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FLORIDA
MUSEUM OF
NATURAL HISTORY
THE DIET OF THE FLORIDA PANTHER
IN EVERGLADES NATIONAL PARK, FLORIDA
George H. Dalrymple and Oron L. Bass, Jr.
Volume 39, No. 5 pp. 173-193
UNIVERSITY OF FLORIDA
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THE DIET OF THE FLORIDA PANTHER IN
EVERGLADES NATIONAL PARK, FLORIDA
George H. Dalrymple' and Oron L. Bass, Jr.2
ABSTRACT
We examined the diet of Florida panthers (Felis concolor coryi) in Everglades
National Park from 1984 to 1991 using data from 113 kill sites of 9 radio-collared panthers,
and 272 scats found at kill sites and from free-ranging panthers. Nine species were
identified at kill sites and 14 species from scats. White-tailed deer (Odocoileus virginianus)
was the most important prey species according to kill and scat analyses. Most kills were of
adult bucks and does. The mean time spent at kills was 3.86 days. Secondary prey species
from scat analysis were marsh rabbits (Sylvilagus palustris) and raccoons (Procyon lotor).
The diet of panthers in Everglades National Park (ENP) was compared to that of panthers
from southwestern Florida, including Big Cypress National Preserve. The estimated
consumed biomass of white-tailed deer in ENP was nearly identical to the combined
consumed biomass of deer and feral hogs from southwestern Florida.
RESUME
Entre 1984 y 1991, se estudi6 la dieta de pumas de Florida (Felis concolor coryi) en
el Parque Nacional Everglades, usando informaci6n obtenida de 113 sitios de matanza de 9
pumas con radio collares y de 272 muestras fecales obtenidas en sitios de matanzas y de
pumas silvestres. Se identificaron 9 species desde los sitios de matanza y 14 species
desde las muestras fecales. De acuerdo a los analisis fecales y de sitios de matanzas, el
ciervo de cola blanca (Odocoileus virginianus) fue la especie presa mas important. La
mayoria de las captures fueron de machos y hembras adults. El tiempo promedio en los
sitios de matanza fue de 3.86 dias. Especies secundarias obtenidas en muestras fecales
George H. Dalymple is Chief Scientist at Everglades Research Group, Inc. 35250 S.W. 212 Ave., Florida City FL 33034, U.S.A.
2 Oron L. Bas, Jr., is a Wildlife Biologist at the South Florida Natul Resources Center, Everglades National Par Homestead FL 33034,
U.S.A.
DALRYMPLE, G. H., AND O. L. BASS, JR. 1996. The diet of the Florida panther in Everglades
National Park, Florida. Bull. Florida Mus. Nat. Hist. 39(5):173-193.
BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL 39(5)
fueron conejos de humedal (Sylvilagus palustris) y mapaches (Procyon lotor). Se compare
la dieta de pumas en el Parque Nacional Everglades (PNE) con la dieta de pumas del
sudoeste de Florida, incluyendo la Reserva Nacional Big Cypress. La biomasa estimada
consumida de ciervos de cola blanca en PNE fue casi id6ntica a la biomasa consumida
combinada de ciervos y cerdos silvestres del sudoeste de Florida.
INTRODUCTION
A complete analysis of the food habits of the Florida panther (Felis
concolor coryi) in Everglades National Park (ENP) has not been reported
previously. Because hunting is illegal in Everglades National Park,
examination of kill sites and prey from scat analysis provided an opportunity
to examine the impact of a large predator on an unhunted deer population.
Maehr et al. (1990) determined that wild hog (Sus scrofa), and white-tailed
deer (Odocoileus virginianus) were the most common species in the diets of
the panthers in southwestern Florida. Although hogs were most important in
the major part of the northern portion of their study area, white-tailed deer
and raccoons were the dominant prey in most of the Big Cypress National
Preserve (BCNP). Wild hogs are very rare in ENP, leading to increased
dependency by panthers on deer (Smith and Bass 1994). The comparative
data presented herein may be valuable in setting hunting regulations for both
deer and hogs in southwestern Florida. Finally, an understanding of food
habits is important in understanding patterns of mercury contamination, a
problem that may be reducing the ability of ENP to support panthers (Jordan
1990; Roelke et al. 1991).
ACKNOWLEDGMENTS
The cooperation and support of the Florida Game and Fresh Water Fish Commission,
in particular, D. Maehr, C. Belden, M. Roelke, and T. Logan is greatly appreciated. We
thank R. Brazie, D. Jansen, and T. Smith for field assistance. Computer assistance was
provided by F. Draughn, D. Buker, and J. Ford, and V. Thue. Laurie Wilkins analyzed all of
the scats, and her efforts, and knowledge are greatly appreciated. Gary Matson (Matson's
Inc.) analyzed the dental material for aging white-tailed deer. We gratefully thank David
Maehr, Melvin Sunquist, and William Robertson for careful readings of the manuscript, and
their many helpful suggestions. Most of all, we thank Roy McBride for his long hours and
dedication to the Florida panther in the Everglades National Park.
