Hunting behavior in West African forest leopards

Abstract

The leopard (Panthera pardus) is a major predator of mammals within the rainforest ecosystem of West Africa. Most of the available information on leopard hunting behaviour comes from studies conducted in open savannah habitats, while little is known about forest leopards. Our radio-tracking data and scat analysis show that forest leopards differ in various ways from the savannah populations. Forest leopards are diurnal and crepuscular hunters who follow the activity pattern of their prey species. They exhibit seasonal differences in activity patterns, and they develop highly individualized prey preferences. These findings challenge the widespread notion of leopards as opportunistic nocturnal predators.
La panthère Panthera pardus est un prédateur majeur de mammifères dans l’écosystème de la forêt pluviale en Afrique Occidentale. La plupart des renseignements sur le comportement de chasse des panthères est tirèe d’études menées dans des habitats ouverts de la savane, tandis que peu est connu sur les panthères forestières. Les données que nous avons rassemblées par radio-émetteurs et les analyses des crottes montrent plusieurs différences entre les panthères forestières et des populations de savane. Les panthères forestières sont des chasseurs diurnes et crépusculaires qui suivent le schéma d'activité de leur proie. Ils déploient des différences saisonnières et développent des préférences de proie fortement individualisées. Nos conclusions défient l'image répandue des panthères comme prédateurs opportunistes nocturnes.

Full text

Hunting behaviour in West African forest leopards
David Jenny
1,2,
* and Klaus Zuberbu
¨hler
2,3
1
Zoologisches Institut, Universita¨t Bern, Switzerland,
2
Centre Suisse de Recherches Scientifiques, Abidjan, Ivory Coast and
3
School of Psychology,
University of St Andrews, St Andrews, Scotland, UK
Abstract
The leopard (Panthera pardus) is a major predator of
mammals within the rainforest ecosystem of West Africa.
Most of the available information on leopard hunting
behaviour comes from studies conducted in open
savannah habitats, while little is known about forest leo-
pards. Our radio-tracking data and scat analysis show that
forest leopards differ in various ways from the savannah
populations. Forest leopards are diurnal and crepuscular
hunters who follow the activity pattern of their prey spe-
cies. They exhibit seasonal differences in activity patterns,
and they develop highly individualized prey preferences.
These findings challenge the widespread notion of leopards
as opportunistic nocturnal predators.
Key words: predation, carnivore, taı
¨forest, selective hunt-
ing, monkey alarm calls
Re
´sume
´
La panthe
`re Panthera pardus est un pre
´dateur majeur de
mammife
`res dans l’e
´cosyste
`me de la fore
ˆt pluviale en
Afrique Occidentale. La plupart des renseignements sur le
comportement de chasse des panthe
`res est tire
`e d’e
´tudes
mene
´es dans des habitats ouverts de la savane, tandis que
peu est connu sur les panthe
`res forestie
`res. Les donne
´es
que nous avons rassemble
´es par radio-e
´metteurs et les
analyses des crottes montrent plusieurs diffe
´rences entre
les panthe
`res forestie
`res et des populations de savane. Les
panthe
`res forestie
`res sont des chasseurs diurnes et cre
´-
pusculaires qui suivent le sche
´ma d’activite
´de leur proie.
Ils de
´ploient des diffe
´rences saisonnie
`res et de
´veloppent
des pre
´fe
´rences de proie fortement individualise
´es. Nos
conclusions de
´fient l’image re
´pandue des panthe
`res comme
pre
´dateurs opportunistes nocturnes.
Introduction
It is widely believed that leopards are opportunistic and
nocturnal predators that hunt their prey in proportion to
abundance (Bailey, 1993; Johnson et al., 1993; Stuart &
Stuart, 1993; Bothma & LeRiche, 1994; Bodendorfer,
1994). However, most of the available evidence comes
from savannah habitats while little is known about forest
leopard behaviour. Information from Ituri forest, DR
Congo (Hart, Katembo & Punga, 1996) and Taı
¨forest,
Ivory Coast (Jenny, 1996), suggests that hunting beha-
viour of forest leopards may differ considerably from that
of savannah individuals. In a previous study, we have
documented a large prey spectrum in a population of
forest leopards in the Taı
¨forest (Zuberbu
¨hler & Jenny,
2002). Here, we present data from radio-tracking and
scat analyses to describe the hunting behaviour and in-
dividual prey preferences of forest leopards. Our data
show that forest leopards (a) are diurnally and cre-
puscularly active, (b) exhibit seasonal differences in ac-
tivity, and (c) may develop individual preferences for
particular prey species.
Methods
Data were collected by the first author in about 100 km
2
of undisturbed primary rain forest of Taı
¨National Park,
Ivory Coast (550¢N, 720¢W; Jenny, 1996). Three adult
leopards were captured and equipped with radio-trans-
mitters (Jenny, 1996). Two of them were monitored from
tree platforms during day and night-time intervals
(‘Cosmos’, adult male, 56 kg, 5 February 1993 to 8 May
1994; day: 82 h, night: 23 h; ‘Adele’, adult female,
34 kg, 16 August 1993 to 30 June 1994; day: 244 h,
night: 92 h; night: 18:00–06:00 GMT, corresponding to
the onset of sunset and sunrise). From the platforms it
was possible to score the individuals’ activity as either
‘moving’ or ‘resting’, depending on the stability of the
received signal. Readings were taken every 15 min
(location accuracy ±0.01 km
2
).
*Correspondence: Suot Aquadotas, 7524 Zuoz, Switzerland.
E-mail: jenny.d@compunet.ch
2005 African Journal of Ecology, Afr. J. Ecol.,43, 197–200 197

