Survival of a native
mammalian carnivore, the leopard cat Prionailurusbengalensis Kerr, 1792 (Carnivora: Felidae), in an agricultural landscape on an oceanic
Philippine island
Ma. Renee P. Lorica 1 & Lawrence R. Heaney 2
1 Conservation Biology Program,
University of Minnesota, 200 Hodson Hall, 1980 Folwell Ave., St. Paul, MN 55108, USA
1 Current address: Crop and
Environmental Science Division, International Rice Research Institute, Los Baños, Laguna 4031, Philippines
2 Division of Mammals, Field
Museum of Natural History, 1400 S. Lake Shore Drive, Chicago, IL 60605, USA
1 loric001@umn.edu (corresponding author), 2 lheaney@fieldmuseum.org
doi: http://dx.doi.org/10.11609/JoTT.o3352.4451-60| ZooBank: urn:lsid:zoobank.org:pub:82D6D568-193A-4062-9A67-23401B554833
Editor: Shomita Mukherjee, Salim Ali Centre for Ornithology and Natural History,
Coimbatore, India. Date
of publication: 26 June 2013 (online & print)
Manuscript details: Ms # o3352 | Received 18
September 2012 | Final received 01 June 2013 | Finally accepted 02 June 2013
Citation: Lorica, M.R.P. &
L.R. Heaney (2013). Survival of a native mammalian carnivore, the leopard cat Prionailurus bengalensis Kerr, 1792 (Carnivora: Felidae),
in an agricultural landscape on an oceanic Philippine island. Journal of Threatened
Taxa 5(10): 4451–4460; http://dx.doi.org/10.11609/JoTT.o3352.4451-60
Copyright: © Lorica & Heaney
2013. Creative Commons Attribution 3.0 UnportedLicense. JoTT allows unrestricted use of this
article in any medium, reproduction and distribution by providing adequate
credit to the authors and the source of publication.
Funding: We thank the following institutions for funding
this project: Conservation Biology Program-University of Minnesota; Council of
Graduate Student’s Travel Fund; Dayton-Wilkie Natural
History Funds; the Ellen Thorne Smith Fund of the Field Museum of Natural
History; Ford Foundation-IFP; Ideawild; and, Rufford Small Grants.
Competing Interest: None.
Acknowledgements: Our sincerest gratitude to
the individuals who supported the project in various ways: JericGonzalez; Steve Goodman; Shannon Hackett; Hda. Dos
Marias staff; Michael Joyce; Kathleen Kelly; Pai Klinsawat; Gerry Ledesma; Paul Lizares; Dee-Ar Paglumotan; Alan Resetar; J.L.
David Smith; Worawidh Wajjwalku;
and, David Willard. Much
appreciation to the Negros Forests & Ecological Foundation, Inc. Permission
to conduct this study was granted by the Department of Environment and Natural
Resources-Region VI office; we especially thank RED Julian Amador and PAWD
Chief Damaso Fuentes for their support. Dr. John
McDonald and Patrick Zimmerman provided advice on the use of the Fisher’s Exact
Test. The maps
were prepared by Andria Niedzielski. Danny Balete and Eric Rickart provided
constructive suggestions that led to improvements in earlier drafts of this
paper. We also thank the reviewer of this manuscript for the comments and
suggestions.
Author Contribution: MRPL collected data from the field with the help
of her research assistant; analyzed them with the help of LRH and wrote the
basic draft of the dietary aspect of this paper. LRH guided MRPL on the
methodology and data analysis, assisted with identifications of scat contents,
and wrote most portions of the paper that deal with island biogeography.
Author Details: Ma.
Renee P. Lorica is a wildlife biologist who has been studying Visayan leopard
cats since 2005. She currently works for the International Rice Research
Institute on rodent ecology in lowland rice fields in the Philippines. Lawrence
R. Heaney is principally interested in biogeography, ecology, evolution,
and conservation of biodiversity in island ecosystems, and conducts most of his
research on the mammals of the Philippines. He serves as Curator and Head of the
Division of Mammals at the Field Museum of Natural History.
