Yuji Takenoshita

How fruit abundance affects the chimpanzee party size: a comparison between four study sites

We examined the relationship between fruit abundance and chimpanzee (Pan troglodytes) party size by comparing data from four study sites: the Kalinzu Forest Reserve, Uganda, the Djinji Camp and Guga Camp in the Ndoki Forest, Congo, and Kahuzi-Biega National Park, Democratic Republic of Congo. Although the difference in the fruit abundance between the sites was responsible for the difference in the party size between the sites, the seasonal changes in fruit abundance did not explain the changes in the party size in each study site. Across the four study sites, there were significant correlations of the mean and minimum of monthly party size with the mean of monthly fruiting-tree density, and a significant correlation of the maximum of monthly party sizes with the minimum of monthly fruiting-tree density. We proposed a hypothesis that (1) the monthly fruit abundance affects the monthly party size in the sites where the fruit availability is as low as to limit the party size during a major part of a year, while (2) the party size does not increase with the increase in the monthly fruit abundance, but is affected by other social factors, in the sites where the minimum of monthly fruit abundance is high enough for chimpanzees to form parties of an adequate size.

Molecular identification of the causative agent of human strongyloidiasis acquired in Tanzania: dispersal and diversity of Strongyloides spp. and their hosts.

In order to identify the causative agent of imported strongyloidiasis found in a Japanese mammalogist, who participated in a field survey in Tanzania, the hyper-variable region IV (HVR-IV) of 18S ribosomal DNA and partial mitochondrial cytochrome c-oxidase subunit 1 gene (cox1) were analyzed and compared with Strongyloides fuelleborni collected from apes and monkeys of Africa and Japan, and S. stercoralis from humans, apes and dogs. The HVR-IV and cox1 of the patients worms were identical to or only slightly differed from those of worms parasitic in Tanzanian chimpanzees and yellow baboons, demonstrating that the patient acquired the infection during her field survey in Tanzania. Phylogenetic analysis with the maximum-likelihood method largely divided isolates of S. fuelleborni into three groups, which corresponded to geographical localities but not to host species. Meanwhile, isolates of S. stercoralis were grouped by the phylogenetic analysis into dog-parasitic and primate-parasitic clades, and not to geographical regions. It is surmised that subspeciation has occurred in S. fuelleborni during the dispersal of primates in Africa and Asia, while worldwide dispersal of S. stercoralis seems to have occurred more recently by migration and the activities of modern humans.

FRUIT PHENOLOGY OF THE GREAT APE HABITAT IN THE MOUKALABA-DOUDOU NATIONAL PARK, GABON

Fruit phenology of the Moukalaba-Doudou National Park (MDNP), Gabon is monitored as basic information on the fl uctuation of food production for great ape populations. During the period from January 2003 to February 2007, we conducted a census on fallen fruits by the line transect method twice a month, in the process counting fallen fruit clusters and identifying fallen fruit species. We recorded 117 fallen fruit species during the study period. The majority of fruits came from trees. The number of fallen fruit clusters obtained in each census session correlated with the number of fallen fruit species found in the sessions. There was a marked seasonal pattern to fruit production, whereas the number of fallen fruit clusters as well as the number of species tended to be larger in the rainy season than in the dry season. Of the 31 major fallen fruit species, 15 species showed a fruiting peak in the rainy season, and fi ve species peaked in the dry season, while 11 species showed no difference in fruiting abun- dance between the rainy and dry seasons. Candidates of keystone fruit species were identifi ed from species that fruit during the dry season. Five species of fruit, including the woody liana Cissus dinklagei, were constantly abundant, occurring in more than 70% of all census sessions. Four of them are important fruit food resources for the great apes. Several species including Klainedoxa gabonensis exhibited super-annual fl uctuation in their fruiting pattern. The exis- tence of constantly abundant fruit species may have supported the high density of great apes in the MDNP.

ESTIMATING GORILLA ABUNDANCE BY DUNG COUNT IN THE NORTHERN PART OF MOUKALABA-DOUDOU NATIONAL PARK, GABON

Nest count is not an appropriate method to estimate abundance of gorillas and chimpanzees where both species live sympatrically. To apply an alternative method that could estimate their abundance separately, we examined dung count for gorillas on line transects. In the northern part of Moukalaba-Doudou National park, Gabon, we conducted a survey of gorilla dung piles (DPs) along the 11 line transects of 44.3 km in total length. First, we counted and marked all encountered dung piles and estimated DP density by the distance sampling method. After two days, we walked the same transects and checked whether the marked DPs were still recognizable, in order to calculate a daily dung disappearance rate. Using DP density, daily dung disappearance rate and the defecation frequency extrapolated from the other western gorilla populations, we calculated the density of gorilla. DP density was estimated at 102.3 dps/ km 2 . Dung piles of gorillas are easily discriminated from those of chimpanzees, so dung pile density is considered as a good indicator of gorilla abundance. However, individual density derived from DP density, daily dung disappearance rate and defecation rate seemed to be signifi cantly overestimated. Precise information on dung decay duration, age/sex difference in defecation rate, dietary effects on defecation rate, and group-level DP production frequency are needed for a reliable individual density estimate. No signifi cant difference was found in the encounter frequency of dung piles between the home range of our habituated gorilla group and those of adjacent areas, suggesting an overall high density of gorillas in the northern part of the