Both individuals were also followed through the forest at
30–150 m (Cosmos, day: 72 h, night: 20 h; Adele, day:
411 h, night: 44 h). Additionally, a third individual was
followed for a short time (‘Cora’; adult female; 32 kg, 14
June 1994 to 28 August 1994; day: 10 h, night: 0 h).
During a proportion of these follows it was also possible
to score activity as either ‘moving’ or ‘resting’ (Adele n ¼
225 h; Cosmos n ¼53.75 h). In addition, it was possible
to make some qualitative observations concerning the
individuals’ hunting behaviour, notably (a) hiding, usually
in dense thickets, (b) approaching monkey groups, and (c)
making kills.
Faecal samples were collected from Adele while follow-
ing her and by tracking her spoor from an infrared-trig-
gered photo-trap set-up along a trail frequently used by
her. This allowed us to compare Adele’s individual prey
spectrum with that of the wider local leopard population
♦
♦♦
♦
♦
♦
♦♦
♦
♦
♦
♦
♦
♦
♦
♦
♦
♦
♦
♦
♦
♦
♦
-5 (n = 12)
-4 (n = 12)
-3 (n = 12)
-2 (n = 12)
-1 (n = 12)
Sunrise (n = 12)
1 (n = 11)
2 (n = 16)
3 (n = 29)
4 (n = 43)
5 (n = 58)
6 (n = 50)
7 (n = 56)
8 (n = 55)
9 (n = 50)
10 (n = 47)
11 (n = 34)
12 (n = 17)
Sunset (n = 20)
-10 (n = 20)
-9 (n = 17)
-8 (n = 16)
-7 (n = 12)
-6 (n = 12)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
Activity (proportion 15-min intervals active)
Time (h since sunrise)
Cosmos (n = 158.75 h)
Adele (n = 561 h)
♦
♦
♦
♦
♦
♦
♦
♦
♦♦♦
♦
♦
♦
♦♦
♦
♦
♦
♦
♦
♦
♦♦
-5 (n = 48)
-4 (n = 48)
-3 (n = 48)
-2 (n = 48)
-1 (n = 48)
Sunrise (n = 48)
1 (n = 47)
2 (n = 76)
3 (n = 116)
4 (n = 165)
5 (n = 207)
6 (n = 205)
7 (n = 223)
8 (n = 213)
9 (n = 178)
10 (n = 144)
11 (n = 62)
12 (n = 35)
Sunset (n = 44)
-10 (n = 48)
-9 (n = 46)
-8 (n = 51)
-7 (n = 48)
-6 (n = 48)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
Activity (proportion 15-min intervals active)
Time (h since sunrise)
(a)
(b)
Fig 1 Relative activity patterns of two
radio-collared leopards plotted as a func-
tion of onset of sunrise and sunset (data
from platform monitoring and direct fol-
lows combined). (a) Cosmos (n ¼
158.75 h); (b) Adele (n ¼561 h).
198 David Jenny and Klaus Zuberbu¨hle
2005 African Journal of Ecology, Afr. J. Ecol.,43, 197–200