STUDY AREA
The overall study area, which was defined by the ranges of the panthers,
included Everglades National Park and adjacent lands to the east, and the
DALRYMPLE AND BASS: FLORIDA PANTHER DIET IN ENP
portion of Big Cypress National Preserve along the western boundary of the
park (Fig. 1). Everglades National Park (ENP) includes approximately
300,000 ha of southernmost Florida's mainland. The climate of the area is
subtropical, with wet (June to November) and dry seasons (December to
May), and a mean annual rainfall of 146 cm (Smith and Bass 1994). The
lowest mean monthly temperatures (18.50C) occur in December and January,
and the highest means are in July and August (270C).
Elevations range from 2 m (in the Long Pine Key upland pine forests) to
sea level at Florida Bay. Soils, composed of marls and peats underlain with
limestone, are poorly drained. About 90 percent of the park's land area has
surface water present for 3-6 months between June and November. The
remaining 10 percent of the park's mainland area is composed of pine and
hardwood forests. Approximately 4,000 ha of the study area are dominated
by rocky pineland with hardwood hammocks, known as Long Pine Key
(LPK), bordered on the east by Taylor Slough, and on the west by Shark
River Slough. Adjoining LPK on the south is an area of former farmland
known as the Hole in the Donut (approximately 4,000 ha). It supports a
nearly monotypic stand of the exotic tree Brazilian pepper (Schinus
terbinthefolius). Further details of the study area and habitats are given by
Smith and Bass (1994). The dominant plant communities of the area are
shown in Figure 1.
METHODS
Radio-collaring Procedures
Panthers and deer were captured, radio-collared, and tracked following
the procedures described in Smith and Bass (1994) and Smith et al. (1996).
Radio-collared panthers were monitored daily from fixed-wing aircraft.
Standard ground and aerial telemetry techniques were used for tracking and
monitoring (Mech 1983). Locations of kills were determined by examining
telemetry locations where a collared panther spent more than one day.
Scats and Kills
A ground search was made of the areas where it was considered likely
that kills occurred. The remains of the kill were collected and identified, and
all scats from the kill site were collected. Scats also were collected while
tracking panthers or searching for sign. Scats were only included if they were
from a known panther kill site, or, in the cases of isolated scats, it was known
Figure 1. Map of study area showing the boundaries of Everglades National Park, with major geographic regions and
plant communities listed.
DALRYMPLE AND BASS: FLORIDA PANTHER DIET IN ENP
that a panther had been in the general vicinity, and the scat exceeded the
maximum known size of bobcat scat. Scats were analyzed at the Florida
Museum of Natural History following methods described in Maehr et al.
(1990), and quantified following Ackerman et al. (1984), and the estimates of
prey mass of Chapman and Feldhammer (1982) were used.
In order to test the null hypothesis that prey remains were distributed
similarly between scat categories, we separated the scats into two categories:
(1) scats from kill sites, and (2) other scats (not attributable to a particular
kill). The two rodent species and two bird species found in scats were lumped
into the categories "rodents" and "birds" for analysis.
The ages of deer from a sample of 64 skulls were determined from
dentitions (Harlow and Jones 1965; Severinghaus 1949; G. Matson, pers.
comm.). Of the deer skulls collected, 35 were from panther kill sites and the
other 29 were picked up randomly on Long Pine Key.
We follow Ackerman et al. (1984) in presenting the results for scat
analysis as frequency of occurrence (the percent of total scats with a prey
type) and as percent occurrence (number of times a prey type was found as a
percent of all prey items). They developed a method for estimating the
relative biomass and numbers of prey based on occurrence in scats. Maehr et
al. (1990) used the mass estimates of prey from Chapman and Feldhammer
(1982) and the procedures of Ackerman et al. (1984) to evaluate scats data
from southwest Florida. They restricted the analysis to the more common
prey species found in scats. We followed the above procedures to allow for
comparison of our data to the previous studies.
In comparisons of central tendencies among data sets, both parametric
(independent t) and nonparametric (Mann Whitney U) tests were performed,
and there were no differences in interpretations of the results. Mean values
with sample sizes, degrees of freedom, and standard errors (se) are reported.
In comparisons of distribution patterns between groups, the chi square
statistic ("Pearson statistic," Sokal and Rohlf 1995:696), and the Kolmogrov-
Smirnov test were used.
Individual Variation Versus Sample Statistics
Generalizations about diet of large predators are often misleading in that
they give the impression that the sample is homogeneous, whereas most
biologists who work with such data are only too aware of the degree of
individual variation. While sample size of kills or scats may be relatively
large, they still come from a small sample of animals, and they are not
177
BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 39(5)
equally distributed among the subjects. In order to make it clear that many
variables, including age, sex, reproductive condition, season, and habitat use
all play a role in the diet of the panthers studied, we briefly list the history of
each cat separately in the results section. This should make it clear how
careful we must be in generalizing about large predator habits, when we work
with small numbers of individuals. If we have learned anything about large
predators, it is that they are dynamic, flexible, and sometimes unpredictable.
