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2006 SOUTHEASTERN NATURALIST 5(2):265–276
Terrestrial Movements and Upland Habitat Use of
Gopher Frogs in Central Florida
W. Boyd Blihovde*
Abstract - In recent years, researchers have begun to focus on the upland habitat
requirements of pond-breeding amphibians. The increased attention is due to a
general lack of knowledge about the terrestrial phase of the life history of most
pond-breeding species and a concern over loss of upland habitats. In this study,
radio telemetry was used to determine the terrestrial behavior of Rana capito
(Gopher Frogs) in central Florida. Frogs were captured at Gopherus polyphemus
(Gopher Tortoise) and Geomys pinetis (pocket gopher) burrows. Surgically implanted
radio transmitters were used to follow nine Gopher Frogs at various times
between September 1999 and May 2000. Radio-located frogs used from one to four
terrestrial shelters (Mean ± S.D. = 2.28 ± 1.11). Terrestrial movements ranged in
total distance from zero to 35 m (Mean ± S.D. = 15.28 ± 15.29). Mean minimum
convex polygons (m2) were calculated for each frog (Mean ± S.D. = 45.29 ± 79.73).
Gopher Frogs showed strong site fidelity to both pocket gopher and Gopher Tortoise
burrows. Drought conditions could have resulted in an underestimate of
movement distance and an overestimate of site fidelity to upland shelters. Upland
habitat should be managed to protect all species of terrestrial burrowers; in doing
so, Gopher Frogs will be managed.
Amphibians are vulnerable to numerous threats in their environment, and
thus may be important indicators of both terrestrial and aquatic habitat
degradation (Dodd 1997). Although much research on amphibians has focused
on breeding sites, it is now apparent that upland habitats are just as
important to the long-term persistence of many species (Semlitsch 1981,
Semlitsch and Jensen 2001). Frogs and salamanders are known to migrate
considerable distances into upland habitats surrounding breeding sites
(Dodd 1996, Dodd and Cade 1998, Franz et al. 1988, Johnson 2003, Muths
2003, Semlitsch 1998). Understanding terrestrial movements of pond-breeding
amphibians is necessary to adequately protect the surrounding uplands
(Semlitsch 1998, Semlitsch and Jensen 2001).
There is increased urgency to obtain data on terrestrial movements of
amphibian species that inhabit areas immediately threatened by habitat
loss from urbanization. In Florida, increases in the human population have
resulted in severe losses of upland habitats (Cerulean 1991). In central
Florida, pond-breeding amphibians and their terrestrial retreats are threatened
by some of the most rapid urban development in the country (US
*Department of Biology, University of Central Florida, 4000 Central Florida Boulevard,
Orlando, FL 32816. Current Address - Lake Wales Ridge National Wildlife
Refuge, 4177 Ben Durrance Road, Bartow, FL 33830; firstname.lastname@example.org.
266 Southeastern Naturalist Vol. 5, No. 2
Census Bureau 2003). One species in particular, Rana capito LeConte
(Gopher Frog), is especially vulnerable to urbanization because individuals
breed in small, isolated wetlands, but spend most of their lives in
Both Rana capito and Rana sevosa Goin and Netting (Dusky Gopher
Frogs) are adapted to living in semi-arid conditions and depend on preexisting
burrows and underground retreats in the uplands they inhabit (Franz
1986, Godley 1992, Wright and Wright 1949). Gopher Frogs may spend
many months away from breeding sites (i.e., fishless ponds) annually, sometimes
moving overland as far as 2 km (Franz 1988, Franz et al. 1988).
Outside the breeding season (typically September to March in central
Florida), they are most often found in sandhill, scrub, sand pine scrub, and
flatwoods habitats (Carr 1940, Godley 1992, Wright and Wright 1949). They
have been observed using burrows made by Gopherus polyphemus Daudin
(Gopher Tortoises), Peromyscus polionotus Wagner (old field mice), and
crayfish (Carr 1940, Gentry and Smith 1968, Lee 1968, Wright and Wright
1949). Gopher Frogs will also use other types of refuges that are associated
with stumps, root mounds, dead vegetation, and clumps of grass (Richter et
al. 2001, Wright and Wright 1949).
