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2006 SOUTHEASTERN NATURALIST 5(3):463–472
Status of Pituophis ruthveni (Louisiana Pine Snake)
D. Craig Rudolph1,*, Shirley J. Burgdorf1,2, Richard R. Schaefer1,
Richard N. Conner1, and Ricky W. Maxey3
Abstract - Extensive trapping surveys across the historical range of Pituophis
ruthveni (Louisiana Pine Snake) suggest that extant populations are extremely small
and limited to remnant patches of suitable habitat in a highly fragmented landscape.
Evaluation of habitat at all known historical localities of P. ruthveni documents the
widespread degradation of the fire-maintained pine ecosystem throughout the historical
range of the species. The primary factors leading to degradation of P. ruthveni
habitat are intensive pine silviculture and alteration of the pre-European fire regime.
Habitat restoration on public lands is feasible and could potentially restore populations
of this critically rare species.
Pituophis ruthveni Stull (Louisiana Pine Snake) has long been considered
one of the rarest snakes in the United States (Conant 1956, Young and
Vandeventer 1988). Pituophis ruthveni is restricted to eastern Texas and
west-central Louisiana, a range that coincides with that of Pinus palustris
Mill. (longleaf pine) on the west Gulf Coastal Plain (Conant 1956, Reichling
1995, Thomas et al. 1976). Prior to recent fieldwork, fewer than 60 records
of P. ruthveni were represented in the literature or museum collections.
Until recently, very little was known concerning the ecology of P.
ruthveni. Available information consisted primarily of distribution and habitat
data based on collection records (Conant 1956, Thomas et al. 1976,
Young and Vandeventer 1988) and reproductive biology in captivity
(Reichling 1990). This paucity of information stimulated recent investigations
into the ecology of P. ruthveni (Himes et al. 2002, 2006a, 2006b;
Rudolph and Burgdorf 1997; Rudolph et al. 1998, 2002). This work suggests
that alteration of the fire regime has led to habitat alteration resulting in
declines of Geomys breviceps Baird (Baird’s pocket gopher), a primary prey
of P. ruthveni (Rudolph et al. 2002). These changes are thought to have led
to population declines of P. ruthveni.
The limited range of P. ruthveni, combined with its apparent rarity, have
led to recent concerns about the conservation status of the species (Reichling
1990, 1995; Young and Vandeventer 1988). Recent authors have suggested
that range restrictions and population declines have been substantial
1Wildlife Habitat and Silviculture Laboratory (maintained in cooperation with the
College of Forestry, Stephen F. Austin State University [SFASU]), USDA Forest
Service, Southern Research Station, 506 Hayter Street, Nacogdoches, TX 75962.
2Current address - US Fish and Wildlife Service, 510 Desmond Drive, Suite 102,
Lacey, WA 98503-1263. 3Texas Parks and Wildlife Department, PO Box 4655,
SFASU, Nacogdoches, TX 75962. *Corresponding author - firstname.lastname@example.org.
464 Southeastern Naturalist Vol. 5, No. 3
(Reichling 1995, Young and Vandeventer 1988). Past and ongoing habitat
alterations—due to loss of forest habitat, intensive silviculture, and alteration
of fire regimes—have been severe throughout the range of the species,
further heightening concern about the status of P. ruthveni (Reichling 1995,
Rudolph and Burgdorf 1997, Rudolph et al. 1998). Vehicle-related mortality
(Himes et al. 2002) and commercial collection are also causes of concern. In
response to these developments, the US Fish and Wildlife Service has
recently initiated an evaluation of the status of the species.
During the course of our investigations of the ecology of P. ruthveni, we
have conducted extensive trapping for the species throughout its historical
range, visited all known localities, and obtained data on habitat, diet, and
behavior (Himes et al. 2002, 2006a,b; Rudolph and Burgdorf 1997; Rudolph
et al. 1998, 2002). A substantial number of recent distributional records
resulted from this field work, and it is appropriate to assess the current status
and distribution of P. ruthveni.
Beginning in March 1993, traps were installed in Texas and Louisiana
within the general limits of the historical range of P. ruthveni. Trap sites
were initially chosen based on recent records and suitability of habitat to
maximize the probability of capturing individuals. Subsequent sites were
chosen from localities within the historical range of the species representing
a range of habitat conditions.