RESULTS
Kills
We searched 113 kill sites of 8 panthers (no kill sites were located for
panther #42, see below), and found prey at 99 of them. Of the 108 prey items
found at the 99 kill sites (4 sites had two prey, and 3 sites had 3 prey), 9
species of prey were identified. White-tailed deer were found most frequently
(57 %), followed by raccoons, alligators, opossums, hogs, marsh rabbits,
otters, armadillos, and bobcats (Table 1).
Age estimates of deer at kill sites ranged from 1 to 15 years (Fig. 2).
The average age, based on premolar data, was 5.09 years (n = 35, se = 0.74).
The average age of a random sample (Eisenberg and Sunquist 1994; Smith et
al. 1996) of 29 deer skulls was 4.4 years (n = 29, se = 0.57). There was no
significant difference between the average age of randomly sampled deer and
those from panther kills (t = -0.77, df = 62, p = 0.44), and the cumulative
frequency distributions by age were not different (Kolmogrov-Smirnov test,
n's = 29, 35, d = -0.119, p > 0.05; Fig. 2).
Adult male deer were killed more frequently than other sex and age
classes of deer (47.5 %, Table 2), and the sex ratio of adult bucks to does
killed by panthers was 2.1:1. The sex ratio of adult deer in ENP (based on
aerial surveys during the peak rut months of July through October) was
estimated as 1:2.4 (Eisenberg and Sunquist 1994). Comparison of the sex
ratios indicates that panthers selected adult bucks over does (x2 = 73.88, df =
1, p < 0.0001).
Panthers spent an average of 3.86 (se = 0.19) days at kills, but this was
biased by the large proportion of deer in the diet. Panthers spent the most
time at adult buck kills (4.74 days, se = 0.411), and the least time at opossum
kills (1.6 days, se = 0.245, Table 3). Panthers spent significantly more days
at deer kills than alligator (t = 3.86), raccoon (t = 5.16), and opossum (t =
4.07) kills (all p's < 0.05), but there was no difference in duration of stay at
178
DALRYMPLE AND BASS: FLORIDA PANTHER DIET IN ENP
Table 1. Summary of kills by nine Florida panthers in Everglades National Park from 99
sites for 108 prey items by species.
Prey Number Frequency Number Percent
Type Kill Sites Occurrence Items Occurrence
Deer 54 59.6 61 56.5
Rabbit 3 2.8 3 2.8
Raccoon 16 16.2 18 16.7
Armadillo 1 1.0 1 0.9
Otter 2 2.0 2 1.9
Hog 5 5.1 5 4.6
Alligator 11 11.1 12 11.1
Opossum 5 5.1 5 4.6
Bobcat 1 1.0 1 0.9
10
8 KILLS
80 .. *RANDOM
LI
.. .. .. .
0
m 4
S.. . .. . . . . . . . . . . . . . . . . . . . . . . . . .
z
S: : : : : :
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
AGE IN YEARS
Figure 2. Distribution by age of white-tailed deer found at kill-sites of Florida panthers, and
of deer in a random sample of skulls from the study area (from Eisenberg and Sunquist
1994; age of deer of one year or greater based on PM2 dental evaluation).
BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL 39(5)
Table 2. Frequency and percent of 54 white-tailed deer of the total prey from kill sites of
radio-collared Florida panthers. Numbers in parentheses are the percent of deer in known
sex/size categories, excluding Unspecifiable
Deer Percent
Category Frequency Total
Adult buck 19 36.2 (47.5)
Adult doe 9 16.7 (22.5)
Yearling 6 11.1 (15.0)
Fawn 6 11.1 (15.0)
Unspecifiable 14 24.9
Table 3. Days spent at kill for prey types with at least five occurrences, for radio-collared
panthers in Everglades National Park. The category All Deer includes deer whose sex or
age were not specified. M = mean; Med = median; Max = maximum; Min = minimum;
SE = standard error; N = sample size of prey type.
Prey M Med Max Min SE N
All deer 4.50 5 11 1 0.214 54
Adult buck 4.74 5 11 2 0.411 19
Adult doe 3.67 4 6 1 0.500 9
Yearlings 4.50 4 6 3 0.563 6
Fawn 3.50 3 7 1 0.806 6
Raccoon 2.12 2 6 0.66* 0.368 14
Alligator 2.50 2 4 1 0.307 10
Opossum 1.60 2 2 1 0.245 5
Hog 4.60 4 9 3 1.123 5
* The minimum number of days at raccoon kills i less than one day because more than one raccoon was found at
several individual kill sites.
180
DALRYMPLE AND BASS: FLORIDA PANTHER DIET IN ENP
kill sites between deer and hog (t = 0.13, p = 0.29). Panthers spent similar
amounts of time at deer kills regardless of the age of the deer (Table 3).
Kills found per month varied from 10 in February to 1 in September.
We found fewer kills during the wet season. The month with the highest
proportion of deer kills was March. The months with the highest proportion
of small prey were March and October. However, there was no statistical
evidence of a seasonal shift in food habits between deer and other prey (Fig.
3).
