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2008 SOUTHEASTERN NATURALIST 7(3):381–400
Counting Pumas by Categorizing Physical Evidence
Roy T. McBride1,*, Rocky T. McBride2, Rowdy M. McBride1,
and Cougar E. McBride1
Abstract - The occurrence of Puma concolor (Cougar) can be confirmed by detecting
physical evidence (i.e., tracks, urine markers). However, determining the number of
pumas responsible for creating this sign is problematic. We addressed this difficulty
by categorizing physical evidence (sign) and applied this method during the Puma
concolor coryi (Florida Panther) project. Three rules were used to distinguish individuals.
(1) Gender was determined by track size or stride length; (2) time (freshness)
was determined by known events within the past 24 hours, such as wind or rain; and
(3) distance between individual track sets was used as an exclusionary tool to avoid
over-counting. We evaluated accuracy by capture and by comparison to 3 other indices.
This method can be adapted to count other large felines.
An accurate method of assessing puma numbers is needed. At Puma concolor
L. (Cougar) workshops in western states, some wildlife managers responsible
for determining statewide puma numbers decline to speculate, simply
because they do not have a reliable cost-effective method to estimate population
numbers (Apeker 2003). In addition, at times when we were employed to
remove all problem pumas from a designated area, without exception our capture
results indicated that population estimates provided to us prior to removal
had been exaggerated. To remedy these problems, we have developed a method
which uses gender, time, and distance to distinguish individual pumas.
Since the early 1960s, as professional puma hunters and field biologists,
we have live-captured pumas for 10 telemetry studies, both in North and South
America. During these experiences with problem animal control and telemetry
work, we had the opportunity to refine our method of counting pumas. Southern
Florida has provided an ideal landscape for further evaluation of our method.
Following the passage of the Endangered Species Act, the critical status of
Puma concolor coryi (Florida Panther) required a reliable population count.
Prior to 1972, population estimates for the Florida Panther were based solely on
sightings, interviews, questionnaires, and unfounded guesses that ranged from
extinction (W. Piper, co-owner of Everglades Wonder Gardens, Bonita Springs,
FL, pers. comm.) to 300 (Layne and McCauly 1976). The usefulness of sightings
became suspect when Schemnitz (1972) received numerous reports of
black panthers. In 1972, the World Wildlife Fund sponsored a preliminary
investigation to determine if panthers still survived in Florida (Nowak 1973).
1Livestock Protection Company, 26690 Pine Oaks Road, Ochopee, FL 34141. 2Project
Jaguar, Faro Moro Eco Research, PO Box 478, Filadelfia, Chaco, Paraguay 9300.
*Corresponding author - (432) 837-3630.
382 Southeastern Naturalist Vol.7, No. 3
Through track surveys and the use of trained hounds, we documented a remnant
panther population in southern Florida (Nowak and McBride 1974, 1975). Encouraged
by empirical evidence that panthers were not extinct, the Florida Fish
and Wildlife Conservation Commission (FL FWC) established a clearinghouse
in 1976 for the purpose of collecting and analyzing all reports of panthers. Subsequently,
panther sightings were reported statewide; however, Belden (1978)
found that most could not be confirmed and determined that sightings were less
reliable than physical evidence. Van Dyke and Brocke (1987) also concluded
that “sighting reports are less efficient, less systematic, and less reliable than
other methods of checking for mountain lion presence.” In an overview of
published papers surveying various techniques for determining or estimating
carnivore populations, Linnell et al. (1998) found that documentation of physical
sign was more accurate than estimates based on extrapolations, computer
models, or statistical sampling methods using transects or grids.
To record verifiable physical evidence, e.g., tracks, scats, kills, and
urine markers (scrapes), qualified field personnel were contracted to search
the areas identified by the World Wildlife Fund (Belden and McBride 1983,
Reeves 1978). These preliminary sign surveys culminated in 1985 with
the documentation of 30 panthers in southern Florida (McBride 1985). Although
pumas are generally perceived to be secretive and difficult to count,
they leave abundant tracks and urine markers over large areas, enabling
trained personnel to detect their presence (Van Dyke et al. 1986). The difficulty
arises when trying to determine the number of pumas responsible
for leaving these tracks and urine markers. The most common mistake is to
overcount by attributing an accumulation of tracks left by one individual
as being made by several pumas. Our objective is to provide an annual
count of panthers based solely on physical evidence and to use these data
to monitor the status of the population and evaluate the effectiveness of
recovery efforts. We define the term “annual count” as an attempt to detect,
identify, and record as many individual panthers as possible in each survey
unit (Fig. 1).
