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2011 SOUTHEASTERN NATURALIST 10(3):409–422
Size and Growth in Two Populations of Black Kingsnakes,
Lampropeltis nigra, in East Tennessee
Ted M. Faust1,* and Sean M. Blomquist2
Abstract - This paper reports information on size and growth of snakes in two populations
of Lampropeltis nigra (Black Kingsnake) over 20 years of study and provides a comparative
analysis that builds on the work of Jenkins et al. (2001). During a 7-year study (1990–1996)
at the Anderson County Wildlife Sanctuary (ACWS) and a 13-year study (1997–2009) at
the University of Tennessee Forestry Resources Research and Education Center (FES) in
Oak Ridge, TN, we captured 265 individual Black Kingsnakes a total of 556 times. The
size of Black Kingsnakes in these two populations are the smallest reported for this species,
with mean (± SD) snout-to-vent length (SVL) of 66.9 ± 24.5 cm (maximum = 112 cm) at
ACWS and 55.8 ± 16.8 cm (maximum = 87 cm) at FES. At FES, the mass-SVL relationship
is represented by an exponential equation (mass [g] = 0.0004 SVL [cm]2.98) similar to ACWS
(mass [g] = 0.0005 SVL [cm]2.95). Across both sites, juvenile kingsnakes grew 1.1 cm/mo
faster than adult individuals. There was a significant decline in body condition index (BCI)
in the combined population during 1990–2009, with BCI declining by 0.960 units annually
at ACWS and by 0.981 units annually at FES over the respective study periods. Declines in
BCI may be a precursor to a decline in abundance.
Many reptiles are long lived, and thus require analysis of long-term datasets
(>5 years) in order to gain insight into their ecology (Gibbons et al. 2000, Madsen
and Shine 2001). Short-term studies of growth can produce misleading results
due to seasonal variation in availability of prey and other resources (Madsen and
Shine 2001), whereas comparative, long-term studies more accurately evaluate
differences in size and growth among snake populations (Hill and Beaupre 2008,
Jenkins et al. 2001). Recent reports of Lampropeltis getula L. (Eastern Kingsnake)
population declines throughout the southeast (Krysko and Smith 2005, Stapleton
et al. 2008, Winne et al. 2007) as well as general declines in herpetofauna worldwide
(Gibbons et al. 2000, Reading et al. 2010) further exemplify the need for both
comparative and long-term studies concerning ecology and habitat use. While
reasons for declines remain enigmatic, habitat loss and degradation, environmental
pollutants, and other anthropomorphic factors are often credited as likely factors
influencing declines in population health and abundance (Krysko and Smith 2005,
Winne et al. 2007).
The Lampropeltis getula species complex was recently split into five species
including Lampropeltis nigra Yarrow (Black Kingsnake, formerly Lampropeltis
getula nigra; Pyron and Burbrink 2009a, b). Black Kingsnakes range from the
Mississippi River east to the Appalachian mountains and from the Gulf coast
1Clinch River Environmental Studies Organization (CRESO), Clinton, TN 37716. 2Department
of Biology, Box 5063, Tennessee Technological University, Cookeville, TN
38505. *Corresponding author - TMFaust21@gmail.com.
410 Southeastern Naturalist Vol. 10, No. 3
north to southern Illinois (Pyron and Burbrink 2009a). This complex was split
based on genetic and morphological evidence (Pyron and Burbrink 2009a), with
ecological differences and allopatric geographic distributions supporting the new
species (Pyron and Burbrink 2009b).
Kingsnakes spend much of their time underground (Linehan et al. 2010) and
often use small-mammal burrows for refuge sites (Steen et al. 2010) and movements
(J. Byrd, Clinch River Environmental Studies Organization [CRESO],
Clinton, TN, pers. comm.). Species within the Lampropeltis getula complex are
commonly found in loose, dry soil types that allow burrowing in edge areas of
natural pine and hardwood forest macrohabitats which contain sufficient levels
of ground-cover microhabitat (i.e., coarse woody debris, leaf litter, ground vegetation;