Kills of Individual Panthers
Panther #14, an adult female, approximately 5-6 years old, was captured
in December 1986. At the time of initial capture, she had two yearling
kittens: one male (#16) and one female (#21). Between December 1986 and
July 1991, panther #14 was radio-tracked in the Long Pine Key and Hole-in-
the-Donut area and southern Taylor Slough. She primarily ate white-tailed
deer (88% of kill sites) and killed 29 radio-collared deer. She also ate one
each of the following prey: marsh rabbit, raccoon, alligator, and opossum. On
21 June 1991, panther #14 was found dead on the east side of the Hole-in-
the-Donut. Her death may have been caused by a combination of chronic
renal diseases, mercury contamination, and stress of a recent pregnancy.
Panther #15, an adult female, was captured December 1986. At the
time of capture she had two kittens. Both kittens (#22 and #23) were
captured in March 1987. Between December 1986 and June 1988 she was
located 505 times. She frequently was located in the western portion of
Long Pine Key and the eastern edge of Shark Slough. Based on kill remains
she ate 14 deer (including bucks, does, yearlings, and fawns), a marsh rabbit,
and an opossum. She also was located in the eastern portion of Long Pine
Key. She was found dead in 1988. The necropsy report listed the cause as
natural, due to bacterial infection from a puncture wound.
Panther #16 was captured in January 1987, as an 18-month-old yearling
male still with his mother, #14. In March 1987, he separated from his mother
and moved north into the East Everglades. Between March 1987 and March
1989, his home range included eastern portions of ENP as far north as
Tamiami Trail and south to the Long Pine Key area. During March 1989, he
crossed Shark Slough and moved into southern BCNP. In late October 1989,
he returned to the eastern side of Shark Slough (ENP). He occupied the
BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 39(5)
0
-J
WU 4
z 2
0
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
MONTH
Figure 3. Kills per month for all nine Florida panthers, separated into the categories deer
and other prey.
largest home range of all the study animals (estimated at about 900-sq-mi),
including most of ENP and southern BCNP, and had the most diverse diet,
including: 7 deer, 5 hogs, 11 alligators, 8 raccoons, a marsh rabbit, an otter,
and a bobcat.
Panther #21 was captured in March 1987, as an 18-month-old yearling
female still with her mother, #14. She separated from her mother in late
March 1987 and traveled eastward. Between April 1987 and July 1988,
panther #21 was radio-located 469 times. She moved out of ENP and crossed
major roads a total of 45 times. She was struck by a vehicle on 21 July 1988.
The areas she used were primarily abandoned farm lands, and sawgrass
marshes with buttonwood hammocks. Prey at three kill sites were two deer
and an armadillo.
Panther #22, an adult female, was captured along with her litter mate
(#23) in March 1987. At five kill sites no prey was found, but at six other
DALRYMPLE AND BASS: FLORIDA PANTHER DIET IN ENP
kills sites there were three deer and three opossum. She separated from her
mother (#15) in December 1987 at 16 months of age. Between December
1987 and March 1989, panther #22 was located 504 times in Long Pine
Key/Hole-in-the-Donut area and southern Taylor Slough. On 19 March
1989, radio transmission was lost. She was not located during subsequent
searches of her home range during the 1989 and 1990 capture seasons. In
February 1991, panther #22 was recaptured and the malfunctioning collar
replaced. Between February and July 1991, she was radio-tracked three
times a week. During this period she used the same general area (western
portion of Long Pine Key/Hole-in-the-Donut). On 22 July 1991, panther #22
was found dead at the bottom of a solution hole in western Long Pine Key.
Preliminary cause of death was by a subcutaneous bacterial infection. At the
time of her death, she had lost 50 percent of her body weight. This suggests
that the infection was progressive over a relatively long period.
Panther #23 was captured as a 6-month-old kitten, along with her sister,
#22, in March 1987. She was a 4-year-old female at the end of the study
period. As a result of capture-related activity, she was abandoned by her
mother and spent the majority of the first 3 years (June 1987-January 1989)
in captivity. In late February 1989, she was returned to ENP and released on
Long Pine Key. Between February 1989 and February 1990, she had an
extensive home-range, covering the eastern portion of ENP, extending from
the mangrove forests to agricultural lands in the East Everglades. In early
March 1990, she crossed Shark Slough and moved into southern BCNP,
using much of the same area as male panther #16. In late June 1990, she
crossed U.S. 41, entering eastern BCNP. By mid-July 1990, she showed
signs of denning, and remained at the same location for the next month. On
13 August 1990, panther #23 moved north from the den site location and did
not return. This movement pattern indicated that she had lost the kitten(s) at
about a month old. A subsequent search of the den site area was unable to
locate any sign of the kitten(s). At the end of the study, panther #23 occupied
the eastern portion of BCNP north of Tamiami Trail. Prey at four kill sites
were four raccoons.
Panther #27, a 3-4 year old female, was captured and radio-collared in
April 1988. Prey at three kill sites were two raccoons and an otter. She was
located 451 times between April 1988 and July 1989. During these 15
months of radio-tracking she occupied portions of northern Long Pine Key,
the East Everglades, and northern Shark Slough. On 26 July 1989, panther
#27 was found dead in a tree island in northeast Shark Slough. A necropsy,
performed by the Florida Game and Fish Commission veterinarian on this
BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL 39(5)
animal, found no obvious cause of death. As a result of recent findings of
high levels of mercury in freshwater fish and alligators in ENP (Roelke et al.
