A New Report of Chimpanzee Ant-Fishing from the Issa Valley, Tanzania

African Primates 11(1): 1-18 (2016)/ 1

A New Report of Chimpanzee Ant-fishing from the Issa Valley, Tanzania

Eden M. Wondra1, Adam van Casteren2 , Alejandra Pascual-Garrido3, Fiona Stewart1,4, and Alexander K. Piel1,5

1Ugalla Primate Project, Box 108, Uvinza, Tanzania; 2Max Planck Weizmann Center for Integrative Archaeology and Anthropology, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany; 3Leverhulme Trust Early Career Fellow, School of Archaeology, University of Oxford, Oxford, UK; 4Department of Archaeology and Anthropology, University of Cambridge, Cambridge, UK; 5School of Natural Sciences and Psychology, Liverpool John Moores University, Liverpool, UK

Abstract: Tool use in chimpanzees (Pan troglodytes) is widespread across their geographical distribution, having been documented in all populations studied to date. Ant-fishing, specifically, is less frequently observed, reported so far in only ten different communities. We describe the first observations of ant-fishing of Camponotus chrysurus by chimpanzees living in the mosaic landscape of the Issa Valley, western Tanzania. After two separate bouts, both occurring in the same position in a fig treeFicus ( lutea vahl), we recovered five ant-fishing tools made from the liana Dichapetalum crassifolium chodat. Tool types closely resemble those described for earlier reports of the same behavior in near-by Mahale Mountains chimpanzees, and thus may have implications for cultural diffusion of the habit across populations.

Key words: Chimpanzee, Camponotus, ant-fishing, insectivory, Issa Valley

INTRODUCTION

Tool use in chimpanzees (Pan troglodytes) is for termites and to access plant underground storage widespread across their geographical distribution, organs (Hernandez-Aguilar et al. 2007; Stewart & having been documented in all populations that have Piel 2014). been thoroughly studied to date (McGrew 2010). The Probably because of the lower mass intake rate type, function, and prevalence in tool use behaviors of ant-fishing (chimpanzee predation of carpenter differ widely, however, suggesting that an interplay ants through the use of tools – Camponotus spp.), between culture, where the behavior is transmitted compared to that of ant-dipping for Dorylus repeatedly through social or observational learning ants (with a higher mass intake rate) and termite to become a community-level-characteristic, and fishing, carpenter ants Camponotus( spp.) are not as the environment explains such variation (McGrew commonly consumed by chimpanzees as are other 1992; Whiten et al. 1999; Koops et al. 2013; Sanz et invertebrates (O’Malley & Power 2014). Compared al. 2014). Chimpanzees exhibit a rich repertoire of to the 21 communities of chimpanzees where tool-use behaviors, used most often to improve or termite fishing has been described, ant-fishing has gain access to a variety of foods including termites, been described in only 10 different communities bees and honeycomb, nuts, and ants (McGrew (Table 1; Figure 1). This is surprising given that 1992). Chimpanzees of the Issa Valley are known to Camponotus has the most ecologically diverse manufacture and use tools made from plants to fish geographical range, and the broadest distribution of

Correspondence to: Alex Piel, School of Natural Sciences and Psychology, Liverpool John Moores University, James Parsons Building, Byrom Street, L33AF, Liverpool, UK; Phone: +44 7557915813; E-mail: [email protected]. 2 / Wondra et al.

2005; et al. et et al. et 2014 References 1991 Muroyama Deblauwe & 2006; Deblauwe 2008 Janssens 1997 Ingmanson 1994 & Carroll Fay 1994 & Carroll Fay Hicks 2010 Hicks & Morgan Sanz 2007, 20013; Sanz al. et Bermejo & Illera 1999

? ? ants +/+/H Camponotus ants ? ? +/+/T +/+/T +/+/T +/+/H Dorylus foraging for this region. this region. for foraging ) Pan +?/- +/+/T +/+/T +/+/T +/+/T +/+/T +/+/T Termites Termites vitrialatus Macrotermes Macrotermes lilljeborgi; M. lilljeborgi; Macrotermes ( M. lilljeborgi; M. M. lilljeborgi; M. M. lilljeborgi; muelleri; M. nobilis muelleri; M. nobilis muelleri; ) +/- mellifera