as determined by scat surveys (Hoppe-Dominik, 1984;
Zuberbu
¨hler & Jenny, 2002).
Results and discussion
Activity patterns
Platform monitoring indicated that both individuals were
more active during the day (46.5%) than at night (28.9%),
in sharp contrast to savannah individuals (Hamilton,
1976; Bailey, 1993). Relative peaks at dawn and dusk
corresponded closely with sunrise and sunset (Fig. 1).
Direct follows of leopards at night are extremely difficult to
conduct in dense rainforest habitat. In total, we managed
to obtain ranging data for n ¼179 h combined over the
16-month study period (platform data and focal follows).
These data revealed that at night activity patterns typically
showed only one of two patterns: (a) complete inactivity
(>10 h) or (b) travelling over large distances, suggesting
that although our data set is small, it accurately represents
the nocturnal activity patterns. Daytime activity showed a
more evenly distributed pattern, but inactive periods were
always short (<5 h). This activity pattern is comparable
with that of Asian forest leopards (Karanth & Sunquist,
1995).
For Adele, the lowest monthly activity rates were
observed during the rainy period, perhaps because heavy
rainfall increased her hunting success. Percent activity per
month was significantly negatively correlated with rainfall
(Spearman-rank correlation, n ¼11, r
s
¼)0.718, z ¼
)2.271, P< 0.03).
Ad libitum observations during direct follows revealed
two interesting aspects of hunting behaviour: (a) during
periods of inactivity the three individuals often hide in
dense thickets and (b) after making a kill, they remained at
the same place for two to three consecutive days.
Similar to savannah individuals there was a distinct
sex-difference in ranging behaviour (Rabinowitz, 1989).
Cosmos was moving in 40.4% of all monitored intervals
(n ¼53.75 h), while Adele only moved during 20.1% of
time (n ¼225 h). Adele tended to remain within a relat-
ively small core area of about one hectare (14.2% of
intervals; n ¼561 h; platform and focal data combined).
During daytime follows, a monkey group came within
50 m of the hiding leopard in 60 of 97 hiding bouts (7.4%
of time; n ¼130 h). In contrast, when the observer sat at
one of ten randomly chosen observation points throughout
the study area, monkeys came within 50 m only four of
ten times (1.9% of time; n ¼99 h; Fig. 2), a statistically
significant difference (z ¼)3.092; P< 0.01; Binomial
test; two-tailed), suggesting that leopards selectively chose
hiding spots close to monkey groups (Zuberbu
¨hler, Jenny &
Bshary, 1999).
Prey spectrum
Adele was not an opportunistic hunter but developed in-
dividual prey preferences. First, Adele avoided chimpanzee
parties: in six of fifteen cases of drumming and/or
screaming of a chimpanzee party 100–250 m away, she
0
30
60
90
120
< 50 m > 50 m
Distance to next monkey group
Observation hours
With leopard
Without leopard
Fig 2 Number of observation hours the observer was sitting close
(<50 m) or far (>50 m) from the nearest monkey group after (a)
having followed Adele (black bars) or (b) having walked to one of
ten randomly selected points throughout the study area.
0
10
20
30
40
50
60
Duikers Monkeys Pangolins Other prey
Percent of prey spectrum
Adele (n = 38)
Others (n = 162)
Fig 3 Prey spectrum of focal animal Adele compared with the
average prey spectrum of other leopards in the study area. Duikers
and monkeys all weigh several kilograms and are amongst the
biggest mammalian prey available in the forest.
Hunting behaviour in forest leopards 199
2005 African Journal of Ecology, Afr. J. Ecol.,43, 197–200

started moving in the opposite direction or changed
direction when already moving. Approach was never
recorded. However, leopards may scavenge on already
dead chimpanzees: In two cases, a female or a subadult
male leopard dragged a dead juvenile chimpanzee (10–
20 kg) for 50–80 m before devouring it. Second, Adele
consumed duikers and monkeys significantly more often
than other leopards (v
2
¼41.49, d.f. ¼8, P< 0.01;
Fig. 3). A successful attack on a primate was observed once
during Adele’s 91 observed hiding bouts when she killed a
sooty mangabey, Cercocebus atys. Third, Adele rarely con-
sumed pangolins, although pangolin remains were com-
mon in other leopard faeces (Hoppe-Dominik, 1984;
Zuberbu
¨hler & Jenny, 2002). Thirty-eight fresh faeces
could be assigned to Adele with reasonable confidence.
Only one sample (2.6%; n ¼38) contained pangolin scales
(population average: 26.7%; n ¼150; Fig. 3). Moreover,
leopard faeces containing pangolin remains varied both
regionally and temporarily. In the south-east part of the
study area, 40.0% of faeces (n ¼50) contained pangolin
remains, whereas in the north-west this was only true for
15.2% of faeces (n ¼138). In addition, in the north-west a
sudden and dramatic change in faeces containing pangolin
remains coincided with the suspected death of a resident
leopard: Before March 1993, 32.7% (n ¼55) of faeces
contained pangolin remains. Afterwards, the rate dropped
to 3.6% (n ¼83). No comparable change was observed in
the south-east (before March: 36.7%; n ¼30;after March:
45.0%; n ¼20). There were no obvious habitat differences
across the study area that could have explained uneven
distribution of prey animals.
In sum, our data suggest that forest leopards may differ
from savannah individuals in important ways. First, they
are predominantly diurnally and crepuscularly active.
Second, one focal animal did not consume some potential
prey species, such as chimpanzees and pangolins, but often
others, such as duikers and monkeys. One possible inter-
pretation of this finding is that forest leopards develop
individual prey preferences. The population density of
leopards is high in the Taı
¨forest with substantial range
overlap particularly between the sexes (Jenny, 1996),
suggesting that individuals experience strong competition
forcing them to use different resources within the shared
range.
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(Manuscript accepted 30 November 2004)
200 David Jenny and Klaus Zuberbu¨hle
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