1991), the animal was screened for pesticides and heavy metals, and high
levels of mercury (98 ppm) and selenium (22 ppm) were found in the
animal's liver. Mercury toxicosis was the most likely cause of death of
panther #27 (M. Roelke, pers. comm.).
Panther #39, an adult male, approximately 3-4 years old, was captured
on a tree island in lower Shark Slough on 19 February 1990. At the time of
capture, he weighed 102 lbs. From February to May 1990, he was radio-
tracked only 81 times, representing the shortest period of data collection for
any of the study animals. During this period, panther #39 ranged from Long
Pine Key and East Everglades area, to the west side of Shark Slough. He
crossed Shark Slough frequently. Between 4 May and 18 May 1991, he
confined himself to a hardwood hammock and willow stand on the west side
of Shark Slough. On 16 May 1990, a ground check of the area was made to
determine the condition of the animal. The cat was approached on the ground
and exhibited only limited movement, remaining out of sight. The decision
was made to recapture the panther for examination. On the day of capture,
18 May 1990, the panther was found dead. The necropsy report listed cause
of death as severe pyothorax from a puncture wound to the chest cavity (M.
Roelke, pers. comm). Two deer were found at two kill sites.
Panther #42 was a subadult male, and 2 years old at the end of this
study. Captured in March 1990, as a 10-month-old yearling still with his
mother, he was the offspring of a backcross between Panther #14 (mother)
and #16 (#14's son). In May 1990, he separated from his mother and moved
north into the East Everglades. During the next 12 months, May 1990-May
1991, he confined himself to the northeast Shark Slough in the East
Everglades. In early May 1991, he moved his center of activity into northern
Shark Slough and west of Shark Valley Tower. He was occupying the area
between Shark Valley Tower Road west to the ENP-BCNP boundary at the
end of this study. No kill sites were found for this panther.
All Scats
In a total of 272 scats, 14 species and 291 prey items were represented
(Table 4). White-tailed deer (Odocoileus virginianus) was the most
important based on frequency of occurrence (69.1 % of scats) and percent
occurrence (64.6 % of the prey items), followed by marsh rabbits (Sylvilagus
palustris) and raccoons (Procyon lotor) (Table 4). A fox squirrel (Sciurus
DALRYMPLE AND BASS: FLORIDA PANTHER DIET IN ENP
niger) was found in one scat, and cotton rats (Sigmodon hispidus) in four
scats. A large wading bird and an unidentified smaller bird were found in one
scat each.
Deer composed 78.4 percent of estimated consumed biomass, followed
by marsh rabbits (10.4 %). Marsh rabbits were also the most common prey
consumed based on this analysis, comprising 57.6 percent of the prey by
numbers (Table 5).
Kill-site Scats Versus Other Scats
There was a significant difference in the frequency of occurrence of prey
found in the scats from kills vs. other locations (x' = 83.2 p < 0.001, df =
7). Deer made up over 80 percent of the prey and occurred in over 80 percent
of the scats from kill sites, while they made up only about half that amount
from scats from other locations. Marsh rabbits were more important in seats
from other locations (39.6 % of the scats, and 35.9 % of prey; Table 4).
Deer were consistently identified as the most important prey item from
kills and scats. Alligators and raccoons were the second and third most
common prey identified in scats from kill sites, while marsh rabbits were the
second most common prey in scats from non-kill sites (57.6 % of prey items,
based on estimates of biomass consumed).
DISCUSSION
Anderson (1983) suggested a sample of 90-100 seats or stomach
contents was necessary to characterize the food habits of mountain lions
within 10 percent of actual use (p = 0.05). Our sample sizes for total scats,
kill-site scats, and other scats all exceed the minimum suggested for our study
period.
When the scats were subdivided between kill sites and other locations,
the disparity in the kill and scat data was clearer. Scats found away from kill-
sites contained many more marsh rabbits and other small prey. Remains of
alligators were found in few scats (0.74 % of prey items) and were only
found in scats from kill sites. Of the ten alligator kills, 5 were made by male
panther #16.
The most obvious inconsistency between kill and scat data was the
complete absence of opossum from the scats, even though opossum made up
6.6 percent of the prey from kills (see Tables 4 and 6). There were fewer
rabbits at kills than from scats, and there were more raccoons and alligators
Table 4. Summary of kill and scat data of Florida panthers in Everglades National Park. Percent occurrence and frequency of occurrence
are given for total scats, and for scats separated into scats from kill sites and other sites. PERC = percent occurrence (the percent of all
the prey items in scats), FREQ = frequency of occurrence (the percent of the scats with prey type). The two rodents and two bird species
are lumped together as "rodents" and "birds." (Opossum was not found in scats, although it was recorded at kill sites.)
