Pan Africa News, 29(1–2):5–8 (2024)

Note

The first case of hunting and consuming an anomalureby chimpanzees (Pan troglodytes schweinfurthii)in Kalinzu forest, Uganda
Shimei Shirasawa1, Hiroyuki Takemoto1, Chie Hashimoto1& Nahoko Tokuyama 1, 2✉

1 Wildlife Research Center, Kyoto University, Japan
2 Department of Biological Science, Faculty of Science and Engineering, Chuo University(
E-mail: ntokuyama653@g.chuo-u.ac.jp)✉

ABSTRACT

Hunting and meat-eating by chimpanzees have long been attracting researchers’ attention. Although chimpanzees consume various vertebrate species, the frequency of meat-eating and prey species differ among populations andgroups. Here, we present the first documented case of chimpanzees consuming Lord Derby's anomalure in the Kalinzu
forest, Uganda. Despite anomalure species inhabit some long-term field sites of chimpanzee, reports of chimpanzees
consuming anomalures are rare, with only one previous case documented in Outamba–Kilimi National Park, Sierra
Leone. In the current case, three males consumed the meat and their meat-eating patterns closely resemble those ofchimpanzees at this site when consuming their usual prey. Obtaining further observations of these rare events may contribute to gaining a more comprehensive understanding of chimpanzee hunting and feeding culture.
Keywords: meat eating, prey image, food sharing, Lord Derby’s anomalure

INTRODUCTION

In this study, we report the first case of hunting andsubsequent consumption of a Lord Derby’s anomalure(Anomalurus derbianus; Figure 1) by chimpanzees in
Kalinzu Forest, Uganda. The rodent family Anomaluridae
comprises seven species that are commonly referred toas anomalure. These are nocturnal mammals that are almost exclusively arboreal, gliding from tree to tree using
the membranes (patagia) that stretch between their foreand hind legs, and generally spend the hours of daylight
hidden within tree hollows. Anomalures are broadly distributed in different types of forests in western to central
Africa and some parts of eastern Africa (Kingdon et al.
2014; Howell et al. 2016), and although they are hunted bysome populations of the genetically close bonobos (Ihobe& Sakamaki 2023; Hirata et al. 2010), to the best of ourknowledge, there has been only one other reported caseof chimpanzees preying upon such animal species in
Outamba–Kilimi National Park, Northern Sierra Leone(Alp 1993; Alp & Kitchener 1993).

Chimpanzees hunt and consume a wide range ofvertebrate species, with the frequency of meat eating andpursuit of prey species differing among populations andgroups (Watts 2020; Bugir et al. 2021; Klein et al. 2021).
Although group- or population-specific prey preferences
are partially determined by the availability of the preyspecies and other food resources, in certain instances they
appear to be independent of ecological variation, which
may constitute one of the cultural components of chimpanzee behavior (Ebang Ella et al. 2023).

METHODS

The observations reported herein were made on
October 5, 2023, at the Kalinzu Central Forest Reserve(30°07ʹE, 0°17ʹS), Uganda. In this region, October falls
during one of the two annual rainy seasons (from midMarch to the end of May, and from the mid-September
to the end of December). Among the seven recorded species of Anomaluridae, only Lord Derby’s anomalure is
known to inhabit this area (Kingdon et al. 2014; Howell
et al. 2016). A group of eastern chimpanzees, referred to

Figure 1. Lord Derby’s anomalure of Kalinzu Forest.
Photo taken by Haruka Kitayama.

5Pan Africa News, 29(1–2):5–8 (2024)
as the M group, has been monitored daily at this site since
1992, and with the exception of some peripheral females,
all group members have been identified and are fully habituated. They regularly hunt sympatric diurnal primates,
namely, red-tailed monkeys (Cercopithecus ascanius),
blue monkeys (Cercopithecus mitis), and Abyssinian colobus (Colobus guereza; our unpublished data).
During a hunting session on the aforementioned date,
we conducted ad libitum observations of the chimpanzees’ behaviors, which were recorded through videos andphotographs. We accordingly witnessed meat-sharing interactions involving four males [Ichiro (35–38 years; highranking male), Goku (approx. 31 years old; alpha male),Buru (45–50 years; low-ranking male), and Deo (45–50
years old; low-ranking male)] and a single female [Ume(approx. 31–32 years old)].
On October 5, 2023, we started searching for chimpanzees at 06:00 h and duly located a party of chimpanzees at 07:10 h. At 08:57 h, when three adult malechimpanzees (Ichiro, Goku, Buru) were ranging using asmall path, they suddenly began to run and subsequently
gathered at a tree, approximately 15 m in height, at a location approximately 2 m above the tree base. Here, theycommenced omitting vocalizations of excitement andscreaming, and after approximately 1 minute, Ichiro be-

gan climbing the tree carrying the carcass of an animal(Figure 2). Given the presence of a distinctive patagium,
we were readily able to identify this animal as an anomalure, which had body lengths of approximately 30 and
40 cm from the head to the gluteal region and head to tail,respectively.
The chimpanzees subsequently spent 31 minutes consuming this prey item. Ichiro held the carcass and started
eating the meat at 09:00 h, and at 09:02h, Goku began tobeg Ichiro by peering and touching Ichiro’s mouth and thecarcass and obtained a small portion of meat. At 09:09h,
Buru began grooming Ichiro and also obtained a small
portion of meat at 09:11 h.
At 09:15 h (Figure 3), when Goku had forcefully
seized the carcass from Ichiro, the skin of the carcass
began to become detached, and Goku commandeered
the torso, legs, and tail, whilst Ichiro was able to retain
the skin and head (Figures 4 and 5). Thereafter, Ichiro
climbed up into the tree canopy and disappeared fromview. At 09:20 h, two sub-adult males, Nobita and Yubo,
arrived and sat at a distance of < 10 m from Goku until hehad finished eating, although showed no apparent begging
behaviours. At 09:26 h, Deo and Ume appeared alongwith one adult male who was not involved in meat-sharing
interactions. At 09:29 h, Ume was seen begging Goku,
although she was attacked by Goku and failed to receive
any meat. Similarly, despite begging Goku, Deo was un-

Figure 2. Ichiro clutching the anomalure immediately after
capture. Photo taken by Shimei Shirasawa.