J. Byrd, pers. comm.; Plummer 2010; Steen et al. 2010).
Our study focuses on size and growth of Black Kingsnakes and will help
further the knowledge of (e.g., general physiology and potential habitat factors
affecting size and growth) and assist in possible conservation strategies for this
newly elevated species. During 1997–2009, we conducted a snake coverboard
study at the University of Tennessee Forestry Resource Research and Education
Center in conjunction with CRESO. This paper compares data on size and growth
between these two nearby but distinct populations of Black Kingsnakes in Anderson
County, TN (Fig. 1A; Jenkins et al. 2001). While superficially similar, these
two sites possess microhabitat differences in soil, prey abundance, and land-use
histories. Our study sought to (1) provide data on snake size (SVL and mass)
and growth in the wild, (2) analyze differences in size and growth between two
nearby populations, (3) analyze long-term, temporal changes in body condition
between sites, and, when possible, (4) explore potential mechanistic reasons for
differences between the two populations.
Anderson County Wildlife Sanctuary (ACWS)
During 1990–1996, research was conducted at the Anderson County Wildlife
Sanctuary (ACWS), situated along the Clinch River in East Tennessee (36°3'N,
84°11'W; Fig 1C). This 60-ha site was used as a county dump from 1962–1972 and
was then upgraded to a landfill which was closed in May 1982. In 1988, this area
became ACWS and was managed by CRESO up until 1996. During the time of
research, the site consisted of forest (≈40 ha), old recovering landfill and other oldfi
eld habitat (≈15 ha), pine plantation (≈3 ha), and limestone bluffs (≈2 ha), with
our study focusing on the woodland-field ecotone and old-field habitats (Jenkins et
al. 2001). See Jenkins et al. (2001) for a full description of ACWS study area.
Figure 1 (opposite page). (A) The two study sites in relation to each other showing the
Clinch River barrier that separates each site. (B) Aerial view of the University of Tennessee
Forest Resources Research and Education Center (FES). (C) Aerial view of Anderson
County Wildlife Sanctuary (ACWS). The highlighted sections of each aerial image show
the fields that were sampled with coverboards, with the approximate study area boundaries
for each site being identified by a black polygon.
2011 T.M. Faust and S.M. Blomquist 411
412 Southeastern Naturalist Vol. 10, No. 3
University of Tennessee Forest Resources Research and Education Center
During 1997–2009, research was conducted by CRESO at the University of
Tennessee Forest Resources Research and Education Center: Oak Ridge Forest
and Arboretum (FES, as it was formerly known as the University of Tennessee’s
Forestry Experimental Station) located in the Ridge and Valley physiographic province
of Anderson County, TN (35°60'N, 84°13'W, about 6 km SW of the ACWS on
the opposite side of the Clinch River; Fig. 1B). The site is about 915 ha and since
1962 has been protected from uncontrolled fire with limited timber harvest.
The FES is a highly fragmented area characterized by regenerating upland
hardwood and mixed pine-hardwood stands. Deciduous forest stands are comprised
principally of duel-aged oak-hickory groups. The site is transected by a
utility corridor containing two parallel electric transmission line right-of-ways,
approximately 1.4 km in length. Our study focused on the open field and woodland-
field ecotone (including the right-of-ways) habitats of 7 distinct fields (mean
field size = ≈1.4 ha, SD = ≈1.9 ha). Distances between fields were not standardized
and ranged from 0.2–2.5 km. The majority of the FES consists of upland
hardwood and mixed pine-hardwood forest that separates each of the relatively
small fields (Fig. 1).
Though the ACWS and the FES sites are in close proximity to one another,
we consider each population to be separate and distinct for two primary reasons.
Firstly, the largest reported cumulative move upon release for a Black Kingsnake
is approximately 1.5 km (Jenkins et al. 2001). Closely related Eastern
Kingsnakes show a maximum range length of approximately 1.6 km (Wund et
al. 2007), and Lampropeltis holbrooki Stejneger (Speckled Kingsnake) showed
an average maximum range length of 1012 m (SE = 120 m) for males (Plummer
2010). All of these movement distances are much shorter than the ≈6 km straightline
distance between sites. Secondly, the sites are separated by the Clinch River
(width = 0.16–0.51 km), which serves as a geographical barrier to snake movement
(Fig. 1A). The area between the sites also contains man-made barriers,
including roads, residential areas, and an active quarry site, which may further
inhibit snake movements.
