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THE JOURNAL OF TROPICAL BIOLOGY AND CONSERVATION
BIOTROPICA 40(4): 494–500 2008
10.1111/j.1744-7429.2008.00404.x
Food Habits and Livestock Depredation of Sympatric Jaguars and Pumas
in the Iguaçu National Park Area, South Brazil
Fernando Cesar Cascelli de Azevedo1
Instituto Pró-Carnı́voros, Av. Horácio Neto 1030, Pq Edmundo Zanoni – Jd Samambaia, Atibaia SP, 12945-010, Brazil
ABSTRACT
Understanding coexistence between sympatric felines with similar body sizes, such as jaguars Panthera onca and pumas Puma concolor, requires knowledge of the way
these predators consume and partition food resources. Yet the importance of livestock predation on jaguar and puma coexistence is poorly known. I investigated
food habits and patterns of livestock depredation of jaguar and pumas in the Iguaçu National Park (INP) in southern Brazil. From 1997 to 2001, I collected scats
opportunistically on trails and roads in INP and visited ranches on the border of INP. I found that jaguars relied mostly on large and medium-sized wild prey species,
while pumas concentrated on medium-sized prey species. Livestock was the fifth most frequent prey found in jaguar scats but the most important one in terms of
biomass consumed. Jaguar and puma diets differed significantly when all prey items were compared and also when livestock was excluded from the jaguar diet. Jaguar
predation on livestock was considerably higher than predation by pumas. However, predation was not substantial relative to availability of livestock, and cattle likely
constitute an alternative source of prey for jaguars. Degree of diet overlap between jaguar and puma in INP suggests that coexistence was likely driven by exploitative
competition through some degree of food partitioning. My results highlight the importance of more actions toward increasing numbers of large ungulates to preserve
the population of jaguars in INP.
Abstracts in Portuguese is available at http://www.blackwell-synergy.com/loi/btp.
Key words: diet; Felidae; food partitioning; large carnivores; Panthera onca; Puma concolor; sympatry.
FOR SYMPATRIC LARGE FELIDS INHABITING TROPICAL FORESTS,
the controversy over factors promoting population viability involves ecological and behavioral factors. When prey resources are
abundant, ecological factors such as availability of appropriatedsized prey and habitat characteristics are of primary importance
(Scognamillo et al. 2003). In contrast, when key resources are in decline, behavioral factors such as the ability to use human-disturbed
areas and diet flexibility through the use of small prey may be more
important in promoting coexistence (e.g., Bailey 1993, Ramakrishnan et al. 1999) and increasing dietary breadth of predators (Neale
& Sacks 2001), thereby leading to likely increases in overlap.
Prey abundance and availability are vital in shaping interactions
between similar large felines and can certainly alter patterns of
coexistence (Iriarte et al. 1990, Ramakrishnan et al. 1999, Núñez
et al. 2000). For large felines with similar body sizes such as jaguars
Panthera onca L. and pumas Puma concolor L., coexistence may be
the result of exploitative competition through some degree of food
partitioning (Johnson et al. 1996) or use of different prey species
(Taber et al. 1997, Núñez et al. 2000, Scognamillo et al. 2003). It
follows that the larger jaguar should specialize on larger prey species
(Gittleman 1985) and likely consumes a larger range of prey types
than the smaller puma (e.g., see Rosenzweig 1966, Gitlleman 1985).
Indeed, some studies have shown that, in general, jaguars take larger
wild prey, but have a narrower dietary breadth than pumas (Taber
et al. 1997, Núñez et al. 2000, Scognamillo et al. 2003). However,
few studies have examined how the availability of alternative sources
of prey, such as livestock, might affect the interaction between
jaguars and pumas (Polisar et al. 2003, Sconamillo et al. 2003).
Received 22 May 2007; revision accepted 10 November 2007.
author; e-mail: [email protected]
1 Corresponding
494
The last significant population of jaguars in southern Brazil
is located inside a protected area, the Iguaçu National Park (INP).