Unique conditions that make a count of panthers in Florida feasible
include the limited spatial extent of occupied habitat, small panther population
size, and isolation from the nearest puma population by >3000 km,
eliminating the possibility of immigration. Another advantage is the constantly
changing weather patterns (e.g., frequent rains and winds) that will
often “wipe the slate clean,” providing the surveyor with known events to
help age tracks and a fresh medium on which to search. Panther range within
the study area has been mapped by >80,000 telemetry locations recorded
from 157 radio-collared panthers captured between 1981 and 2007 (Fig. 1).
The northern boundary of the occupied panther range extends north to
2008 R.T. McBride, R.T. McBride, R.M. McBride, and C.E. McBride 383
within 16 km of the Caloosahatchee River (Fig. 1). North of this river, in
south-central Florida, transient males are found periodically. Extensive surveys
and recovery of highway mortalities north of the river during the past
3 decades have produced no evidence of reproduction or females (Belden
and McBride 2005).
The panther’s range in southern Florida, where reproduction does occur,
encompasses approximately 890,000 ha (Kautz et al. 2006). It contains a
mosaic of swamps, freshwater marshes, prairies, and hardwood hammocks,
all of which are used by panthers and their prey. This habitat is seasonally
fl ooded in summer and fall by convection rainfall, tropical storms, and hurricanes.
The spring dry-down that follows the wet season exposes broad
expanses of clay marl and fine-grained sand, producing an ideal substrate for
locating and identifying panther tracks (Fig. 2). Viewed from the outside, the
Big Cypress Swamp looks challenging and difficult to penetrate, but even
this large swamp system is laced with old logging trams, swamp buggy ruts,
fire breaks, and game trails where panther sign is easily found by qualified
trackers (i.e., professional puma hunters and/or wildlife biologists who have
been extensively trained to locate and identify puma sign).
Figure 1. The occupied
range in Florida
has been clearly
mapped by track
>80,000 radio telemetry
Since 1999, the
has been divided
into 9 survey units
to make an annual
9, north of the
River, is used only
no evidence of
384 Southeastern Naturalist Vol.7, No. 3
The study area was divided into 9 geographic units separated by identifiable landscape features, such as highways, canals, and rivers (Fig. 1).
The current telemetry record of collared panthers in each unit was useful in
distinguishing tracks of un-collared panthers. When sign of an un-collared
panther was discovered, date and location were recorded, along with gender
and age of the sign. In addition to field notes, we began duplicating the same
information on data sheets in 1997, noting precise locations when hand-held
GPS units became available. Photos of physical evidence were used as additional
documentation (Fig. 2).
The capture season usually extended from November to March, but
population data were collected year round. During capture season, the
houndsman and other members of the capture team (i.e., tree climber, veterinarian,
and capture team biologist), would search for panther sign from
all-terrain vehicles (ATV) or swamp buggies. Team members traveled
from 1 to 20 km apart on trails, firebreaks, old swamp buggy tracks, and
logging and ranch roads in a designated unit. Units that were not hunted
during the capture season were investigated later by the houndsman and
Figure 2. Sample
showing the location
tracks made after
a rain the
track size and
adult male and
2008 R.T. McBride, R.T. McBride, R.M. McBride, and C.E. McBride 385
hounds. Survey units are small enough that one person can identify the
resident panther population with sufficient effort. This year-round effort
maximized the possibility that resident adult and juvenile panthers living
in each survey unit could be detected. This hypothesis is supported by
Van Dyke et al. (1986), who used collared pumas to evaluate their track
detection success and concluded that “probably all collared lions on the
Kaibab would have been detected by consistent track searches, however,
it may have taken months to do so, depending on tracking conditions.”
Results of our annual counts are found in Figure 3.
Additional panther data were provided opportunistically by other agency
biologists while conducting deer track counts, disking fire breaks, surveying
with trail cameras, investigating depredation complaints, and conducting a
variety of other field activities. Un-collared panthers were also documented
when sighted and photographed by the biologist or pilot from the telemetry
Figure 3. The number of Florida Panthers documented by physical evidence from
1981 to 2007. The small dashed line between 1981 and 1985 refl ects the increasing
number of panthers added to the sample as we discovered them. Thereafter, the
graph refl ects increases and decreases in the known population. In 1994 and 2004,
the population was unknown due to an incomplete census. There is no evidence that
the panther population increased or decreased during these years and this unknown
is expressed by a dotted line. Each census year begins at zero and increases as panthers,
other than collared panthers, are discovered. The panther population fl uctuated
between 19 and 30 adults prior to 1995. After 1995, population numbers began to
increase, coinciding with genetic restoration efforts.