Species richness was similar between the two sites; however, species abundance
was often vastly different. We captured 180 Black Kingsnakes a total of
400 times at ACWS and 85 Black Kingsnakes a total of 156 times at FES; these
captures made up 54.8% and 7.2% of all snake encounters including recaptures,
respectively (Jenkins et al. 2001; T. Faust, unpubl. data).
We placed coverboards along the woodland-field ecotone of fields and utility
company right-of-ways. Coverboards were wood (ACWS: n = 50, FES: n =
110; mean size = 1.5 m2, range = 0.4–4.4 m2) and metal (ACWS: n = 99, FES:
n = 110; mean size = 1.7 m2, range = 0.4–4.4 m2). Coverboards were generally
placed as coverboard units (each unit = one wood and one metal coverboard
2011 T.M. Faust and S.M. Blomquist 413
<5 m apart), but 49 metal coverboards were placed singly at the ACWS. At FES,
25 coverboard units were placed along P field in 1997, with the addition of 6
more coverboard units in April 2001. In May 2001, 79 coverboard units were
added to 7 new fields at FES (Fig. 1B). Black Kingsnakes showed no preference
for wood or metal coverboards at either site (Jenkins et al. 2001). Other studies
that utilized coverboards have shown an absence of size-related biases in snakes
(Willson et al. 2008) and produced capture rates for kingsnakes that varied greatly
from FES and ACWS rates (e.g., Johnson  for Black Kingsnakes and
Grant et al.  for Eastern Kingsnakes). This research suggests that the use
of coverboards resulted in small to negligent sampling bias for the kingsnakes in
our studies. Coverboard units were placed 6.5–124 m (SD = 22.6 m) apart. On
average, searches were conducted 6.4 (SD = 3.7) times per month from April–
September and 1.0 (SD = 0.8) times per month in March, October, and November.
Our standard protocol consisted of 30-second visual searches of the coverboard
substrate, usually by two or more individuals (Jenkins et al. 2001).
Snout-to-vent length (SVL, ± 0.1 cm) and vent-to-tail length (VTL, ± 0.1 cm)
were recorded by straightening snakes along a 100-cm measuring stick (Fitch
1987). Usually two independent length measurements were taken for each snake
to ensure accuracy. Independent measurements were usually within 1 cm, and
means were used when independent measurements differed. Rarely, only one researcher
was present and measurements were taken only once. An Ohaus digital
scale was used to record mass (± 0.1 g). Snakes were released under the original
capture site coverboard within 24 h after capture, and individuals recaptured
within 14 days of previous capture were not remeasured. At ACWS, individuals
were marked by clipping caudal scales (Blanchard and Finster 1933), and photocopies
of ventral patterns were used as an additional identification technique
during the last four years of the study (Jenkins et al. 2001). At FES, passive integrated
transponder tags (PIT-tags) were injected into snakes in order to identify
individuals (Gibbons and Andrews 2004). Cloacal probing was used to determine
sex at both sites (Blanchard and Finster 1933, Schaefer 1934).
Mass and SVL were analyzed based on one corresponding data point from
each individual. Some individuals were captured multiple times over multiple
years resulting in a large range of measurements for these individuals. For individuals
that were captured more than once during the study, a representative
mass and SVL data point was selected randomly. Points were randomly selected
to meet the statistical assumption of independent data points. Kingsnakes that
were not PIT-tagged (n = 16) were treated as the same individual unless date,
location, and size of the snake made it obvious that the unmarked snake was a
separate individual. We identified 8 individuals during the study that were not
PIT-tagged. These methods yielded a full dataset of 252 individuals (n = 170 at
ACWS; n = 82 at FES) for mass and SVL analyses, and all statistical analyses
were performed in SAS (version 9.1, SAS Institute, Cary, NC). We investigated
if the SVL and mass of snakes varied among the two sites and sexes (including
unsexed animals as a third category) using two-way multivariate analysis of
414 Southeastern Naturalist Vol. 10, No. 3
variance (MANOVA statement in PROC GLM). We tested the effect of site, sex,
and the interaction of these two factors, and used Tukey’s post-hoc pairwise
comparisons to examine differences within each factor. Following Jenkins et al.