Traps consisted of treated plywood tops and bottoms (1.2 x 1.2 m) supported
by wooden uprights 0.45 m in height. The sides were screened with
hardware cloth (3.2- or 1.5-mm mesh). A hinged door in the top allowed access
by investigators. Snakes could enter the traps through 4 funnel entrances
constructed of hardware cloth and placed in the midpoint of each side of the
trap. Drift fences extended approximately 15 m from each funnel entrance.
These were constructed of hardware cloth approximately 60 cm in width and
buried approximately 10 cm in the soil. A water source was placed in each trap.
Traps were operational from early March to late October inclusive, the
approximate activity period of P. ruthveni (D.C. Rudolph, unpubl. data).
Captured P. ruthveni were brought to the laboratory. Each snake was
sexed; snout-vent length, total length, and mass were recorded; and either
a PIT tag or radio-transmitter, depending on current research needs, was
implanted. Snakes were returned to the point of capture within 2–14 days
of implanting procedures.
Habitat was assessed at each trap site. In addition, all historical localities
of P. ruthveni were visited and their habitat assessed. For purposes of this
research, habitats were ranked, on a four-category scale, from excellent to
poor based on the following criteria: excellent = forested habitat, welldrained
sandy soils predominate, at least 50% herbaceous cover, and pocket
gophers widespread and common; good = forested habitat, well-drained
sandy soils present, at least 25% herbaceous cover, and pocket gophers
present; marginal = forested habitat, well-drained sandy soils present, at
2006 D.C. Rudolph, S.J. Burgdorf, R.R. Schaefer, R.N. Conner, and R.W. Maxey 465
least 10% herbaceous cover, and pocket gophers present (at least along
highway and utility rights-of-way); and poor = failure to meet any one of the
above minimum criteria. These general criteria were based on information in
the literature and obtained during our radio-telemetry studies (Ealy et al.
2004, Himes et al.2002, Rudolph and Burgdorf 1997).
Traps were placed at 14 sites (3–20 traps/site) in 10 counties in Texas and
at 9 sites in 5 parishes in Louisiana between 1993 and 2001. A total of 101,828
trap-days were accumulated during this nine-year period, resulting in the
capture of 2372 snakes of 23 species. Twenty-six P. ruthveni were captured,
including two recaptures (Table 1). Overall, trap success was one P. ruthveni
per 3775 trap days. However, for sites where at least one P. ruthveni was
captured (n = 6), the success rate was one snake per 733 trap days (range = one
Table 1. Trap results for Louisiana Pine Snakes in Louisiana and Texas (1993–2001).
# # trap # snakes # days/
Location County/parish traps days captured capture
Kepler Lake area Bienville Parish 3–10 3900 11 (10) 355
Kisatchie NFA, Winn District Nachitoches /Winn Par. 18 5664 3 1888
Kisatchie NF, Kisatchie District Nachitoches Parish 7 8575 0 -
Kisatchie NF, Vernon District Vernon Parish 3 260 0 -
Cravens Vernon Parish 5 2550 0 -
Hoy Beauregard Parish 5 3675 0 -
Singer Beauregard Parish 5 3675 0 -
Dido Vernon Parish 5 735 0 -
Anacoco Vernon Parish 5 2252 0 -
Sabine NF, Foxhunter’s Hill Sabine County 4 5226 6 (5) 871
Sabine NF, Stark Tract Newton County 5 2425 0 -
Sabine NF, San Augustine San Augustine County 5 1235 0 -
Sabine NF, pineland San Augustine County 5 2425 0 -
Scrappin’ Valley, north Newton County 4 1260 3 420
Scrappin’ Valley, south Newton County 5 2425 0 -
Little Rocky Jasper County 5 2208 0 -
Angelina NF, southern portion Angelina/Jasper Cos. 5-10 3018 3 1006
Angelina NF, western portionB Angelina County 20 22,270 0 -
Mill Creek Ranch Wood County 5–15 4595 0 -
Roy E. Larsen Sandylands Hardin County 5 5875 0 -
Brushy Creek Trinity County 4 4480 0 -
Gus Engling WMAA Anderson County 10 3640 0 -
Tonkawa Nacogdoches County 10–15 9460 0 -
Total all areas 101,828 26 733C
ANF = National Forest, WMA = State Wildlife Management Area.
BFour closely associated sites.
CLocations with 0 captures deleted.