386 Southeastern Naturalist Vol.7, No. 3
aircraft. Repeated documentation of an un-collared panther in a home-rangesized
area of a survey unit, regardless of the method (i.e., tracks, treeing with
hounds, trail camera photos, or spotting from an airplane) was considered
confirmation of one un-collared panther, rather than the discovery of an additional
Panther tracks were used to determine gender, indicate family groups, and
to identify areas used by panthers. Panthers occupy large home ranges and
are constantly on the move within those ranges; therefore many tracks simply
represent an accumulation of sign made by the same animal. To avoid overcounting
(especially males) or under-counting (females whose movements
were restricted if denning), we developed a method of exclusion that enabled us
to distinguish between individual panthers using gender, time, and distance.
We used track size only to differentiate gender (Fjelline and Mansfield
1989, Ross and Jalkotzy 1992, Stoner et al. 2006). No attempt was made to
identify individuals by measuring track size, and we acknowledge the difficulties associated with this technique (Grigione et al. 1999, Karanth et al.
2003.). Logan and Sweanor (2001) reported that in a sample of 64 females
>17 months old, the width of their right hind heel pads did not exceed 4.8
cm. In a sample of 46 males >17 months old, only 2 were <4.9 cm. Out of
their sample of 110 pumas of this age group, pad sizes of only 2 males overlapped
those of females. None of the female pad sizes overlapped those of
males. Before juvenile males reach dispersal age, their tracks are larger than
their mothers’ and have developed sufficiently for gender identification. To
further assist in determination of gender, we used length of stride by measuring
from the heel of the left front foot to the toe of the right front foot. In
a slow walk, adult female strides ranged from 46 cm to 55.5 cm, and adult
male strides ranged from 61 cm to 74 cm (Fig. 2). During the slow walk, the
hind foot is placed closely in front of the front foot (overstep). Other gaits
include an extended walk (the hind foot being placed in the track of the front
foot) or side by side when jumping or running. As a cautionary note, length
of stride should be measured using only the slow walk and only on level
ground. The comparison of different gaits vs. the slow walk will invalidate
the method. Once gender was determined, our system used time and distance
to differentiate between adult individuals of the same sex. We did not use
urine markers to determine gender because both sexes make this sign.
Rather than relying on subjective track decomposition to determine
freshness, our method relied on determining if the tracks had been made
within the past 24 hours. Thus, to age tracks and to make our method accessible
to less experienced trackers, we used known events that occurred
within the previous 24 hours (e.g., tracks made after a rain the previous day,
clear tracks in loose sand following wind, tracks found on top of our vehicle
2008 R.T. McBride, R.T. McBride, R.M. McBride, and C.E. McBride 387
tracks or on roads we had brushed with a drag the day before, and tracks with
lingering scent that could still be detected by trained hounds. Even when
tracks <24 hours old were visible to observers, our hounds were not able to
detect scent trails >12 hours old).
Knight et al. (1995) described using trained observers to record date and
distance between sightings of female grizzly bears with cubs-of-the-year to
determine distinct family groups. These data were used to estimate a minimum
number of adult females. In the case of panthers, we used distance in
a similar fashion, but we relied on tracks instead of sightings due to their
nocturnal nature and use of cover. When panther tracks <24 hrs old were
located in a survey unit, we identified them by gender and computed their
distance with any additional sets of panther tracks of the same gender found
during the same 24-hour period. We applied a distance rule of >10 km to
separate one individual female tracks from another and a >17 km rule for
separating individual males. For example, female tracks <24 hrs old and >10
km from the nearest additional set of fresh female tracks were determined
to be 2 different females (Fig. 4). We applied a <17 km and <24-hour rule
to differentiate between males (Fig. 5). Although we have successfully used
this method extensively without the aid of telemetry, telemetry made it easier
by enabling us to identify tracks of collared panthers in order to distinguish
them from tracks left by un-collared panthers.
We initially based our distance rules for the Florida Panther on our experience
while trailing pumas with hounds. The maximum distance from point
of origin (abandoned kill site) to capture was <10 km for females and <17
km for males. Our distance rules are consistent with those of Janis and Clark
(2002), who collected daily panther locations in Florida from 1995 to 1998.