(2001), we used simple linear regression to test if an exponential function (y =
axb) described the relationship between mass and SVL (PROC REG). We used
one-way analysis of covariance (ANCOVA, PROC GLM) with site as a factor in
the model and mass as a covariate to examine if the slopes of the regression line
describing the relationship between mass and SVL varied from the relationship
reported by Jenkins et al. (2001) where mass = 0.0005 SVL2.95.
We used a subset of 44 (27 at ACWS, 17 at FES) individuals that were
recaptured at least once during the study to investigate differences in growth
rate. Growth rates were calculated by taking the initial capture SVL and the
final capture SVL and dividing the change in SVL by the total months of
growth. Using a 30-day month, we eliminated snakes with fewer than two
months of growth and calculated change in SVL based on a six-month growing
season (April–September) for individuals that were captured in more than
one year (Jenkins et al. 2001). Size at maturity (60 cm SVL) was based on
previous reports for Black Kingsnakes (Jenkins et al. 2001, Mitchell 1994)
and on field observations at our two study sites. We calculated growth rates
for snakes based on the SVL at initial capture for juvenile (≤60 cm SVL) and
adult snakes (>60 cm SVL). To investigate if the growth rate of snakes varied
among the two sites and by sexual maturity, we used two-way analysis of
variance (ANOVA, PROC GLM). We tested the effect of site, maturity, and
the interaction of these two factors, and used Tukey’s post-hoc pairwise comparisons
to examine differences within each factor. Furthermore, we tested the
assumption that maturity influenced growth rate over the course of an individual’s
life by using simple linear regression to determine if growth rate was
related to size at initial capture.
To evaluate changes in the body condition of snakes over the study period,
we calculated a body condition index (BCI) based on the relationship for Eastern
Kingsnakes: BCI = (mass/SVL3) x 105 (Winne et al. 2007). Following Winne et
al. (2007), only the first capture record for each individual was used in analysis;
additionally, we also removed gravid females and snakes that were known to
have recently fed due to evident bulges or regurgitations. This procedue resulted
in 5 individuals from ACWS and 3 from FES being removed from the full 252-
snake dataset, and a total of 244 individuals (n = 165 at ACWS, n = 79 at FES)
being used for BCI analyses. We investigated if BCI varied over time and if the
change in BCI varied among the sites and sexes. Although comparison of sites
is not a direct comparison because of the temporal differences in the studies, we
compared sites to examine if widespread changes were occurring at both sites.
We used simple linear regression to determine if BCI changed across years with
site and sex. We used one-way ANCOVA with either site or sex as a factor in
the model and year as a covariate to examine if the slopes of the regression line
describing the relationship between BCI and year varied.
2011 T.M. Faust and S.M. Blomquist 415
The data were primarily normal based on histograms, skewness, and kurtosis
of each variable. For regression analyses, we visually examined residuals to assess
variance homogeneity; all regression analyses met this assumption. Means ±
standard deviation are reported unless otherwise specified, and α = 0.05 was used
to evaluate all tests.
Kingsnakes ranged from 25.0–86.5 cm SVL, 29.2–95.6 cm TL, and 6.6–
250.0 g at FES (n = 82) and from 25.0–112.0 cm SVL, 28.5–129.2 cm TL, and
4.6–521.0 g at ACWS (n = 170) (Table 1; Jenkins et al. 2001). Snakes at the FES
were on average 11.1 cm shorter (partial-F1,246 = 6.06, P = 0.015) and 82.1 g lighter
(partial-F1,246 = 6.81, P = 0.001) than snakes at the ACWS (two-way MANOVA:
Wilks’ λ= 0.97, F2,245 = 3.42, P = 0.034). Snout-to-vent length and mass of males
and females were not significantly different (two-way MANOVA: Wilks’ λ=
0.99, F4,490 = 0.82, P = 0.516), and the effects of site and sex were independent
(two-way MANOVA: Wilks’ λ= 0.98, F4,490 = 1.19, P = 0.314). Tail length-to-total
length ratios of sexually mature males and females (SVL > 60 cm) ranged from
12.3–15.4% (n = 20) and 10.3–13.6% (n = 15), respectively, at the FES, which
is within the range reported by other studies on this species (e.g., Kaufman and
Gibbons 1975). An exponential curve (mass [g] = 0.0004 SVL [cm]2.98) described
the relationship between mass and SVL at the FES (r2 = 0.95, F1,81 = 1449.58,
P < 0.001; Fig. 2). This relationship was not significantly different than that described
by Jenkins et al. (2001) for the ACWS (mass [g] = 0.0005 SVL [cm]2.95;
ANCOVA site factor partial-F1,251 = 1.01, P = 0.316).
