Blue Duiker Research Articles

Patch Occupancy and Potential Metapopulation Dynamics of Three Forest Mammals in Fragmented Afromontane Forest in South Africa

Abstract: We investigated the persistence of three medium‐sized (2–9 kg), rare forest mammals in the fragmented mist‐belt Podocarpus forests of the midlands of KwaZulu‐Natal Province, South Africa. We recorded patch occupancy of blue duiker ( Philantomba monticola), tree hyrax ( Dendrohyrax arboreus), and samango monkey (Cercopithecus mitis labiatus) in 199 forest patches. Their rarity is ascribed to the fragmentation and destruction of their forest habitat. Incidence functions, derived from presence and absence data, were formulated as generalized linear models, and environmental effects were included in the fitted logistic models. The small and mostly solitary hyrax and duiker persisted in smaller patches than the large and social monkey. Although this result follows expectations based on relative home‐range sizes of each species, the incidence probability of the samango monkey was invariant with increasing isolation, whereas a gradual decrease with increasing isolation was observed for the hyrax and duiker. Group dynamics may inhibit dispersal and increase the isolation effect in social species such as samango monkeys. A mainland‐island metapopulation model adequately describes patterns of patch occupancy by the hyrax and duiker, but the monkeys' poor dispersal ability and obvious area‐dependent extirpation suggest that they exist in transient, nonequilibrium (declining) metapopulations. Through identification of large forest patches for careful protection and management, the survival of all three species—especially the monkey—could be prolonged. Because no functional metapopulation may exist for the monkey, however, this is an emergency measure. For the duiker and hyrax, larger patches should form part of a network of smaller and closer patches in a natural matrix.

Harvesting, rumination, digestion, and passage of fruit and leaf diets by a small ruminant, the blue duiker.

Because small ruminants (<15 kg) have a high ratio of metabolic rate to fermentation capacity, they are expected to select and require low-fiber, nutrient-dense concentrate diets. However, recent studies suggest that small ruminants may not be as limited in their digestive capacity as previously thought. In this study, we examined harvesting, rumination, digestion, and passage of three diets (domestic figs Ficus carica, fresh alfalfa Medicago sativa, and Pacific willow leaves Salix lasiandra) ranging from 10 to 50% neutral detergent fiber content (NDF) in captive blue duikers (Cephalophus monticola, 4 kg). Harvesting and rumination rates were obtained by observing and videotaping animals on each diet, and digestibility and intake were determined by conducting total collection digestion trials. We estimated mean retention time of liquid and particulate digesta by administering Co-EDTA and forages labelled with YbNO3 in a pulse dose and monitoring fecal output over 4 days. Duikers harvested and ruminated the fig diet faster than the alfalfa and willow diets. Likewise, they achieved higher dry matter, energy, NDF, and protein digestibility when eating figs, yet achieved a higher daily digestible energy intake on the fresh willow and alfalfa than on the figs by eating proportionately more of these forages. Duikers maintained a positive nitrogen balance on all diets, including figs, which contained only 6.3% crude protein. Mean retention time of cell wall in the duikers' digestive tract declined with increasing NDF and cellulose content of the diet. Digestibility coefficients and mean retention times of these small ruminants were virtually equivalent to those measured for ruminants two orders of magnitude larger, suggesting that they are well adapted for a mixed diet.

Censusing rainforest game species with communal net hunts

SummaryThis paper presents a method to address two wildlife management problems in central African rainforests: the need for local communities to take responsibility for wildlife management, and the lack of simple and appropriate wildlife monitoring techniques. The method uses encounters of game species during net hunts to calculate abundance indices as well as to estimate population densities for the four principal game species in the Dzanga–Sangha region: the duikers Cephalophus monticola (10.7–20.4 km−2), C. dorsalis (1.2–2.0 km−2), and C. callipygus (0.9–1.2 km−2), and the brush‐tailed porcupine Atherurus africanus (2.7–5.3 km−2). Game species behaviour, the hunting practice, and comparisons with results from other research across central Africa suggest that the method can provide valid density estimates for C. monticola and C. dorsalis, but only abundance indices for C. callipygus and A. africanus. Nevertheless, the method can be applied by hunters in the course of their normal activities, and is adapted to the local habitat types and game species. As such, it can be an important tool for local communities in developing sustainable wildlife management programmes.