466 Southeastern Naturalist Vol. 5, No. 3
snake per 355 to 1888 trap days). Eleven of the 23 sites were within 15 km of a
historical locality for P. ruthveni, and the species was captured at five of these
sites. Nine of these eleven sites, including the 5 with P. ruthveni captures, had
good or excellent habitat. The twelve remaining sites were within the general
area of the historical range, but > 15 km from known locality records; P.
ruthveni was not captured at any of these sites. Eleven of these 12 sites had
some good or excellent habitat remaining. Habitat that qualified as good or
excellent is currently rare in eastern Texas and west-central Louisiana due to
habitat alteration. Most sites with good or excellent habitat remaining are
small, typically a few hundred hectares or less, and isolated.
The 137 records of P. ruthveni available through 2001 are from 15
counties in Texas and nine parishes in Louisiana (Fig. 1). Since 1990, a total
Figure 1. Louisiana
records by county
and parish, and localities
indicate total records
Pine Snakes, historical
study, for each
county or parish.
Open squares indicate
where pine snakes
were not captured;
solid squares indicate
location of trapping
were captured or
known to occur
2006 D.C. Rudolph, S.J. Burgdorf, R.R. Schaefer, R.N. Conner, and R.W. Maxey 467
of 37 records of P. ruthveni are available. All but two of these records are
from six limited areas in four counties (Angelina, Jasper, Newton, Sabine) in
Texas and four parishes (Bienville, Natchitoches, Vernon, Winn) in Louisiana
(Fig. 2). The two additional records are single individuals from Tyler
and Montgomery Counties in Texas.
The recent habitat conditions (1999–2000) at all known P. ruthveni localities
in Texas and Louisiana is summarized in Table 2. A total of 118 localities
Table 2. Habitat quality assessments of historical Louisiana Pine Snake localities on public and
private lands in eastern Texas and eastern Louisiana. Entries are numbers of localities,
followed by the percentages of localities in parentheses, for all known records.
Ownership Excellent Good Marginal Poor
Public 16 (43) 10 (27) 3 (8) 8 (22)
Private 14 (17) 13 (16) 16 (20) 38 (47)
Total 30 (25) 23 (19) 19 (16) 46 (39)
Figure 2. Approximate
(black) of extant
records since 1990).
Bienville Parish and
a portion of Natchtoches
Peason Ridge Military
(2), Fort Polk Military
(3), southern portion
of Sabine National
(5), and southern
portion of Angelina
National Forest (6).
Question marks indicate
in areas lacking
468 Southeastern Naturalist Vol. 5, No. 3
were evaluated, and 53 (45%) of the localities retain some habitat in excellent
or good condition. On public lands, 26 of 37 localities (70%) fall into the
excellent or good categories, and on privately owned lands, only 27 of 81
(33%) of the localities retain some habitat in excellent or good condition.
Pituophis ruthveni has always been considered rare (Conant 1956, Stull
1940). Recent studies have expressed concern about the current status of the
species (Reichling 1990, 1995; Young and Vandeventer 1988). The results
of our trapping surveys and our assessment of habitat condition at all known
P. ruthveni localities support the concern that P. ruthveni may have declined
in geographic distribution and possibly in local abundance. Detailed locality
information is not provided due to the intense collecting effort to supply the
commercial pet trade, especially in Louisiana.
Trap success was low at all sites where P. ruthveni is known to occur. We
are, however, confident that our traps were effective in capturing snakes.
Large numbers of snakes were captured, including all of the larger species
regularly occurring in upland habitats in the region. Although our trap
surveys were not designed to provide estimates of population size, low
capture rates, occasional recaptures (n = 2), and limited habitat suggest that
the currently existing populations are not large. How the current population
densities compare to those prior to extensive habitat alteration is unknown.
Currently, P. ruthveni populations are known to exist, based on multiple
records since 1990, in six general areas. In Texas, populations exist on the
southern portion of the Angelina National Forest in Angelina and Jasper
Counties, on the southern portion of the Sabine National Forest in Sabine
County, and on private land immediately south of the Sabine National Forest
in Newton County. In Louisiana, P. ruthveni populations currently exist on
Fort Polk Military Reservation and the adjacent unit of the Kisatchie National
Forest in Vernon Parish, and on Peason Ridge Military Reservation in
Vernon and Natchitoches Parishes. Another population exists in an extensive
area on primarily private lands, mostly industrial timber lands, in
Bienville and extreme northern Natchitoches Parishes.