Table 1. Mean mass (g), snout-to-vent length (SVL; cm), vent-to-tail length (VTL; cm), and total
length (TL; cm) in two populations of Black Kingsnakes in Anderson County, TN (FES = University
of Tennessee Forest Resources Research and Education Center; ACWS = Anderson County
n SVL (SD) VTL (SD) TL (SD) Mass (SD)
Females 38 55.3 (19) 7.4 (2.8) 62.6 (21) 85.2 (71)
Males 43 56.7 (15) 8.8 (2.6) 65.5 (18) 78.0 (50)
Unknown sex 1 33.5 4.6 38.1 12.0
All 82 55.8 (17) 8.1 (2.7) 63.8 (19) 80.5 (61)
Females 60 63.2 (22) 8.4 (2.9) 71.6 (25) 126.6 (116)
Males 62 63.9 (25) 9.6 (3.7) 73.5 (28) 138.9 (143)
Unknown sex 48 75.3 (26) 10.9 (4.3) 86.2 (30) 237.8 (159)
All 170 66.9 (25) 9.5 (3.7) 76.4 (28) 162.4 (146)
Females 98 60.1 (21) 8.0 (2.9) 68.1 (24) 110.5 (103)
Males 105 61.0 (21) 9.3 (3.3) 70.2 (25) 113.9 (118)
Unknown sex 49 74.4 (26) 10.8 (4.3) 85.2 (30) 233.1 (160)
All 252 63.3 (23) 9.1 (3.5) 72.3 (26) 135.8 (131)
416 Southeastern Naturalist Vol. 10, No. 3
Based on recaptures of 44 individuals (27 at ACWS, 17 at FES) with a minimum
of 2 (mean = 9.2) growing months between first and last capture of each
individual, growth rates varied from 0.0–4.2 cm/mo (Table 2). Across both sites,
we found that juvenile kingsnakes grew at a 1.1-cm/mo-faster rate than adult individuals
(two-way ANOVA: F3,43 = 5.77, P = 0.002; maturity factor partial-F1,43
= 12.84, P < 0.001). Further, growth rates declined with increasing SVL at initial
capture at the FES (r2 = 0.26, F1,16 = 5.16, P = 0.038), which is similar to the pattern
described by Jenkins et al. (2001) for the ACWS site. Additionally, snakes at
Table 2. Monthly growth (cm/mo) in two populations of Black Kingsnakes in Anderson County,
TN (FES = University of Tennessee Forest Resources Research and Education Center; ACWS =
Anderson County Wildlife Sanctuary).
Female Male Overall
Mean SD n Mean SD n Mean SD n
Monthly growth (cm/mo) 2.0 1.2 11 1.9 1.3 6 2.0 1.2 17
Juvenile monthly growth (cm/mo) 2.2 0.7 8 2.7 2.1 2 2.3 0.9 10
Adult monthly growth (cm/mo) 1.5 2.1 3 1.4 0.8 4 1.4 1.3 7
Monthly growth (cm/mo) 0.9 0.7 11 1.6 1.1 16 1.4 1.0 27
Juvenile monthly growth (cm/mo) 1.2 0.9 4 2.7 0.9 6 2.1 1.1 10
Adult monthly growth (cm/mo) 0.8 0.7 7 1.0 0.7 10 0.9 0.6 17
Figure 2. Relationship between mass and snout-to-vent length in two populations of
Black Kingsnakes in Anderson County, TN. Mass and snout-to-vent length of snakes
from the University of Tennessee Forest Resources Research and Education Center (filled
diamonds, solid line) and Anderson County Wildlife Sanctuary (open diamonds, dashed
line) showed the same pattern within each population.