A Preliminary Report on the Impact of Chimpanzee Hunting on Mammal Populations at Mahale, Tanzania

The impact of chimpanzee hunting on populations of several mammalian species was examined by analyzing the data of population census on these mammals and the previous reports of chimpanzee hunting at the Mahale Mountains National Park, Tanzania. The annual kill rates (1.3-9.0%) of red colobus monkeys by the chimpanzees were estimated to be almost the same as the population growth rate of this species. These kill rates were equal or slightly higher than those reported from the Tai National Park, Ivory Coast, but extremely lower than those reported from the Gombe National Park, Tanzania. The impact of chimpanzee hunting on other prey mammals (redtailed monkey, blue monkey, blue duiker, bushbuck and warthog) seems to be small, because the annual kill rates of these species by the chimpanzees were estimated to be smaller than their population growth rates or the hunting frequencies on them by the chimpanzees were very low.

The impacts of BaAka net hunting on rainforest wildlife

Conservation programs often implicitly assume that subsistence hunting by indigenous peoples using traditional hunting methods is ecologically sustainable. Indeed communal net hunts are less detrimental to wildlife than are the other principal hunting methods in central African forests, namely cable snares and firearms. However, research in the Dzanga-Sangha Special Reserve of the Central African Republic suggests that BaAka net hunters may overexploit primary game species including the blue duiker Cephalophus monticola and the bay duiker Cephalopus dorsalis. The method itself spares protected and endangered species, but overexploitation of game species results from increases in hunting intensity as BaAka populations grow and hunting ranges decline. Given the dynamic socio-economic conditions, subsistence hunting over the long-term is not ecologically sustainable. Wildlife management programs therefore must address not only hunting method and hunting area, but also must develop viable subsistence and economic alternatives for local residents.

Long-Term Antelope Population Monitoring in Southern Cape Forests

SYNOPSIS The results of population monitoring of two forest antelope species in the Knysna forests (South Africa), the bushbuck (Tragelaphus scriptus) and blue duiker (Philantomba monticola) are presented. Most monitoring was done by faecal pellet group counting, but some track counts, strip transect counts and direct observation recording were also carried out sporadically. Both faecal pellet group counting and strip transect count methods were found suitable for population monitoring of the two forest antelope species. The results reveal meaningful patterns of habitat preferences and population changes over time (1970–1997). Blue duiker populations declined sharply between 1970–1980 and have remained low since. Bushbuck densities increased from 1970–1990, but were low again in 1997. The current state of the monitoring programme is outlined and recommendations are made for its improvement.

Distribution and Abundance of Diurnal Mammals, Especially Monkeys, at Kasoje, Mahale Mountains, Tanzania.

Censusing was done by direct observation along three survey routes to estimate the distribution and abundance of medium- and large-sized diurnal mammals in the Kasoje area of the Mahale Mountains National Park, western Tanzania between 1995 and 1996. The census area is located within the home range of M Group chimpanzees who have been observed to consume at least 14 species of sympatric mammals. The vegetation along the three census routes was divided into two types of habitat (forest vs. woodland); as a result, six census subunits were distinguished. Preference of habitat by eight species of mammals-red-tailed monkey, blue monkey, yellow baboon, red colobus monkey, bushbuck, blue duiker, warthog, and forest squirrels-has been suggested and their group and/or individual densities have been estimated in at least one census subunit. In 1974, most villagers moved out of the Kasoje area following a government edict and the wild animal population in general appears to have increased in number since then. However, expansion or contraction in distribution of three species of mammals at Kasoje since the 1970s differs from species to species: yellow baboons and warthogs have apparently expanded their ranges while vervet monkeys seem to have contracted theirs. The abundance of red colobus monkeys appears to correspond with the high frequency of colobus hunting by the chimpanzees. However, it should be explained in the future why the second most abundant red-tailed monkeys, another resident arboreal species, have been eaten only infrequently by them. Further accumulation of observations on actual encounters between the chimpanzees and their potential prey is necessary.