Jaguars at INP have mainly faced the effects of direct persecution by
humans through opportunistic killing and retaliation for livestock
predation, since livestock are relatively abundant just outside of the
park (Crawshaw 1995, Conforti & Azevedo 2003). Pumas are also
present, but livestock predation by this species has been rarely documented in the area (Conforti & Azevedo 2003). In addition, direct
competition from poachers eliminating some of the most important
prey species of large carnivores has affected the local prey population. For instance, once reported as one of the most important
large prey species for jaguars and pumas in INP (Crawshaw 1995),
the white-lipped peccary Tayassu pecari has apparently disappeared
from INP mostly because of illegal hunting (Conforti & Azevedo
2003). Under these circumstances, predator–livestock conflicts are
expected to increase as cats expand their diet to include livestock as
an alternative source of food (Schaller & Crawshaw 1980, Schaller
1983, Woodroffe 2001). In the present study, I investigated the
food habits and patterns of livestock depredation of jaguars and
pumas in INP. I was particularly interested in determining the size
and range of prey classes used by the two predators and assessing
the effect of livestock on their coexistence in INP.
METHODS
STUDY SITE.—Fieldwork was conducted in Iguaçu National Park,
southern Brazil (25◦ 05 –41 S, 53◦ 40 –54◦ 38 W), which covers
1852 km2 of subtropical forest along the international boundary
between Brazil and Argentina. In Argentina, the protected forest
C 2008 The Author(s)
C 2008 by The Association for Tropical Biology and Conservation
Journal compilation Food Habits and Livestock Depredation
at Parque Nacional Iguazú joins INP, and the combined protected
area covers about 2400 km2 of subtropical forest separated by the
Iguaçu River. The landscape is comprised mostly of flat terrain,
of elevation 100–300 m (Salamuni et al. 1999). Mean monthly
temperatures range from 15◦ C to 26◦ C, and the climate is predominantly rainy without defined dry seasons, averaging 1712 mm
of rainfall per year (Salamuni et al. 1999). The vegetation consists
mainly of dense tropical semi-deciduous forest with some former
clearings and regenerating forest left over from prior human settlement. Roads and trails are rare inside INP. The principal prey
species of jaguars and pumas in INP included white-lipped (T.
pecari) and collared (T. tajacu) peccary, red-brocket deer (Mazama
americana), rufous-brocket deer (M. rufina), capybara (Hydrochaeris
hydrochaeris), paca (Agouti paca), tapeti (Sylvilagus brasiliensis), coati
(Nasua nasua), armadillo (Dasypus novemcinctus), opossum (Didelphis sp.), agouti (Dasyprocta azarae), and tegu-lizard (Tupinambis
teguixim) (Crawshaw 1995). Prey density estimates for Iguaçu are
scanty. Estimates were only available for white-lipped peccaries
(1.5 animals/km2 ; Crawshaw 1995) and collared peccaries (0.9
individuals/km2 ; Crawshaw 1995). Livestock were present in relatively large numbers along the edge of the Park (Azevedo & Conforti
1999).
Along the border of INP, livestock were raised in rudimentary
farms, with no clear allotments, few fences, and no direct protection
against predators (Azevedo & Conforti 1999). Fences or streams
served as barriers separating INP from livestock grazing areas, and
these barriers did not constitute obstacles to jaguars and pumas.
In 2004, the 14 towns surrounding INP had a total population of
479,000 residents, with an average of 34,000 inhabitants per town.
Subsistence economy through crop farming was the main activity
in the region, with livestock ranching being a secondary source of
food (MMA/IBAMA 2006).
LIVESTOCK HOLDINGS AND RANCH CHARACTERISTICS.—During
1997–2000, a total of 150 ranches from 14 towns on the border of INP were visited; a subsample of 85 ranches was selected
for intensive study based on location and proximity to INP border.
This selection provided a sample of farms immediately adjacent to
INP, each having livestock present. Ranches were visited at least
twice a month. During site visits to the ranches, I collected data on
the amount and type of livestock, as well as the general measures of
protection from predators (e.g., fences, clearings, etc). Most ranches
did not protect livestock in corrals during the night. To document
predation events, I recorded cases of livestock attacked by predators. A survey of the species, gender, and age of depredated livestock
was conducted. To minimize biased sampling, only livestock mortality events associated with actual carcass recovery were included
in the data set (Mondolfi & Hoogesteijn 1986). Identification of
predation on old carcasses was based on the presence of signs of
bites or punctures on ribs, skulls, vertebras, clavicles or other long
bones. Identification of predation on wounded animals was based
on bite marks and infected wounds that would be detectable for
approximately 1 mo after the attack. In the case of claw marks left
on wounded livestock, signs of an attack remained evident up to
several years after the attack (Hoogesteijn & Mondolfi 1992).