2011 T.M. Faust and S.M. Blomquist 417
FES had 0.6-cm/mo-higher growth rates than at ACWS (two-way ANOVA: site
factor partial-F1,43 = 4.27, P = 0.045). We found no evidence that there was an
interaction between site and growth rate of juvenile and adult individuals (twoway
ANOVA: interaction partial-F1,43 = 0.19, P = 0.665).
The body condition index of Black Kingsnakes declined by 0.191 units annually
(r2 = 0.02, F1,243 = 5.21, P = 0.023; Fig. 3) from 1990 to 2009 across sites. During
1990–1996 at the ACWS site, BCI declined by 0.960 units annually (r2 = 0.04,
F1,164 = 7.35, P = 0.007), and BCI declined by 0.981 annually during 1997–2009 at
the FES site (r2 = 0.18, F1,78 = 16.39, P = 0.001; Fig 3). The BCI ranged from 21.3–
71.6 across both study sites (n = 244), and mean BCI was 37.5 ± 6.4 at FES (n =
79) and 38.4 ± 8.7 at ACWS (n = 165). Mean BCI was 37.6 ± 7.2 for males (n = 43)
and 37.4 ± 5.3 for females (n = 36) at FES, and mean BCI was 37.5 ± 8.1 for males
(n = 61), 36.0 ± 8.1 (n = 55) for females, and 42.3 ± 9.0 for unsexed snakes (n = 49)
at ACWS. Body condition did not vary between the two sites (ANCOVA: F2,243 =
9.46, P < 0.001; site partial-F1,243 = 0.75, P = 0.386), but the change in BCI showed
the same increasing then decreasing pattern across each of the two studies (year
partial-F1,243 = 18.17, P < 0.001; Fig. 3). The BCI values of unsexed snakes were
5.1 points higher than males and females (ANCOVA: F3,243 = 6.01, P < 0.001; Sex
Figure 3. Body condition index for two populations of Black Kingsnakes in Anderson
County, TN. Body condition of snakes declined by approximately 1.0 BCI unit per
year at both the Anderson County Wildlife Sanctuary study site during 1990–1996 (y =
-0.960x + 1951; r2 = 0.04) and at University of Tennessee Forest Resources Research
and Education Center study site during 1997–2009 (y = -0.981x + 2004; r2 = 0.18).
Across both studies during 1990–2009, snake body condition declined by approximately
0.2 BCI units per year (y = -0.191x + 419.8; r2 = 0.02). The lines represent the linear
regression of body condition irrespective of sex for each site separately (solid lines) and
together (dashed line).
418 Southeastern Naturalist Vol. 10, No. 3
partial-F2,243 = 6.30, P = 0.002), but BCI did not co-vary with sex from 1990–2009
(year partial-F1,299 = 0.16, P = 0.694).
Black Kingsnakes may show local and rangewide geographic variation in
body size. The mass and SVL of our two populations are the smallest reported
for this species. Despite obvious size differences between populations, the mass-
SVL relationships and growth rate similarities between geographically distinct
kingsnake populations suggest that growth patterns may be consistent across the
Black Kingsnake’s and Eastern Kingsnake’s ranges regardless of maximal size.
Differences due to land-use histories in soil, prey compositions, and other microhabitat
aspects may have a significant effect on SVL and mass, even between
The limited published literature on Black Kingsnakes indicates there may be
some geographic variation in body size among populations (Johnson 1964, Meade
and Palmer-Ball 2003, Pyron and Burbrink 2009a), and the mean mass and SVL
of Black Kingsnakes at our two study sites were the smallest reported for this species.