Temporal and spatial patterns in blue duikers Philatomba monticola and red duikers Cephalophus natalensis

Forest duikers spend a large proportion of the day engaged in sedentary behaviour. Both species were most active shortly after dawn and just before dusk and were relatively more active in habitats of higher quality. Though home‐range boundaries were dynamic (changing slightly during the year), core areas were permanent and remained fixed.Blue duikers showed exclusive family home ranges with no overlap between neighbours, for this species home range and territory are synonymous. Red duiker home‐range overlap varied greatly (up to 100% in some cases) indicating the absence of territoriality. Core areas in the home range of both duiker species were usually associated with bedsites. In blue duiker, home ranges and core areas were fixed all year with no overlap between neighbours, while home ranges and core areas of red duikers overlapped extensively. Temporal separation in red duikers is suggested between some individuals and not others.

Seed dispersal in African forest ruminants

The role of ungulates in the dispersal of fleshy fruited plants is still poorly documented. The first reports on endozoochory mentioned the egestion of small intact seeds in the faeces of various ungulates in open tropical habitats (Eloff 1959, Gwynne 1969, Hofmann 1973, Lamprey 1963, Lamprey et al. 1974). Endozoochory has since been described for wild ruminants in tropical forests (Alexandre 1982, Sabatier 1983) and in experimental studies on cattle and horses (Janzen 1981, 1982, 1983, Janzen et al. 1985). I have observed endozoochory of small seeds with duikers. A second, less well reported form of endozoochory is specific to ruminants. Large viable seeds are spat out after some time in the rumen (Bodmer 1989, Feer 1989a, Gauthier-Hion et al. 1985, Halder 1976, Janzen 1982). This note reports the morphology of fruits and seeds of the plant species subject to spit dispersal by duikers (Cephalophinae) in an African rainforest. In north-east Gabon, 12 Peter's duikers (Cephalophus callipygus Peters) and five bay duikers (C. dorsalis Gray), two fairly common medium-sized species (body weight 20-21 kg) were captured with nets near Makokou (00 34' N, 120 52' E) and followed by radio-tracking for 1600 hours (see Feer 1989b). The resting places, where most of rumination occurred, were examined shortly after use. I analysed 63 rumen contents (method as in Feer 1989a) of each of C. callipygus and C. dorsalis, and also 176 of the blue duiker (C. monticola Thiinberg) and 23 of the yellow-backed duiker (C. sylvicultor Afzelius), noting the maturity of fruit and the presence of identifiable pulp: 150 fruit and seed species were described and measured. The seeds were considered as hard when the external envelope resisted crushing by exertion of maximum strength with my own molars. This simple test later proved to be equivalent to the crushing capacity of medium-sized duiker species since all hard seeds remained intact after

Market Dynamics of Bushmeat Species in Equatorial Guinea

1. Wild animals are an important protein source in many countries in West Africa. Studies of numbers and fluctuations of game species entering markets can provide vital information on wildlife use and exploitation in the consumer regions. 2. Two market sites in each of the most important towns, Malabo (Bioko Island) and Bata (Rio Muni) in the Republic of Equatorial Guinea, central Africa, were studied from October 1990 to October 1991. 3. 15 and 38 species of mammals, birds and reptiles were recorded in Bioko and Rio Muni, respectively. A total of 18012 carcasses was counted; 61.2% in Bioko and 38.8% in Rio Muni. 4. Abundance and availability of individual bushmeat species were described by: (a) the daily abundance of species (DA) as the average number of carcasses species -1 day -1 during all sampled days; (b) the carcass volume (CV) for each species as the average number of carcasses species -1 day -1 sold during available days, and (c) the species availability (MA) in markets as the percentage number of days per month during which a species was present for sale. 5. Two species, Cephalophus monticola and Cricetomys emini, in Bioko and C. monticola and Atherurus africanus in Rio Muni accounted for more than half of all carcasses brought into markets. 6. Seasonal differences in number of carcasses entering markets in Bioko were observed between dry and wet periods. In Rio Muni, increases were observed during the short dry and long rains periods. 7. Monthly changes in number of carcasses of species (>50 year -1 ) were compared between markets using Spearman rank correlation tests. Two main clusters appeared in relation to abundance of species in markets. 8. Bushmeat demand in the large towns in Equatorial Guinea may possibly exceed supply at present. Studies of bushmeat dynamics in markets can be used to monitor use of wildlife resources in the country.

