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Comparative Feeding Ecology of Felids in a Neotropical Rainforest
Author(s): Louise H. Emmons
Source:
Behavioral Ecology and Sociobiology,
Vol. 20, No. 4 (1987), pp. 271-283
Published by: Springer
Stable URL: http://www.jstor.org/stable/4600019
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Behavioral Ecology
Behav
Ecol Sociobiol
(1987)
20:271-283
and
Sociobiology
?
Springer-Verlag
1987
Comparative
feeding ecology
of
felids
in
a
neotropical
rainforest
Louise
H.
Emmons
Smithsonian
Institution,
Division of
Mammals,
Washington,
DC
20560,
USA
Received
July
9,
1986
/ Accepted
December
27,
1986
Summary.
Diet and habitat use
of
jaguar, puma,
and
ocelot,
and
populations
of
their mammalian
prey,
were
studied
in an undisturbed
rainforest
in
southeastern
Peru.
Analysis
of scats
(feces)
showed
terrestrial
mammals
to be the chief
prey
of
all three
felids,
but
reptiles
and
birds
were
also
numerically
important
in
the
diets of ocelot and
jaguar.
Prey
diversity
is
high
and
the cats
evidently
take
any
readily
captured
vertebrate. For
major
terrestrial
mammal
prey
of
felids,
density,
biomass,
prey/pre-
dator
ratios,
and
annual
offtake
from the
study
area
are estimated.
All three cat
species
seem to
hunt
by opportunistic
encounter
of
prey.
Most
mammalian
prey
species
were
taken
in
about
the
ratios
of
occurrence,
but
peccaries
were
taken
by
jaguar
more
often
than
expected.
Most
prey
of
jaguar
have a
body weight
of
> 1
kg,
those
of oce-
lot,
<
1
kg.
Jaguar
often
used
waterside
habitats,
where
they captured
caiman
and river
turtles.
Puma
did not
use
these habitats
or
resources,
al-
though
the
puma prey
sample
was too small
for
much
inference.
The
possible
effects of
felids
on
study
area
prey populations
are discussed.
Large
and small
cats
partition
prey
at
the
body
weight
region
where
prey
switches
from
low to
high repro-
ductive rates.
Introduction
The diets
of
many species
of mammalian
carni-
vores are
well
documented
(see
Gittleman
1983 and
Bekoff
et al.
1984,
for extensive
bibliography)
and
new
prey-species
lists from
new localites
bring
few
surprises.
Studies
of
predator-prey
relations
for
mammalian
carnivores
are
scarcer,
and
for the
most
part
limited
to
temperate
zone,
single-species
examples,
such as wolf-moose
(Mech 1970),
puma-
cervid
(Hornocker
1970),
and
lynx-hare
(Parker
et al.
1983);
or to
tropical
savannas,
including
the
best-studied
of all
predator-prey
communities: the
Serengeti
(Schaller
1972;
Sinclair and Morton-
Griffiths
1979;
Waser
1980).
Felids are the
only large
mammalian
predators
found
in
all three
tropical
rainforest
regions
of
Africa,
Asia,
and the
Neotropics.
As
for most
mammalian
taxa
except
primates,
less is known
about
the
ecology
of
rainforest
populations
than
about
those
in
other
habitats. The
only tropical
rainforest
carnivore
that has been
well-studied is
the
tiger
(Schaller
1967;
Seidensticker
1976;
Sun-
quist
1981),
and
this, moreover,
in
partially open
habitats
with
grassland. Leopards
have been the
object
of some
studies
in
dry
habitats
(Schaller
1972;
Muckenhirn
and
Eisenberg
1973;
Seiden-
sticker
1976),
and there
is a
list
of
prey
for the
leopard
in
Ivory
Coast rainforest
(Hoppe-Dominik
1984),
but
published
information
on the
diets of
other
entirely
rainforest
populations
of
large
Car-
nivora
is
chiefly
anecdotal.
The
largest
neotropical
felids,
jaguar
and
puma,
have been studied
in
grassland/forest
mosaic
in Brazil
(Schaller
and
Vasconcelos
1978;
Schaller
and
Crawshaw
1980),
and
Mondolfi
and
Hoogesteijn
(1987)
have
com-
piled
an extensive
review
of
the diet and
natural
history
of
jaguar
in
Venezuela.
Diets
of
puma
have
been
recorded
for
temperate
South
America
(Wil-
son
1984;
Yafiez
et al.
1986).
The
aim of
this
study
was to describe
the
diets,
habitat
use,
and
prey population
base
of a
com-
munity
of three
felid
predators;
ocelot,
puma
and
jaguar;
on a
plot
of
undisturbed
lowland
tropical
rainforest
in
southeastern
Peru,
and
to
analyse
the
relationships
of the
felids
to each
other
and to
the
array
of
prey.
272
Study
area
and
methods
This
study
was done at Estaci6n
Biologica
de Cocha
Cashu,
Parque
Nacional
Manu,
Dpto.
Madre de
Dios,
Peru
(ca.
11?22'S,
71?22'W),
from
August
1982 to
February
1985. The
study
area is
undisturbed,
lowland
evergreen
tropical
rainforest
in
the
floodplain
of the
Rio
Manu. Its climate
and
vegetation
are described
in
Terborgh (1983).
The
area around Cocha
Cashu is uninhabited and has not
been hunted
by
humans since
establishment of the Park
in
1968. Prior to
1968
it
was hunted
sporadically
by
itinerant
skin-
and subsistence
hunters.
The
only
access to Cocha Cashu is
by
boat
and once
there,
the
only
land
transport
is
by
foot. Because of the
difficulty
of
monitoring large
areas on
foot,
the
object
of this
study
was
to examine the
predator-prey
interactions that look
place
in
a limited zone of about 7.5 km2.
Three
species
of felids were
common
on the
study
area:
jaguar
(Panthera
onca),
puma
(Felis
concolor),
and ocelot
(Felis
pardalis).
The three
other cat
species
that do or could occur
in
the
region
were not encountered
during
this
study.
Analysis
of
diet
Felid diets were studied
by analysis
of
scats
(feces).
These were
collected whenever found
during
five months
in
1982,
11.5 months
in
1983-84,
and
sporadically
for 10 months subse-
quently.
The scats were stored
in
plastic bags
in
10%
formalin
or 70% ethanol.
For
analysis, they
were broken
up
and washed
with water over a fine-mesh
screen, dried,
and examined under
a
microscope.
Hair was
compared
with reference
slides of hair
from mammals
trapped
at
Cocha
Cashu or from
specimens
in the United States National Museum.
Plastic
impressions
were
made of some hair
samples
and
surface scale
patterns
examined
under
Nomarsky optics.
Hard
parts
(bones,
teeth, nails,
scutes)
were
compared
directly
with museum
specimens
of mammals
and
reptiles.
The
minimum number of
prey
in
a scat was
counted
from hard
parts;
hair
only
was
counted as one
prey
of that
species.
Scats were identified
by
their association
with
tracks,
with
a
trapped
individual,
with a radio-monitored
individual,
or
by
size
and
presence
of hair
ingested
while
grooming.
The maxi-
mum width
of each
piece
of a
dropping
was measured and
a scale
established from scats
of known
origin.
Scats of
puma
and
jaguar
could not
be
distinguished
with
certainty
by
size,
but
ocelot and
"big
cat" scats differ
significantly.