+/+/T +/+/T +/+/T +/+/T Honey BeesHoney Apis ( Note: We incorporate the Sonso, Busingiro and Kasongoire communities to the table (even though (even though the table to communities Kasongoire and Busingiro the Sonso, incorporate We Note: ) +/+/T +/+/T +/+/T +/+/T +/+/T +/+/T Trigona Trigona beccardi beccardi Meliponini ( gribodoi Mag (Hypotrigona) (Hypotrigona) Stingless BeesStingless Trigona gribodoi; gribodoi; Trigona Trigona (Meliplebia) Trigona Meliponula nebulata Meliponula Hypotrigona gribodoi; Hypotrigona Name of of Name Community Campo Dja Biosphere Reserve, La Belgique Ntale Bai Hokou Ndakan Ngotto Goualougo Lossi African Republic African Republic African Republic Republic Republic Country 1. Cameroon 2. Cameroon 3. Cameroon 4. Central 5. Central 6. Central 7. Congo 8. Congo Table 1. Presence or absence and type insectivory absence and insects of or products: +/+ their with 1. Presence chimpanzee gathering reports or of in communities use tool for Table ? unknown; consumed eaten; H consumed with T consumed with H? probably hands; tools; +/+?, present/probably eaten; +/− present/not present/eaten; its or presence/absence prey’s report of any we failed to find where thosesites for blank left consumed with Spaces were tools. with T? probably hands; Species provided are targeted when known.consumption. in the local insects) address variability to gathering for tools manufacture to known not they are Ant-fishing in Issa Chimpanzees / 3 . 1979 1996 . 1995; et al. al. et et al. al. et ., l. et al et al. et et al et a et al References Suzuki Kuroda Bermejo & Illera 1999 Boesch & Boesch 1990 Hicks data; unpublished C. pers. Hicks, comm. Hicks data; unpublished C. pers. Hicks, comm. Yamagiwa & 1988; Yamagiwa Basabose 2009 Takemoto 2005 1974; Pi Sabater McGrew

+/- +?/- ants +/+/T Camponotus

D. kohli ants . D +/+/T +/+/T +/+/T opacus +/+/H? +/+/H? with long long with short tools) D. wilverthi wilverthi D. D. terrificus; terrificus; D. D. nigricans; nigricans; D. Dorylus D. gerstaeckeri D. thin wand); thin wand); tools); tools); wilverthi (both D. terrificus; D. terrificus; D. consumed with with consumed (consumed with with (consumed (both consumed (both consumed ) +/- +/- +/- +/+/T +/+/T +/+/T +/+/T +/+/H muelleri Termites Termites M. muelleri M. lilljeborgi; M. lilljeborgi; Macrotermes Macrotermes Macrotermes ( ) mellifera +/-? +/-?

+/+/T +/+/H? Honey BeesHoney Apis ( ) + +/+/T +/+/T +/+/T +/+/T Meliponini ( consumption) Stingless BeesStingless (no evidence of evidence(no of Name of of Name Community Ndoki Ndoumbi Taї Forest Bili-Gagu Bili-Uele Bili-Uele Southern (Leguga Forests / Bambesa / Aketi) Kahuzi-Biega Mboete Okorobiko Republic d’Ivoire Guinea Guinea Republic Country 9. Congo 10. Congo 11. Côte Congo 12. DR 13. DR Congo 13. DR 14. DR. Congo 15. Equatorial 16. Equatorial Table 1. Presence or absence and typeinsectivory and absence insectsof or (continued.) products their with 1. Presence chimpanzeegathering reports or of in communities use tool for Table 4 / Wondra et al.

2009 et al al et 2013; 2015a et al. et et al. al. et et al. al. et et al. et et al. et al. et References & Rogers McGrew 1983 Boesch 1992; McGrew & Fernandez Tutin 1992; Tutin 1995 Nishimura & 2003; Wilfried 2014 Yamagiwa Sugiyama 1995; Humle & 1999; Humle 2002; Matsuzawa Yamamoto 2008; Sanz 2009 Koops Koops Koops

ants +/+/T +/+/T C. brutus C. brutus Camponotus +/- ants +/+/T +/+/T Dorylus D. kohli; D. D. mayri; mayri; D. D. emeryi; D. D. gribodoi D. D. lamottei; D. D. militaris; D. D. nigricans D. D. nigricans; nigricans; D. D. burmeisteri; burmeisteri; D. ) nobilis +/- +/- +/- +/+/T +/+/T . ? +/+?/T? Termites Termites M M. bellicosus Macrotermes ( ) +/- +/- mellifera