Figure 4. Goku holding the lower half of the anomalure.
Photo taken by Shimei Shirasawa.

Figure 3. Buru watches Ichiro holding the anomalure.
Photo taken by Nahoko Tokuyama.

Figure 5. Goku and Ichiro sitting in the same tree. Ichiro
is perched above, holding the skin of the anomalure in his
hand, and Goku is below, holding the lower half. Phototaken by Shimei Shirasawa.

OBSERVATIONS

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Pan Africa News, 29(1–2):5–8 (2024)
successful in obtaining any meat. During this time, Goku
occasionally consumed mature leaves plucked from thetree in which he was sitting.

served during the consumption of anomalures by bonobos(Hirata et al. 2010; Ihobe & Sakamaki 2023; Tokuyama
personal observation). We accordingly tend to believe thatthe hunting of anomalure is long-established feature ofthis group, although it has probably been overlooked todate on account of its infrequency. Accordingly, obtaining
further observations of these rare events may contributeto gaining a more comprehensive understanding of chimpanzee hunting and feeding culture.

DISCUSSION

To the best of our knowledge, this is the first observedcase of chimpanzees hunting and consuming an anomalure in Kalinzu, and the second case of chimpanzees
consuming an anomalure. The one previous case wasreported from Outamba–Kilimi National Park, Sierra
Leone, in which remains of an anomalure were foundfrom the chimpanzee faeces (Alp 1993). Chimpanzees
have rarely been reported to prey upon anomalure. Thisbehavior might be attributed in part to the distribution of
the rodents, which are not found in some study sites ofeastern chimpanzees; for example, Mahale and Gombe.
However, according to Kingdon (2014) and Howell et al.
(2016), at least one species of anomalures inhabits multiple sites at which long-term research on eastern chimpanzees (Kibale, Budongo, Nyungwe), central chimpanzees(Goualougo, Lopé), Nigerian-Cameroon chimpanzees(Ebo) and western chimpanzees (Taï Forest, Bossou,
Fungoli, Sapo) has been conducted. Considering thatchimpanzees hunt other arboreal rodents, i.e., squirrels(Bugir et al. 2021; Watts 2020), and that bonobos at somefield sites hunt anomalures (Wamba, Kokolopori, Iyondji,
and Lilungu; Ihobe & Sakamaki 2023; Hirata et al. 2010),
it is worth mentioning that anomalure hunting by chimpanzees has not been reported from these field sites. It is
plausible that this lack of sightings may simply reflect thefact that compared with diurnal mammals, chimpanzees
rarely encounter nocturnal anomalures. Previous studies
have identified the approximate repertoire of animal preyspecies consumed by chimpanzees, most of which are
predominantly diurnal species (Watts 2020). However,considering that bonobos at some field sites actively huntand consume anomalures (especially in Wamba, wherebonobos almost exclusively hunt anomalures), as well as
chimpanzees at some field sites have been reported tohunt nocturnal primates regularly (Fungoli: Pruetz 2006;
Pruetz et al. 2015, Mt. Assirik: McGrew et al. 1988; Hunt
& McGrew 2002), the nocturnality of anomalures may
not be the only reason why chimpanzees rarely recognize
them as prey. It is possible that chimpanzees in only a few
study sites had opportunities to learn about anomalure as
potential prey due to the infrequent encounters with theseanimals.
Although this is the first time that researchers observed anomalure hunting by chimpanzees in Kalinzu,
one of the local assistants at this site has recounted observing chimpanzees eating anomalure many years ago.
Whilst feeding on the anomalure, the chimpanzees observed in the present case did not appear to show any evidence of hesitation, curiosity, or play-like behavior, whichtends to contrast with the behavior shown chimpanzees
and bonobos when capturing an unusual prey item (e.g.,
Carvalho et al. 2010; Yokoyama 2021). Indeed, the patterns of meat-eating and sharing we recorded closely
resemble those observed when they consume their moregenerally eaten prey species, as well as the patterns ob-

ACKNOWLEDGMENTS

This study was f inancially suppor ted by JSPSK A K E N H I (19H0 0629 a nd 20K 214 48 t o Sh i nya
Yamamoto, 21H04380 to Naoki Matsuura, 18KK0204
to Chie Hashimoto, 21H02572 to Takeshi Furuichi). We
would like to thank Dr. Hiroshi Ihobe and Mr. Haruka
Kitayama for providing useful information. We also
thank the local assistants at the Kalinzu Forest Reserve
for their expertise in chimpanzee research. In addition,
we thank the Uganda National Council for Science andTechnology, National Forestry Authority, and Uganda
Wildlife Authority for granting us permission to conduct
the research, and Makelele University for their assistance.

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Received: 22 February 2024
Accepted: 11 May 20248