 1. ?Use of artificial cavities by red-cockaded woodpeckers (Picoides borealis) in
the Sandhills region of North Carolina (Copeyon, 1990).
Species Age #Constructed #Active
Longleaf Old 29 25
Moderate 7 4
Young 2 2
Total 38 31
Loblolly Old 4 3
Young 2 1
Total 6 4
Cavity construction for red-cockaded woodpecker management is an effective tool for
inducing the formation of new colonies in the species' historical range, and may prove to
increase reproductive success in already established colonies (Copeyon et al., 1991).
RESULTS
Further research is necessary to establish the impact of management for the red-cokaded
woodpecker on other species (Masters et al., 1996). Initial studies indicate that
management practices involving the clearance of hardwood understory and the initiation of
prescribed burns in red-cockaded woodpecker habitat increase forage for white-tailed deer
(Odocoileus virginianus) (Masters et al., 1996). Studies continue to examine concerns
about possible negative effects of single species management practices in association
with red-cockaded woodpecker recovery effort (Masters et al., 1996).
In the 25 years since the identification of the red-cockaded woodpecker as an endangered
species, establishing a unified recovery program among the diverse federal agencies
responsible for the administration of lands within the species' range has been difficult
(Jackson, 1986). In the first 15 years of listing, no programs existed to effectively
manage habitat for the red-cockaded woodpecker. Jackson (1986) described the situation
as especially urgent, as the red-cockaded woodpecker was becoming dependent on widely
dispersed islands of habitat, isolating colonies and creating the potential for
catastrophic losses due to natural occurrences and inter-species competition for roosting
and nesting sites. Since 1986, research into habitat requirements for successful
red-cockaded woodpecker colonies have been identified (Copeyon et al., 1991; Jackson,
1986). Improvements in identifying suitable habitat, altering existing cavities to
decrease competition for roosting and nesting sites, and initiating formation of
red-cockaded woodpecker colonies through construction of artificial cavities have been
synthesized into a specific technique of managing federal lands for the red-cockaded
woodpecker (Copeyon et al., 1991; Ertep and Lee, 1994; Rossell and Gorsira, 1996).
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