Janette Wallis

Primate Conservation: The Prevention of Disease Transmission

We address the strategies to prevent disease transmission from human to non-human primates in natural settings. Some field research methods, such as gaining close proximity for observation, provisioning for habituation, or reintroducing for repopulation, may place primate subjects at risk for acquiring human-carried diseases. Additional risks arise through inadequate waste disposal or nonhygienic conditions of humans residing at the study site. We describe several disease outbreaks at primate field sites, emphasizing the need for proper protocols to diagnose, to treat, and to prevent recurrence. Finding solutions to the disease transmission problem requires effecting change in the behavior and policies of many individuals, including field researchers, veterinarians, human health care providers, park personnel, government officials, local villagers, and tourists. The prevention of exposure to infectious disease is an important, fundamental aspect of primate conservation; the assurance of good health and longevity in wild primate populations is paramount to the more traditional conservation issues of poaching control and forest protection.

HUNTING DECISIONS IN WILD CHIMPANZEES

While field studies of wild chimpanzees have investigated the proximate determinants of hunting success, little attention has been paid to the decision to hunt. We present evidence from Gombe National Park, Tanzania, showing that the social factors that most strongly influence the decision to hunt red colobus monkeys are the presence of female chimpanzees with anogenital sexual swellings in the foraging party, the number of adult and adolescent males in the party, and the total size of the foraging party. Of these, the presence of one or more swollen females was the best predictor of a decision to undertake hunts of red colobus groups at all but the smalles chimpanzee foraging party size. Two likely explanations for this pattern are discussed. First, swollen females may be a primary influence on male grouping patterns, which in turn promotes hunting. Second, this finding, together with previous research showing that male chimpanzees preferentially give meat to estrous females, suggests that male chimpanzee hunting performance may be under sexual selection. While nutritional and ecological factors may influence chimpanzee hunting patterns at times, chimpanzees appear to hunt red colobus at least partially to obtain meat for use as a social and reproductive tool.

Paternity exclusion in a community of wild chimpanzees using hypervariable simple sequence repeats

We report the use of hypervariable simple sequence repeat (SSR) nuclear loci to study paternity in a community of wild chimpanzees (Pan troglodytes schweinfurthii) in Gombe National Park, Tanzania. All 43 living members of a habituated community were sampled and 35 were genotyped at 8 SSR loci using DNA amplified from hair. Paternity exclusions were performed for 25 chimpanzees including 10 for whom the mother was also genotyped. In each case 12–20 males were potential fathers based on their age and/ or direct observation of sexual behaviour. 179 tests involving potential father/offspring combinations were performed. In four cases the data permit the probable identification of the previously undetermined father; these are the first such determinations for free‐ranging chimpanzees, and the first based on non‐invasive sampling. In another four cases we were able to exclude all but two to five potential fathers, and in the remaining cases we were able to exclude all living males. For molecular ecologists SSR genotype databases offer important advantages over currently popular minisatellite DNA fingerprinting: they can be analysed unequivocally using traditional population genetics techniques and they can be expanded through time and space by other researchers.

Synchrony of estrous swelling in captive group-living chimpanzees (Pan troglodytes)

Recent findings suggest that menstrual synchrony may occur in humans and is more dependent on factors of close personal association than simple prox imity. Part I of this study analyzed the estrous cycles of 10 captive group living chimpanzees (Pan troglodytes) housed in two separate groups in the same building. Each group contained at least one male. The mean discrepan cies for (1) the approximate day of ovulation (last day of maximum swelling) and (2) the day of onset of estrous swelling were determined for all possible pairs within groups and compared to the mean discrepancies of pairs between groups. With respect to the probable day of ovulation, the mean discrepancy of animals caged together was 8.0 days and that of animals caged separately was 10. 7 days. Comparing the onset of estrous swelling, the mean between groups was 10.4 days, whereas females caged together averaged only 5.7 days. A repeated-measures analysis of variance indicated a significant group effect in the onset of estrous swelling (F = 5.68,p < 0.05), whereas there was no significant difference between the animals caged together and those caged separately with respect to the last day of maximum swelling (F = 1.37, NS). Part II of the study compared the onset of the first postpar tum estrus (PPE) to the onset of estrus in cagemates. During a 6-year period, 13 females exhibited 33 PPEs while in social contact with cycling females. Of 86 paired comparisons, the PPE onset of 43 (50%) occurred with in 6 days of the swelling onset of a cagemate. The results suggest that, as in other species (including humans), the social contact and time spent together influence the synchrony of chimpanzee estrous cycles, especially in terms of swelling onset. The synchrony of estrous swelling and possible mediation by olfactory and/or hormonal cues are discussed as they relate to chimpanzee social structure and female reproductive strategy.

Non-invasive sampling and DNA amplification for paternity exclusion, community structure, and phylogeography in wild chimpanzees

Genetic studies of free-ranging primates have been seriously impeded by difficulties of sampling tissues, including the undesirability of bleeding habituated animals, of transporting frozen samples to the laboratory, and of the inherent inadequacies of accessible variation including allozymes, mtDNA RFLP patterns and DNA fingerprints. We have developed methods of non-invasive DNA sampling and DNA-level genotyping which, when combined with a hierarchical analysis of mtDNA sequences and hypervariable nDNA simple sequence repeat (microsatellite) loci size length polymorphisms, facilitate the resolution of most questions at the individual, social group (community), population, and species (phylogenetic) levels. This approach, based on DNA amplified from shed hair, represents an important new tool for the acquisition of genetic information and will facilitate the study and management of both captive and free-ranging chimpanzees (Pan troglodytes). Our hierarchical analysis of population genetics of chimpanzees has revealed high historical levels of gene flow and large effective population sizes, as well as substantial divergence between the West African subspecies and chimpanzees from central and East Africa. At the community level, closer relatedness among philopatric males than among females supports the view that kin selection has been an evolutionary force shaping male-male cooperation in this species. Results from our study of the now relatively isolated Gombe community suggest that habitat fragmentation affects population genetic structure and possibly population viability.