Because
no
other small cat
species
was
identified on the
area
during
the
study,
all small cat
scats are assumed
to be those of
ocelot.
Prey
identified from
separate
scats is assumed
to
represent
independent captures.
This
assumption
seems
justified
because
in
general
only big
cats feed on
prey
that is consumed
in
several
meals. So
few
big
cat
scats were
found,
and these
spread
widely
in
time,
that there
are
only
two cases
where the same
prey
individual could
be
represented
in
two scats.
For
ocelot,
there
were also
only
two cases
where scats
including
the same
large
prey
item were
found on
the same or
sequential
days.
In
all
these
cases,
I
have counted
the two
incidences as
a
single prey.
In
the environment
on the
study
area,
fresh
scats
in the forest
are
usually destroyed
within hours
by
dung
beetles
and
trigonid
bees.
Only
those
consisting
of mats
of coarse
hair,
or
those
placed
in
dry sunny
areas
(beaches)
survive a
few
days.
Felid use
of
the
study
area
Felid
presence
on the
study
area was recorded
by:
(1)
quantita-
tive
monitoring
of tracks on
prepared tracking
areas
during
the
dry
seasons
of two
years
(Emmons
et al.
1987);
(2)
record-
ing
the
presence
of tracks at other times and
locations,
and
other
sign
such
as
scrapes,
scats,
the
roaring
of
jaguar,
and
direct
sightings;
and
(3)
radiolocation of
radiotagged
individ-
uals
(9
ocelot,
two
jaguar,
one
puma).
The
study
area is
en-
closed on
three sides
by
a
loop
of the Rio
Manu and an
oxbow
lake,
so
that it was
clear whether
a cat was
in
or out of it.
Estimation
of
prey
density
and size
Densities of
larger
mammals
on
the
study
area were
estimated
by day
and
night
transect census
(Emmons
1982,
1984),
or
in
the
case
of
capybara,
from known
groups.
Small
mammals
were
estimated
by monthly
capture-mark-release
trapping
on
a
4
ha
grid during
12
months of
1983-84 and 5
months
in
1979
(methods
in
Emmons
1982,
1984).
Biomass of small
mammals was
estimated from the
actual
mean
body weights
of all members
of the
population
trapped,
including
juveniles.
For
larger
mammals,
a mean
weight
was
estimated at about
3/4
of adult
weight
of animals
captured
on the
study
area,
field-collected
museum
specimens,
or
the
literature
(field
weights only).
Results
Use
of
the
study
area
by felids
Temporal
use. Ocelots were
permanent
residents
of the
study
area:
three adult
females and their
young
had most of their
home
ranges
within the
area,
while a
dominant male had
part
of his
range
on
it,
for an estimated
population
of about 0.8 oce-
lot/km2.
Breeding
females had
non-overlapping
territories,
young occupied
the mother's
territory,
and dominant
males
overlapped
more than one
female
range (details
to be described
elsewhere).
Ocelots
hunted
solitarily
and
terrestrially.
Big
cats
(jaguar
and
puma)
were recorded on
the
study
area on
178
of 530
days,
or on
33.5%
of all
possible
days.
Of
these,
jaguar
were recorded
on 20%
of
days,
and
puma
on
14%.
These
figures
represent
only
a
minimum
prescence,
as
big
cats
certainly
sometimes
escaped
detection,
especially
during
the
rainy
season,
when tracks are washed
away
and
many
trails flooded.
In
any
month,
big
cats were
recorded
in the area on
12%
to
60%
of all
days.
Two
puma
and
three to five
jaguar
shared the area.
With the
following
few
exceptions,
both
puma
and
jaguar
were
solitary.
In
1982,
a female
jaguar
traveled with a cub.
A
pair
of
jaguar
of unknown
sex,
with
small
female-sized
feet,
traveled
together,
entering
the
region
several times from
May
to
July
1984. This
may
have been a
pair
of
siblings
recently
become
independent. During
three
and a half
weeks,
from
11
Aug
to 6
Sep
1983,
the male
puma
that
used the
study
area
appeared
to
be
consorting
with
the
female,
as
they
were three times
on the
area
simultaneously, although
not recorded on
the
same
part
of it.
At no other time
during
the
study
were
they
noted
in
the area
on the same
day.
Only
one other
lengthy
interaction
was
observed: on
five
273
of
the six
days
8-13
Sep
1983,
jaguar
roared
from
in
and
around the
study
area
in
six
episodes
of
up
to
two
hours each. At
least
two
jaguar
were
involved,
one
of
which
was
a
male.
There is
evidence that
the
big
cats avoided
each
other
temporally
both
intra-
and
interspecifically:
of
199
big-cat/days (an
individual
big
cat known
to
be on the
area
during
a 24 h
period,
excluding
the
jaguar kitten),
recorded on
the
study
area,
two
big
cats were
simultaneously
present
on
only
20
days,
and
on one
day,
three.
Most of these in-
stances
were
the few
interactions
described
above,
but even with
these,
when
two cats were
present,
they
were
usually
on
opposite
sides of the
study
area.
Only
twice were
tracks
of
two
individuals
found
on
the same
day
crossing
the
same
spot
or
trail
section. One
of these was
the
above-men-
tioned
pair
of
jaguar
that
traveled
together,
the
other a
jaguar
and
puma
traveling
in
opposite
di-
rections.
Ocelots
and
big
cats did
not
appear
to
avoid
each
other: tracks of both were
found
on
the
same
trail 14
times,
often
superimposed,
either
large
or
small cat
following
the
other
down a trail.
All
three
species
have
behaviors which
could
facilitate
temporal
avoidence.
Puma
mark
their
path
with
frequent
scrapes
(this
study;
Seiden-
sticker et
al.
1973);
but
jaguar
of both sexes
go
through episodes
of intense
scraping (every
few
hundred
m,
always urinating
and
occasionally
de-
fecating
on
the
scrapes)
only
at
long
and
irregular
intervals,
suggesting
more
restricted
social context
than
scraping by
puma.
All
three
species
often claw
horizontal
logs
that
lie
across
trails,
and
both
male
and female ocelot
spray
trailside
vegetation
with
pungent
urine.
Only
jaguar
were
heard
to
give
long-distance
vocal
signals. Roaring, by
both
males and
females,
was
rare,
and
may
have been
stimulated
by
detection
of
another
jaguar
nearby,
as the
most
intensive bouts involved counter-call-
ing
between
two
individuals.
For
both
puma
and
jaguar, radio-tracking
and
footprints
showed similar
patterns
of
behavior:
an
individual
typically
entered the
study
area,
circu-
lated
widely
within it for 3-10
days,
left the
area,
and
then returned several weeks
later. Each
cat
usually
visited
about once a
month,
or
less.
Habitat
use.
Within the
small
confines
of the
study
area,
there was one clear-cut difference
in
habitat
use between
puma
and
jaguar.
Tracks
of
jaguar
and
puma
were recorded
in
the
forest
on the
study
area
on
equivalent
numbers
of
days
(35
and
32,
respectively);
whereas
jaguar
tracks
were recorded
on
river
or lake
margins
on 39
d,
but
puma
tracks
on
only
five d
(one
record/day/habitat
type/indi-
vidual;
dry
season
only,
when
beaches and
lake
margins
were
exposed).
All
of the
latter five
puma
records
were tracks
of the
male,
who
habitually
left
the
study
area
by
swimming
the
river from
a
particular
spot.