Ecological studies of Gopher Frogs have primarily focused on breeding
ponds (Bailey 1989, Palis 1998). In one study, Gopher Frogs were
tracked as they migrated from a breeding pond into the surrounding uplands
(Richter et al. 2001). However, no study has focused exclusively on
the ecology of Gopher Frogs in the terrestrial environment, and therefore,
information is lacking on use of terrestrial habitats by these frogs. For
example, there are no data available on the number of or specific types of
Gopher Tortoise burrows used by Gopher Frogs, or the amount of time
they spend at individual burrows. Additional research on the breeding
biology of Gopher Frogs is certainly needed. However, studies of their
terrestrial requirements are crucial for land managers attempting to conserve
these imperiled species.
The purpose of this investigation was to determine the terrestrial locations
of Gopher Frogs in central Florida using radio telemetry. This study
focused on habitat use, movements, and site fidelity of Gopher Frogs at their
I established two study areas in locations known to harbor Gopher Frogs;
Chuluota Wilderness Area (CWA) (28°38'10"N, 81°05'30"W) in Seminole
County and Rock Springs Run State Reserve (RSR) (28°47'31"N,
81°26'50"W) in Lake and Orange Counties. One study plot was established
at CWA (Fig. 1), and two study plots (RSR1, RSR2) were established at RSR
(Fig. 2). Prior to the protection of CWA and RSR, they were both used as
cattle ranches (among other uses). Chuluota Wilderness Area, a 625-acre
site, contains remnant sandhill habitat surrounding the one-hectare study
2006 W.B. Bilhovde 267
Figure 1. Burrows occupied and unoccupied by Gopher Frogs at Chuluota Wilderness
Figure 2. Burrows occupied and unoccupied by Gopher Frogs at Rock Springs Run
State reserve, FL.
268 Southeastern Naturalist Vol. 5, No. 2
plot that has been overtaken by oak species due to the lack of fire. At CWA,
the only potential breeding pond was approximately 460 m from the center
of the study plot (Fig. 1). Rock Springs Run State Reserve, 13,850 acres in
size, has been intensively managed and contains many acres of restored
sandhill communities. At RSR, the closest confirmed breeding pond, on the
east side of County Road 433, was 130 m from the center of RSR1 (Fig. 2).
The pond on the west side of CR 433 was 218 m from the center of RSR1;
Gopher Frogs were heard calling at both sites.
During each of fourteen months (April 1999 to May 2000), I conducted a
systematic search in each one-hectare study plot to locate Gopher Frogs at
vertebrate burrows that could serve as retreat sites. I marked every potential
terrestrial retreat found with a surveyor’s flag, and later recorded the specific
locations via GPS with a Trimble Pro XR/XRS and a TDC1 data logger. The
GPS locations of burrows were overlaid onto aerial photos in ArcView GIS
software. Burrows where I observed a Gopher Frog at least once during the
study were designated as “occupied burrows.” I never observed frogs at
I fitted Gopher Frogs with radio transmitters to monitor their movements
among terrestrial retreats. Because of potential problems associated with
externally attached transmitters (e.g., Rathbun and Murphey 1996), I chose
to implant transmitters (see below). Candidate frogs for radio-tracking were
found during nocturnal or early-morning surveys of the one-hectare study
sites. Every burrow was investigated while I walked transects through the
study sites. I used a flashlight to thoroughly scan the burrows before I
approached them. I captured frogs by quickly placing a net between frogs
and the entrances to burrows they used as terrestrial retreats.
I surgically implanted small, 1.5-g radio transmitters (AVM Instrument
Company, Ltd, Colfax, CA) into the coelomic cavity of the frogs. Surgical
procedures followed those for Bufo marinus (Linneaus) and B. americanus
(Holbrook) (Seebacher and Alford 1999, Werner 1991). Frogs were held for
24–72 hours until the incisions were healed and the frogs recovered. Frogs
were then toe-clipped, measured (snout-to-vent length), and weighed. All
frogs, except #8 and #9 at RSR, were released at their original burrows. I
displaced these two individuals to the nearest active tortoise burrow (approx.
10 m away from their capture locations), to determine if they would move
back to their original burrows. Initially, I attempted to locate radio-implanted
frogs every 24 hours. However, once it was clear that they were
sedentary, I extended the tracking interval to every 72 hours. I made more
frequent attempts to track implanted frogs during rainfall events, when I
expected them to be more active.