+/+/T +/+/T Honey BeesHoney Apis ( ) +/- +/+/T +/+/T +/+/T +/+/T Meliponula Meliponini ( Stingless BeesStingless Trigona, Meliponula Trigona, Meliponula lendiana Meliponula Meliplebeia nebulata;Meliplebeia Meliponula bocandei; bocandei; Meliponula Meliponula lendliana; Meliponula Name of of Name Community Belinga Loango Lope Moukalaba- Doudou Bossou Seringbara, Nimba Mountains Country 17. Gabon 18. Gabon 19. Gabon 20. Gabon 21. Guinea 22. Guinea Table 1. Presence or absence and typeinsectivory and absence insectsof or (continued.) products their with 1. Presence chimpanzeegathering reports or of in communities use tool for Table Ant-fishing in Issa Chimpanzees / 5 et 2013 . 2005; et al. al. et et al al. et et al. al. et 2012; O’Malley 2012; O’Malley References & Sommer Fowler 2007; Pascual- Garrido 2012; Dutton Dutton & Chapman 2015a, 2015b 2010 Easton McGrew McGrew Bogart & Pruetz 2008, 2011 McGrew 1988; McBeath 1992; & McGrew 1992 McGrew 1993 Alp 1974; McGrew Goodall 1986; Schoning 2008; O’Malley al. 2014; & Power R., pers. O’Malley, comm.

. sp. 1 . sp. ants +/+/T +/+/T +/+/T +/+/T C C. vividus; C. vividus; C. crhysurus C. nr. perrisi C. nr. C. chrysurus; C. chrysurus; Camponotus D. ants +/+/T +/+/T +/+/T +/+/T +/+/T +/+/T D. kohli Dorylus +/+/? D. rubellus burmeisteri D. anomma D. D. nigricans D. nigricans D. D. molestus;D. ) +/- +/- +/+/T +/+/T +/+/T Termites Termites with hands) M. bellicosus M. bellicosus Macrotermes M. subhyalinus M. subhyalinus ( M. subhyalinus; M. subhyalinus; M. subhyalinus; M. subhyalinus; this species eaten this species eaten spp. (only alates of of alates (only spp. Pseudacanthotermes ) +/+ mellifera

+/+/T +/+/T +/+/T +/+/H +/+/H? Honey BeesHoney pers. comm.) Apis ( (use of tools seen tools (use of rarely; O’Malley, R., O’Malley, rarely;

) +/+/T +/+/T +/+/H Meliponini pers. comm) ( Stingless BeesStingless (use of tools seen tools (use of Meliponula erythra Meliponula erythra rarely; O’Malley, R., O’Malley, rarely; Trigona; HypotrigonaTrigona; Hypotrigona gribodoi; Hypotrigona gribodoi; Hypotrigona Name of of Name Community Gashaka-Gumti Nyaki Ngel Nyungwe Fongoli Mt. Assirik Mt. Tenkere- Outamba- Kilimi Gombe (Kasekela) Leone Country 23. Nigeria 24. Nigeria 25. Rwanda 26. Senegal 27. Senegal 28. Sierra 29. Tanzania Table 1. Presence or absence and typeinsectivory and absence insectsof or (continued.) products their with 1. Presence chimpanzeegathering reports or of in communities use tool for Table 6 / Wondra et al. et

et al. al. et et al. et 2008; Sanz 2008; Sanz References et al. Schoning 2008; O’Malley 2011; O’Malley 2014; & Power pers. D., Mjunju, O’Malley, comm.; R. pers. comm. 2014 & Piel Stewart 1966; & Itani Izawa 1966 Suzuki 1982; Uehara & Collins McGrew 1985 & Hiraiwa Nishida 1982; 1982; Uehara & Uehara Nishida 1983; Schoning al. 2015; 2009; Kiyono M., Nakamura, pers. comm. & Uehara Nishida 1983; McGrew & Collins 1985; Schoning 2011; 2008; Nishie 2015; Kiyono M., Nakamura, pers. comm.