Abstract: Concerns about vulnerability of mammalian carnivores to extinction,
especially on small islands, appear to conflict with prior reports of endemic
populations of leopard cat Prionailurus bengalensis (Kerr, 1792) surviving in agricultural
landscapes on oceanic islands. We
investigated the persistence of the Visayan leopard cat (P. b. rabori) in the sugarcane fields on Negros, an
oceanic island in central Philippines. A population remained throughout the year at our study site on a
sugarcane farm, and reproduction was noted. Non-native rodents form the bulk of the
cat’s diet, followed by reptiles, birds, amphibians, and insects. Prey species identified from the samples
commonly occur in agricultural areas in the Philippines. Prey composition did not vary
significantly with respect to wet and dry season, or sugarcane harvest
cycle. This study provides evidence
that an intensively managed agricultural landscape on this oceanic island
supports a native obligate carnivore that subsists primarily on exotic
rats. This study supports a prior
prediction that leopard cats will show flexibility in prey selection on islands
with few or no native small mammal prey species, but in this case they do so
not by switching to other vertebrates and invertebrates, but rather to exotic
pest species of rodents.
Key words: Diet, exotic rats, extinction threat, habitat use, islands,
Negros Island, prey selection, Prionailurus bengalensis, scats
Abbreviations: bp - base pair; DNA -
deoxyribonucleic acid; GPS - global positioning system; IUCN - International
Union for Conservation of Nature.
For figures, images, tables -- click here
Introduction
Because of their high trophic
level, high metabolism, and low population density, mammalian carnivores are
considered to be among the organisms most vulnerable to extinction, often due
to fragmentation of habitat or over-hunting (e.g., Primack1993). This view of mammalian
carnivores being vulnerable to extinction is especially prominent in literature
on island biogeography. On
post-Pleistocene land-bridge islands (and habitat islands of progressively
smaller area), carnivore species richness declines more rapidly than any other
group of mammals (e. g., Brown 1971; Heaney 1984; Lomolinoet al. 2010) and they often are entirely absent from oceanic islands (e.g., Lawlor et al. 2002; Whittaker & Fernández-Palacios
2007).
This hypothesized
vulnerability of native carnivores was strongly corroborated by an analysis of
mammalian carnivores on East Asian islands, which found a strong correlation
between carnivore species richness and island area, and an even stronger
correlation between carnivore richness and prey richness (Watanabe 2009). That study highlighted what appears to be
an incongruity with prior reports of a small native felid, the leopard cat Prionailurus bengalensis (Image 1), maintaining populations on several small oceanic islands,
including Tsushima (696km2) and Iriomote(289km2) in Japan. Most
populations of this cat occur on islands of 1000km2 or larger, where
at least seven species of native small mammals (Soricomorphaplus Rodentia) are present. However, on Tsushima only six native
small mammals are present, and on Iriomote there are
none. Watanabe’s (2009) study,
which focused on the leopard cat, concluded that “the
probability of existence of the leopard cat is extremely low on small islands
with poor small mammal fauna[s] and several species of carnivores”. The study showed that on the two Japanese
islands, leopard cats consumed large amounts of non-mammalian prey (e.g.,
birds, reptiles, amphibians, crustaceans, and insects). Their persistence on such small islands
was evidence of versatility in feeding habits where close competitors,
especially small carnivores of the family Viverridae,
are absent (Watanabe 2009).
Despite their widespread
occurrence, relatively few studies have been conducted on leopard cats (de Alwis 1973; Rabinowitz 1990; Bumstead et al. 1992; Nowell& Jackson 1996). As Watanabe
(2009) noted, leopard cats primarily feed on rodents and, usually to a lesser
extent, birds, reptiles, amphibians and invertebrates (Inoue 1972; Yasuma 1981; Rabinowitz 1990; Sakaguchi 1990; Grassman 1998; Grassman 2000; Scott & Gemita2004; Grassman et al. 2005; Austin et al. 2007; Rajaratnam et al. 2007). In some agricultural areas, their
primary prey are exotic rat species that are major
pests (Delibes et al. 1997; Stenseth et al.
2003). In an oil palm plantation in
Sumatra, leopard cats moved through a complex matrix of habitats and fed on
small mammals, including exotic pest rats and other small vertebrates and
invertebrates (Scott & Gemita 2004). Similarly, in Malaysian Borneo, a study
of habitat selection in an oil palm plantation found that leopard cats relied
heavily on small mammals, especially rodents, and also on reptiles and
amphibians (Rajaratnam et al. 2007).