Much of the remaining suitable habitat in Bienville Parish is currently
undergoing a major increase in the intensity of the silvicultural management
of pine plantations, and the future of this population is unclear. In Sabine and
Newton Counties in Texas, currently occupied habitat is limited to a few
hundred hectares. Only three areas—Fort Polk Military Reservation and the
adjacent unit of the Kisatchie National Forest, Peason Ridge Military Reservation
in Louisiana, and the southern portion of the Angelina National
Forest in Texas—have extensive areas of suitable, frequently burned
longleaf pine habitat remaining that is not currently subject to extensive
change in management intensity.
Our extensive trapping and collecting at 17 additional sites since 1993
failed to document the existence of other extant populations. Most of these
sites are at or near historical P. ruthveni localities. We suggest that the
2006 D.C. Rudolph, S.J. Burgdorf, R.R. Schaefer, R.N. Conner, and R.W. Maxey 469
combined effects of habitat alteration and fragmentation have eliminated P.
ruthveni from significant portions of its historical range. However, the
single individuals recorded from Tyler and Montgomery Counties in Texas
during the 1990s suggest that remnant populations may still persist in these
fragmented and degraded habitats. In addition, substantial amounts of suitable
habitat still exist on the Kisatchie District of the Kisatchie National
Forest in southern Natchitoches Parish, LA. Historical records are known
from the Kisatchie District and our trapping in this area did not, in retrospect,
sample the best remaining habitat. This area probably has the highest
potential for finding additional extant populations of P. ruthveni, and we
recommend that surveys be conducted in this area.
Pituophis ruthveni is closely associated with longleaf pine growing on
sandy, well-drained soils (Conant 1956, Himes et al. 2006b, Reichling 1995,
Young and Vandeventer 1988). The once extensive longleaf pine ecosystem
of the southeastern United States is one of the most threatened ecosystems in
the United States (Bridges and Orzell 1989, Conner et al. 2001, Frost 1993).
Less than 5% of the original extent of the longleaf pine ecosystem survives,
and much that remains is extensively altered by changes in fire regimes,
silviculture, and land use (Frost 1993). Pituophis ruthveni is also closely
associated with a well-developed herbaceous ground cover of grasses and
forbs, and with Geomys breviceps that are dependent on herbaceous vegetation
(Ealy et al. 2004, Himes et al. 2006b, Rudolph and Burgdorf 1997,
Rudolph et al. 2002). Pituophis ruthveni prey heavily on pocket gophers,
and use pocket gopher burrow systems for subsurface retreats, including
hibernacula and escape from fire (Rudolph and Burgdorf 1997; Rudolph et
al. 1998, 2002; Young and Vandeventer 1988).
Most of the longleaf pine ecosystem that occurred on the West Gulf
Coastal Plain has been converted to other land uses including urbanization,
agriculture, and intensive silviculture. These land uses appear to be incompatible
with the survival of P. ruthveni populations. The less intensive
silvicultural practices of the past, specifically longer rotations and use of
prescribed fire, were apparently more compatible with the existence of P.
ruthveni populations. However, the development and increasing implementation
of more intensive silvicultural practices is eliminating much of the
remaining suitable habitat on private lands. These practices include clearcutting,
intensive mechanical site preparation, planting of pine species other
than longleaf, short rotations, fertilization, and use of herbicides instead of
prescribed fire for control of competition. The substitution of herbicides for
prescribed fire likely has an important impact on P. ruthveni. Silvicultural
managers use herbicides to control herbaceous as well as woody vegetation,
both of which compete with the pine crop. The absence of fire allows the
continuous buildup of a thick duff layer further suppressing the herbaceous
layer. The ultimate result is a highly altered forest with a minimal herbaceous
component, conditions apparently unsuitable for pocket gophers or P.
ruthveni (Reichling 1995, Rudolph and Burgdorf 1997).
The known existing populations of P. ruthveni are concentrated on
public lands (national forests and military installations) and private lands
470 Southeastern Naturalist Vol. 5, No. 3
managed for a diversity of wildlife values. Compared to most private lands,
management of public lands tends to include less intensive site preparation,
longer timber rotations, retention of longleaf pine, and use of prescribed fire
both for control of competing vegetation and management of a fire-maintained
ecosystem. However, even on public lands, the current fire regime on
most sites is insufficient to maintain a sparse midstory and diverse herbaceous
understory (Conner and Rudolph 1989). Consequently, most pine
habitat has a well-developed hardwood midstory and only a sparse herbaceous
component due to competition from woody species in the mid- and
understory. Recent records of P. ruthveni are primarily from the isolated
patches of habitat where the influence of fire has been most effective in
maintaining well-developed herbaceous understory conditions.