. sp. ? ants +/+/? +/+/T +/+/T +/+/T (maybe); C. brutus C. brutus C. vividus C. vividus C. chrysurus; C. chrysurus; C. chrysurus; Camponotus C. vividus; C. C. vividus; maculatus; C. maculatus; brutus; C. brutus; Current study Current ? +/- +/- +/- +/- ants +/+/T D. kohli Dorylus D. molestusD. molestusD. D. molestus;D. ) (tools are are (tools spp. (only (only spp. (tools were were (tools +/+T +/+/T +/+/T +/+/T +/+/T +/+/T hands) Termites Termites M. ?herus Macrotermes Pseudacantho- ( M. subhyalinus; M. subhyalinus; were eaten with with eaten were termes termes spiniger spiniger rarely used; alates used; alates rarely eaten with hands) with eaten spiniger spiniger alates of this species of alates Pseudacanthotermes Pseudacanthotermes rarely used, alates are are used, alates rarely are eaten with hands) with eaten are ) +/- +/- +/? mellifera

+/+/? +/+/? +/+/H comm.) Honey BeesHoney Apis rarely to widen to rarely ( entrance of nest, nest, of entrance Mjungu, D. pers. D. Mjungu, (use of tools only only tools (use of ) ? +/- +/+/T +/+/T +/+/T +/+/H Trigona Trigona Trigona comm.) Trigona?; Trigona?; Meliponini ( Hypotrigona? Stingless BeesStingless rarely to widen to rarely entrance of nest, nest, of entrance Mjungu, D. pers. D. Mjungu, (use of tools only only tools (use of Name of of Name Community Gombe (Mitumba) Issa Kasakati Mahale (B-Group) Mahale (K-Group; extinct) Mahale (M-Group) Country 30. Tanzania 31. Tanzania 32. Tanzania 33. Tanzania 34. Tanzania 35. Tanzania Table 1. Presence or absence and typeinsectivory and absence insectsof or (continued.) products their with 1. Presence chimpanzeegathering reports or of in communities use tool for Table Ant-fishing in Issa Chimpanzees / 7 ., in et al References Newton-Fisher 1999; Reynolds, pers. comm. V., pers. J., Wallis, comm. A., pers. Oxley, comm. & Hedges 2012 McGrew Mugisha Hobatier, press; C., pers. comm. 2011; McLennan 2014

. C ( found found ? +/- +/- ants +/+/H +/+/H +/+?/H reported) reported) (one single single (one observation observation brutus Camponotus (one possible possible (one C. vividus once in dung) once +/- +/- +/? ants (rare) +/+/T +/+/H Dorylus D. wilverthi wilverthi D.

)

and +/? +/? +/H rarely seen) rarely eaten) +/+/H +/+/H +/+?/H Termites Termites Macrotermes Macrotermes ( clearings, rarely rarely clearings, (present only in only (present Macrotermes (alates eaten only) eaten (alates Pseudocanthotermes spiniger Pseudocanthotermes ( ) +/- +/- +/? mellifera

+/+/H +/+/T? (use of tools tools (use of Honey BeesHoney primarily for for primarily Apis ( acquiring honey) acquiring ) +/- +/- +/? +/+/T +/+/H Meliponini ( Stingless BeesStingless Meliponula lendliana Meliponula Name of of Name Community Budongo (Busingiro) Budongo (Kasokwa) Budongo (Kasongoire) Budongo (Sonso) Budongo (Waibira) Bulindi Country 36. Uganda 37. Uganda 38. Uganda 39. Uganda 40. Uganda 41. Uganda Table 1. Presence or absence and typeinsectivory and absence insectsof or (continued.) products their with 1. Presence chimpanzeegathering reports or of in communities use tool for Table 8 / Wondra et al.

et et et

et al. et

. et al. al. et et al. et et al. et et al 2011; Nelson 2011; Nelson 2008; Sanz 2008; Sanz l. 2009; Potts 2009; Potts l. References Stanford 2000; Stanford & Nkurunungi & 2003; Kajobe 2006 Roubik Koops 2015b Koops 2015b Wrangham 1991; Schoning al. a al. 2013 2008; Watts 2014; McLennan *Bee taxa were in the listed not tool of reports Watts use by this (2008) but located is site 10km from Kanyawara Webster 2014

+/- +/- +/- ants Camponotus +/- +/- +/- ants +/+/T +/+/T +/+/H Dorylus D. wilverthi D. wilverthi D. D. terrificus; terrificus; D. terrificus; D. ) - = +/- +/- +/+/H Termites Termites Macrotermes ( ) mellifera

