John A. Hart

Stable isotope ecology in the Ituri Forest

The Ituri Forest, Democratic Republic of Congo (formerly Zaire) is an example of a closed canopy forest showing extreme depletion in 13C. δ13C values for plants from the canopy top, from gaps in the canopy, and from the subcanopy average −29.0±1.7‰, −30.4±0.9‰, and −34.0±1.5‰, respectively. The δ13C of forest mammals show these differences, with the subcanopy browsers (okapi, dwarf antelope) having δ13C values for tooth enamel much more negative than subcanopy frugivores who derive their food from the canopy top, and from folivores and omnivores living in gap or clearing areas. Nitrogen isotopes in plants from this ecosystem have an average δ15N value of 5.4±1.8‰ and do not show significant differences at the 95% confidence interval between plants from the canopy top, from gaps in the canopy, and from the subcanopy. The δ18OSMOW values of surface waters in the study area are between −2.0 and −2.7. The δ18OPDB for tooth enamel ranged from −3 to +7‰.

The ecological basis of hunter-gatherer subsistence in African Rain Forests: The Mbuti of Eastern Zaire

The Mbuti pygmies, hunter-gatherers of the Ituri Forest of Zaire, trade forest products and labor for agricultural foods. It has been assumed that the Mbuti lived independently in the equatorial forest prior to its penetration by shifting cultivators. We assessed forest food resources (plant and animal) to determine their adequacy to support a hunting and gathering economy. For five months of the year, essentially none of the calorically important forest fruits and seeds are available. Honey is not abundant during this season of scarcity. Wild game meat is available year round, but the main animals caught have low fat content. This makes them a poor substitute for starch-dense agricultural foods, now staples in Mbuti diet. In general, in the closed evergreen forest zone, edible wild plant species are more abundant in agriculturally derived secondary forest than in primary forest. Similarly, they are more common at the savanna ecotone and in gallery forests. We suggest that it is unlikely that hunter-gatherers would have lived independently in the forest interior with its precarious resource base, when many of the food species they exploit are more abundant toward the savanna border.

Forest Elephant Crisis in the Congo Basin

Debate over repealing the ivory trade ban dominates conferences of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). Resolving this controversy requires accurate estimates of elephant population trends and rates of illegal killing. Most African savannah elephant populations are well known; however, the status of forest elephants, perhaps a distinct species, in the vast Congo Basin is unclear. We assessed population status and incidence of poaching from line-transect and reconnaissance surveys conducted on foot in sites throughout the Congo Basin. Results indicate that the abundance and range of forest elephants are threatened from poaching that is most intense close to roads. The probability of elephant presence increased with distance to roads, whereas that of human signs declined. At all distances from roads, the probability of elephant occurrence was always higher inside, compared to outside, protected areas, whereas that of humans was always lower. Inside protected areas, forest elephant density was correlated with the size of remote forest core, but not with size of protected area. Forest elephants must be prioritised in elephant management planning at the continental scale.

Range Occupation and Population Estimates of Bonobos in the Salonga National Park: Application to Large-scale Surveys of Bonobos in the Democratic Republic of Congo

Conservation of the bonobo, Congo’s endemic ape, is one of the most important conservation priorities in the Democratic Republic of Congo (DRC). Bonobos are classified as endangered by both the IUCN (1996) and CITES (2001). In determining where bonobos occur, their population numbers and the threats to them are critical for development of a range-wide conservation strategy for the species. The need for information on the bonobo’s status is all the more urgent given the imminent opening of their range to logging and other extractive activities following the end of DRC’s conflict. The potential bonobo range, variably estimated from 341,000 – 472,000 km, is restricted to DRC’s central cuvette; however, occupation of this area by bonobos is not contiguous (Butynski 2001, Meyers Thompson 1997). Large areas of forest contain few or no bonobos, while the species occurs in relatively high numbers in other areas. Most studies of bonobos have been conducted in very small study areas, widely dispersed within the range. Even at this scale, researchers report wide variability in occurrence and population size. Speculative estimates of the bonobo’s global population range from 13,500 – 100,000, though figures from 20,000 – 50,000 are the most widely cited (Butynski 2001). Some authors suggested that 50% of the bonobo’s range might have been lost over the past several decades (Dupain and Van Elsacker 2001, ThompsonHandler et al. 1995), though early records of bonobos suggest that there were major discontinuities in their distribution over 80 years ago (Kortland 1995). Until recently, much of the bonobo’s range was isolated from major settlements and had historically low human population density. This has likely ensured the protection of many bonobo populations. Passive protection, however, may no

Distribution and conservation status of Congo Peafowl Afropavo congensis in eastern Zaire

Between 1993 and 1995 the occurrence and status of Congo Peafowl Afropavo congensis were assessed at 89 sites in eastern Zaire based on interviews with local hunters (114 locations) and forest surveys (24 locations). The survey region covered approximately 125,000 km 2 and was bounded by the Lomami River (24° 30′) to the west, the Albertine Rift Highlands (29°) to the east, the Aruwimi River (20° 30′) to the north and the Kahuzi Biega Park (3° S) to the south. Congo Peafowl have been extirpated or were only doubtfully present at 16 of 65 sites where survey coverage was adequate and where the species was reported to have occurred in the past. Occurrence of the species was confirmed or probable at the remaining 49 sites. Congo Peafowl were reported as locally common (> five reported encounters since 1990) at only 12 sites. We observed or heard peafowl at five sites. A single nest was found which contained two eggs. Observations on group size and habitat associations were also made. Congo Peafowl were considered to be seriously threatened at 19 of the 65 sites. Captures in snares set for small mammals and antelope are a major threat to Congo Peafowl throughout most of the survey region. Mining, shifting cultivation and logging leading to habitat loss were significant threats in several locations. Congo Peafowl appear to have disappeared from several sites where human activity was frequent, but habitat loss was not extensive. The mass movements of Rwandan refugees into eastern Zaire, which began in 1994, pose, a threat to Congo Peafowl in a number of areas. Conservation of the Congo Peafowl in eastern Zaire is best assured in the Maiko National Park where the species appears to be locally common. Further surveys within the Congo Peafowls range in central Zaire, and study of the behaviour and ecological needs of the species are recommended.