He
was once
seen
sunning
on
a
log
there,
the
only
sighting
during
the
study
of
a
puma
out in
the
open.
In
contrast,
jaguar
were
often
seen
resting,
sunning
or
walking
on
beaches
or
lake
edges,
and
their
tracks
could
be
followed
for
thousands
of
meters
along exposed
beaches
and
mudbanks in the
dry
season.
Ocelot
intensively
used
all
areas:
forest, river,
and
lake
edges,
but
unlike
jaguar,
which
used them
day
or
night,
ocelot
only
frequented
exposed
areas
at
night (Emmons
et
al.
1987).
Hunting
behavior. The
primary
hunting
method of
all
three
felid
species,
reconstructed from
tracks
and
from
movements
during
continuous radio-
tracking,
appeared
to
be
extensive
walking
until
prey
was
encountered. A
jaguar
was
seen
walking
along
the lake
edge
and
charging
at a
limpkin,
which it
missed.
Three track
sequences
on the
beach
showed a
jaguar
walking
steadily along
the
river
edge
and
charging
a
basking
caiman
or turtle
from
distances of 7 m
to 30
m
(all
three chases
were
unsuccessful).
A
reliable local
hunter de-
scribed to
me
being
attacked
by
a
jaguar
that
jumped
down
at him
from
a
high
horizontal
log
above a
trail. Ocelots
were seen
attacking
prey
three times: twice
by
rushing
at
large
birds,
once
by
crouching
in
wait on
a
log,
then
pouncing
at
a
rat below.
Prey
distribution
by
size and taxon
The
104 scats
analysed
for this
study
included 62
from
ocelots,
comprising
177
prey
(excluding
ar-
thropods);
25 from
jaguar,
with 40
prey;
7 from
puma,
with
12
prey,
and
10
from
unidentified
"big
cats"
with 22
prey,
for
a total
minimum
of
251
prey.
The
taxonomic distribution of
prey
taken
is
remarkably
wide
(Table 1).
Ocelot and
jaguar,
for
which there are the
best
samples, evidently
take
all
vertebrate
taxa
which
they
can
handle.
Terres-
trial
mammals are the
primary prey
of
all three
species,
but
reptiles
are
also
a
major
component
of the diets of ocelot
and
jaguar
at Cocha Cashu.
Approximately equal
percentages
of arboreal
mammals,
bats,
birds,
and fish are taken
by jaguar
and
ocelot alike
(Table
2).
These
prey,
likely
to
be taken
by
rare
encounter of a
vulnerable individ-
ual,
are
relatively
unimportant components
of
all
diets
reported
here.
274
Table
1. List of
prey
taxa identified from felid
scats,
and number of each
prey
found
in
total
sample
for a
given
species.
Small rodents are identified to
genus
only.
There are three
species
of
Proechimys
and
about
six
species
of
Oryzomys,
sensu
latu,
at
Cocha Cashu
[all
specific
characters
of
Proechimys
are lost
in
digestion,
and
most
dental
characters
of
Oryzomyines
eroded
beyond
certain
recognition, although
a
few
species
(not listed)
were
identified].
Total no of
scats
analysed
=
104: ocelot
=
62;
jaguar
=
25;
puma
=
7;
unidentified
big
cat
=
10
Taxon Adult mass
Ocelot
Jaguar
Puma
Big
cat Total
Small mammals
(<
1
kg)
Marsupials
Didelphis marsupialis
1.0
2 1
3
Metachirus
nudicaudatus
0.42
2 1
3
Marmosa cinerea
0.15 3
3
Marmosa
noctivaga
0.08
2 2
Marmosa
spp.
1
1
Total
10
2
12
Bats
Artibeus
fuliginosus
1
1
Micronycteris sp.
1
1
Unidentified
1
1
2
Total
3
1
4
Small rodents and
rabbits
Oryzomys spp.
large
0.07
38
3
41
Unident.
mice,
small
8
8
Mesomys hispidus
0.2
1
1
Proechimys spp.
0.28
56
2
1
59
Sciurus
spadiceus
0.6
1
1
2
Sylvilagus
brasiliensis
1.0
2
2
Total
106
1 2
4 113
Larger
mammals
(>
1
kg)
Large
rodents
Agouti paca
8.0
1
2 3
1
7
Dasyprocta
variegata
4.0
3
3
4
1
11
Hydrochaeris
hydrochaeris
45
1
1
Myoprocta pratti
1.5
5
5
Total
9
6
7
2
24
Other
large
terrestrial
Mazama
americana
30
2
1
3
Nasua nasua
4.5
1
1
Tamandua
tetradactyla
5.0
1
1
Tayassu
tajacu
25
6
4
10
Total
9
6
15
Arboreal
mammals
Saguinus fuscicollis
0.4
1
1
Saimiri
sciureus
1.0
1
1
2
Ateles
paniscus
9.0
1
1
2
Unidentified
primate
1
1
Bassaricyon
alleni
1.0
1
1
2
Coendou
prehensilis
4.5
1
1
Total
5
2
2
9
Total
mammals
177
275
Table
1
(continued)
Taxon
Adult mass
Ocelot
Jaguar
Puma
Big
cat Total
Birds
19
4
23
Snakes
9
2
3 14
Lizards
8
1
1
10
Snake/lizard
2
2
Snake
egg
1
Geochelone
denticulata~
7
6 6
Podocnemis
unifilis~
6
2
2
Platymys
platycephala
1 1
Caiman unidentified 2
3 5
Fish
4 2
6
Snails1
1
Total 71
Other
(no.
scats
with)
Insects
14
Grass 7
12
Unidentified
scaly lumps
2
1
Total number of
prey
177 40
12
Table
2.
Distribution
of felid
prey
by
size and taxonomic
group,
from
all
scats
collected
in Rio
Manu
region
and
identified
to
species
of
origin.
Percent of
minimum
total
number
of
prey
individuals
in
scats
(Table
1)
Prey
type
Total
prey
(%)
Ocelot
Jaguar
Puma
(n
=
177)
(n
=
40)
(n=
12)
Small
rodents,
opossums
66
8
17
Large
rodents
(>
1
kg)
5 15 58
Other
large
mammals
0
23
0
Arboreal
mammals,
bats
5
5
8
Birds
11
10
0
Reptiles
12 33
17
Fish
2 5
0
The three
cats concentrate
on different taxa
(Table 1).
Of
reptiles,
ocelots
primarily
ate snakes
and lizards
(9%
of
items
in
the
diet)
while
jaguar
fed on
turtles,
tortoises and caiman
(30%).
The
small
sample
for
puma
included
only
snakes.
Among
mammal
prey,
small rodents
made
up
59%
of the diet of ocelots
at Cocha
Cashu,
with
spiny
rats
(Proechimys spp.)
the
single
most
numerous
item
(32%
of
prey).
The
staples
of
jaguar
were
ungulates
and
large
rodents
(>2
kg),
with collared
peccary
(Tayassu tajacu
15%)
and
agouti
(Dasy-
procta
variegata,
10%)
the most
important.
Puma
fed
chiefly
on two
large
rodents,
agouti
(33%)
and
paca
(Agouti
paca,
27%);
but the
sample
is too
small for
confident
inference.
There
is
relatively
little
overlap
in
prey
weight
between
ocelot
and
jaguar.