Frogs that were radio-located at more than one burrow (e.g., activity
center) during the study were included in estimates of upland home range. I
used ArcView GIS software and the GPS locations for each frog’s activity
center to calculate home ranges. Several frogs made only one documented
movement to a new activity center and then back to their original burrow. In
2006 W.B. Bilhovde 269
these cases, the minimum rectangular path was used to represent the polygon
the frogs likely traveled.
During statistical analysis of the Gopher Frog movements (number of
burrows used and home-range size), frogs #4 and #9 were removed. This was
done because frog #4 moved to the breeding pond (making much greater
movements than frogs that stayed in the uplands) and because #9’s transmitter
failed before movements could be observed.
In total, 127 burrows were located during surveys to find potential
terrestrial retreat sites. These included 66 burrows at CWA, 30 burrows at
RSR1, and 31 burrows at RSR2. At CWA, at least 21 (31.8%) burrows were
occupied at some point during the study. Burrows were not used as heavily at
RSR, where seven (23.3%) burrows were occupied at RSR1, and six (19.4%)
burrows were occupied at RSR2 (Fig. 2).
The following individuals are included as examples of either extraordinary
site fidelity to a single burrow or use of several burrows. Frog #1 at
RSR was seen throughout the observation period (e.g., during the 14-
monthly burrow survey period). This frog made no documented movements
during the survey period. Frog #3 at RSR was found at the same abandoned
pocket gopher (Geomys pinetis Rafinesque) burrow, in the same hunting
position for 14 months. However, it was documented making a short movement
while being radio-located (see below). Frog #7 at CWA was located
approximately 33 m from its original burrow. This frog was a male that was
located at three different burrows (including its original).
I successfully performed surgery to implant transmitters in nine individuals
that were captured at their burrow entrances. To replace failed
transmitters, I performed multiple surgeries on some frogs. Surgery was
performed four times on frog #1 (two insertions and two removals). It
received two separate transmitters because the first transmitter’s battery
failed. Frog #2 was implanted with one transmitter, and therefore surgery
was performed two times (one insertion and one removal). Surgery was
performed three times on frog #3 (two insertions and one removal). This
frog’s first transmitter failed immediately after surgery and was replaced
with a new transmitter the following day. Frogs #4 and #5 were implanted
with transmitters on 6 October 1999 and those transmitters were not removed.
Frog #6 was implanted with a transmitter on 5 November 1999 and
that transmitter was removed on 3 March 2000. Two surgeries were performed
on frog #7 (two transmitters had to be inserted). The first transmitter
failed immediately after surgery and was replaced on the following day. The
second transmitter was not removed. Frogs #8 and #9 had transmitters inserted
on 1 May 2000. These transmitters were not removed from either frog.
270 Southeastern Naturalist Vol. 5, No. 2
No frog died during surgery, and frog #8 was the only individual to
show signs of infection. This frog had a slight swelling around the incision,
including a slight purple discoloration. Incisions always healed in two to
three days, and after several weeks, incisions were no longer evident. Nine
frogs were implanted with transmitters however, six of those transmitters
failed completely. Those transmitters were replaced with working transmitters,
unless adequate movement data had been gathered prior to the
transmitter failing. In addition to transmitter failure, transmitter range was
lower than expected (approx. 20 m).
Movements of individual frogs
The length of time a frog stayed at a burrow varied greatly. Frog #1
was radio-located for six weeks. This frog, implanted with a transmitter
on 12 September 1999, made no movements during the duration of its
transmitter’s life (Table 1, Fig. 3). After the transmitter battery failed,
this frog continued to use the same burrow for the duration of the
monthly burrow surveys.
Frog #2 moved a total of 35 m and used three different burrows during
the three months that it was tracked (Fig. 3, Table 1). Although it was a
female, it was never documented at the breeding pond, most likely due to
unfavorably dry conditions that persisted during the study period.
Frog #3 was implanted with its first transmitter on 12 September 1999;
its second transmitter was implanted on 13 September 1999. This frog’s only
movement was documented during heavy rain on 1 November 1999, during
which it moved 10-m from the original burrow (Table 1). The frog was back
inside its original burrow the next day.
Frog #4, a male, moved the greatest distance (286 m) of all animals in the
study. It made a breeding migration of approx. 90 m on 10 October 1999.