In the Philippines, leopard
cats occur on islands that range from ca. 14,000km2 down to 319km2,
where most native habitat has been converted to agricultural or human
residential uses (Institute of Environmental Science for Social Change 2002; Lorica & Oliver 2006; Pedregosaet al. 2006; Heaney et al. 2010). A
subspecies of leopard cat endemic to the islands of the west-central Philippines,Prionailurus bengalensis rabori Groves 1997, is listed as Vulnerable by
the IUCN Red List of Threatened Species (Lorica 2008)
and by the Philippine Department of Environment and Natural Resources
(2004). They have been reported as
extinct or close to extinction on the two smaller islands in their range, Cebu
(4468km2) and Masbate (3270km2), and persist principally
on Panay (12,011km2) and Negros (13,075km2), both of
which have lost 90–95 % of their natural habitat (Lorica& Oliver 2006; Heaney et al. 2010). Previous publications concerning P.b.rabori on Negros Island have suggested that they
may maintain populations in heavily utilized agricultural landscapes. As early as 1898, John Whitehead (cited
in Taylor 1934) stated that, “In Negros we obtained a specimen of Felis minuta [= P.
b. rabori]. The animal frequented sugarcane plantations, where it finds an abundance
of rats. During the harvesting
operations, this cat is often captured by the natives, who form a ring around
the last patch of standing cane.” Subsequent studies have provided some support for this observation
(Alcala & Brown 1969; Heideman et al. 1987; Lorica & Oliver 2006; Fernandez & de Guia 2011), though all were limited by
focusing on captive animals, dealing with small samples, or relying on
problematic methodologies. These islands have few or no native, non-volantsmall mammals (only two are known from Negros, three from Panay, and none are
known from Cebu or Masbate), and two civets (family Viverridae)
occur on all four islands (Steppan et al. 2003;
Heaney et al. 2010).
The purpose of this study was
to investigate the diet of wild leopard cats inhabiting a sugarcane farm on
Negros Island to determine if they remain as a resident population on the farm
throughout the year, reproduce on the farm, and subsist on exotic rats, as
suggested by earlier studies. We
conducted visual transects to detect tracks and scats, and determined prey
through detailed analysis of scat contents whose origin was verified by DNA
analysis. This allowed us to test
the prediction of Watanabe (2009) that on an island with two native small
mammals and two potential competitors, as is the case on Negros, leopard cats
would have a broad feeding niche, with a highly diverse prey base that includes
a relatively small percentage of small mammals.
Methods
Study site
Like most Philippine islands,
Negros arose from the ocean floor de novo (Hall 1996, 2002). Its volcanic origins make the soil ideal
for agriculture, and about 80% of arable land has been cultivated. The land area (including small offshore
islands) totals 13,328.4km2, of which 2,091km2 was
planted to sugarcane, as of crop year 2011–2012 (Sugar Regulatory
Administration, pers. comm. 25 January 2012).
Our study site, Hacienda Dos
Marias, is a 238-hectare private sugarcane farm in Barangay Ara-al,
La Carlota City, Negros Occidental. Throughout the perimeter of the
hacienda, wooded areas and bamboo-dominated shrubby patches were present along
the creeks and rivers. There are
two small human settlement areas within the hacienda. Planted cover (Fig. 1)
refers to monospecific stands of mahogany (Swietenia macrophylla),
mixed plantations of exotic tree species, and one stand of a native tree (ilang-ilang, Cananga odorata). Heavily disturbed riparian vegetation of small trees and shrubs grew
naturally along the banks of rivers and creeks. Bamboo groves were made up of
either planted or naturally-growing bamboo species (Bambusa spp.) growing in clumps.
Spoor observation and scat
collection
Scats and tracks were
collected and observed, respectively, during transect walks for ten months
within the study area from August 2010 to June 2011, and opportunistically
elsewhere in the study area. Transects were conducted on a weekly basis, and on days within the week
when transects are not walked, the study area was searched for scats. Scat, track and nest locations were georeferenced using a GPS device. Fifty fourscats were observed but only 51 were collected and subsequently analyzed due to
lack of teeth and bones from the three samples, though these samples were
composed mostly of mammalian hair. Each sample was stored in a plastic container in 90% ethanol, and
labeled accordingly. Several
methods were used to ensure that scat samples, and tracks in the study were
from leopard cats. Based on scats
from captive leopard cats from a local rescue center, and from the literature (Rajaratnam et al. 2007; Fernandez & de Guia 2011), we used the average diameter of 1–1.5 cm
to distinguish leopard cat scats from scats of other carnivores in the area.