495
DATA ANALYSIS.—I determined predator diet from scat content analysis. Scat collection occurred opportunistically on trails and roads in
INP Park and its border (1997–2001). I identified predator species
by their association with tracks close to the site of scat collection;
scats deposited in sites where tracks were not found were excluded
from the analysis (Emmons 1987, Núñez et al. 2000, Scognamillo
et al. 2003). I further calculated error rates for identification of
predator species based on the comparison between the presence of
tracks associated with scats and predator hairs present in scats. I dried
scats at 72◦ C for 24 h, separated contents under running water and
collected fragments in a 600 μm sieve. I identified food contents
to genus and species using hair, skull fragments, teeth, scales, and
via comparison with reference material from INP. Note that among
prey species identified as consumed by jaguars and pumas, I combined two species of deer (M. americana and M. rufina) averaging
species weight as a single prey item.
To quantify and compare diet between species, I determined
the frequency of occurrence of food items by calculating the percent
of scats containing each food item (Kitchen et al. 1999, Sovada
et al. 2001). Chi-square with Fisher’s exact tests served to compare
frequency of occurrence of food items between predator species.
When multiple items were recovered from a single scat, I calculated
the relative frequency of each food item as the number of times
a specific item was found as a percentage of all items identified
(Ackerman et al. 1984, Hidalgo-Mihart et al. 2001, Neale & Sacks
2001). To evaluate the influence of sample size on the results of scat
analysis, I chose five scats randomly, analyzed food contents, and
then included five additional scats. I continued this procedure until
all scats were included in the analysis. I then assessed the cumulative
frequency of occurrence of the most common prey items (relative
frequency of occurrence ≥ 5%) to infer the effect of sample size on
the final dietary results (Biswas & Sankar 2002).
Although frequency of occurrence has been widely used to
quantify carnivore diet, this measure can inadequately overestimate
the presence of small prey (Ackerman et al. 1984) and underestimate
the presence of large mammalian prey (Weaver 1993). To account
for variation in prey sizes and minimize sampling bias, I also estimated relative biomass consumed by converting estimates of relative
biomass and relative number of prey consumed through the use of
a correction algorithm: Y = 1.98 + 0.035 X given by Ackerman
et al. (1984) for puma, where Y is the weight of prey consumed
per scat and X is the live weight of the prey. To analyze temporal
patterns of jaguar or puma diet change and compare results to previous work in the same area (see Crawshaw 1995), I calculated the
mean weight of vertebrate prey (MWVP) in jaguar and puma diets
as described in Iriarte et al. (1990). Prey live weight estimates were
based on published references (Ackerman et al. 1984; Robinson &
Redford 1986; Emmons 1987, 1990; Crawshaw 1995). To classify
prey biomass consumed by each predator species, I divided prey in
three size categories according to their mean adult mass (e.g., see
Iriarte et al. 1990). The three major groups were: small prey ≤ 1 kg;
medium = 1–15 kg; and large ≥ 15 kg.
I calculated measures of niche breadth (Levins 1968) using the
relative frequency of occurrence of food items (where B = 1/ p2 j,
where B = Levin’s measure of niche breadth; pj = fraction of items in
496
Cascelli de Azevedo
the diet that are of food category j), and standardized dietary breadth
on a scale from 0 to 1.0 using Hulbert’s measure (1978): B A =
(B − 1)/(n − 1), where B A= Levin’s standardized niche breadth;
B = Levin’s measure of niche breadth; n = Number of possible
resource states (see Krebs 1999). This approach enabled me to
assess the extent to which carnivore-specific food selection patterns
focused on particular food categories. I used the Renkonnen index
n
P jk =
min( pi j, pik) ,
i=1
where P = percentage overlap between sample j and k; pij = proportion of resource i is of the total resources utilized by species j;
pik = proportion of resource i is of the total resources utilized by
species k; n = total number of resources used to examine overlap in
resource use between the two predator species (see Krebs 1999).
I examined patterns of livestock predation by regressing number of predation events against livestock numbers per farm. I performed a Chi-square goodness-of-fit tests to investigate whether the
recorded frequency of predation on different livestock species deviated significantly from the expected. Expected numbers of livestock
were based on the availability of domestic prey species within visited
ranches. I calculated predation detection rates by comparing the total number of confirmed predation incidents to the total number of
visits to all ranches during the period of study.