This movement was initiated by heavy rain that prompted several frogs to
start calling in the nearest breeding pond. This frog was then located at a new
burrow south of the breeding pond the next night (11 October), was located
back at the pond by 16 October, and was located at the east side of the pond
Table 1. Movement distances for the 9 tracked Rana capito at Chuluota Wilderness Area and
Rock Springs Run State Reserve, FL. Frogs #4 and #9 were not included in the burrow and
Number of Total distance
Frog # Sex Dates tracked SVL (cm) burrows used moved (m)
1 F 13 Sept–27 Oct 1999 8.8 1 0
2 F 15 Sept–29 Nov 1999 8.3 3 35
3 F 15 Sept–26 Nov 1999 8.7 2 20
4 M 7 Oct–15 Nov 1999 7.5 2 286
5 M 7 Oct–15 Nov 1999 8.7 1 0
6 F 5 Nov, 99– 3 Mar 2000 9.7 2 1
7 M 18 Feb–10 Apr 2000 9.0 3 33
8 F 1 May–22 June 2000 9.1 4 18
9 F 1 May–5 May 2000 9.0 1 0
Mean 8.76 2.28 15.28
Standard deviation 0.60 1.11 15.29
2006 W.B. Bilhovde 271
on 19 October (Fig. 3, Table 1). On 5 November, the frog was back in the
middle of the pond, and then located at the north end of the pond on 9
November. The transmitter could no longer be heard on 11 November.
Frog #5 was tracked for five weeks. It was never located away from its
original burrow (Table 1), and thus had only one activity center.
Frog #6, which I located via radio transmitter for almost 4 months, made
one short movement. This frog was documented using two burrows, which
were 1 m apart (Table 1).
Frog #7 was released on 21 February 2000 at its original burrow and was
located at another burrow 10 m away on 29 February. The frog was located
back at its original burrow on 10 March where it stayed until the transmitter
failed (Fig. 4, Table 1). This frog was also documented moving during the
burrow surveys after the transmitter had been removed.
Frog #8 was released at a burrow 10 m from its original burrow. Within
three days of its release, frog #8 had returned to its original burrow. On 8
May 2000, it was located at a second burrow, approx. 3 m southeast of the
release burrow, at a third burrow on 12 May, and then a new burrow 2 m
south of the original burrow on 26 May. This frog was then located back at
its original burrow on 22 June (Fig. 3, Table 1).
Frog #9 was also released at a different burrow 10 m away from its
original burrow. The transmitter in frog #9 worked at the time of release,
however three days after its release there was no signal from its transmitter
Figure 3. Movement of Gopher Frogs 2, 4, and 8 at Rock Springs Run State Reserve,
FL. Movements made by each frog are numbered in the order they were made.
272 Southeastern Naturalist Vol. 5, No. 2
(most likely due to transmitter failure or predation; Table 1). Therefore,
frog #9 could not be found and no data were gathered on site fidelity or
Frogs #2 and #4 at RSR had the largest minimum convex polygon
estimates based on their number of upland activity centers. Frog #2 had
the largest upland home range, yet it only moved a total of 35 m. Frog #4
had the greatest movement distance by far, and had a home range of
approximately 169 m2 (Table 2). Because frogs #3, #6, and #8 had very
Figure 4. Movements of frog 7 at Chuluota Wilderness Area, FL.
Table 2. Upland home range estimates for Gopher Frogs from Chuluota Wilderness Area and Rock
Springs Run State Reserve, FL. Frogs #4 and #9 were not included in the home range analysis.
Frog # of activity centers (burrows) Minimum convex polygon (m2)
1 (RSR) 1 0.00
2 (RSR) 3 221.88
3 (RSR) 2 20.59
4 (RSR) 2 169.98
5 (RSR) 1 0.00
6 (CWA) 2 11.15
7 (CWA) 3 50.53
8 (RSR) 4 12.91
9 (RSR) 1 0.00
Standard deviation 79.73
2006 W.B. Bilhovde 273
restricted movements, the estimates for their minimum convex polygons
were small. Home-range estimates could not be calculated for three frogs
(#1, #5, and #9) because they had one activity center (Table 2).
Data from this radio telemetry study yielded important information on
the natural history of Gopher Frogs in central Florida. Frogs spent most of
their time in subterranean retreats, primarily the burrows of Gopher Tortoises
and pocket gophers. Frogs used from one to four retreats, but moved
little during the study. However, one frog moved a total of 286 m, which
included a breeding migration of approximately 90 m.