Most mammal
prey
of
ocelot
(92%) weigh
less
than one
kg,
most mammal
prey
of
jaguar
(85%),
more
than one
kg.
The small
sample
of
puma prey
falls
in
the
weight
region
where
jaguar
and ocelot
diets
overlap (1-10
kg).
Between
them,
ocelot and
jaguar
take
prey
ac-
ross
the entire
weight
range
of mammal
species
at Cocha Cashu.
The sole
exception
is that
tapir,
which are
common
in
the
area,
were
not found
in
scats of this
sample.
Selectiveness
ofpredation
Prey
taken vs
prey density.
These felids
will evi-
dently
eat
almost
any type
of
prey;
but is
hunting
directed,
or
random?
Comparison
of
prey
fre-
quency
in
scats
with
independent
estimates of
pop-
ulation
density
is
possible
only
for terrestrial mam-
mals.
Ocelots took small
mammals
(<1
kg)
in ra-
tios close to those
shown
by
trapping
(Table 3a).
The
slightly
fewer
Oryzomys
and
opossums caught
by
ocelots
is
likely
to be
because
the latter are
somwhat
scansorial,
but
Proechimys
are
entirely
terrestrial. There
is thus
no evidence for selection
between
small mammal
prey by
ocelots.
In con-
trast,
the
distribution
of
large prey
eaten
by
ocelots
is
not in
proportion
to their
occurrence,
but
in
inverse order
of size
(Table
3
b).
Adult
paca
(8 kg)
are
surely
too
large
a
prey
for
ocelot,
which
prob-
ably only
take
the occasional
juvenile.
Moreover,
at
least two of
the three
agouti
(4 kg
adult)
eaten
by
ocelots
were subadult
or
juvenile.
Jaguar
took
agouti,
paca,
deer,
and
capybara
in
similar
ratios
to those
estimated
for
the
study
276
Table
3. Relative densities of
major,
terrestrial mammalian
prey
estimated on the
study
area
compared
to relative numbers
of
those
species
in
felid diets determined from scats. a Mean
monthly
small mammal densities estimated
by trap-mark-re-
lease on a
grid.
b
Large
mammal densities estimated
by
transect
census,
calculated
by
King
method
(Emmons 1982)
a
Small
Density
on
study
area Rel. no.
in
scats
mammals
Ocelot
No./km2
Rel.
no.
Proechimys
spp.
230 100 100
Oryzomys spp.
180 78 65
Opossums
50
22 16
b
Large
Density
on
study
area Rel. no.
in
scats
mammals
No./km2
Rel.
no. Ocelot
Jaguar
Puma
Tayassu
5.6 108
200
Myoprocta
5.3 102 166
Dasyprocta
5.2
100 100
100 100
Agouti
3.5
67 33
67
75
Mazama
2.6
50
67
Hydrochaeris
1.6 31
33
area
(Table
3
b). Peccary,
in
contrast,
were taken
more
often,
suggesting
that either success rate
per
encounter is
higher,
or that
they
are
sought
out.
Peccary
usually
travel
in
groups
and
generally
walk
in
single
file,
leaving
a
strong
odor and visible
trail,
and
they
are
often
noisy. Jaguar
should
be able
to detect them from
a
distance,
and their
herding
behavior
may
make it hard for them
to
excape
pursuit
by hiding.
Puma also took
agouti
and
paca
in
close to
the
proportions
of
occurrence
(Table
3b).
Al-
though
the
sample
size
of
12
prey
is far too small
to
be
conclusive,
the dominance
of
large
rodents
suggests
that
puma
did
not
preferentially
seek
peccary
as do
jaguar.
Circadian
activity of prey
The mammalian
prey
of ocelots and
big
cats differs
in
representation
of diurnal
versus
nocturnal activ-
ity
(Fig.
1). Numerically,
most
prey
species
of oce-
lot at
Cocha Cashu
are
nocturnal,
while most
prey
of
jaguar
and
puma
are
diurnal,
or
diurnal/noctur-
nal,
although
nocturnal
prey
are also
well
repre-
sented.
These results
are a natural
consequence
of
the
relationship
between
body-size
and
activity
cy-
cle
in
rainforest
mammals:
most
small mammals
are
nocturnal;
intermediate-sized
mammals
are
nocturnal
or
diurnal;
and
the
largest
mammals are
diurnal/nocturnal
(Emmons
et al.
1983).
The activities
of the
felid
predators
in
turn
re-
flect those
of
their
prey.
Ocelots
are
chiefly
active
at
night,
with much
less
activity by
day (Emmons
0
J&P
40-
0
~uJi
~ ~ ~ ~
-J
30
J&P
o
20
J&P
100
0.1
1
10
100
PREY
BODY
WEIGHT
CLASS,
KG
Fig.
1.
Circadian
activity
of
mammalian
prey
of
ocelot
(O
co-
lumns)
and
jaguar
and
puma (J&P
columns)
as a
function
of
prey body weight
class.
Open
bars
nocturnal
prey;
black
bars
diurnal
prey;
striped
bars
nocturnal/diurnal
prey
Table 4. Estimated food
consumption by
felids
Species
kg g/day/
Reference
meat/
kg
day
cat
Puma
(captive)
1.2
34 Altman and Dittmer 1973
Puma
(wild)
1.9-2.7 32-45a
Hornocker
1970
Jaguar (captive)
1.4
34 Altman and Dittmer 1973
Lion
(wild)
6.8
43a
Schaller
1972:457
Tigress
(wild)
5-6 34-41
a
Sunquist
1981
Jagouaroundi
0.6 60-90 Altman and Dittmer 1973
(captive)
Lynx
(captive)
0.6 60-90 Altman and Dittmer 1973
Lynx
(wild)
1.0
~
110b Parker et al. 1983
a
My
calculations
based on
weights reported
in
the same arti-
cles:
puma,
59
kg;
lion,
160
kg; tigress,
145
kg
b
Crude,
based on Parker et
al.'s estimate of about one
hare/day
et
al.
1987),
whereas
jaguar
are almost
equally
ac-
tive
day
and
night
(Schaller
and Crawshaw
1980).
Body
size of mammalian
prey
thus constrains
prey
and
predator
circadian
activity
alike.
Estimatedfood
consumption
Mass
of prey
in
scats.
I
could not measure
prey
consumption
by any
of the cats
studied,
but esti-
mates
can be derived
from the literature
(Table
4).
The
agreement
between
the estimates
from differ-
ent
sources
is
close,
with
big
cats
consuming
34-43
g/d/kg
and ocelot-sized
cats 60-90
g/d/kg.
The
puma
and
jaguar
at Cocha Cashu
are
general-
ly
small.
The
captured
female
puma weighed
29
kg,
the female
jaguar
weighed
31
kg,
and
the
male,
277
37
kg.
All were
adults
in
good
condition.
From
the
track
sizes of the
captured big
cats and
the
others
known on the
study
area,
the
average puma
and
jaguar
would
each
weigh
about
34
kg,
and
would
eat
1.2
to 1.4
kg/d.
The
average
adult
ocelot
weighed
9.3
kg
and
should
eat
558
g
to 837
g/d.
Female ocelots
on
our
study
area killed three teth-
ered
chickens;
each
time
they
ate about half
of
the chicken
during
the
night,
and returned
the
next
night
for the other half.
The
chickens
weighed
about 1.5
kg,
so
the ocelots ate about
0.75
kg per
meal,
or about
88
g/d/kg
ocelot.