RESULTS
DIETARY ANALYSIS.—I identified a total of 75 different prey items
(mean per scat: 1.43 ± 0.70 SD, N = 51) from 12 taxa for jaguar and
a total of 62 different prey items (mean per scat: 1.15 ± 0.36, N =
54) from 13 taxa for puma. Error rates for identification of predator
species were 12 percent for jaguar (6 samples) and 20 percent for
puma (11 samples). These samples were previously identified based
on close association with one predator species tracks but later found
to contain hairs of the other predator species. Thirty-two jaguar
scats (63%) had a single prey item, while 19 scats (27%) had two
or more prey items. Forty-six puma scats (85%) had a single prey
item, while only eight scats (15%) had two or more prey items. After
successive draws of five scats from the total sample size, I found that
the proportion of different prey species in scats tends to stabilize
once a sample of 50 scats were analyzed in both predator species
(Fig. 1). The only exceptions pertained to the relative contribution
of tegu-lizard in jaguar diets and small rodents in puma diets. I
therefore considered my sample size sufficient for the dietary analysis
described herein, but suggest an increase in sample sizes to better
understand how consumption of these two prey items would affect
diets of jaguars and pumas in INP.
The most important wild prey species for jaguars in order of
relative biomass consumed were collared-peccary, coati, and deer;
combined these species comprised 66.7 percent of the biomass consumed. Overall, jaguar relied mostly on large prey species (Table 1)
which comprised 41.2 percent of prey items and 50.0 percent of the
biomass consumed when livestock was not included. Medium-sized
prey species comprised 54.4 percent of prey items and 49.5 percent of the biomass consumed. The remaining 4.4 percent of prey
items and 0.5 percent of the biomass consumed were comprised of
small prey species. Pumas relied mostly on medium prey species,
which comprised 58.0 percent of prey items and 55.4 percent of the
biomass consumed. Large prey species comprised 32.2 percent of
prey items and 44.0 percent of the biomass consumed, while small
prey comprised 9.7 percent of prey items and only 0.8 percent of
the biomass consumed. The most important wild prey species for
pumas were deer, agouti, and paca, contributing 55.2 percent of
the biomass consumed (Table 2). When livestock was included in
the analysis, large prey species comprised 46.6 percent of prey items
and 63.1 percent of the biomass consumed by jaguars. Livestock
was the fifth most frequent prey found in jaguar scats but the most
important one in terms of biomass among all prey species, comprising 26.2 percent of all biomass consumed. No livestock was found
in puma scats.
FIGURE 1. Effect of sample size on the frequency of occurrence of most important prey species (frequency of occurrence ≥ 5%) in jaguar (a) and puma (b) scats in
INP between 1997 and 2001.
Food Habits and Livestock Depredation
497
TABLE 1. Relative biomass of prey consumed by jaguars based on 51 scats collected at Iguaçu National Park, Brazil, 1997–2001.
Relative
frequency of
occurrence (%)
Relative
frequency of
occurrence (%)
Frequency of
occurrence (%)
with
livestock
without
livestock
Prey
weight (kg)
35.3
17.6
2.0
24.0
12.0
1.3
26.5
13.2
1.5
13.7
9.3
Dasyprocta azarae
Dasypus novemcinctus
Nasua nasua
11.8
9.8
27.4
Agouti paca
Procyon cancrivorus
Tupinambis teguixin
Prey species
Relative
biomass
consumed (%)
Relative
biomass
consumed (%)
Correction
factor
with
livestock
without
livestock
25.0
22.5
45.0
2.9
2.8
3.6
23.7
11.5
1.7
32.1
15.6
2.3
0.0
175.0
8.1
26.2
0.0
8.0
6.7
18.7
8.8
7.3
20.6
3.2
3.5
5.5
2.1
2.1
2.2
5.8
4.9
14.0
7.8
6.6
19.0
5.9
2.0
15.7
4.0
1.3
10.7
4.4
1.5
11.8
10.0
10.0
1.6
2.3
2.3
2.0
3.2
1.1
7.5
4.4
1.5
10.2
3.9
2.0
0.0
2.7
1.3
0.0
2.9
1.5
0.0
0.1
0.7
0.5
0.1
0.7
0.5
0.1
0.3
0.0
0.1
0.4
0.0
Large prey size (> 15 kg)
Tayassu tajacu
Mazama sp
Hydrochaeris hydrochaeris
Livestock
Medium prey size (1–15 kg)
Small prey size (< 1 kg)
Small rodents
Birds
Snakes
Jaguar standardized niche breadth was 0.41 with seven prey
items identified as frequently consumed (relative frequency of consumption ≥ 5%). The MWVP for jaguars was 9.19 kg. When
livestock was excluded from the analysis, MWVP was reduced to
8.89 kg and width of niche breadth was 0.35. Standardized niche
breadth for puma was broader than for the jaguar, 0.47. The number of prey items frequently consumed by pumas (eight) was slightly
higher than by jaguars. However, the MWVP consumed was lower
than for jaguar (8.64 kg), even when only wild prey species were
included.