Although not included in their published research, the 24-hour data collected
during their study supported our distance rules. Of 3015 observations of
24-hour movements for females, 99% were <9.6 km; of 824 observations
of 24-hour movements for male panthers, 99% were <16.7 km (M.W. Janis,
Texas Parks and Wildlife, Matador Wildlife Management Area, Paduca,
TX, unpubl. data.). More recently, data from 2 GPS collars programmed to
collect hourly locations on 1 resident male and 1 resident female provided
additional support for our distance rules. The female moved maximum
straight-line distances of 0.08 km to 7.4 km (mean = 2.1 km, SE = 0.2,
n = 60) from starting locations during 5 randomly sampled 24-hour periods
per month from March 2005 to February 2006 (J. Benson, Trent University,
Peterborough, ON, Canada, unpubl. data). The male moved maximum
straight-line distances of 0.08 km to 8.2 km (mean = 3.5 km, SE = 0.4, n =
25) from starting locations during 5 randomly sampled 24-hour periods per
month from April 2005 to August 2005 (J. Benson, unpubl. data). It is widely
recognized that subadult male pumas travel extensively while dispersing, but
388 Southeastern Naturalist Vol.7, No. 3
Figure 4. Tracks A, B, and C represent fresh female Florida Panther tracks <24 hrs
old as determined by known events. Each of the three tracks were located >10 km
from the other two. The distances separating these fresh tracks of the same gender
indicate 3 different animals.
Figure 5. The same criteria were used when categorizing male tracks, except that the
distance rule was increased to >17 km
2008 R.T. McBride, R.T. McBride, R.M. McBride, and C.E. McBride 389
even the longest subadult male puma movement recorded (Thompson and
Jenks 2005) still averaged well below our 24-hour distance rule for male
movements of <17 km in <24 hours.
When fresh female tracks were found <10 km from another set of female
tracks, or male tracks <17 km from another set of male tracks, the panthers
were not added to the inventory. We recognize that adult panthers of the
same sex at times are in close proximity to one another and not distinguishable
by distance rules. However, repeated searches afford the opportunity for
track sets to be found far enough apart that they can be identified as separate
individuals. Occasionally, we differentiated between individuals using some
exclusive anomaly in the track (e.g., crooked toes, missing toes, a leading
toe, a crooked foot, an injured heel pad, or a female accompanied by juveniles).
These track irregularities can be used for conclusive identification.
Trained hounds were used to increase survey productivity in areas
where tracking was difficult. These hounds, relying on their keen sense of
smell rather than sight, were able to follow the unique scent trails left by
panthers and tree them in areas where tracks were not visible. Un-collared
panthers treed by hounds during track surveys were photographed, GPS locations
taken, and genders noted.
Our annual population count refl ects the total number of panthers confirmed by physical evidence during one calendar year. Each year’s annual
count included a list of collared panthers still active in their respective geographic
unit. Collared panthers ranging over the boundaries between two
survey units were assigned to a single unit in order to avoid over-counting.
The count included only adult and juvenile panthers, not kittens at the den.
Although some of our annual counts have been reported in the past based
on the FWC fiscal year (i.e., 1 July to 30 June; McBride 2000, 2001, 2002,
2003), the counts reported herein have been recomputed to represent the
number of panthers documented during a calendar year.
Collecting data for comparable indices
Captures per day of hunting effort. We have used trained hounds to
capture panthers as study animals in Florida since 1981. “Hunting effort”
is defined as a day when the full capture team was present and the dogs
were released to sweep an area. Prior to releasing the hounds, members of
the capture team scanned the vicinity with telemetry equipment to avoid
casting the hounds near collared panthers. If we discovered that the hounds
were trailing a collared panther, we attempted to intercept them. In spite of
these efforts, we accidentally treed collared panthers frequently, but these
panthers were not included in the capture-per-hunting-effort results. Collared
panthers that were scheduled for routine re-collaring or for booster
vaccinations were also omitted from the hunting-effort-per-capture data. We
avoided using radio-collared panthers in determining capture rates because
390 Southeastern Naturalist Vol.7, No. 3
of the bias associated with using a radio signal to guide the dogs to a collared
panther or to interrupt the pursuit of a collared panther.