Ixodid ticks and other ectoparasites of wild ungulates in Swaziland: regional, host and seasonal patterns

Ixodid ticks and other ectoparasites were collected from impala ( Aepyceros melampus ). blue wildebeest ( Connochaetes taurinus ), kudu ( Tragelaphus strepsiceros ), common duiker ( Sylvicapra grimmia ) and warthog ( Phacochoerus aethiopicus ) in the Mlawula-Mbuluzi-Simunye Nature Reserve and Protected Area complex and Hlane Wildlife Sanctuary in the Swaziland lowveld, and from blue wildebeest and warthog in Malolotja Nature Reserve in the highveld from October 1985 to August 1986. The most commonly collected ticks were Amblyosomma hebraeum, Boophilus decoloratus, Rhipicephalus appendiculatus, R evertsi evertsi, R maculatus, R muehlensi and R simus . The diversity and intensity of infestation were greater in the lowveld, where the ectoparasite community was similar to that reported from these host species in the eastern Transvaal lowveld and Kwazulu/Natal. A hebraeum was collected throughout the year, but the largest samples were in October and November when the animals were in poor condition. The seasonal occurrence of R. appendiculatus adults on impala was later than that reported for other host species, possibly owing to seasonal changes in habitat use. Seasonal changes in habitat use and temperature effects on pre-oviposition and development of the eggs may have caused the seasonal patterns in the occurrence of B. decoloratus .

Rumen ciliate protozoa of the blue duiker (Cephalophus monticola), with observations on morphological variation lines within the species Entodinium dubardi.

Protozoal concentrations were determined in rumen and cecal contents of 20 blue duikers (Cephalophus monticola). Ten animals of each sex were fed either a high concentrate or high roughage diet. Rumen protozoa were present in 19 of the 20 animals and concentrations ranged from 4.5 to 33.7 x 10(6) per g of rumen contents. At the higher concentrations, protozoal cells equaled between 30-40% of the total rumen contents volume. No protozoa were found in cecal contents. Weight of rumen contents was higher in females than in males (P < 0.01), and rumen protozoa concentrations were higher in males (P < 0.05) and in those animals fed the high concentrate diet (P < 0.05). All the protozoa were identified as belonging to a single species, Entodinium dubardi. However, an average of about 30% of the E. dubardi cells varied from the typical morphology of this species. These cells appeared to be on variation lines leading toward 7-10 other non-caudate species of Entodinium. The present data were used to evaluate and discuss the concept of variation lines within E. dubardi.

Hunting among Moka Bubis in Bioko: dynamics of faunal exploitation at the village level

Hunting by Bubi villages around Moka, Bioko, and their impact on the local prey fauna was studied during July–August, 1992. Questionnaires were sent to 45 known hunters in the region in order to find out their techniques and hunting procedures. Hunting trips were also followed (a total of 204 km covered) and counts of animals brought to the villages from 103 recorded trips were also made. There were two main hunting methods employed: trapping and shooting. Most commonly used was snare trapping. At least five different types were used during the study. Guns were less commonly employed. Both techniques are efficient and productive but prey caught by each method differed. Most animals caught by snares were large rodents (Atherurus africanus, Cricetomys emini) and small antelopes (Cephalophus monticola) whereas those shot were usually antelopes (C. monticola and C. ogilbyi), monkeys (Cercopithecus spp.) and, when accompanied by dogs, drills (Mandrillus leucophaeus). The effects of hunting in the region is acute especially since they incur upon the proclaimed protected areas in the south of the island. Hunting trips are gradually being lengthened and areas which were originally unaffected by this activity are now part of the villages' hunting zones.