TABLE 2. Relative biomass of prey consumed by pumas based on 54 scats collected at Iguaçu National Park, Brazil, 1997–2001.
Frequency of occurrence (%)
Relative
frequency of occurrence (%)
Prey weight (kg)
Correction factor
Relative biomass consumed (%)
7.4
18.5
6.4
16.1
25.0
22.5
2.9
2.8
8.2
20.0
9.3
1.8
8.1
1.6
45.0
60.0
3.6
4.1
12.9
2.9
1.8
24.1
1.6
21.0
1.0
3.2
1.0
2.1
0.7
19.7
Dasypus novemcinctus
Cebus apella
3.7
1.8
3.2
1.6
3.5
3.0
2.1
2.1
3.0
1.5
Nasua nasua
Agouti paca
Tupinambis teguixin
14.8
14.8
5.5
12.9
12.9
4.8
5.5
10.0
1.6
2.2
2.3
2.0
12.6
13.5
4.4
Small prey size (< 1 kg)
Small rodents
9.3
8.1
0.1
0.1
0.4
1.8
1.6
0.5
0.5
0.4
Prey species
Large prey size (> 15 kg)
Tayassu tajacu
Mazama sp.
Hydrochaeris hydrochaeris
Caiman latirostris
Medium prey size (1–15 kg)
Sylvylagus brasilienses
Dasyprocta azarae
Snakes
498
Cascelli de Azevedo
Jaguar and puma diets differed significantly when compared
including all prey items (χ 2 = 35.0, df = 15, P = 0.002) and
also when livestock was excluded from the jaguar diet (χ 2 = 28.7,
df = 14, P = 0.011). Among wild prey consumed by both predators, the main difference was the higher consumption of collared
peccaries by jaguars (χ 2 = 8.9, df = 1, P = 0.003). No remains
of white-lipped peccaries were found in any predator scats during
the whole course of this study. We found high dietary overlap between jaguar and puma. The Renkonnen index for overlap in diet
including livestock was 55.9 percent, indicating substantial overlap
between predators.
LIVESTOCK DEPREDATION.—The total area occupied by sampled
ranches was 155.2 km2 (mean: 1.8 ± 3.0; range: 0.03–15.7 km2 ).
The majority of ranches (61.2%) comprised < 1 km2 . All ranches
had cattle, whereas fewer had horses (24.7%), pigs (23.5%) sheep
(16.5%), and goats (3.5%). When grouped into categories, the majority of the ranches (52.9%) had ≤ 50 head. The mean number of
livestock animals per ranch was 217.9 ± 396.6 and ranged between
three and 2000 head. I visited ranches an average of 2.6 ± 2.1 times
per month during the study. My detection rate for the period of
study was of one predation incident confirmed to 149 possibilities
of finding an event of predation through visits to ranches. Of 85
ranches visited during 1997–2000, I recorded livestock attacks in
all 4 yr on only 20 ranches (23.5%). I recorded 60 animals attacked
during the study, which comprised 0.3 percent of the total livestock
holdings on the sampled ranches. Of the 60 incidents, 81.6 percent
(N = 49) resulted in livestock mortality whereas the remainders
were wounded.