Research has suggested that Gopher Frogs move without preference
through upland habitats (Greenberg 2001), but my study indicates that they
can regularly navigate distances of at least 10 m. In addition, one study
documented a Rana sevosa individual move 236 m to a breeding pond and
then back to the original burrow (Richter et al. 2001). In this study, two frogs
released away from the burrows where they were captured moved back to
their capture burrows. One returned to its capture burrow the following day.
Several frogs in my study used multiple terrestrial retreats and did not
appear to move among potential retreats at random.
Gopher Frogs do not make many movements outside of the breeding
season. Richter et al. (2001) found that Dusky Gopher Frogs exhibited
inactivity following breeding migrations. Similarly, frogs in my study were
sedentary before and after breeding migrations. Data from my burrow surveys
and radio locations of animals in the uplands showed that Gopher Frogs
commonly stayed inactive in their upland shelters for months at a time,
spending up to 14 months away from breeding ponds. Despite relatively
sedentary behavior of the frogs, the mean home-range size for all frogs was
45.29 m2 (not including breeding movements).
Drought that occurred during the study period likely contributed to the
sedentary nature of the frogs. After successive years of drought, ponds in
central Florida (including those at RSR and CWA) held very little water,
which may have increased the level of site fidelity frogs exhibited. Rainfall
has significant effects on the behavior of this species (Jensen et al. 2003);
lack of moisture may therefore have affected my findings. Even though it is
the most terrestrial ranid frog in Florida, Gopher Frogs are susceptible to
desiccation in the dry, sandy uplands they inhabit. They depend on upland
retreats to avoid predators and maintain adequate hydration, especially during
drought. Thus, my results underscore the importance of well-managed
upland habitats with numerous subterranean shelters for the persistence of
Because they require numerous upland shelters, Gopher Frogs also depend
on those species that build burrows. The loss of the Gopher Tortoise or
the pocket gopher would remove the primary source of their upland shelters.
For instance, one such threat (a large Gopher Tortoise die-off) occurred just
274 Southeastern Naturalist Vol. 5, No. 2
after this study near the RSP site (Rabatsky and Blihovde 2002). Increases in
tortoise mortality events across Florida may exacerbate the decline of burrow
commensals, including Gopher Frogs (Eisenberg 1983, Gates et al.
2002). My data indicate that pocket gophers, via the construction of burrows,
are extremely important to Gopher Frogs. Without burrow shelters in
the uplands, Gopher Frogs would very likely have a difficult time surviving
a drought like the one encountered in this study.
Increased scientific focus on pond-breeding amphibians has led to important
life history discoveries for many amphibians in the Southeast (Dodd
1997). There are numerous studies that promote the establishment of buffer
zones, and perhaps more appropriately, core habitat around breeding ponds
(Semlitsch 1998). The upland habitat around isolated ponds in central
Florida, including the microhabitats of Gopher Tortoise and pocket gopher
burrows, is part of the Gopher Frog’s core habitat. Removal of the upland
habitat and loss of the shelters there would be as destructive to Gopher Frogs
as removing the essential breeding pond where eggs are deposited. Researchers
have recommended a terrestrial buffer surrounding the core habitat
to protect upland habitat for semi-aquatic species of amphibians (Semlitsch
and Jensen 2001). The aquatic buffer, core habitat, and terrestrial buffer can
be combined into a life zone for some species. For instance, the Gopher Frog
spends a great deal of time in the terrestrial uplands. The uplands are so
important to the Gopher Frog that they should be considered essential
portions of their life zone.
I thank L.M. Ehrhart, W.K. Taylor, J.F. Weishampel, P.E. Moler, R. Mulholland,
and R.A. Seigel for their critiques of earlier versions of this paper. J. Duby, J.
Fillyaw, R. Franz, J. Gibson, E. High, T. Hirama, J. Jensen, B. Kermeen, T. Mallow,
J.C. Mixon, D. Nickerson, J. Plitt, S. Richter, F. Seebacher, P. Small, I.J. Stout, and
Seminole County Natural Lands and Wetiva River Basin State Parks provided
assistance. The Gopher Tortoise Council, Hughes Supply Co., S. Fullerton, L.M.
Ehrhart, J.F. Weishampel, and UCF Department of Biology provided crucial funding.
Thanks to Steve Johnson (for extraordinary editing assistance on the latest
version), Stephen Richter, and one anonymous reviewer for great suggestions to the
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