Total Scats Kill Sites Other Sites
Prey Total Kill Other
Species Scats Sites Sites Perc Freq Perc Freq Perc Freq
Deer 188 143 45 64.6 69.1 82.2 86.1 38.5 42.5
Rabbit 54 12 42 18.6 19.9 6.9 7.2 35.9 39.6
Raccoon 19 9 10 6.5 7.0 5.2 5.4 8.6 9.4
Armadillo 9 2 7 3.1 3.3 1.2 1.2 5.9 6.6
Rodents 5 0 5 1.7 1.8 0.0 0.0 4.3 4.7
Otter 6 4 2 2.1 2.2 2.3 2.4 1.7 1.9
Birds 3 1 2 1.0 1.1 0.6 0.6 1.7 1.9
Hog 2 1 1 0.7 0.7 0.6 0.6 0.9 0.9
Alligator 2 2 0 0.7 0.7 1.2 1.2 0.0 0.0
Grey fox 1 0 1 0.3 0.4 0.0 0.0 0.9 0.9
Skunk 1 0 1 0.3 0.4 0.0 0.0 0.9 0.9
Snake 1 0 1 0.3 0.4 0.0 0.0 0.9 0.9
Total scats 272 166 106
Total prey 291 174 117
Table 5. Estimated biomass (kg) and number of prey consumed by Florida panthers based on scats from panthers in Everglades National
Park. (No correction factor for prey was used when the estimated mass of a prey type was less than 2 kg, as suggested by Ackerman et
al. [1984].)
Estimated
Prey Correction Total Percent Number Percent
Type Freq Mass Factor Biomass Biomass Consumed Consumed
Deer 188 36.0 3.2 609.12 78.36 16.9 18.1
Rabbit 54 1.5 81.00 10.42 54.0 57.6
Raccoon 19 5.0 2.2 40.94 5.27 8.2 8.7
Armadillo 9 6.0 2.2 19.71 2.54 3.3 3.5
Otter 6 8.0 2.3 13.56 1.74 1.7 1.8
Hog 2 23.0 2.8 5.57 0.72 0.2 0.3
Alligator 2 8.0 2.3 4.52 0.58 0.6 0.6
Skunk 1 2.5 2.1 2.07 0.27 0.8 0.9
Rodents 5 0.1 0.50 0.06 5.0 5.3
Birds 3 0.1 0.30 0.04 3.0 3.2
BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL 39(5)
at kills than from scats (Table 6). The difference in prey species from kills
and from scats suggests that there are differences in the amount of time
needed by panthers to consume prey of different species. Small prey are
consumed quickly, and produce fewer scats compared to large prey (Karanth
and Sunquist 1995).
Maehr et al. (1990) identified 14 species in 270 scats and 7 species of
prey at 38 kills in southwestern Florida. In ENP we found 14 species in 272
scats and nine species at 99 kills where the prey was found. We did not find
livestock or panther remains in our samples, and bobcats, otters, foxes, and
skunks were not represented in the BCNP data (Fig. 4; Table 7). The number
of species recorded in kills and scats from ENP and southwestern Florida are
very similar; however, the two areas shared only six actual prey species.
Hogs, which were especially important in the diet of some southwestern
Florida panthers, were insignificant in the ENP panthers, which may be due
to the generally wetter conditions in ENP. Based on the analysis of consumed
biomass, the amount of deer and hogs taken by panthers in southwestern
Florida was about equal to the deer biomass taken in ENP.
Regular use of alligators as prey appears to be a distinctive, perhaps
idiosyncratic, characteristic of panthers in the ENP ecosystem. However, a
three-year drought during the study may have increased the availability of
alligators to panthers, since panthers prefer upland habitats (Smith and Bass
1994).
Iriarte et al. (1990) analyzed puma diets across the species' range. They
noted a general tendency for pumas to consume a wider variety of prey in the
tropics. They suggested that prey availability and vulnerability, habitat
characteristics, and potential competition from jaguars (Panthera onca)
explained the differences they found between North America and the tropics.
They noted that the panther data of Maehr et al. (1990) in southwestern
Florida did not follow the typical North American pattern of reliance on large
ungulate prey, and they emphasized the fact that the southwestern Florida
data revealed a low rate of deer consumption. The data for the panthers in the
Everglades National Park show characteristics of both the North American
pattern of reliance on white-tailed deer, and the wider food niche breadth
described for tropical pumas. The wide food niche breadth of Florida
panthers in the Big Cypress area is not explained merely by a lack of deer in
that part of the panther's range, because the panthers in ENP also show this
tendency while relying heavily on an unhunted deer population.
DALRYMPLE AND BASS: FLORIDA PANTHER DIET IN ENP
Table 6. Comparison of percent of total scats and total kill sites that contained prey
species in Everglades National Park.
Percent Occurrence
Prey
Species Scats Kills
Deer 64.6 56.5
Rabbit 18.6 2.8
Raccoon 6.5 16.7
Armadillo 3.1 0.9
Rodents 1.7 -
Otter 2.1 1.9
Birds 1.0
Hog 0.7 4.6
Alligator 0.7 11.1
Grey fox 0.3
Skunk 0.3
Snake 0.3 -
Opossum 0.0 4.6
Bobcat 0.0 0.9
DEER
RACCOON WILD HOG PANTHER
RABBIT ARMADILLO LIVESTOCK
Figure 4. Estimated percent of biomass consumed from scat data for Florida panthers in
Everglades National Park compared to data from the Big Cypress region of southwestern
Florida from Maehr et al. (1990).