Jaguar predation on livestock (95.0%; N = 57) was considerably higher than puma predation (χ 2 = 48.60, df = 1, N = 60,
P < 0.001). Pumas were responsible for the killings of only a few
medium-sized livestock species, such as sheep (5% of all livestock
attacks; N = 3) and did not attack cattle. The number of jaguar
attacks on livestock was not based on livestock density since the
number of livestock losses due to predation did not increase as densities of livestock increased by ranch (R2 = 0.114, P = 0.299). There
were significant differences in number of attacks per year during the
period of the study (χ 2 = 21.5; df = 3; N = 60; P < 0.01). The
greatest numbers of attacks were recorded in 1998 and 1999 (N =
29 and N = 16, respectively), which comprised the same period
during which livestock was found in jaguar scats.
DISCUSSION
DIETARY BEHAVIOR.—Although jaguars and pumas consumed similar numbers of prey species, 12 and 13, respectively, I found that
jaguars had a narrower dietary breadth than pumas. This result
indicates that jaguars were preying more heavily on certain prey
species while pumas were taking prey in more similar proportions.
Large and medium-sized prey species comprised the bulk of jaguar
diet, while medium prey species comprised the majority of prey
consumed by pumas. Similar dietary patterns showing narrower di-
etary breadth and higher use of larger prey species by jaguars were
found in other regions of South America where jaguars and pumas
are sympatric (Taber et al. 1997, Núñez et al. 2000, Scognamillo
et al. 2003). However, my results contrast with dietary behavior of
sympatric jaguars and pumas showing similar preferences toward
prey species in areas where the prey base is subjected to several levels
of hunting pressure (Núñez et al. 2000, Novack et al. 2005).
The MWVP for jaguars at INP was among the lowest reported for most Neotropical sites (Rabinowitz & Nottingham 1986,
Hoogesteijn et al. 1993, Taber et al. 1997, Núñez et al. 2000, Scognamillo et al. 2003). The MWVP for jaguars also declined temporarily. From 1990 to 1995, when peccaries were more abundant
in INP, MWVP for jaguars was considerably higher, 14.4, even
without the inclusion of cattle (Crawshaw 1995). Reduction in the
MWVP for jaguar in INP reflects the importance of medium prey
items, such as coati, tegu-lizard, and agouti (Novack et al. 2005).
Jaguars seemed to adapt their feeding behavior to prey on more
likely available prey items, thus supporting the pattern of opportunistic hunting to optimize foraging (Rabinowitz & Nottingham
1986).
Conversely, MWVP for pumas in INP was similar to that reported for other sites where pumas occur in sympatry with jaguars
(Novack et al. 2005). Although no comprehensive dietary analysis
has been conducted for puma in INP prior to my study, previous
data indicated that the MWVP for pumas (10.8 kg) was lower
than for jaguars, and peccaries and deer comprised the bulk of
biomass consumed (Crawshaw 1995). Therefore, it seems that apparent recent changes in prey availability did not affect puma dietary
behavior. During my study, pumas concentrated their feeding on
medium prey items and seemed to use large mammals other than
peccaries, such as deer and capybara, to complement their diet. The
preference for deer has been widely recorded throughout most of the
puma’s range (Iriarte et al. 1990). However, in regions of sympatry
with jaguars, pumas seem to rely more heavily on medium size prey
species such as agouti, paca, and coati (Novack et al. 2005), thus
alleviating overall levels of competition with jaguars. The similarity
in the consumption of medium-sized prey species by jaguar and
puma in INP might result from the decline of primary food sources
for jaguar, such as peccaries, thus increasing dietary breadth and
therefore overlap between these two sympatric predators (Neale &
Sacks 2001). The homogeneity of the landscape in INP and the
degree of diet overlap suggest that coexistence between these two
predators is likely driven by exploitative competition through some
degree of food partitioning (Johnson et al. 1996, Scognamillo et al.
2003, Novack et al. 2005).
Despite the length of my study (ca 5 yr), I was able to collect a
limited number of scats from jaguar and puma in INP. Difficulties
in finding jaguar and puma scats were also apparent in a previous
study in the area. During 5 yr of research on the ecology of jaguars
in INP, Crawshaw (1995) was able to analyze 73 scats from jaguars
and only 28 from pumas. The low number of trails and roads,
the denseness of the forest, and the high average temperatures and
humidity in INP may have limited my ability to find more samples
during the study.
Food Habits and Livestock Depredation
LIVESTOCK DEPREDATION.—For some species of large felines, the
lack of available habitat and increasing population densities may
drive or keep some individuals of a population outside of protected
areas (Stander 1990, Saberwal et al. 1994). In INP, however, empty
adult home ranges inside the Park were occupied by young male
jaguars, indicating vacant territories of available habitat and a likely
stable or declining trend in population numbers (Crawshaw 1995).