At both sites, most Black Kingsnakes fell below the reported range (mean
TL = 90–122 cm; Pyron and Burbrink 2009a). The only other noteworthy report
on the size of Black Kingsnakes indicates geographic variation among populations;
Meade and Palmer-Ball (2003) report the size range of 28 adult males of
73.6–148.0 cm TL and 65.4–130.9 cm SVL in Kentucky and southern Indiana,
with the largest individual found in southern Indiana. The closely related Eastern
Kingsnake and Speckled Kingsnake have maximum lengths of 208 cm TL (Ernst
and Barbour 1989) and 183 cm TL (Pyron and Burbrink 2009a), respectively,
indicating further geographic variation within this complex. For example, 2
Eastern Kingsnake and 1 Speckled Kingsnake radio-telemetry studies reported
mean SVLs and masses (reported in 2 studies only) that were larger than either
of our site’s means (Plummer 2010, Steen et al. 2010, Wund et al. 2007). These
researchers likely selected larger individuals for radio-telemetry, thus likely
skewing the means towards the high end. However, maximum SVL and mass were
substantially higher for Eastern Kingsnakes (Steen et al. 2010, Wund et al. 2007)
and approximately equal for Speckled Kingsnakes (Plummer 2010) when compared
to our study. Krysko (2002) reported a majority of individuals near 90 cm
SVL, with a maximum SVL of 160 cm in southern Florida. Variation among these
studies suggests that the Lampropeltis getula complex likely has both intra- and
inter-specific body size variation in the 3 species discussed (Black Kingsnakes,
Eastern Kingsnakes, and Speckled Kingsnakes), with Speckled Kingsnakes falling
the closest to our reported size ranges (Plummer 2010).
The Lampropeltis getula complex also appears to exhibit geographic variation
in size at maturity. Krysko (2002) reported an SVL of 80 cm for maturity in Eastern
Kingsnakes which has been used to define maturity in other kingsnake studies
(e.g., Plummer 2010). Speckled Kingsnake females are known to mature at less than 70
cm SVL (Trauth et al. 1994). Our reported value for maturity (60 cm SVL) was, in
part, based on a gravid female (SVL = 66.5 cm, mass = 101.8 g) found with 9 eggs
2011 T.M. Faust and S.M. Blomquist 419
at ACWS. Additionally, a male (SVL = 72.5 cm, mass = 133 g) and a female (SVL =
71.0 cm, mass = 146 g) were found in copulation at FES in early 2009.
Geographic variation was even evident between sites; Black Kingsnakes
at FES were significantly smaller in both SVL and mass than those at ACWS
(Jenkins et al. 2001). Although some size differences can be expected between
geographically distant populations (Beaupre 1995, Grant and Dunham 1990), it is
less intuitive that populations <6 km apart would show such distinct differences
as found between FES and ACWS. However, Hill and Beaupre (2008) showed
significant size differences between populations of Agkistrodon piscivorus leucostoma
Troost (Western Cottonmouth) located <50 km apart.
The Black Kingsnake mass-SVL relationship (mass = 0.0006 (SVL)2.98) at
FES is similar to what Jenkins et al. (2001) reported at ACWS (mass = 0.0005
(SVL)2.95) and Kaufman and Gibbons (1975) reported (mass = 0.0004 (SVL)2.94)
in a South Carolina population of Eastern Kingsnakes. Jenkins et al. (2001) suggested
that this metric can be used to monitor the health of an individual or a
population. These similar body-size relationships among different populations of
kingsnakes provide a useful range for comparison among populations and indicate
that these two species may have similar growth patterns.
Juvenile Black Kingsnakes grew faster than adult Black Kingsnakes, and
growth rate declined with increasing SVL at both FES and ACWS. Both Madsen
(1983) and Pearson et al. (2002) also showed that growth rates declined
with increasing SVL in two other snake species; however, both of these studies
show that female snakes do not slow their growth to the same extent as males.
Compared to these studies, our growth data was limited, but we did not find
any differences in growth between sexes. Although FES snakes grew 0.6 cm/
mo faster than ACWS snakes, this may be in part due to the larger proportion of
mature snakes at ACWS because the similar mass-SVL relationships between
sites suggest a similar growth pattern. We hypothesize that FES kingsnakes may
be lacking the resources (e.g., habitat and prey) needed to reach the larger sizes
seen at ACWS. Although we cannot address this with our dataset, an analysis of
size and age-specific growth and survival rates may help to clarify such observed
differences among populations.