The panthers used to determine capture rates consisted of un-collared
panthers or panthers with non functioning collars (Fig. 6). Panthers with
nonfunctioning collars were considered to be the same as un-collared panthers
because they were just as difficult to capture. For optimum safety and
efficacy, captures were normally scheduled during the cooler months of the
year (November to March). Between 1981 and 1995, as many as 3 houndsmen
worked simultaneously in different survey units. Since 1995, only 1 to
2 houndsmen have been used simultaneously in different survey units. To
compensate for variation in number of teams, we counted 2 hunting days if
2 hound teams were working simultaneously on the same day, and 3 hunting
days if 3 teams were working. Hunting effort per capture was determined by
dividing the number of hunting days by the number of panthers treed. Captures
per day of hunting effort (i.e., capture rate; Fig. 6) were determined by
dividing the number of captures by the number of days hunted.
Figure 6. In 1983 and 1994, the capture rate dropped to zero because only re-collaring
efforts were conducted during those 2 years. The capture rate closely followed
the annual count until 2003. The sharp decline in 2003 refl ects the combination of 26
mortalities, 3 removals from the population, and possibly the effects of feline leukemia.
Our capture efforts were focused in areas where feline leukemia mortalities had
occurred in order to vaccinate survivors. In addition, juvenile offspring of collared
females were often allowed to disperse without collaring. This protocol represents
a change in policy from previous years, when most juveniles were collared before
dispersal. The capture rate returned to its post-1995 trend in 2007.
2008 R.T. McBride, R.T. McBride, R.M. McBride, and C.E. McBride 391
Highway mortalities. During the past 28 years, FWC has collected and
recorded highway mortalities and performed post-mortem necropsies (FWC,
Naples, FL, unpubl. data). The Florida Museum of Natural History is the
repository for these specimens.
Number of dispersals outside the occupied range. Since 1976, Belden
and McBride (2005) have periodically conducted intensive surveys to document
the presence and number of panthers found in central Florida north
of the Caloosahatchee River, as confirmed by telemetry, tracks, or highway
mortality data. Because no females or evidence of reproduction have been
found in these areas since 1973, these male panthers are considered to have
dispersed from the occupied range in southern Florida.
The number of panthers detected and verified by physical evidence from
1981 to 1994 fl uctuated between a high of 30 and a low of 19 adult and
juvenile panthers, with the lowest point occurring in 1991 following the
removal of 7 juveniles and 3 neonate kittens to initiate a program for captive
breeding. In 1995, 8 female pumas from Texas were released to address the
suspected deleterious effects of inbreeding. The last of these females was
removed in 2003. The number of panthers detected and verified by physical
evidence increased to 117 by 2007 (mortalities not subtracted; Fig. 3).
From 1981 to 1997, highway mortalities averaged 1.4 per year; from
1998 to 1999, the highway mortality average more than doubled to 3 per year;
from 2000 to 2007, it has more than tripled to an average of 10.8 per year. The
record high was recorded in 2007 with 15 highway mortalities, which corresponds
with our record high annual count (Fig. 7).
Captures per day of hunting effort
From 1981 to 1994, we conducted 12 capture seasons. During this period,
we hunted panthers 1258 days, averaging 104.8 days per capture season. We
treed 67 un-collared panthers and panthers with failed collars, averaging
5.5 panthers per season with an average of 18.7 days of effort per capture.
From 1995 to 2007, we conducted 13 capture seasons. We hunted panthers
920 days, averaging 70.7 days per capture season. We treed 168 un-collared
panthers and panthers with failed collars, averaging 12.9 panthers per season
with an average of 5.5 days of effort per capture. Therefore, after 1995, the
rate of captures increased by a multiple of 3.4 (Fig. 6).
Number of dispersals (collared and un-collared) outside the occupied
Ten male panthers were documented in central Florida from 1981 to
1991. No panthers were recorded in this region from 1992 to 1997. However,
392 Southeastern Naturalist Vol.7, No. 3
17 male panthers were documented there from 1998 to 2007 (Fig. 8). Given
the absence of female and juvenile panthers in this same area, the males that
were recorded likely dispersed from the population in southern Florida.
The Endangered Species Act requires the US Fish and Wildlife Service
(USFWS) to use the best available science in the listing, recovery, and
delisting of endangered species. To establish and maintain credibility, this
science should rely on verifiable physical evidence. Our annual count has
been used for important management decisions by the agencies entrusted
with panther recovery since 1981 (e.g., captive breeding and genetic restoration).
Our system of counting panthers relies entirely on the collection of
physical evidence and circumvents the need to identify individuals by track
size. We avoided using track size to identify individuals because we repeatedly
discovered that, when following an unbroken sequence of tracks obviously
left by a solitary panther, track size varied widely (e.g., as the animal
stepped from wet sand to dry sand or from soft mud on the edge of a road to
a firmer medium in the center of the road). However, we did use track size,
or stride, to determine gender. In the western US, the distinction between
male and female pumas, without the need to measure track size, is widely
Figure 7. A comparison of the annual count to annual highway mortalities. The number
of annual highway mortalities is derived from FWC unpublished data. This figure
demonstrates similar trends in both indices.