Prevalence and genetic diversity of Oesophagostomum stephanostomum in wild lowland gorillas at Moukalaba-Doudou National Park, Gabon

SummaryUsing a sedimentation method, the prevalence of the nodular worm Oesophagostomum stephanostomum (Nematoda: Strongylida) in western lowland gorillas at Moukalaba-Doudou National Park (MDNP), Gabon, was determined in fecal samples collected between January 2007 and October 2011, along with their coprocultures. Concurrently, possible zoonotic Oesophagostomum infections in villagers living near MDNP were assessed from their fecal samples collected during October and November of 2011. In the gorillas, strongylid (Oesophagostomum and/or hookworm) eggs were found in 47 of 235 fecal samples (20.0 %) and Oesophagostomum larvae were detected in 101 of 229 coprocultures (44.1 %). In the villagers, strongylid eggs were found in 9 of 71 fecal samples (12.7 %), but no Oesophagostomum larvae were detected in coprocultures. The internal transcribed spacer (ITS) region of ribosomal RNA gene (rDNA) and cytochrome c oxidase subunit-1 (cox-1) region of mitochondrial DNA (mtDNA) of coprocultured Oesophagostomum larvae were amplified using parasite DNA extracted from 7–25 larvae/sample, cloned into Escherichia coli, and sequenced. Sequenced rDNA contained 353/354-bp long ITS1, 151-bp long 5.8S rDNA, and 227-bp long ITS2. Parts of clones showed variations at 1–3 bases in the ITS1 region at a frequency of 24/68 (35.3 %) and at 1–2 bases in the ITS2 region at a frequency of 7/68 (10.3 %), whereas the 5.8S rDNA was essentially identical. Sequenced cox-1 gene of the parasites, 849 bp in length, showed a higher number of nucleotide variations, mainly at the third nucleotide position of the codon. The majority of clones (27/41 (65.9 %)) had an identical amino acid sequence. These results suggest that at MDNP, Gabon, only a single population of O. stephanostomum with a degree of genetic diversity is prevalent in western lowland gorillas, without zoonotic complication in local inhabitants. The possible genetic variations in the ITS region of rDNA and cox-1gene of mtDNA presented here may be valuable when only a limited amount of material is available for the molecular species diagnosis of O. stephanostomum.

Assessment of landscape‐scale distribution of sympatric great apes in African rainforests: Concurrent use of nest and camera‐trap surveys

Information on the distribution and abundance of sympatric great apes (Pan troglodytes troglodytes and Gorilla gorilla gorilla) are important for effective conservation and management. Although much research has been done to improve the precision of nest‐surveys, trade‐offs between data‐reliability and research‐efficiency have not been solved. In this study, we used different approaches to assess the landscape‐scale distribution patterns of great apes. We conducted a conventional nest survey and a camera‐trap survey concurrently, and checked the consistency of the estimates. We divided the study area (ca. 500 km2), containing various types of vegetation and topography, into thirty 16‐km2 grids (4 km × 4 km) and performed both methods along 2‐km transects centered in each grid. We determined the nest creator species according to the definitions by Tutin & Fernandez [Tutin & Fernandez, 1984, Am J Primatol 6:313–336] and estimated nest‐site densities of each species by using the conventional distance‐sampling approach. We calculated the mean capture rate of 3 camera traps left for 3 months at each grid as the abundance index. Our analyses showed that both methods provided roughly consistent results for the distribution patterns of the species; chimpanzee groups (parties) were more abundant in the montane forest, and gorilla groups were relatively homogeneously distributed across vegetation types. The line‐transect survey also showed that the number of nests per nest site did not vary among vegetation types for either species. These spatial patterns seemed to reflect the ecological and sociological features of each species. Although the consistent results may be largely dependent on site‐specific conditions (e.g., high density of each species, distinct distribution pattern between the two species), conventional nest‐surveys and a subsequent check of their consistency with independent estimates may be a reasonable approach to obtain certain information on the species distribution patterns. Further analytical improvement is necessary for camera‐traps to be considered a stand‐alone method. Am. J. Primatol. 75:1220–1230, 2013.

Monitoring the reproductive status of Japanese monkeys (Macaca fuscata) by measurement of the steroid hormones in fecal samples

The menstrual cycles as well as the pregnancy in female Japanese monkeys (Macaca fuscata) were monitored by measuring the fecal estradiol concentrations and relative amounts of fecal progesterone. Steroids from fecal samples were extracted by using a previously developed simplified two-step method and then measured by radioimmunoassay. We successfully demonstrated that the two-step method is effective and convenient for monitoring the reproductive status of Japanese monkeys.

Male Homosexual Behaviour Accompanied by Ejaculation in a Free-Ranging Troop of Japanese Macaques (Macaca fuscata)

Homosexual behaviour among males in free-ranging Japanese macaques (Macaca fuscata) has not been reported, whereas that among females has frequently been reported under both free-ranging and captive conditions [1, 2]. Mountings between males, commonly seen in Japanese macaques, have not been regarded as ‘sexual behaviour’. In most cases, such interactions consist of a single mount and are not accompanied by ejaculation [3]. In this paper, I analyse observed cases of male-male mountings with ejaculation among a free-ranging troop of Japanese macaques and examine whether this behaviour can be classified as ‘sexual behaviour’. The causal factors and effects of such behaviour are discussed.