The common palm civet Paradoxurus hermaphroditus is roughly the
same size as the leopard cat while the Malay civet is generally larger (Nowak
2005; Heaney et al. 2010) and has larger scats. Scats from palm civets are about the
same size as those of leopard cats, but contain more fruits than small
vertebrates (Rabinowitz 1991; Joshi et al. 1995;
Shore et al. 2005; Nakashima et al. 2010). Upon analysis of each scat, samples containing seeds and plant matter
other than grass were discarded, as they could belong to either species of omnivorousviverrid in the area (Rabor1977; Heideman et al. 1987). Finally, DNA analysis to confirm the
origin of some scats was performed by the laboratory of Prof. Worawidh Wajjwalku at Kasetsart University. Thirty scat samples were analyzed, and of the 30, only eight were found
to have useful DNA, half of which were leopard cats, while two belong to its
prey, Rattus tanezumi.
The universal primer cb0/cb2 (forward primer/reward primer) was used to amplify
420 bp of the cytochrome b region of the mitochondrial
DNA. This primer
is designed by Prof. W. Wajjwalku. The sequencing results were compared
with those reported in GenBank© sequences
for species identification.
Domestic cats have also been
observed around human habitation. We employed several means to distinguish leopard cat tracks from that of
a domestic cat. Those that accompany scats that were proven to be of a leopard cat’s via DNA analysis were included. Tracks found in close proximity to human
habitation were immediately discarded. We did not include tracks or scats from such places in our analyses;
these scats (which were not subjected to DNA analysis) typically contained
undigested rice, pieces of plastic food wrappers, and house mouse skeletal
remains. This procedure may have
led us to exclude actual leopard cat tracks and/or scats (from places near
houses), and to include some house cat scats (from places away from houses),
but we believe it substantially reduces the likelihood of misidentifications
overall.
Scat analysis
Each sample was placed in a
1-mm sieve and washed with hot water to separate the elements in the scat. Only bones, teeth, scales and feathers
were collected from each scat sample, dried, and kept in small envelopes for
identification. Hair was not used
as the basis for identification given the variability of its morphology even
between individuals of the same species (Mayer 1952; Dagnall1995; Broeck et al. 2000). These samples were compared against
specimens at the Field Museum of Natural History, Chicago, Illinois. Data were analyzed using R version
2.13.2 (©The R Foundation for Statistical Computing). Fisher’s Exact Test was used due to
small sample size (McDonald 2009).
Results
Site use
Leopard cats were active
throughout the study area (Fig. 1), as documented by scats and tracks. In two cases, nests
with kittens were uncovered by workers during the harvest. Three bird kills were found in the study
area; we cannot be certain that they were attributable to leopard cats, but
this was likely because tracks and feces of leopard cats were found nearby.
Leopard cat activity occurred
during every month of the study. The pre-harvest season (September–October), when cane was tall and
not often disturbed by human activity, yielded the highest observation of spoor:
eight out of 27 sub-transects were found to contain leopard cat signs of
presence during both months (Table 1). During the harvest months of November to April, the average number of
spoors observed was 4.8/month, and during the post-harvest months of May and
June, the average was 4.5/month. Fisher’s Exact Test (P>0.05) showed no significant differences among
the three periods, perhaps associated with the small sample sizes, in spite of
the larger number observed in the pre-harvest period.
We also examined the presence
of spoor according to climatic seasons (Table 2). The wet season (n=4) yielded an average
of 6.75 observations/month, and the dry season yielded an average of 4.5/month. This difference was not statistically
significant (Fisher’s Exact Test, P>0.05).
Evidence of reproduction
During the harvest period,
cane cutters found two litters within the study area (Fig. 1). A litter found on 1 March 2011 consisted
of two kittens that were about 2–3 weeks old; the second litter, found 10
March 2011, was a lone kitten of about 4–5 weeks old. Two additional litters were rescued from
areas adjacent to the study site; one was a lone kitten and the other a litter
of three, all of which were less than a month old.
Food habits
Fifty one leopard cat scat samples
were examined. Mammals were present
in 96% of the scats. Grass (33%),
reptiles (20%), birds (12%), amphibians (8%) and insects (4%) also occurred in
the samples (Table 3). These
percentages represent the relative frequency of occurrence of each prey group
in all 51 scat samples. There was
one sample in which the prey species could not be identified due to the
breakdown of the bones to unidentifiable pieces, and the absence of teeth.