2008 R.T. McBride, R.T. McBride, R.M. McBride, and C.E. McBride 393
practiced by experienced hunting guides to select for males in order to avoid
wasting time and effort trailing females or females with young.
Linnell et al. (1998:12) reported that minimum counts, although they
produce no “statistical measure of error,” are “often the best measures that
we are able to obtain.” We agree. Linnell et al. (1998) also stated that the
main problem with traditional minimum counts is that there is no way to
determine if 2 to 3 times that number of undetected individuals might be
present. However, Van Dyke et al. (1986) reported that up to 100% of resident
radio-collared Mountain Lions, 78% of transient Mountain Lions, and
57% of cubs could be detected by track surveys in Utah. They also noted that
it would have taken months of consistent track searches for this successful
detection rate to be duplicated across their entire study area. We grant that
our method is effort dependent, requiring either multiple qualified observers
over a short period of time or 1 qualified observer over a longer period,
repeatedly and persistently returning to the survey areas. However, as Van
Dyke et al. (1986) also noted, “Analysis of track surveys suggest that under
“good dirt” tracking conditions, there is a direct relationship between trackfinding frequency and lion density” and “under good tracking conditions,
Figure 8. The number of dispersals across the Caloosahatchee River (Belden and
McBride 2005; FWC, Naples, FL, unpubl. 2007 data) includes collared and uncollared
male panthers. Although more modest in increase than the annual count, the
trend nonetheless shows a sustained rise after 2001. Due to the absence of females or
kittens in our sample, it is assumed that male panthers north of the Caloosahatchee
are dispersers from southern Florida.
394 Southeastern Naturalist Vol.7, No. 3
the majority of lions present will be found with relatively little effort.” Our
method also demonstrated density sensitivity. We detected an increase in
physical evidence and a corresponding increase in the capture rate within the
original survey area as the population increased (Figs. 3, 7).
In areas where we have captured pumas in both North and South America,
we found that resident pumas can be easily detected. Pumas travel over
large areas while hunting prey, but concentrate their movements to specific
geographic features when marking their territory, while searching for other
pumas, or when moving from one watershed to another. Generations of
puma trappers and sheep ranchers in the Trans Pecos region of Texas recognized
vulnerabilities associated with these movements and kept puma
traps set in these locations long after pumas had been removed. Dispersing
pumas, upon arrival in an unfamiliar territory, would soon be trapped in the
same locations as their predecessors. Some of these trap sites were maintained
for decades. As a result, pumas had difficulty re-colonizing parts of
their historic range until the traps were removed following the decline in
the sheep industry. For example, these high-use areas in mountainous terrain
include gaps along divides, overhangs along rocky escarpments, and
dry creek beds. In Florida, panther sign is commonly found on abandoned
logging trams, along secondary dirt roads that connect swamp systems, and
on banks of levees. Thus, one experienced puma hunter, concentrating his
search in optimum puma use areas and aided by trained hounds, can survey
large tracts of land over time with more dependable results than searches
set up using transects or grids.
Since 1981, our capture efforts have corroborated the accuracy of our
surveys by capturing panthers in the genders and numbers predicted both
with hounds and later by trail cameras as well. We consider the primarily
roadless area of freshwater marsh, surface limestone, and scattered tree
islands in Everglades National Park (ENP) (Survey Unit 1) (Fig. 1) as the
most difficult area of the 9 survey units in which to see tracks and capture
panthers. For this reason, we use it as an example. Following completion
of the 1985 track survey in ENP (McBride 1985), we determined that the
population east of Shark River Slough within Unit 1 included only 1 adult
male. Urine markers and tracks of this male were found on a regular basis
until the first week in October 1986, after which we never saw them again.
We speculated that he may have died. The remainder of the population consisted
of 7 panthers: 1 adult female without young and 2 adult females with
2 juveniles each. We determined there were 2 family groups when we found
their fresh tracks over 10 km apart on the same day. In support of this conclusion,
we were able to differentiate between the two females with juveniles
by tracks, because 1 of the juveniles was male. Our capture work began in
November 1986, and we subsequently treed all 7 of the panthers previously
identified by physical evidence (3 adult females, their 3 juvenile females,
and 1 juvenile male). Intensive efforts to capture panthers that we might
2008 R.T. McBride, R.T. McBride, R.M. McBride, and C.E. McBride 395
have over-looked turned up no further sign of un-collared panthers. The
adult females missed their breeding cycles the next year due to the absence
of the aforementioned adult male, whose sign was last seen in October 1986.