The relative use of abandoned farm clearings and old forest habitats by primates and a forest antelope at Tiwai, Sierra leone, West Africa

West Africa's high canopy forests have largely been replaced by a mosaic of active and abandoned agricultural fields. Use of the regenerating habitats by local fauna has not been well documented. I investigated the relative value of young successional forests, aged 5–12 years, and high forest, to primates and ungulates at Tiwai in West Africa. Four primates, Cercopithecus campbelli, Cercopithecus petaurista, Cercocebus atys, and Pan troglodytes, selected regrowth habitats more often than expected, and three primates, Cercopithecus diana, Colobus polykomos, and Procolobus badius, selected high forest habitat. The Maxwell's duiker Cephalophus monticola used both habitats equally. The Cercopithecus spp. exhibited seasonal fluctuations in abundance in the two habitats, presumably in response to different fruit availabilities. The old forest supported a greater diversity and biomass of primates per unit area compared to regrowth habitats. The high forest was more valuable to the primate community, but young forests were also used by resident fauna, suggesting potential for management as wildlife habitat.

Effects of varied dietary calcium and phosphorus on renal function of male Blue Duiker antelope

Sixteen adult male Blue Duikers ( Cephalophus monticola bicolor) were fed a basal diet with four levels of Ca and P for 4 months. Pretrial, 24-h urine clearance was studied in each Duiker while they consumed the herd diet (1.38% Ca/0.66% P) (The Pennsylvania State University (PSU) formulation). Pretrial, 24-h urine clearance values revealed no differences ( P > 0.05) among treatment groups consuming the PSU diet. However, younger males did have higher serum P and lower serum and urine Ca concentrations ( P < 0.05). Posttrial renal function studies indicated age differences for [P] Plasma, [K] Urine, urine/plasma [K], and absolute excretion of K, which were higher in younger males, and free water clearance and tubular P excretion, which were highest in older males. Renal function was affected by the level of Ca and P in the diet. Glomerular filtration rate (GFR) and effective renal blood flow (ERBF) were lower ( P < 0.05), and fractional excretion (FE) of electrolytes and creatinine (Cr) were higher ( P < 0.05) in the T 3 group (0.8% Ca/0.4% P), indicating possible onset of renal dysfunction in these Duikers. Clearance of creatinine ( C Cr) was negatively correlated with [Cr] Plasma, suggesting tubular secretion of Cr increased during decreased renal function. Endogenous C Cr was not an accurate approximation of GFR, as determined by clearance of inulin ( C In, in Blue Duiker under varying nutritional conditions. FE of all electrolytes, as calculated by C In, regressed against the FE calculated from C Cr, indicated a poor correlation except for P. This suggests that FE P as measured by C Cr may be a useful index of early renal dysfunction in Blue Duiker. It appears that Blue Duiker have the ability to maximize P retention that may be available in limited quantity in the wild. The Ca/P ratio of 0.5:0.4% in the ration appears to be best suited for adult males.

Blue duiker &lt;i&gt;Philantomba monticola&lt;/i&gt; densities in the Tsitsikamma National Park and probable factors limiting these populations

Numbers of blue duikers recorded on 157 and 28 variable width transect counts, done over a two year period in the Tsitsikamma Coastal National Park (TCNP) and Tsitsikamma Forest National Park (TFNP) respectively, did not differ significantly {P &gt; 0,10) with seasons (summer v. winter). Population density estimates from transects were similar to those from game drives (0,18 v. 0,19 duikers/ha (TCNP) and 0,13 v. 0,17 duikers/ha (TFNP); P &gt;0,10), higher than from faecal pellet counts (P &lt; 0,10) and at least three times lower than estimates from the Kenneth Stainbank Nature Reserve and Umdoni Park in Natal. Factors contributing to the low population densities in the Tsitsikamma national parks were investigated. Twentyseven and seven percent of leopard (25) and caracal (12) scats respectively analyzed contained blue duiker remains, but predator numbers appear to be low. Forest characteristics were investigated, and results from this and other studies suggest that undergrowth cover does not markedly influence blue duiker densities in the southern Cape forests. Field and stomach analysis indicate that blue duikers feed primarily on freshly fallen leaves and fruit, and are selective foragers. In the Tsitsikamma national parks (TNPs) the frequency of occurrence of trees known to be palatable to duikers are low, while less than 45 percent of the dominant tree species fruit fully annually. This apparent scarcity of food, the low numbers of antelope species and individuals in these forests and results from duiker research in Zaire, suggest that habitat rather than predation is limiting duiker numbers in the Tsitsikamma national parks.