Geographic variation among populations has been explained by regional differences
in elevation, habitat, temperature, and precipitation (Ernst and Barbour
1989, Grant and Dunham 1990, Hill and Beaupre 2008, Reinert 1993). Between
our two sites, differences in elevation were not notable and neither were temporal
temperature or precipitation differences (NOAA 2010). Consistent differences
seen in SVL and mass between the two sites may suggest the habitat is of higher
quality or more suitable habitat exists at ACWS. On a macrohabitat level, ACWS
and FES sites were relatively similar; however, there were distinct differences
between sites on a microhabitat level. The sites differ in both soil composition
and prey compositions, which we hypothesize as the primary factors for size differences
between the sites. Additionally, we believe that land-use histories are
the primary mechanism for differences in soil and prey compositions. The FES
soils are composed of a compact clay soil with abundant chert rock, and this
420 Southeastern Naturalist Vol. 10, No. 3
area possesses a relatively mild history of soil disturbances (Jenkins et al. 2001).
Conversely, the ACWS soils are loose and porous from many years of disturbance
(e.g., intensive farming and landfill activities; Jenkins et al. 2001). Small
mammals, especially Microtus pinetorum LeConte (Pine Voles), are much more
abundant at the ACWS site (F. Holtzclaw, Webb School of Knoxville, Knoxville,
TN, unpubl. data; Jenkins et al. 2001), possibly due to the soil structure, and this
may be important for the snakes at that site for two reasons. First, the loose soils
at ACWS allow for a high density of burrows, which are refuge sites for kingsnakes
(J. Byrd, pers. comm.; Steen et al. 2010). Second, small mammals are also
a food source of kingsnakes (Jenkins et al. 2001, Wilson and Friddle 1946, Winne
et al. 2007). Black Kingsnakes appear to exhibit an ontogenetic shift in diet from
primarily snakes as juveniles to small mammals as adults (T. Faust and J. Byrd,
unpubl. data; Jenkins et al. 2001), and the combination of fewer small mammals
and more compact soils at the FES might explain why few snakes grow beyond
80 cm SVL there. These mechanistic reasons for the size differences we have
described in this paper are an avenue for future research.
Body condition index may be helpful in determining changes in a population’s
health over time. Both FES and ACWS showed significant declines in body condition
over their respective study periods. Declines in BCI have been followed by
declines in abundance (Winne et al. 2007), and stable BCIs have been shown in
seemingly stable populations of Eastern Kingsnakes (Linehan et al. 2010, Winne
et al. 2007). Currently, there is no apparent population decline in the FES Black
Kingsnake population, and snakes continue to be captured at rates similar to
those from previous years (J. Weber, CRESO, Clinton, TN, pers. comm.). Though
a declining survival and BCI have been strongly correlated in other taxa (e.g.,
Reading 2007), it is unclear if survival and BCI are strongly related in Black
Kingsnakes, and future research should evaluate the strength of this relationship.
It is also unclear if BCI declines in our two studies were independent of sampling
influence since both sampling methods and apparent declines were very similar.
Though recaptures were not included, it is possible that simply lifting coverboards
disrupted prey population and, in turn, affected BCI over the course of
each study period.
Our study adds to the limited body of research on the growth rates within
the Lampropeltis getula complex, and this could be a productive avenue for
future research. Reports of declines in multiple Eastern Kingsnake populations
(Krysko and Smith 2005, Stapleton et al. 2008, Winne et al. 2007) illustrate the
need to better understand the effects that a declining yearly BCI may have on a
population. Declining BCI could potentially serve as a forewarning of population
decline if the relationship among vital rates (e.g., survival and population growth
rate) and BCI were better understood.
We especially thank J. Byrd, K. Fox, F. Holtzclaw, and the rest of the CRESO staff.
Additional thanks to R. Evans and the UT Forest Resources Research and Education
Center. Finally, we would like to thank all of the CRESO coverboard team, especially
2011 T.M. Faust and S.M. Blomquist 421
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