In addition, the lack of suitable habitat and a consistent prey base
outside of the Park make habitat available for jaguars only within
INP limits. However, my results indicated that, in addition to a
significant reduction of consumption of peccaries by jaguar and
puma from 1997 to 2001 compared to consumption from 1990
to 1995 (Crawshaw 1995), cattle became important in terms of
biomass consumed by jaguars. Therefore, jaguar movement toward
the outside of INP and hence predation on livestock seemed to
reflect a temporal absence of available food within INP.
Predation on livestock may be substantial when availability or
diversity of large wild ungulates is low, which might provoke a shift
toward the use of domestic rather than wild ungulates (Meriggi
& Lovari 1996, Stahl et al. 2001). Under these circumstances, I
would expect livestock predation by jaguars to be established as
a common pattern on the borders of INP. I found, however, that
livestock depredation was not substantial based on the availability
of livestock. Even though ranches had no direct protection against
predators, results of this study show low numbers of domestic animals attacked relative to the total livestock holdings in the INP
region. Moreover, the impact of jaguars on livestock was not heavier on ranches with higher density of livestock. Most herds were not
affected by predation and those that were, suffered only sporadic
attacks. If only mortality of cattle is considered (0.26%), my results
were lower than estimates of annual predation on cattle ranches in
the Pantanal region of Brazil (0.84% of the total livestock holdings;
Dalponte 2002), in Venezuela (1.3% and 3.5% of the total livestock holdings; Hoogesteijn et al. 1993), and in other tropical areas
(Madhusudan 2003, Patterson et al. 2004). The small number of
attacks for the extent of the study (1997–2000) limited the analyses of the effect of some variables that might have had influence
on livestock predation patterns, such as rainfall regime or calving
period (Michalski et al. 2006).
In my study, I found a concentration of predation incidents
in 2 yr surveyed (1998 and 1999). In addition, the fact that only
jaguars and not pumas were a real threat to livestock likely reflected
the lack of enough large wild prey species for jaguars in INP. This
predation pattern suggests that, as opportunistic feeders, jaguars
may have adapted their land-tenure system and behavior to suit local
circumstances, using alternative sources of prey such as domestic
stock (Schaller & Crawshaw 1980, Quigley & Crawshaw 1992,
Polisar et al. 2003, Patterson et al. 2004). In contrast, it seems that
the wild prey base in INP was sufficient for pumas and that this
smaller predator had no need to use alternative prey species such as
domestic stock.
Most conservation strategies for protection of large carnivores
have focused on the establishment of wildlife reserves or sanctuaries to preserve intact habitat and avoid illegal hunting of predator
species (Rabinowitz & Nottingham 1986, Quigley & Crawshaw
499
1992, Woodroffe 2001). At INP, predation incidents on livestock
on neighboring ranches have threatened the conservation of jaguars
because of retaliation actions from ranchers (Conforti & Azevedo
2003). It appears that habitat protection and control of illegal hunting of predators are not necessarily sufficient conservation actions
to ensure persistence of jaguars in INP. Increasing numbers of large
wild ungulates and the establishment of management actions to
mitigate jaguar–cattle conflicts might be essential to preserve the
population of jaguars in INP. Moreover, studies focusing on the spatial distribution and dietary patterns of jaguars and pumas should
be conducted concurrently with a monitoring of prey abundance if
we want to fully understand the coexistence of predators and predator responses to changes in prey abundance in the protected area of
INP.
ACKNOWLEDGMENTS
I thank J. Rachlow for constructive comments on this paper and V.
A. Conforti for her help during fieldwork activities. I also thank P.
Crawshaw for the opportunity to work in the Iguaçu National Park
and the support provided by local people surrounding Iguaçu National Park who participated in this project. I gratefully acknowledge
the Brazilian Institute for the Environment and Renewable Natural Resources—IBAMA, the National Center for the Conservation
of Predators CENAP/IBAMA and Iguaçu National Park for their
support and permission to work in the Park. This study was supported in part by Ilha do Sol Turismo and Navegação—MACUCO
and EUCATEX S.A. Institutional support was provided by INSTITUTO PRÓ-CARNÍVOROS.
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