Effect of dietary calcium and phosphorus on mineral metabolism and acid-base balance in Blue Duiker antelopes

Sixteen adult, male Blue Duiker antelopes were fed a basal diet with four levels of calcium (Ca) and phosphorus (P): 0.5:0.4%, 0.8:0.8%, 0.8:0.4% and 1.25:0.4% for four months. Time × treatment interactions existed for serum Ca, P, Cl, and urine K, Na, and P. Feed consumption was different by age; older males consumed more feed regardless of treatment. Blood bicarbonate was lowest in the high-Ca-low-P group and highest in the low-Ca-low-P group. Volumetric urine clearance data indicated a significant elevation in Ca clearance for older males, differences between treatments, and trends for P intake over time. P clearance was highest in the high-P treatment group and showed a relationship to Ca intake, with the low-Ca-low-P group having higher serum P values and slightly higher phosphorus clearance than the high-Ca-low-P diet. No consistent difference by age or treatment was found for clearance of K. Clearance of Na, Cl, and creatinine showed differences by treatment, and Na and Cl clearance were positively correlated with intake. It appears that adult, male Blue Duiker respond to different dietary levels of Ca, P and other minerals with altered serum and/or urinary concentrations of these elements. Unlike domestic ruminants, Blue Duiker serum P levels are affected by Ca intake and their serum Ca concentration is not decreased by increasing P intake. Volumetric urine clearance data appear to be valuable in this species to help understand Ca and P homeostasis and dietary balance of minerals. From these experiments the Ca: P ratio of 0.5%:0.4% appears to be best suited for these animals. However more experiments are required to elucidate exact requirements for dietary Ca and P.

Bacterial and Fungal Numbers in Ruminal and Cecal Contents of the Blue Duiker ( Cephalophus monticola )

[This corrects the article on p. 469 in vol. 57.].

A comparative study of metabolic rates and thermoregulation of two African antelopes, the steenbok Raphicerus campestris and the blue duiker Cephalophus monticola

1. 1.|The steenbok, a small diurnal antelope is widely distributed in the southern African subregion even in extreme deserts. The blue duiker is limited in its distribution to forests on the eastern coast of the subregion. 2. 2.|A comparative study of heat production and dissipation was carried out in order to assess the ability of these two species to cope with dry habitats. 3. 3.|Low metabolic rates, a high lower-critical point and high overall minimal thermal conductance as found in the steenbok when compared to the blue duiker seem to be important adaptations which help the steenbok to conserve water even when exposed to high ambient temperatures and, therefore, to inhabit extreme arid habitats.

Bacterial and Fungal Numbers in Ruminal and Cecal Contents of the Blue Duiker ( Cephalophus monticola )

Total and cellulolytic bacterial and fungal numbers were determined in ruminal and cecal contents of 20 blue duikers (Cephalophus monticola). The animals were equally divided by sex and fed two diets, either high roughage or high concentrate. The mean concentration for total bacterial numbers in the rumen was 26.0 x 10/g of contents, with values ranging from 2 x 10/g to 93 x 10/g. Cellulolytic numbers averaged 6.0 x 10/g with a range of 1.5 x 10/g to 24.0 x 10/g. No differences related to sex or diet were found. In contrast, total bacterial numbers in the cecum differed between diets (P < 0.02), i.e., 1,046 x 10 bacteria per g for animals fed the high-forage diet compared with 166 x 10/g for those fed the high-concentrate diet. Cellulolytic bacterial counts in the cecal contents averaged 3.1 and 7.0% of the total counts for the high-forage and high-concentrate diets, respectively. Low concentrations of fungi were found in both ruminal and cecal contents of some, but not all, animals. Unexpectedly, concentrations of bacteria and fungi in the rumen and cecum were highly correlated with their total numbers (concentration multiplied by total weight of contents).