Among mammal species (Table
4), Rattus tanezumi was most frequently represented in scats (67%), followed by R. exulans (34%). Rattus norvegicusand Mus musculuswere present but uncommon. Three
samples were identified only to the genus Rattus,
while three were identified only as mammalian. All of these rodents are non-native
species. Amphibians could be
identified only to the family level, Ranidae;
reptiles were also identified only to the family level, Gekkonidaeand Agamidae. Two scat samples were found to contain skink bones; one species of skink
is most likely to occur in the cane fields, Eutropis multifasciata (A. Diesmospers. comm. 21 August 2011 & R. Brown pers. comm. 14 October 2011). Snake bones were only identified to the
suborder Serpentes, while three scats contained
unidentified reptilian bones.
Two species of birds were
identified from feathers, the Yellow-vented Bulbul Pycnonotus goiavier and the White-bellied Munia Lonchura leucogastra. Insect parts were also found in two of the scat samples; one was identified as orthopteran while
the other was an unidentified insect.
There was no significant
difference in prey composition between pre-harvest, harvest, and post-harvest
seasons (Fisher’s Exact Test, P>0.05; Table 4). There was also no significant difference
in rodent species occurrence in the scats between pre-harvest, harvest, and
post harvest seasons (Fisher’s Exact Test, P>0.05).
There was no significant
difference in prey composition between wet and dry seasons (Fisher’s Exact
Test, P >0.05; Table 5). There
was also no significant difference in rodent species occurrence in the scats
between wet and dry seasons (Fisher’s Exact Test, P>0.05).
Discussion
and Conclusion
Site use
Tracks and scats were found
on nearly all transects in the study area (Fig. 1). Our transects principally followed
unpaved roads and trails within sugar cane fields, since tracks and scats are
easiest to see where there is no ground cover, and because leopard cats tend to
deposit scats in open areas. Signs
are more difficult to detect in natural habitats, such as riparian areas with
ground cover. This possibly
accounts for our few observations of spoor in natural habitats, even if the
cats use those areas. The nearness
of some spoor to areas heavily used by humans suggests that these leopard cats
tolerate human proximity.
The two litters found within
the study site further demonstrate that adult females use the cane fields, as
reported by John Whitehead in 1898 (cited in Taylor 1934). Given the gestation period of leopard
cats of 56–70 days (Nawa 1968; Hemmer 1976),
the age of the kittens from each litter, and the close proximity between the
dates of discovery, it can be inferred that the study site had at least two
adult female leopard cats. The two
other litters were found in the area bordering the study site, though GPS
locations for these were not recorded due to unreliable information from
workers in the other hacienda. This is consistent with information from a local rescue center that has
received donations of unweaned kittens rescued from
sugarcane farms near our study area since 1997 (Lorica& Oliver 2006).
Previous studies have shown
leopard cats to occur in a range of habitats, including primary and secondary
forest, mixed agriculture and secondary forest, and mixed oil palm plantations
and secondary forest (Taylor 1934; Lekagul &
McNeely 1977; Rabor 1977; Sunquist& Sunquist 2002; Scott & Gemita2004; Lorica & Oliver 2006; Rajaratnamet al. 2007). Our study site
appears to represent the most heavily disturbed, most purely agricultural site
at which this species has been shown to maintain a population.
Diet composition
Most previous studies have
shown that mammals dominate the diet of leopard cats throughout its range
(Alcala & Brown 1969; Inoue 1972; Lekagul &
McNeely 1977; Santiapillai & Suprahman1985; Rabinowitz 1990; Sakaguchi& Ono 1994; Tatara & Doi1994; Grassman 1998; Grassman2000; Grassman et al. 2005; Austin et al. 2007; Rajaratnam et al. 2007; Fernandez & de Guia 2011). Earlier
studies conducted in predominantly forested areas found that rodents, usually murids, were the most prominent mammalian prey. In Huai Kha Khaeng Wildlife Sanctuary in
Thailand, rodents occurred in 76.3% of the scats (Rabinowitz1990). In north-centraland in central Thailand, high frequencies of occurrence for rodents (89% and
82%, respectively), were also found (Grassman et al.
2005). In south-central Thailand,
rodent frequencies were lower at 36%, but mammals in total were the predominant
prey (Grassman 2000). Murid rodents
dominated the diet of leopard cats in the Sundarbansin Bangladesh, though the frequency was not as high at 52% (Khan 2004).