The situation on most private lands is different. Industrial forest lands and
significant portions of smaller private ownerships are intensively managed for
fiber production. The practices used, especially the short rotations and substitution
of herbicides for prescribed fire, preclude the existence of a
well-developed herbaceous community. These lands, based on recent records
and trapping surveys, do not support viable populations of P. ruthveni.
Populations of P. ruthveni are also subject to impact by the increasing
density of roads and associated vehicular traffic, including off-road vehicles.
Although the absolute numbers were small, 20% (3 of 15) of mortalities of
radio-tracked P. ruthveni were caused by vehicles (Himes et al. 2002). In
addition, research conducted in association with surveys for P. ruthveni
suggests that populations of large snake species may be reduced by 50%
within 500 m of roads with moderate traffic levels (Rudolph et al. 1999).
Most existing P. ruthveni habitat is within 500 m of currently existing roads.
Pituophis ruthveni is currently rare in the relict patches of fire-maintained
pine habitat that remain, primarily on public lands. These areas are
reasonably well dispersed throughout the historical range of the species.
Intervening habitats that once supported populations of P. ruthveni are
increasingly altered, primarily by intensive silviculture, and the species is,
or may soon be, extirpated. The existing populations on national forests,
military installations, and private lands are presumably small and increasingly
fragmented due to habitat alteration. The long-term survival of these
populations depends on sufficient management to reverse the decline of the
fire-maintained pine ecosystem, primarily in the longleaf pine habitats.
Most critical is the restoration of a prescribed-fire regime sufficient to
prevent the encroachment of a dense hardwood midstory and recovery of a
vigorous herbaceous community. Economic considerations may preclude
improvement on private lands, with the limited exception of small areas
specifically managed for P. ruthveni and other species adapted to firemaintained
pine ecosystems. However, even on public lands, numerous
obstacles exist, especially in implementing an adequate prescribed-fire
regime. Managers need to resolve issues relating to liability, smoke management,
air-quality standards, and agency regulations to effectively use fire as
a management tool to support viable populations of P. ruthveni and overall
biodiversity in the long term. Federal court rulings, in response to lawsuits
2006 D.C. Rudolph, S.J. Burgdorf, R.R. Schaefer, R.N. Conner, and R.W. Maxey 471
filed by environmental groups, limiting the use of prescribed fire on National
Forests and Grasslands in Texas, constitute an additional obstacle.
The potential for restoration on public lands is considerably greater than
on private lands. Management of national forest lands and military installations
within the range of P. ruthveni currently include prescribed fire as a
management tool. Increased use of prescribed fire is planned, driven primarily
by the management needs of Picoides borealis (Vieillot) (Red-cockaded
Woodpecker), a federally listed endangered species. Habitat management
appropriate for Picoides borealis is also appropriate for P. ruthveni, and
numerous additional species adapted to fire-maintained pine ecosystems,
many of which are of conservation concern (Bridges and Orzell 1989,
Conner et al. 2001).
The current status of P. ruthveni is presumed to be a result of habitat
alteration due primarily to widespread intensive silviculture and alteration of
the pre-European fire regime. Extant populations appear to be extremely
small, and inhabit limited patches of suitable habitat that are highly fragmented
and isolated. Without improved management of fire-maintained pine
habitats, recovery—and possibly even survival—of P. ruthveni is unlikely.
We thank Steve Reichling, Lee Fitzgerald, and four anonymous reviewers for
comments on an early draft of this manuscript. Partial support for this research was
provided by the US Fish and Wildlife Service, Texas Parks and Wildlife Department,
the Louisiana Department of Game and Fisheries, and Temple-Inland, Inc. Access to
study areas was provided by Temple-Inland, Inc., Champion International, International
Paper Company, The Nature Conservancy, and Mill Creek Ranch. We also
thank David Baggett, Ross Carrie, Jim Cathey, Chris Collins, Mike Duran, Marc
Ealy, Robert Fleet, Mac Hardy, Jason Helvey, John Himes, Rich Johnson, Trish
Johnson, Ellis Jones, Eric Keith, Wendy Ledbetter, Theron Magers, Chris Melder,
Ken Moore, Kevin Mundorf, John Neiderhofer, Scott Riddle, Steve Shively, Preston
Taylor, Toni Trees, John Tull, and others for field assistance. Texas Parks and
Wildlife Department and the Louisiana Department of Wildlife and Fisheries provided
the necessary scientific collecting permits. The USDA Forest Service’s Joint
Fire Science Program provided additional funding through a grant to Robert B.
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