..... .. ........ . E N P
: BICY SOUTH
M BICY NORTH
....... . ... ...... .. ..... .... ....... ....... ..... ......... ..
...... ....... . ......
BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 39(5)
Table 7. Comparison of estimates of percent of total biomass consumed by Florida
panthers, based on formula of Ackerman et al. (1984), for Everglades National Park and
the Big Cypress region (Maehr et al. 1990). = one alligator found in scat from study by
Maehr et al. (1990), but not listed by location.
Big Cypress
Everglades
National Park North South
Deer 78.36 27.00 43.00
Rabbit 10.42 1.70 3.40
Raccoon 5.27 3.00 19.00
Armadillo 2.54 4.60 9.30
Otter 1.74 0.00 0.00
Hog 0.72 58.70 22.70
Alligator 0.58 0.00* 0.00*
Skunk 0.27 0.00 0.00
Rodent 0.06 0.05 0.10
Birds 0.04 0.00 0.00
Livestock 0.00 4.90 0.00
Panther 0.00 0.00 2.00
Bobcats are a frequent predator on white-tailed deer in parts of southern
Florida (Land 1991, Boulay 1992). However, the degree to which bobcats
compete with panthers is still unclear. Potential competition from recreational
hunting of white-tailed deer is an issue in the Big Cypress region, where
panthers show a higher use of wild hogs, and livestock. Where hunting does
not occur, as within the confines of Everglades National Park, there was a
clear reliance by panthers on deer. The seasonal variation in standing water
levels, the lower densities of prey populations in southern Florida, and the
seasonal variation in the use of tree island habitat may all contribute to a
more opportunistic feeding strategy by panthers. However, white-tailed deer
remain the principal prey species, especially in Everglades National Park.
The data from scats found away from kill sites in this study suggest that a
wide range of small prey species are taken opportunistically.
Since the data presented above indicate that panthers selected older deer,
and bucks over does, it is reasonable to hypothesize that Florida panthers in
the Everglades are stalking isolated individuals in and along tree island edges.
DALRYMPLE AND BASS: FLORIDA PANTHER DIET IN ENP
Selective predation on older deer by pumas has also been noted by Horocker
(1970), Spalding and Lesowski (1971), and Ackerman et al. (1984), and
Robinette et al. (1977) noted increased vulnerability of bucks in Utah and
Nevada. In the southern Everglades, Miller (1993) and Eisenberg and
Sunquist (1994) stated that adult bucks spent more time alone, and prefer to
spend time on tree islands. Isolated bucks in the dense cover of tree islands
may be easier to stalk by panthers. They also noted that females tend to stay
in groups in more open prairie habitat. Such groups may be more difficult to
approach and stalk by panthers.
Moreover, the reduced rate of deer kills in the wet months of July
through September in the current study correspond to the months when
bucks are more commonly associated with groups of does in open prairie
habitat (Eisenberg and Sunquist 1994; Smith et al. 1996), and again this may
make close approach by stealth more difficult for panthers to successfully kill
deer.
In the Big Cypress National Preserve, Miller (1993) found adult male
deer to be twice as likely to use hardwood tree islands as females. Miller also
suggested groups of female deer may use open habitat more often as part of a
predator avoidance behavior.
In evaluating bobcat predation on fawns in the Big Cypress, Boulay
(1992) pointed out that peak rates of bobcat predation on fawns were June
and July, and that rates of fawn kill were much lower from August to
December. Boulay also suggested that the higher rate of predation on male
fawn vs. females may be due to tendency for male fawns to wander farther
and use tree island habitat more commonly, which may make them more
susceptible to the stalking behavior of bobcats. In summary, the data
available for both ENP panther and BCNP bobcats, indicate that deer that
are isolated and use tree islands are more susceptible to panther predation.
Iriarte et al. (1990:188) related diet to body size in pumas, suggesting
that smaller pumas forage selectively on smaller prey. They relied on the data
from scat analysis by Maehr et al. (1990) to argue that: "Low deer densities
in much of the puma's range in Florida may explain, in part, the low MWVP
[mean weight of vertebrate prey] value of Florida pumas when compared
with the rest of North America. Deer populations and densities of alternative
prey species in portions of Florida may be low since pumas in areas of low
deer densities are smaller, are in poorer condition, and have lower
reproductive rates... ." But, Maehr and Moore (1992) compared growth rates
of southwestern Florida panthers to pumas from California, and determined
that adult mass and growth rates were not different. They stressed that
BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 39(5)
California pumas relied heavily on wild hogs, and that deer were not
commonly taken. However, several issues should be clarified before any
conclusions are drawn regarding Florida panthers as a whole. First, Maehr et
al. (1990) were considering only panthers from southwestern Florida, but we
consider that panthers from ENP readily fit their curve for growth rate.
Second, Maehr et al. (1990) relied on scat data for their estimates of prey
importance, and as has been shown in this study, scat data should be
separated into scats from kills and scats from other locations whenever
possible, because scats that are not from kill sites show a bias toward smaller
prey, while scats from kill-sites are more likely biased toward large-size prey.