The mean biomass
of mammalian
prey repre-
sented
in
each
ocelot scat is
688
g.
If
bird,
reptile,
and fish
prey
items
are estimated to
average
100
g
each,
then
the total animal
mass
represented per
scat would
be 748
g.
This
is about
the amount ex-
pected
to
be
eaten
in a
day
by
an
ocelot-sized
cat
(Table 4).
For
big
cats,
the
mean total
mammalian bio-
mass
represented
per
scat is
9.2
kg.
The
approxi-
mate
weight
of meat
on
tortoises
can be estimated
from
the
weight
of
live animals minus
the
weight
of
empty carapaces.
For Geochelone
denticulata
in
Brazil,
this
is 4.4
kg
per
animal
(D.
Moskovits
pers.
comm.).
Podocnemis
unifilis
I
weighed
were
in
the same
range
as
Geochelone,
and are
assigned
similar
weights.
The
mass
of
turtle/tortoise
meat
represented
in
big
cat
scats
is
thus about
43
kg.
If an estimated
weight
is added
for other
reptiles,
birds and
fish,
the total
mean
biomass
represented
per
scat
is 12.3
kg
for
jaguar,
or
about
8
d
food;
and 4.4
kg
for
puma,
or 3 d
food. For
the
larger
sample
of
all
big
cat
scats,
the mean
total biomass
per
scat is
10.6
kg.
Several
factors
can influence
the
degree
to
which scats
represent
the amount
of
prey
killed
or
eaten.
It
is
unlikely
that
a scat
represents
a
single
day's
food:
parts
of
a meal with
different
digestibil-
ities have
different
retention times
in
the
gut
and
may
be excreted
for
several
days.
The
largest prey
species
(deer
and
capybara,
relatively
small
by
non-
rainforest
standards),
would
probably
be about
75%
consumed
(all
but the
skull,
larger
bones and
digestive
tract: the
feet are
found
in
scats).
For
smaller
prey
such
as
pacas,
all but the
digestive
tract is eaten.
Finally, jaguar
may
abandon
major
parts
of their
large prey
uneaten
(Schaller
and Vas-
concelos
1978).
The
prey
numbers
reflected
in
jaguar
scats thus
should
represent
the
amount
of biomass
killed,
but
probably
not
the
amount
of
mass
eaten,
whereas
ocelots
eat the
whole
of their
small
prey
(except
intestines)
and the
biomass
calculated
from
numbers
of
prey
in a scat is
a
good approximation
of biomass eaten.
For
puma,
the use of
prey
in
rainforest is
unknown,
but in
Idaho
large
prey
are
closely
guarded
and
completely
eaten
(Hornocker
1970).
The small
prey
in
puma
scats at Cocha
Cashu could
be
easily
eaten
in
one
meal
(cf.
Hor-
nocker
1970),
thus these
scats
probably
reflect the
biomass both
killed
and
eaten. This seems
sup-
ported
by
the
relatively
smaller biomass
repre-
sented
per
puma
scat.
Ocelots
probably
produce
scats at a
regular
rate,
as
they
hunt small
prey
almost
every day.
For
big
cats
the
rate
is
probably irregular,
and
depends
on
irregular capture
of
large prey.
The
numbers of scats
found
at
Cocha
Cashu have the
same
crude
relationship
as the known
temporal
use
of the area
by
different
species
(ocelots
100%,
jaguar,
20%, Puma,
14%);
for identified
scats the
proportions
are:
ocelot:jaguar:
puma,
100:37:11;
but
total
big
cat scats
(including
unidentified)
are
58%
of the
number of ocelot scats
found.
The re-
corded
big
cat
use of the
area
(34%
of the
time)
must be
an
underestimate,
but
nonetheless
jaguar
scats
are
overrepresented, perhaps
they
kill rela-
tively greater
amounts
of
prey
than do
puma
or
ocelot.
Impact
offelid
predators
on mammalian
prey
The
following
analyses
are
based
on three
assump-
tions:
(1)
that
the scats
are a
random
sample
of
all scats
produced;
(2)
that
if
big
cats
produced
scats
on the
study
area
derived
from
meals
eaten
outside
it,
those
scats
sample prey
populations
of
similar
structure
to that
on the
study
area;
and
(3)
that the
probability
of
finding
a
scat
of
any
cat
species
is
the
same;
thus,
that the relative
numbers
of
prey
in
the
scats
represent
an
equiva-
lent
sample
of
what the
predators
have taken
from
their
environment
over
an
equivalent
time.
This
last
seems reasonable
because
the cats
have
similar
behavior
in
that
they
all
intensively
use the
same
trails,
where their
scats
are found.
The
puma
and
jaguar
data are
in some
cases
combined,
because
they
are
predators
of
the same
prey
range.
We
can
thereby
include
"big
cat"
scats
that were
not
identified
to
species.
Omitted
from
this
sample
are
scats
collected
sporadically
after
I left Cocha
Cashu,
although
these
are
included
in
other
analy-
ses and
Table
1.
Relative
numbers
of
prey
taken.
If the
total
numbers
of
terrestrial
mammalian
prey
repre-
sented
in the
sample
of
scats are
plotted
by body
weight
class
(Fig.
2A),
small
mammals
predomi-
nate,
as
might
be
expected
from
the
larger
contri-
278
A
Jaguar
& Puma
20-
oc
Q.
.
60
0
L
Ocelot
m
4
40
z
20-
0.1
1 10
100
PREY
BODY WEIGHT
240
Jaguar
& Puma
200- B
160-
0
120-
cn
0,
40
-8
I-
oc
JJ
40-
40-
Ocelot
0.1
1
10
100
PREY
BODY
WEIGHT,
KG
Fig.
2. Crude
numbers
(A)
and biomass
(B)
of
terrestrial mam-
malian
prey
represented
in
scats,
as a
function
of
prey body
weight
class
bution
by
ocelot
prey,
from
both
larger
number
of scats
(60)
and
larger
mean number of
prey/scat
(x
=
3.0 +
1.4),
when
compared
to the
big
cats
(N
=
36;
x
=
1.7
+
0.7
prey per scat).
When the same
prey
numbers are converted
to
biomass
(Fig. 2B),
there
is a
dramatic
reversal
in
importance,
only
part
of
which is
due to
classical
Eltonian
pyramid
rela-
tions.
The
standing
crop
numbers
and
biomass
of
selected,
terrestrial
prey species
on the
study
area
can be
compared
with the
representation
of
those
species
in
the
sample
of
scats
(Fig. 3).
It
is
apparent
that in
either
numbers or
biomass,
large
species
are
preyed upon
to a
relatively
greater
extent than
small ones. If
this
converted
into terms
of the
area
occupied by
the
standing
crop
of
prey
represented
by
all
individuals of a
species
in
the
scat
sample
(Table 5),
we
see that:
(1)
the
terrestrial
prey
is
divided
by
weight
into
two classes of
under
or over
1
kg.
Within
each size
class,
felid
predators
are
taking
roughly equivalent
proportions
of
each
prey
species;
and
(2)
as
expected,
arboreal and
scansor-
ial
species
are taken
relatively rarely.
This
phenom-
enon is
not related to
predator
species: acouchys
(Myoprocta)
were taken
only
by
ocelots in
this
sample,
but
were taken
in
the
same
relative
numbers as
big
cats
took
larger
prey. Agoutis (Da-
syprocta),
which
are
prey
of all
three
cats,
had the
highest predation
level.