Reproduction did not resume in ENP until the juvenile male we had collared
reached sexual maturity.
Trail camera traps were deployed in 2000 in Unit 1 (D. Shindle, FL
FWC, Naples, FL, pers. comm.), providing another means of confirming
survey results. In Spring 2000, we determined by track counts (gender,
time, and distance) that the population in Unit 1 consisted of 6 collared
panthers and 1 un-collared female. Shindle’s trail camera survey from 20
September 2000 to 18 November 2000, prior to capture efforts, also recorded
1 un-collared female. As confirmation that an un-collared panther
was present, this panther was successfully treed and radio-collared on 7
November 2000. Subsequent trail camera results in Fall 2000 showed no
other un-collared panthers (D. Shindle, pers. comm.). When an un-collared
male did arrive the following Fall, we determined his presence by tracks.
His presence was further confirmed by capture on film between 3 October
2001 and 1 December 2001 (D. Shindle, pers. comm.). We had comparable
capture results following surveys in the other geographic units, which
consisted of cypress swamps, hardwood hammocks, pine flatwoods, and a
mosaic of habitats that were much easier to work in than ENP. We have no
example to offer where survey results differed from capture results by more
than 1 or 2 panthers during the 27-year study.
To further assess the soundness of our annual count (Fig. 3), we compared
our results to 3 other indices: highway mortality (Fig. 7), capture per
unit effort (Fig. 6), and dispersals outside the occupied range (Fig. 8). All
indices reflect similar patterns of fluctuation. Highway mortalities have
increased despite the fact that the primary areas where panthers were killed
in the early days of the study were bordered with panther-proof fencing in
1993 to funnel panther movements through wildlife underpasses. These
modifications have proven successful in reducing highway mortalities to
zero in the areas protected and should have produced a decline in overall
highway mortalities had the population size remained stable. Instead,
mortalities rose after 1998. Although traffic has also increased in Florida
during the past decade, panther mortalities are now occurring on secondary
and unpaved roads, some of which dead-end at private lands where traffic
has not increased and where mortalities were not occurring during the early
years of the study. Whereas adult males, adult females, and juvenile panthers
of both sexes have been recorded as highway mortalities in southern
Florida, only adult male panthers have been victims of vehicle collisions
outside this occupied range. The last female recorded in south-central
Florida was a 10-year-old barren female treed by one of the authors during
the 1972 World Wildlife Fund Survey (Nowak 1973). Van Dyke et al.
(1986) “suggest that resident females are relatively easy to detect through
396 Southeastern Naturalist Vol.7, No. 3
track surveys” and found “no support for the idea that resident lions exist
in the East but remain undetected by deliberately avoiding roads.” Since
1972, our surveys outside the occupied range have detected only dispersing
males, consistent with the fact that only males have been recovered as
Our second indicator, captures per day of hunting effort, could be related
to the efficacy of various techniques or, when hounds are used, to
the skills of the houndsmen. Noss et al. (2002), reporting on a study using
trained dogs to capture ungulates in the Bolivian Chaco, concluded:
“Finally, all hunters and all dogs in the research area are not equal, but
expert hunters and dogs can be extremely efficient.” Aside from expertise,
the results have more comparative value if the hunter, the hounds,
and the capture techniques remain unchanged throughout the study period.
The authors have captured and recaptured every panther treed in the
Florida Panther project for the past 27 years. In doing so, we have applied
identical methods in the use of hounds and even hunt with descendents
of the original hounds. This consistency in capture methods, rather than
expertise, is essential if hunting effort and capture results are used to assess
population trends. This notion would be equally true if the capture
methods included snares, cages, or traps, as long as the personnel, equipment,
methods, and study area remained consistent over the duration of
the study. Although our capture methodology has remained constant, the
project goals changed after 1995. Specific animals were targeted for capture,
fewer capture teams were operating at the same time, and capture
seasons themselves were shortened by approximately 34%. These changes,
accompanied by narrowing the focus to areas where feline leukemia mortalities
had recently occurred, and no longer hunting for kittens of collared
females, should have resulted in a dramatic decrease in captures. On the
contrary, we were catching panthers 3 times faster. Prior to 1995, each
capture required an average of 19 days of effort. Following the implementation
of genetic restoration (release of eight Texas pumas in 1995),
subsequent captures required less than 6 days of effort. Although it may
be suggested that our proficiency was increasing rather than the population,
the authors were chosen for this project because of extensive prior
experience in puma capture, over a wide geographic range and often under
conditions more difficult than those in Florida.