+/+/T +/+/T Honey BeesHoney Apis ( ) +/+/T +/+/T +/+/T +/+/T* Meliponini M. nebulata; M. nebulata; M. lendliana ( M. ferruginea; M. ferruginea; Stingless BeesStingless Meliponula bocandei, bocandei, Meliponula Name of of Name Community Bwindi Kalinzu (M-Group) Kalinzu (S-Group) Kibale (Kanyawara) Kibale (Ngogo) Toro-Semliki Country 42. Uganda 43. Uganda 44. Uganda 45. Uganda 46. Uganda 47. Uganda Table 1. Presence or absence and typeinsectivory and absence insectsof or (continued.) products their with 1. Presence chimpanzeegathering reports or of in communities use tool for Table Ant-fishing in Issa Chimpanzees / 9

Figure 1. Map of reported tool-use for insectivory by chimpanzees. Those communities with Camponotus consumption are underlined. The Issa Valley study area is denoted with a triangle. all ant genera across Africa (Wilson 1975; Nishida tools from various plant parts and exhibit multiple & Hiraiwa 1982; McGrew 1992). Their colonies of extraction techniques (Nishida & Hiraiwa 1982). For hundreds to thousands of soldier and worker ants example, in the Mahale Mountains National Park, are commonly found in nests made in the trunks Tanzania, Nishida (1973) discussed three different of trees, dry branches, or hollow grass stems from types of techniques (wiping handkerchief, expelling dispersed-open to dense-tropical forests (Nishida & stick, and poking rod) in his description of how Hiraiwa 1982). Direct observations of chimpanzees chimpanzees consumed Camponotus ants (see also preying on Camponotus have been described from Nishie 2011), as well as twenty-two different species Gashaka-Gumti National Park, Nigeria (Fowler & of plants used as raw material and six different types Sommer 2007), Bossou, Guinea (Yamamoto et al. of tools according to the physical characteristics and 2008), Lope Reserve, Gabon (Tutin & Fernandez technique used for each tool (Nishida & Hiraiwa 1992), Mahale, Tanzania (Nishida & Hiraiwa 1982; 1982). At Gombe, only 150 km north of Mahale, Nishie 2011) and Gombe, Tanzania (O’Malley et al. decades of intense research initially resulted in the 2012), while at Mt. Assirik (Senegal), also a dry, open, acceptance that Camponotus was never consumed mosaic habitat such as Issa, McGrew (1992) inferred (Nishida & Hiraiwa 1982), followed by the possibility their consumption from tool remains at a disturbed of their consumption (Goodall 1986), and more ant colony. Other sites where consumption has been recently, a detailed analysis of the dissemination inferred from tools left abandoned at targeted nests of the behavior across numerous members of the include Ngel Nyaki (Nigeria) and Taï National Park Kasekela community (O’Malley et al. 2012). About (Ivory Coast) (Boesch & Boesch 1990; Dutton 2012). halfway between Gombe and Mahale, in Kasakati, Similar to how researchers document Suzuki (1966) reported Camponotus consumption chimpanzee ant-dipping, researchers have noted through analysis of chimpanzee fecal remains, but the various techniques that chimpanzees employ ant-fishing was never confirmed with behavioral when fishing for carpenter ants, the reduction observations or through the indirect evidence of processes involved during tool manufacture, as well tools. as the diverse types of raw material used (Nishida & Here we report on the first direct observations Hiraiwa 1982). Tool structure is not only important of ant-fishing of Camponotus by chimpanzees in for efficiency, but also for avoiding the aggressive the Issa Valley, adding this type of tool use to the biting defenses of carpenter ants, which appear to repertoire of tool using behavior for this community discourage chimpanzees from predation (Nishida and describing a third occurrence of the behavior in & Hiraiwa 1982). Even within consumption of a western Tanzania. single prey species, chimpanzees may manufacture 10 / Wondra et al.