Predator-prey
ratios.
If
the
big
cat
biomass at Co-
cha Cashu is taken at its
minimum estimate
(per-
cent of
cat/days, days
with two cats
present
counted twice
=
2
kg
big cat/km2),
the ratio of
big
cat:prey species standing-crop
biomass is
about
136kg
prey/kg
big
cat. This includes
only major,
large
terrestrial mammalian
prey
of
species
found
in
scats
(excludes
tapir
and
white-lipped peccary)
and
is
an underestimate
of
actual
prey
biomass,
which
includes
other taxa as well.
The
population density
and biomass of ocelot
is known more
accurately (
6
kg/km2).
For the
major prey
items
of
Proechimys, large
mice
(Ory-
zomys),
acouchys,
and
agoutis,
which
comprise
89%
of
all
mammalian biomass
represented
in oce-
lot
scats,
and for which
I
have
standing crop
esti-
mates,
the ratio
is
only
12
kg prey/kg
ocelot. Even
were
this
doubled,
to include other
prey,
it would
still show the
striking
effect of
scaling
on
predator-
prey
ratios.
Absolute
numbers
of prey
taken. From the amount
of
time
spent
on the
study
area,
the
standing crop
of
prey,
and the calculated
minimum food
require-
ments,
the
approximate
minimum offtake
by
felids
of
their
prey
on
the
study
area can
be
estimated.
If
20%
of one
jaguar-year
is
spent
on
the
study
area,
the
total
offtake should
equal
about
110
kg
of
prey.
From relative
numbers
in
scats,
89
kg,
or
12
kg/km2
of
this,
is
comprised
of
large
rodents
and
Artiodactyla.
For
puma,
with
14%
presence
279
A
B
l
I
250-
_
200-
-I
0
3
Z
cc
2
l
o1
0
o
(c
0
100
z
I
Fig.
3.
Standing crop density/km2
and
biomass/
km2
on the
study
area of
major,
terrestrial,
50C
---
-
"
____
mammalian
prey species (solid
lines);
compared
with absolute
numbers and
biomass of the
same
species
represented
in
the entire
sample
of
cat
----i_ _
_
-
- -
^.
scats
(dashed lines),
as a
function of
prey
body
I
~
--
____
-
weight
class
0.1
1
10
100
0.1
1
10
100
PREY BODY
WEIGHT
CLASS,
KG
Table 5. Area that would be
occupied by
a
standing-crop
of
the total numbers
of
prey represented
in
felid scats. One scan-
sorial
species
(Sciurus
spadiceus)
added
for
comparison
with
others,
which are
major,
terrestrial
prey.
Species
listed
in
increasing
order of
body
size
Species
km2
Oryzomys spp.
0.2
Proechimys spp.
0.3
Sciurus
spadiceus
0.01
Myoprocta pratti
1.0
Dasyprocta
variegata
2.3
Agouti paca
1.7
Tayassu
tajacu
1.6
Mazama americana
1.2
Hydrochaeris
hydrochaeris
0.6
on the
study
area,
the same calculation
gives
an
offtake of 10
kg/km2.
The
standing crop
biomass
on the
study
area
at
Cocha
Cashu,
for these
prey
species
only,
is estimated
at 271
kg/km2.
Together,
the annual offtake
by
puma
and
jaguar
would thus
be about 8%
of
the
standing-crop
biomass. Note
that this is a minimum
estimate
only, assuming
minimum known
occupancy
of the
study
area
by
large
felids,
low
mean
felid
body weights,
and
no
gross
wastage
of
prey
(but balancing
this is the
likewise
minimal estimate of
prey
density,
based
on
direct census
numbers,
with no
adjustments
for
animals
missed).
The result
of the same calculation
for ocelots
is
a
startling
contrast:
for an 8
kg
cat that eats
the lower value
of 60
g/kg/d,
for a total of 175
kg/
year,
or 135
kg/km2/year
average
for the
study
area, the
contribution of
Proechimys,
Oryzomys,
and
Myoprocta
would
be about
63
kg/km2.
How-
ever,
the
standing crop
of
these
species
is
only
83
kg/km2.
For
Proechimys
alone the
figure
is
39
kg/km2 eaten/year,
of
a
standing crop
biomass
of 61
kg/km2;
or
64%
of the
total
standing crop
biomass.
Discussion
Predator-prey
ratios
The mammalian
prey/predator
biomass ratios
roughly
estimated for Cocha
Cashu,
135
kg prey/
kg
big
cats,
falls
easily
within the
range
of total
mammalian
large prey:large
predator
ratios
of
94-301
kg prey/kg
predator
calculated
by
Schaller
(1972:454)
for five African savanna
ecosystems.
All
of these are lower than
Sunquist's
(1981)
esti-
mate
of
390-630
kg
prey/kg tiger
in
Nepal,
which
to be
comparable
should also include
leopard
and
dhole
biomass.
However,
Sunquist
(1981)
esti-
mates that
tiger
kill
8-10%
of the
standing crop
of their
prey per year;
Schaller
(1972:397)
esti-
mates that
together,
large Serengeti
predators
kill
9-10%
of their
standing crop
of
prey;
while
my
estimate
for
big
cats
at Cocha Cashu is 8%
of
their
large
terrestrial mammalian
prey.
I
believe
that the
similarity
of these
numbers is not
coinci-
dental,
but reflects a
limiting
equilibrium
state
for
large predators
and
large
mammalian
prey.
280
For
ocelots,
which eat
small
prey,
the
standing-
crop
ratio
of
12
kg
prey/kg
ocelot,
and annual
off-
take
of
75%
of
standing-crop
biomass
of
major
terrestrial
mammal
prey,
clearly
reflects a different
situation.
For
prey species
with
high reproductive
rates,
standing-crop
biomass is
obviously
a
poor
estimate
of the resource-base available
to
preda-
tors.
When
Proechimys
consumption by
ocelots
is
calculated
as
a function
of
potential
productivity,
151
animals are
estimated taken
from a
possible
production
of 2400
Proechimys/km2,
or
6%
of the
crop.
This corrected
offtake
is now
in
the same
range
as that
estimated for
big
cats
and their
prey.
Even
if
we use
higher
estimates
of mass eaten
per
day
and
biomass
of
ocelots,
the
consumption
of
Proechimys
stays
within an
ecologically
feasible
range,
with
the
predator-prey
equilibrium
close
to
that
for
large species.
The
estimated
high productivity
of
small
ro-
dents
at Cocha
Cashu
is
due
almost
exclusively
to
effects
of short
generation
time:
Proechimys
breed
year
round,
are
pregnant again
while lactat-
ing,
and are
reproductive
at
3.5 months
(Emmons
1982
and
unpublished
data).
Although
the
litter
size
of
Proechimys
is
small
(mode=
2-3),
a female
can
produce
18 descendants
a
year.
In
contrast,
a
capybara
or
peccary,
with
similar
litter
size,
on
average
may produce
only
2-3
young
annually,
with the
first
litter born
at a
maternal
age
of
about
two
years.
Large Oryzomys
species
likewise
breed
much
of the
year,
but litter
size and
generation
times
are not
known
for Cocha
Cashu.
Body
size.
It
is
striking
that
two
species
alone,
ocelot
and
jaguar,
readily
divide
the entire size
range
of mam-
malian
prey
between
them.