Leopard cats take a wide
variety of mammalian prey. Aside from murid rodents,
which were the primary prey overall, other small mammals found by the
previously mentioned studies were bamboo rats (Spalacidae:Cannomys badius),
squirrels (Sciuridae: Callosciurus spp., Menetes berdmorei,Petaurista petaurista, Tamiops spp.), tree shrews (Tupaiidae: Tupaia glis), gymnures (Erinaceidae: Hylomys suillus), and fruit
bats (Pteropodidae: Pteropus dasymallus,); medium-sized mammals include hare (Leporidae: Lepus peguensis), hog badger (Mustelidae: Arctonyx collaris) and
chevrotain (Tragulidae: Tragulus javanicus). Remains of relatively large-bodied mammals, such as pigs (Suidae: Sus scrofa) and langur (Cercopithecidae: Semnopithecus obscurus) were also found in the scats although
some surmised that those had been scavenged rather than hunted (Santiapillai & Suprahman1985; Grassman 1998).
On Tsushima Island in Japan,
rodents were found in 73% of the scats, but birds and insects were found in 42%
and 44% of the scats, respectively (Inoue 1972), which are much higher rates
than noted elsewhere. On Iriomote Island, Japan, rodents were found in only 20% of
the scats, birds in 48%, reptiles in 33%, amphibians in 34%, and insects in 24%
(Watanabe 2004, 2009; see also Sakaguchi 1990),
leading Watanabe (2009) to predict that on any islands with few or no native
rodents or shrews (such as Negros), leopard cats would show similar flexibility
in prey selection, with great diversity in the taxa consumed.
We found mammals in 96% of
our samples. There are ca. 41
species of bats inhabiting the island, many of which occur in agricultural
lowlands (Heaney et al. 2010), but chiropterans were not found as prey in this
study. One shrew (Crocidura negrina) and one mouse (Apomyssp.) are native to Negros, but both are confined to high-elevation forest (Heideman et al. 1987; Steppan et
al. 2003; Heaney et al. 2010), and neither was present in our samples. Suncus murinus, the Asian house shrew, occurs in
human habitation and agricultural areas on Negros, but it also was not found in
this study. Of the four rodent
species that made up the great majority of leopard cat prey at our study site,
all are non-native pest species. Rattus tanezumi (a
member of the Rattus rattusgroup) occurred most frequently in the scats (66.7%); R. exulans (58.8%) and R. norvegicus (5.9%) followed. Mus musculus, more
commonly associated with human habitation than agricultural areas in the
Philippines (Heaney et al. 2010), occurred in only 3.9% of the samples. We found no significant variation in
utilization of prey based on climatic season or harvest schedule. Most other studies also did not note
significant seasonal changes in diet (Alcala & Brown 1969; Inoue 1972; Lekagul & McNeely 1977; Santiapillai& Suprahman 1985; Rabinowitz1990; Sakaguchi & Ono 1994; Tatara& Doi 1994; Grassman1998; Grassman 2000; Grassmanet al. 2005; Austin et al. 2007; Rajaratnam et al.
2007; Fernandez & de Guia 2011).
We note that a brief earlier
study (Fernandez & de Guia 2011) in the area also
reported heavy reliance of leopard cats on exotic pest rodents: Mus musculus (96%) and Rattus tanezumi (96%) occurred most frequently in 25 samples (Fernandez & de Guia 2011). This study also reported R. argentiventer hair
from the scats they collected from the area; this species has not been
confirmed for the island though it is possible that it occurs on Negros (Heaney
et al. 2010). Identifications of
mammals based on hairs in scats, which are prone to morphological variability
between individuals of the same species, are thought to be difficult to
determine with certainty (Mayer 1952; Dagnall 1995; Broeck et al. 2000).
Our results strongly support
previous evidence that sugarcane plantations on Negros Island with only very
small and scattered patches of non-agricultural vegetation support populations
of leopard cats throughout the year, and that reproduction occurs within these
populations. Clearly, leopard cats
have been able to adapt to the massive conversion of their native forest
habitat to sugarcane fields that began in the 1850s (Larkin 1993), the
widespread logging on the island in the 1900s onwards (Kummer1992), and the current threats from illegal pet trade and poaching (Lorica & Oliver 2006). In doing so, the cats have shown
flexibility both in their use of habitat and in their use of prey: in this
study, the great majority of their food consisted of exotic pest species of
rats and mice. Thus, our findings
are consistent with the prediction by Watanabe (2009) that leopard cats on
islands that have few or no native mammalian prey should show flexibility in
prey selection, but this flexibility on Negros is manifested as a shift to
overwhelming reliance on exotic rodents, rather than the shift to a wide range
of vertebrates and invertebrates predicted by Watanabe. Overall, the ability of this carnivorous
mammal to survive in a highly anthropogenic habitat by utilizing non-native
prey is remarkable, given the general vulnerability of mammalian carnivores to
extinction.
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