METHODS well, while the other three chimpanzees remained close by, including two adult males and one adult Study Site female. We observed them directly consuming ants The Issa Valley is located about 100km east of directly by their mouths or by using their hands, Lake Tanganyika, almost halfway between Gombe sweeping them across the surface of the tree. After and Mahale Mountains National Parks (Figure a few minutes, the young female reached down and 2). The region is one of the driest, most open and broke off a piece from a liana, before inserting it into seasonally extreme habitats in which chimpanzees a tree-hole (Figure 3; see supplementary video1). live (Moore 1992), with the landscape characterized She repeated this process multiple times, making by miombo woodland (dominated by Brachystegia numerous new tools, using them briefly, and then and Julbernardia), interspersed with grasslands, changing tools until approximately 11:30 when she swamps and steep gallery forest ravines (Piel et al. left the tree, after over two hours of fishing. Given 2015). Annual temperature and precipitation ranges our obscured visibility of the ant-fishers, details of from 11° to 35°C, and 900-1400mm, respectively. the manufacturing process, technique used and The Ugalla Primate Project established a whether the new tools were taken from the same permanent research presence at Issa in 2008, but liana, or a stem or branch could not be seen. shorter-term (temporary) studies have occurred In a second observation on July 8, 2015, AVC in the area since 2001. As of May 2016, the Issa observed an adult female (possibly the same as community was partially habituated: fourteen previously observed) ant-fishing. On this occasion chimpanzees were individually identifiable and the individual was alone, fishing in the same the community size was estimated to be at least location of the same tree, and also fishing with her 67 individuals based on genetic analyses, with a right hand. Fishing occurred between 10:00 and minimum estimated home range of 85km2 (Rudicell 11:00, lasting almost one hour. Despite visiting the et al. 2011). tree on subsequent days, we observed no further fishing bouts. Data Collection Subsequent tool collection and botanical Research teams consisting of two people identification revealed all tools to be manufactured searched for chimpanzees on a near-daily basis. from Dichapetalum crassifolium chodat (Table 2) Usually, we relied on known feeding trees, and the host tree of the ant colony to be Ficus lutea preferred nesting sites, and dawn vocalizations to vahl. Tool types (Figure 4) most closely resembled locate chimpanzee parties. When we encountered Type B, described in Nishida and Hiraiwa (1982) as chimpanzees, we recorded data on party size, a tool made from the bark fiber of a liana, peeled location, habitat, demography, and behavior. For off and often divided into thin strips used for small the current observations, chimpanzees were found nest entrances. One other tool that we recovered in a tree that was already being monitored because suggested a similarity to Type BBr - made of a branch its fruit had recently ripened and we had observed of a liana that has had its bark partially or completely chimpanzees feeding there for several days. All removed, to facilitate it fitting into a small ant hole, research complied with protocols approved by the and with its distal end showing evidence of wear with Tanzania Wildlife Research Institute and adhered to a slightly split end. Two additional plant remains the legal requirements of Tanzania and the American were also collected from the same area that may Society of Primatologists Principles for the Ethical have been tool fragments that had detached from Treatment of Non-Human Primates. the tool during the course of its use or manufacture. However, their small size makes validity or tool type RESULTS classification unreliable, although they seem to be of similar age based on color and condition (Figure 4). Observation On July 2, 2015, researchers encountered five chimpanzees feeding in a Ficus lutea vahl tree in DISCUSSION the core study area. At 09:15, EW and field assistant MR observed one young adult female perched on Whereas tool use for insectivory is nearly a tree with a vine for balance 19 meters above the pervasive across chimpanzee communities, ant- ground, using a tool with her right hand to fish ants from the crux of the tree, before the four others later 1 Supplementary video may be viewed at: https://youtu.be/ joined her. Only an estrous female then fished as ejGiYbEljrs. Ant-fishing in Issa Chimpanzees / 11

Figure 2. Map of western Tanzania with the Issa study site highlighted in the center. The two closest study sites where ant-fishing has also been recorded, Gombe and Mahale National Park, to the north and south, respectively, are also highlighted. Vegetation, river and roads that may act as barriers between these populations and could influence cultural transmission are indicated. Map credit: L. Pintea, Jane Goodall Institute. fishing has been reported in only 10 communities Camponotus chrysurus in the Issa chimpanzees of (Figure 1), surprising given the widespread western Tanzania, making it the third description distribution of Camponotus across Africa (although for the region. Given the previous reports of this possibly under-represented due to the elusiveness behavior, where chimpanzees were preying on the of the tools [Bolton 1995]). We have now added same species of arboreal ants at nearby Mahale to this list with two observations of ant-fishing of (Nishida & Hiraiwa 1982; Nishie 2011) and further 12 / Wondra et al.