One area of uncertainty in our survey is based primarily on the unknown
number of panthers that occupy private lands. We were allowed to survey
and hunt these areas in southern Florida during the early years of the study
and discovered the same densities of panthers as found on adjacent public
lands. After 1990, we gradually lost access to virtually all of the private lands
because landowners feared the discovery of an endangered species would be
accompanied by restrictive regulations. The private land constitutes 22% of
the occupied range (Kautz et al. 2006). Some of the private land is currently
2008 R.T. McBride, R.T. McBride, R.M. McBride, and C.E. McBride 397
being cleared for housing, schools, shopping centers, etc, with even more
permitted for future development.
Collared panthers captured on the private land or on the adjacent public
lands have always shared and overlapped both areas. These private lands
are adjacent to public lands where survey and capture activity is conducted
routinely. Furthermore, these private lands are often intersected by public
roads and canals to which we do have access and record panther tracks on
a regular basis. Although a small percentage of the panthers on private land
may remain undetected, this area does not represent an exclusive portion of
habitat that is home to an isolated and completely unidentified population
During the 12-month period in which data collection occurs, it is certain
that some of the panthers recorded will die. Kittens previously documented
at the den may become dependent-aged juveniles. Un-collared subadults,
particularly males, may disperse into other units. However, because all
wildlife populations are in a constant state of fl ux, these caveats would be
true with any survey method. Our survey results were improved in 2007 by
initiating a synoptic method using an increased number of qualified trackers
during the spring dry down, when tracking conditions are at their best. This
method helps place dispersing males into one survey unit before they have
time to move on. These dispersers sometimes travel through multiple units
in the course of a year. Recognition of this problem, demonstrates the propensity,
regardless of the method, to over-count subadult males. However,
the percentage of the male population that consists of dispersers is small
enough that the possibility of over-counting some of them is within acceptable
It is also important to note that one segment of the population consists
of non-breeders. Some are past breeding age, some are too young to breed,
some have reproductive deficiencies that preclude breeding, and some are
geographically isolated from mates. Caution must therefore be exercised
when comparing the annual count to the estimated number of breeding adults
that would constitute a minimum viable population. It has also been argued
that un-collared panthers that appear as highway mortalities represent unknown
and uncounted panthers. However, the proximity of these mortalities
to tracks recorded in our annual count and/or the presence of transponder
chips implanted in kittens of collared females, support the likelihood that
these panthers have been documented.
The annual count will continue to be important to Florida Panther recovery
as this isolated population confronts habitat loss, inbreeding, and
the unknown effects of the multi-billion dollar hydrological restoration of
the Everglades. We encourage the testing of our method in multiple locations.
We believe it will prove more accurate than population estimates
based on sightings, extrapolations, computer models, and grid- or transectbased
398 Southeastern Naturalist Vol.7, No. 3
Pumas may be secretive; nonetheless, they can be counted. To establish
realistic harvest quotas where pumas are hunted, or to measure the recovery
efforts of endangered populations, qualified trackers can adapt our method
of gender, time, and distance to conduct synoptic surveys. Our method can
be used for counting isolated populations of other large felines, especially in
snow or in conditions similar to those we describe in southern Florida.
We thank the following agencies and individuals for funding our panther surveys:
Hughes and Hughes Oil and Gas, Natural Resource Management Corps, Florida Fish
and Wildlife Conservation Commission, Exxon Oil Company, Everglades National
Park, Big Cypress National Preserve, and the thousands of citizens who purchased
Florida Panther Trust Fund license plates. We are grateful to the US Fish and Wildlife
Service for funding a two-year project in 2007, to conduct the Synoptic Survey.
Special thanks to D. Jansen and C. Belden, who were present on the capture of
Florida Panther #1 and have been dedicated to panther recovery ever since, and to
the perseverance of the 4-legged surveyors who worked harder and with better results
than anyone else to find panthers. J. Benson assisted with graphic design and GPS
data, B. Nelson was helpful throughout development of the manuscript, and J. Kellam
provided final manuscript edits and upgrades of the graphics. Thanks to Ralph
Arwood for providing the photos in Figure 5. We appreciated and used the editorial
recommendations of the journal’s reviewers and subject editor.
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