Integration of Long-Term Research into a GIS Based Landscape Habitat Model for the Red-Cockaded Woodpecker Page: 4 of 10
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STUDIES IN AVIAN BIOLOGY
1990 1991 1992 1991 1994 1995 1998
Male I Female
FIGURE 1. Sex ratio and population growth in response to intensive management of Red-cockaded Wood-
peckers at the Savannah River Site, South Carolina (198551996; Franzreb 1997).
Fish and Wildlife Service aluminum leg band
and with a unique color plastic leg band com-
bination to allow individual identification in the
field. Birds were banded either as nestlings,
when first captured on the site, or when relocat-
ed to the site from elsewhere.
Group and cavity monitoring data indicate
population status, reproductive success, spatial
distribution, and group composition. Survivor-
ship and mortality rates are determined during
monthly observations of groups throughout the
year. During the breeding season (April-July)
monitoring efforts are intensified and each group
is observed weekly. Red-cockaded Woodpeckers
return each night to roost singly in cavities. By
checking the last known nightly roost, the status
of individual Red-cockaded Woodpeckers usu-
ally can be determined. Data are obtained rou-
tinely for each group on survival, sex ratio,
number of helpers, number of active/inactive
pairs, location of nests, identity of breeding
adults, fledging dates, number and sex of fledg-
lings, and reproductive success. These data have
been instrumental in monitoring the status of the
population and our management efforts.
From the late 1985 population level of four
birds, the population at the SRS has grown to
21 active groups and a total of 99 individuals by
the end of the breeding season in 1996 (Fig. 1).
Of these 21 groups, there were 19 breeding pairs
of which 16 were reproductively successful, pro-
ducing 43 fledglings (Franzreb 1997).
For all years but 1988, the number of fledg-
lings produced has increased every year and has
varied from 3 to 43 (Fig. 2). Generally, male
fledglings outnumber females; however, in 1988
all fledglings were female. From 1985-1996, the
mean fledging success defined as the number of
fledglings/successful nesting attempt, was 2.3.
The low was 1.6 in 1991 (N = 8 nesting at-
tempts) and the high was 3.0 in 1985 (N = 1
POPULATION VIABILITY ANALYSIS AND GENETIC
Haig et al. (1993) performed a series of pop-
ulation and pedigree analyzes on the birds on
the SRS to determine the prospects for long-
term population viability at the site. They used
OGENES gene-drop pedigree analysis, a tech-
nique to measure genetic diversity in the current
population relative to allelic diversity of its
founders. Population viability, evaluated as the
probability of persistence over the next 200
years, was estimated using VORTEX, a Monte
Carlo simulation of demographic events. Using
these procedures, Haig et al. (1993) concluded
that during the next 200 years, the population
has a 68-100% chance of extinction, with out-
come depending on stochastic environmental
events and the extent of inbreeding depression.
By annually translocating at least three females
and two males to the SRS from donor popula-
tions for a period of 10 years, the likelihood of
survival of the population for the next 200 years
is 96% (Haig et al. 1993). Based upon an as-
sessment of genetic similarities of Red-cockaded
Woodpecker populations, the Francis Marion
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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/m1/4/: accessed October 17, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.