Physical attractiveness and the personality resemblance of identical twins

The physical attractiveness of 25 pairs of monozygotic (MZ) twins was rated independently for twins A and B. The MZ twins were rated alike in their physical attractiveness (r=0.54; corrected for attenuation,r=0.94). Physical attractiveness was uncorrelated with verbal intelligence but was associated, controlling statistically for the sex difference in attractiveness favoring females, with three of the eight traits in the Comrey inventory: Conformity, Extraversion, and Emotional Stability. In both sexes, greater emotional stability was associated with attractiveness; in males greater extraversion; and in females, greater conformity. When these twin correlations were adjusted for this association with attractiveness, the mean change in the value ofr was only 0.03, indicating that physical attractiveness does not appear to bias conclusions from twin studies.

Seasonal Influence on Reproduction in Chimpanzees of Gombe National Park

Although wild chimpanzees are not seasonal breeders, there are seasonal effects on several aspects of chimpanzee reproduction. I examined the seasonal incidence of anogenital swelling in cyclic, pregnant, and acyclic female chimpanzees in Gombe National Park, May 1975–April 1992, and surveyed important reproductive events to determine whether there is a seasonal effect. I analyzed data by season (wet vs. dry) and seasonal quarter;early dry season = May–July;late dry = August–October;early wet = November–January;late wet = February–April. When data for the 17 years are combined, the percentage of females in each reproductive state remains consistent throughout the year. In a given month, 30–35% of subjects were in the cyclic category, 11–15% were pregnant, and 54–61% were acyclic. Cyclic females showed full swelling more often during the late dry season. Pregnant females exhibited anogenital swelling more often during the late dry and early wet seasons. Acyclic females also exhibited a seasonal effect with more anogenital swelling during the late dry season. There is no seasonal difference in frequency of live births (dry, 20;wet, 23). However, the timing of conception showed a seasonal effect (dry, 32;wet, 16). Consistent with earlier reports, the onset of postpartum cycles is highly seasonal;30 occurred during dry season, 9 during wet season. The occurrence of first full swellings for young females is also concentrated in the late dry season. It appears that the dry season is a time of great change for Gombe chimpanzee reproductive physiology. Previous studies indicated that seasonal changes in food availability play a role in increasing group size during the dry season and social contact between females can enhance cyclicity. Accordingly, I suggest that seasonal changes in diet may play a role, either directly (food content) or indirectly (social contact), to alter reproductive physiology.

Fragments, Sugar, and Chimpanzees in Masindi District, Western Uganda

Masindi District in western Uganda contains the Budongo Forest, with a population of approximately 600 chimpanzees (Pan troglodytes schweinfurthii). In 1999, a group of chimpanzees was discovered living in semi-isolation in the Kasokwa riverine forest fragment outside the main forest block (Figure 1). Although there is growing local support among village residents for saving the chimpanzees, immigrant sugar farmers pose a problem as they have been removing forest cover at an alarming rate.

Chimpanzees in mantraps: lethal crop protection and conservation in Uganda

A main concern of farmers worldwide is how to reduce crop losses to wildlife. Some potentially lethal crop protection methods are non-selective. It is important to understand the impact of such methods on species of conservation concern. Uganda has important populations of Endangered eastern chimpanzees Pan troglodytes schweinfurthii . Farmers sometimes use large metal mantraps to guard their fields against crop-raiding wildlife, particularly baboons Papio anubis and wild pigs Potamochoerus sp.. Chimpanzees that range onto farmland also step in these illegal devices and without rapid veterinary invention face severe injury or eventual death. Unlike inadvertent snaring of great apes in African forests, the problem of mantraps in forest–farm ecotones has received little attention. We report 10 cases of entrapped chimpanzees in the cultivated landscape surrounding Ugandas Budongo Forest during 2007–2011, undoubtedly only a portion of the actual number of cases. Mantraps currently present a substantial threat to ape populations in this important conservation landscape. Our data underscore the need for conservation programmes to consider the techniques used by rural farmers to protect their livelihoods from wild animals.

Ovarian hormone concentrations and genital swelling patterns in female chimpanzees with Norplant implants

The purpose of this study was to assess the effects of Norplant implants on ovarian hormone secretion and genital swelling patterns in female chimpanzees. Urine samples were collected during one natural cycle before (n = 5 females) and one cycle ∼6 months following (n = 7 females) insertion of Norplant implants. Genital swelling data were recorded daily for all seven females. During Norplant treatment, two females exhibited minimal ovarian activity consistent with anovulation. Hormone data from five subjects indicated both follicular and luteal activity, suggesting that ovulation may have occurred during Norplant treatment. Among cycles presumed to be ovulatory, the concentration of estrone glucuronide did not differ from concentrations during the control phase. However, mean (F = 12.253, P = 0.001) and peak (F = 4.127, P = 0.003) concentrations of pregnanediol glucuronide were significantly lower during Norplant treatment. Cycle duration did not differ during Norplant treatment (F = 1.415, P = 0.200); however, duration of the total swelling phase (F = 3.311, P = 0.0011) and full swelling phase was shorter (F = 5.906, P = 0.011), whereas number of days with partial swelling increased (F = 2.635, P = 0.011). The results of this study indicate that Norplant provided effective contraception while not inhibiting ovarian hormone secretion or the expression of cyclic genital swelling in the majority of the chimpanzee subjects. Zoo Biol 16:209–223, 1997.