Third, Roelke et al. (1991) have pointed out that much of the poor condition
in some southern Florida panthers may be due to high mercury poisoning
levels that, again, confuse the question of body condition and size. Fourth, the
analysis of duration of stay with prey in the current study revealed no
significant difference in the duration of stays for deer and hog, which may
mean that as large a portion of a hog's mass was taken as from a deer.
Moreover, many hogs are approximately the same size as the deer taken in
southern Florida. The results of the current study identify many similarities in
the diets of panthers from southwestern and southeastern Florida, and also
indicate the importance of drawing data from as many potential sources (i.e.
scats and kills) as possible to adequately characterize the diet of this species.
LITERATURE CITED
Ackerman, B. B., F. G. Lindzey, and T. P. Hemker. 1984. Cougar food habits in southern
Utah. J. Wildl. Mgmt. 4:147-155.
Anderson, A. E. 1983. A critical review of literature on puma (Felis concolor). Spec. Rept.
No. 54. Colorado Div. Wildl., Denver. 91 pp.
Belden, R. C. 1983. Florida panther recovery plan implementation a 1983 progress
report. Pages 159-172 in S.D. Miller and D.D. Everett, eds. Cats of the world:
Biology, conservation, and management. Natl. Wildl. Fed., Washington, DC.
Boulay, M. C. 1992. Mortality and recruitment of white-tailed deer fawns in the wet
prairie/tree island habitat of the Everglades. M.S. thesis. Univ. Florida. Gainesville.
77pp.
Chapman, J. A., and G. A. Feldhammer. 1982. Wild mammals of North America. Johns
Hopkins Univ. Press, Baltimore, MD. 1147 pp.
Eisenberg, J.F., and M.E. Sunquist. 1994. Ecology of white-tailed deer in eastern
Everglades National Park. Final Rept. Everglades National Park, unpubl. doc.,
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DALRYMPLE AND BASS: FLORIDA PANTHER DIET IN ENP
Harlow, R.F., and F. K. Jones, Jr. 1965. The white-tailed deer in Florida. Florida Game
Fresh Water Fish Comm. Tech. Bull. 9. Tallahassee. 240 pp.
Hornocker, M.G. 1970. An analysis of mountain lion predation upon mule deer and elk in
the Idaho Primitive Area. Widl. Monogr. 21. 39 pp.
Iriarte, J.A., W. L. Franklin, W. E. Johnson, and K. H. Redford. 1990. Biogeographic
variation of food habits and body size of the American puma. Oecologia. 85:185-190.
Jordan, D. 1990. Mercury contamination: Another threat to the Florida panther.
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Karanth, K. U., and M.E. Sunquist. 1995. Prey selection by tiger, leopard, and dhole in
tropical forests. J. Animal Ecol. 64: 439-450.
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July 1986-30 June 1991 (Study No. E-l-11 II-E-5b). Florida Game Fresh Water Fish
Comm., Tallahassee. 24 pp.
Maehr, D. S., R. C. Belden, E. D. Land, and L. Wilkins. 1990. Food habits of panthers in
southwest Florida. J. Wildl. Mgmt. 54:420-423.
Maehr, D. S., and C. T. Moore. 1992. Models of mass growth for 3 North American cougar
populations. J. Wildl. Mgmt. 56:700-707.
Mech, L. D. 1983. Handbook of animal radio-tracking. Univ. Minnesota Press,
Minneapolis. 107 pp.
Miller, K.E. 1993. Habitat use by white-tailed deer in the Everglades: tree islands in a
seasonally flooded landscape. M.S. Thesis. Univ. Florida, Gainesville. 105 pp.
Roelke, M. E., D. P. Schultz, C. F. Facemire, S. F. Sundlof, and H. E. Royals. 1991.
Mercury contamination in Florida panthers. A report of the Florida Panther Technical
Subcommittee to the Florida Panther Interagency Committee, December 1991.
Severinghaus, C. W. 1949. Tooth development and wear as criteria of age in white-tailed
deer. J. Wildl. Mgmt. 13:195-216.
Shaw, H. G. 1983. Mountain lion field guide. Spec. Rept. 9. Arizona Game Fish Dept.,
Phoenix. 38 pp.
Smith, T. R. and 0. L. Bass, Jr. 1994. Landscape, white-tailed deer, and the distribution of
Florida panthers in the Everglades. Pages 693-708 in S. Davis and J. Ogden, ed.
Everglades. The Ecosystem and its Restoration. St. Lucie Press. Delray Beach FL.
Smith, T. R., C. G. Hunter, J. F. Eisenberg, and M. E. Sunquist. 1996. Ecology of white-
tailed deer in eastern Everglades National Park: An overview. Bull. Florida Museum
Nat. Hist.. 39(4):141-172.
Sokal R. R, and F. J. Rohlf. 1995. Biometry. Third Ed. W. H. Freeman and Co. New York.
887 + xix.
Spalding, D.J. and J. Lesowski. 1971. Winter food of the cougar in south-central British
Columbia. J. Wildl. Mgmt. 35: 378-381.
193
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