Table 2. Dimensions and types of tools found at site of fishing. Type B = strip of bark removed from a liana; Type BBr = branch of liana with some or all bark removed.

Tool Length Width Match to Nishida and Hiraiwa Material number (mm) (mm) (Nishida & Hiraiwa 1982) 1 214 < 1 Dichapetalum Type Ba crassifolium chodat 2 109.48 < 1 D. c. chodat Type B 3 88.34 1.48 D. c. chodat Type BBrb 4 97.78 1.38 D. c. chodat Type B 5 99.80 1.82 D. c. chodat Type B Types are taken from Nishida and Hiraiwa’s (1982) descriptions of the variations of ant-fishing tools made by chimpanzees. a Type B = a tool made from the bark fiber of a liana, pealed off and divided into thin strips used for small nest entrances. b Type BBr = a tool made of a branch that has had its bark partially or completely removed to facilitate it fitting an ant hole.

Figure 3. Picture of Camponotus chrysurus and the area where ants were observed on the Ficus tree where fishing occurred. Photograph by A. van Casteren. Ant-fishing in Issa Chimpanzees / 13

Figure 4. All five tools made from the bark of Dichapetalum crassifolium chodat, and additional fragments that we collected from the fork of the Ficus tree where ant-fishing was observed. Photograph by E. Wondra. 14 / Wondra et al.

north, Gombe (O’Malley et al. 2012), this could be thorough comparative study. More information on a case of diffusion of the habit, where the behavior the abundance of carpenter ants in Issa, their range spread from one or both of the other study sites east in habitat and altitude will be essential to addressing to Issa, by social learning (Whiten et al. 2001, 2007; this. This is both a rare and important occasion to McGrew 2004). However, an independent invention document and pursue for it may help to increase our in similar ecological contexts cannot be ruled understanding of tool use, cultural transmission and out: ant-fishing has been recognized as habitual insect foraging in chimpanzees, which is a viable in chimpanzees from the Mitumba community approach to anthropology and cultural evolution living in the northern parts of Gombe for decades, (McGrew 2004, O’Malley & Power 2014). while remaining absent from neighboring Kasekela community. It was only relatively recent that ant- fishing became a customary behavior in Kasekela, ACKNOWLEDGMENTS practiced exclusively by younger individuals and immigrant females (O’Malley et al. 2012). This We thank the Tanzanian Wildlife Research suggests that a possibility of ant-fishing traditions, Institute (TAWIRI) and the Commission for Science even if having a common origin, going extinct and and Technology (COSTECH) for permission to subsequently becoming re-established might exist. conduct research in the Issa valley. We greatly Only further observations of the behavior will appreciate the help of Msigwa Rashid, Busoti allow for more detailed comparisons of tools and Juma, and Shedrack Lukas for field assistance. extraction techniques between communities. APG is grateful to The Leverhulme Trust / UK for Regardless of whether techniques overlap across providing an Early Career Fellowship during the communities, Ficus appears not to be a commonly production and revision stage of this manuscript used tool source anywhere. In his summary analysis and AVC thanks the Max Plank Society for partially of over a half-century of Camponotus fishing in funding this work. We would also like to thank Mahale, Nishie (2011) described chimpanzee Caspar Schöning for ant-prey identification and use of 92 different trees to ant fish representing Yayha Abeid for botanical identification of tools. 24 different tree species, of which only one was Our special thanks to Paul Dutton, Cleve Hicks, Ficus (exasperata). Also at Gombe, O’Malley et al. Catherine Hobaiter, Kathelijne Koops, Bill McGrew, (2012) reported eighteen different observations Matthew McLennan, Deus Mjungu, Tweheyo that occurred over two years in seven different tree Mnason, Michio Nakamura, Rob O’Malley, Aimee species (three sources were unidentified) and again, Oxley, Vernon Reynolds and Janette Wallis for only one was Ficus sp. Continued monitoring at Issa providing information on chimpanzee insectivory will reveal whether a similar pattern holds. at field sites, and to reviewers for their constructive At Issa, fruit availability peaks in the late dry feedback. The UCSD/Salk Center for Academic season when Parinari curatellifolia and Strychnos Research and Training in Anthropogeny (CARTA) spp. comprise a large proportion of chimpanzee provides support to the Ugalla Primate Project. diet (Piel et al. unpublished data), whereas termite fishing is most frequent at the onset of the rains, in October-November (Stewart & Piel 2014). 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