This is
possible
because
of the absence
of
truly
large
mammals
in
the
Neo-
tropics.
The
sizes
of the cats
divides
them
at
a
prey
size
of
one
kg,
a
point
of
scaling
where
prey
species
life
history patterns
switch
from
multiple
to
single
litters
per
year
and
short to
long genera-
tion times.
For the known
terrestrial
mammal
fauna
of Cocha
Cashu,
100%
of
species
<1
kg
adult
weight
should
have
multiple
litters
per year
and
early
age
of first
reproduction.
For terrestrial
mammals
>1
kg,
only
one
species,
or
4%,
should
be
in
this
category,
and
this
species
(Didelphis
mar-
supialis),
could
equally
be
placed
in the
lower
weight
range (females
breed
at 700
g),
which would
split
the
species
100%
into each
category.
Note
that this
division
does not
apply
to
arboreal
mam-
mals,
of
which
many
small
species
have
low
repro-
ductive
rates.
The terrestrial
species
one
kg
and
under
are
rodents,
opossums,
and a
lagomorph,
and
I
assume that
species
for which there are
few
data have
life
histories similar to those
for which
there
is
information.
Just above one
kg
in
the
body weight range
of
mammals
in
the
community
there is a
marked
decrease
in
species
packing:
there
are
10
species
> 0.4-1.0
<
kg;
five
species
>
1-4
<
kg
body
mass,
and 16
species
>4-8
<
kg body
mass.
In
a
mam-
mal
community
in
African rainforest the
primary
consumers show a
pronounced
drop
in
species
packing
at the same
point
in
the
weight range
(Em-
mons
et
al. 1983:
Fig.
1).
The size-related
life
history
difference
of ocelot
and
jaguar
prey
has
a number of
consequences:
high
ocelot biomasses
are
supported
by
low stand-
ing
biomass,
but
high productivity
of
prey;
ocelots
can
defend
small territories on areas
of dense
and
predictable
resources;
most of their
prey weighs
less than
5%
of their own
body
mass,
and
they
spend
many
hours
foraging
to
catch
several
prey
each
day
(Emmons
et
al.
1987).
Ocelot
prey
is
mostly
nocturnal,
and ocelots
are
in
competition
for
their
prey
with
many
snakes,
raptors,
and
other
small
Carnivora
of several families.
Jaguar
and
puma,
in
contrast,
have lower
biomass
in
relation
to their
standing crop
of
prey,
have
consequently
larger
home
ranges
for
their
body
mass,
and
ap-
pear
not to defend territories
although
they
avoid
each
other
(Seidensticker
et
al.
1973;
Schaller
et al.
1984).
They
kill
prey
that
generally
weighs
10%
to 80%
of their
own
body
mass,
at
intervals
of
several
days (Seidensticker
et al.
1973;
Schaller
and
Crawshaw
1980).
They
have no other
competitors
but each
other
for
large
mammal
prey,
most
of
which
is diurnal
or
diurnal/nocturnal.
The
world's
cats are
sharply
divided
into
large
and
small
sizes:
0-10
kg,
21
species;
11-20
kg,
5
species;
21-35
kg,
0
species;
36-60
kg,
5
species;
>61
kg,
2
species
(Guggisberg
1975;
Gittleman
1983).
I
conjecture
that this
split
corresponds
gen-
erally
to the
prey
life
history
pattern
shift
that oc-
curs
in terrestrial
mammals
at
about
on
kg,
with
its
concomitant
shift
of
predator population,
circa-
dian
activity, foraging
strategy
(many
small
prey),
and
social
adaptation,
as
exemplified
by
ocelot
and
jaguar
at Cocha
Cashu.
In
Asia,
Africa
and
North
America,
healthy
adults
of the
largest
mammalian
herbivores
escape
predation
because
of size
alone
(e.g.
Schaller
1972;
Sunquist
1981).
It is
likely
that a
predator
energeti-
cally adapted
to its
median
prey
would
be smaller
than
required
to
readily
fell the
prey
at the
largest
end
of
the
spectrum.
Of
the
neotropical
forest
fauna,
the
tapir
is four
to six
times
heavier
than
281
the next
largest
species.
Adult
tapir
would
appear
to
be above the
limit
for
easy
prey
of
forest
jaguar.
Jaguar
do
attack
tapir,
but at
least
sometimes can-
not
bring
them
down
(Andre
1904;
Mondolfi
and
Hoogesteijn,
in
press;
anecdotes
reported
to me
by
hunters).
In
contrast,
the
species subject
to heaviest
pre-
dation
are
those whose
size
falls
in
the
area of
overlap
between
several
predators.
In
the
neotropi-
cal fauna
agoutis
are
in
this
class
(Table
1,
Ta-
ble
5),
as
are
Thompson's
gazelle
in
African
sa-
vanna
(Schaller
1972).
For
their
size,
such
species
might
be
expected
to have
particularly cryptic
be-
havior
or
high reproductive
rates to
compensate
for
multiplied
predation pressures. Species
of
body
mass below one
kg
have
many
predators
and
high
reproductive
rates.
Prey diversity
Some
studies show
that the
larger
of
a
pair
of
simi-
lar,
sympatric
carnivores takes
a
larger range
of
prey
than the
smaller,
because
the
larger
takes
large
and small
prey,
and the smaller
only
small
prey
(Rosenzweig
1966;
Gittleman
1983).
For oce-
lot and
jaguar,
this
is
clearly
not
the
case:
in
prey
taxonomic
richness or
size,
ocelot
(24
mammal
species
eaten,
small and medium
sizes)
are
taking
as
wide a
range
as
jaguar
(16
mammal
species
ea-
ten,
medium
and
large
sizes):
in
fact
the
prey
range
is almost
exactly
divided
between
them
(34
non-
flying
mammal
species
<
1
kg,
35
species
>
1
kg
at Cocha
Cashu;
list
for
small mammals
probably
incomplete).
Constraints
of
rainforest
habitat
In
contrast
to
the
felid
community
in
African
sa-
vanna
where as
well
as
generalized
hunters
(leop-
ard), specialized
felids are
adapted
to
cursorial
pur-
suit
of
small
game
(cheetah, caracal),
and
commu-
nal
pursuit
of
large game
(lion)
(Schaller 1972),
rain forest
appears
to
support
only highly oppor-
tunistic
solitary
felid
hunters
(Schaller
1967;
Sei-
densticker
1976;
Sunquist
1981).
The
general
hunt-
ing pattern
seems
to
be
that of extensive
walking:
doubtless
because
in dense forest
prey
is
widely
scattered
throughout,
cannot
be seen for
more
than
a few
meters,
and
cannot be located
at
pre-
dictable
sites such
as waterholes.
The
high
diversity
of
prey reported
for rain forest
leopard (Hoppe-
Dominik
1984), jaguar
in
several
habitats
(Gugg-
isberg
1975;
Schaller and
Vasconcelos
1978;
Mon-
dolfi
and
Hoogesteijn
1987),
and
jaguar
and
ocelot
at Cocha
Cashu,
attests
to
the
unpredictability
of
rain forest encounters.
This lack of
prey
selection
differs from the behavior of
big
cats
in
open
habi-
tats,
where
puma
(Hornocker 1970),
probably ja-
guar (Schaller
and Vasconcelos
1978),
tiger (Sun-
quist 1981),
lion,
and cheetah
(Schaller
1972),
fo-
cus
on
certain
prey species.
Effects
on
prey populations
No doubt
because
of their
opportunistic
hunting,
felids at Cocha
Cashu took terrestrial
mammalian
prey species
with remarkable evenness.
Conse-
quently,
these
predators
should
exert an
equalizing
influence
on
prey
numbers,
and
they
may
be a
cause of the
surprizingly
even
densities of
large
terrestrial
species
on
the
study
area.
A
possible
bias in the
results
(Table
3b)
is that
the
prey
den-
sity
estimates are derived
in
the
same
way
that
the cats
presumably
hunt:
by my
counting
the
number
of
animals
met
while
I
walked.
Both
cen-
sus and cat encounters
would thus have the
same
bias
towards animals most
easily
detected. Never-
theless,
that
the relative numbers of
major
prey
species
taken
by
cats
approximate my
census ra-
tios,
reinforces
the view
of non-selective
hunting
behavior.
Comparable density
estimates are
available
for
only
one
other
completely
rain-forested
habitat
in
the
Neotropics,
Barro Colorado
Island,
(BCI)
Pan-
ama
(Glanz
1982).
BCI
has
a
few
ocelots,
but
puma
and
jaguar,
formerly
present,
are
now ex-
tinct.
Large
mammal
populations,
censused
and
calculated
by
the same means
I
used
for
Cocha
Cashu,
are:
Mazama
americana,
11/km2; Tayassu
tajacu, 9/km2; Agouti paca, 20/km2,
and
Dasy-
procta
punctata,
94/km2
(Glanz
1982).
There
is a
tenfold
range
of
density
difference
on
BCI between
the same
or
equivalent
species
that
at Cocha Cashu
have almost
equal
densities.
It is
perhaps signifi-
cant
that
agoutis (Dasyprocta),
which
I
suggest
should
be
adapted
to the heaviest
predation pres-
sure because
of
their
size,
have achieved the
highest
populations
in
the absence
of
large
predators.
That
predators
may
limit numbers of
prey
does
not
imply
that the
prey
are
all,
or
always,
limited
by
predation.
Food is
clearly limiting during
some
bad seasons
or
years (e.g.
Foster
1982),
but
in
other
years,
predation
could
limit
prey population
growth.
Mammal
densities at Cocha
Cashu.
A
few comments on
prey populations
seem
in
order.
Densities of
large
rodents and
armadillos
are
low at
Cocha Cashu.
This
is
partly
due to
the
282
floodplain
habitat:
up
to
30%
of the land surface
is
covered
with
shallow
standing
water
for
several
months a
year,
with
higher
floods
periodically.
Ar-
madillos
disappeared
after severe
flooding
in
1982.
Numbers of
agoutis, acouchys,
and deer have var-
ied from
year
to
year
since
my
first observations
in
1979,
but the most dramatic recent
change
in
the fauna has been a drastic reduction of white-
lipped peccary. Groups
of scores were common-
place
until 1979
(Kiltie
and
Terborgh
1983).
Now,
groups
of
less than
10
appear
at rare
intervals. The
most
likely
cause
of this extinction
is
epidemic
dis-
ease,
but whatever the
cause,
a
major
contributor
to
biomass
and a
prey
species
of
jaguar
was no
longer
of
importance
in
the
ecosystem during
this
study.
It
would
clearly
be
imprudent
to
generalize
mammal
densities from
Cocha Cashu
either from
year
to
year
or to other
localities.
Ecological
differences
between
puma
and
jaguar
Puma
overlap
the entire
geographic
range
of
ja-
guar,
so it can be assumed
that
they
differ
enough
ecologically
for stable coexistence.
In
the
similar
case
of
leopard
and
tiger,
the smaller
leopard
takes
smaller
prey
(Seidensticker
1976);
but there
is
also
evidence that
in some
regions leopards
are
re-
stricted
to habitats
little
used
by tigers
(Schaller
1967;
Seidensticker
1976).
Schaller
and Crawshaw
(1980)
found
puma
and
jaguar
to
be
syntopic
in
the
Pantanal,
but there
was a
suggestion
of
spatial
avoidance.
I
likewise have
observed
puma
and
ja-
guar
to occur
syntopically
in
terra
firme rainforest
in
several
regions
of
Amazonia,
as
they
do at
Co-
cha Cashu.
In
open
habitats,
jaguar
appear
to
be
much
larger
than
puma
(Schaller
et al.
1984),
but
nonetheless
the
species
overlap
in
size and
take
largely
the
same
prey
(Schaller
and Crawshaw
1980).
The
apparent
temporal
avoidance
observed at
Cocha Cashu
between
individual
big
cats
of both
species
does
not seem
to involve
interspecific,
more
than
intraspecific,
competition.
It would
clearly
be
counter-productive
for a cat to
use a trail
just
used
by
another that
hunts
the same
prey.
From
this limited
study,
only
two interrelated
differences
were evident
between
the
ecologies
of
puma
and
jaguar
at Cocha
Cashu.
The
intensive
use
of waterside
habitats
by jaguar,
also
noted
by
Schaller
and Crawshaw
(1980)
and
Guggisberg
(1975),
and
avoidance
of
such
areas
by
puma,
is
correlated
with the
quantitatively
important
pres-
ence
in
the
jaguar
diet
of
turtles,
caiman,
and
fish.
Turtles,
caiman
and
tortoises
have
exceedingly
hard
integuments.
Jaguar
break
the
carapaces
of
chelonians
to extract the meat. The
massive head
and stout canines of
jaguar
would seem better
adapted
to
crushing
resistant
materials than are
the
relatively
small head and thinner
canines of
puma,
which have not been recorded
killing
large,
armoured
reptiles.
Many
of these
reptiles
are now
scarce,
but once
they
were common
(Bates
1892),
and
jaguar predation
on them was
reported by
early
explorers
(Humboldt
1853;
Andre
1904).
In
the
Pleistocence,
five
genera
of
large
felids lived
in
North
America
(Anderson
1984).
With the ex-
tinctions of
large
herbivores,
all
but two
of
these,
puma
and
jaguar,
subsequently
disappeared.
Its
unique ability
to
use the once-abundant
reptile
re-
sources of the
Neotropics may
be a
key
to the
heavy
build
(Guggisberg
1975),
predilection
for
wet
habitats,
and survival of the
jaguar,
which is
now
threatened
not
only by
skin hunters
and
habi-
tat
destruction,
but also
by
extinction of
many
of
its
prey, every species
of which
is
intensively
hunted
by
man.
Acknowledgements.
This
study
was
supported by
Wildlife Con-
servation International and World Wildlife Fund-US.
I
thank
the Direcci6n
General Forestal
y
de
Fauna, Peri,
for
permitting
us to work
in
Manu National
Park,
and Luis
Yallico,
Director
of Manu
Park,
for his
encouragement
and
support
of the re-
search.
Dr. John
Terborgh
co-administered the
project
and un-
dertook much of the tedious
paperwork
and
logistic support.
Able
and
enthusiastic field assistance was
given by
D.
Bolster,
Jesus
Crisostomo,
A.
Goldizen,
T.
Hildebrandt,
P.
Sherman,
and J.
Paneck.
I
owe a
special
debt to
Fernando
Cornejo
for
careful collection
of
scats.
R. Voss and J. Seidensticker
im-
proved
the
manuscript
with constructive comments.
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