Retrieval of four adaptive lineages in duiker antelope: evidence from mitochondrial DNA sequences and fluorescence in situ hybridization

Independent molecular markers (mitochondrial DNA sequences from two genes and fluorescence in situ hybridization with satellite DNA sequences as hybridization probes) were employed to investigate phylogenetic relationships among duiker antelope. When analyzed singly or taken together, the molecular and cytogenetic data allowed for the delimitation of four adaptive groups: the conservative dwarfs which are basal, a savanna specialist which groups apart from the forest duikers, the giant duikers, and the red duikers. Within the latter, a further subdivision comprising an east African and a west African red duiker clade is evident. The placement of the endangered zebra duiker and Aders' duiker remains problematic. Several of the nomenclatural divisions in current use are questioned by our results. These include the recognition of Philantomba as genus name for the blue and Maxwell's duiker and that Harvey's duiker be relegated to a subspecies of the Natal red duiker. We place our results in a biogeographic context and argue that duiker speciation has been driven predominantly by habitat fragmentation which probably led to the disruption of gene flow between geographic populations.     

The influence of forest variation and possible effects of poaching on duiker abundance at Ngogo, Kibale National Park, Uganda

Duikers were censused at the Ngogo study area, Kibale National Park, Uganda, between July 2002 and August 2004. Censuses were conducted along three transects, of which, two (colonizing forests 1 and 2) were located in colonizing forests naturally replacing anthropogenic grasslands and one in old growth forest. Colonizing forest 1 was more prone to poaching than both colonizing forest 2 and the old growth forest that were closest to the research camp. Duikers that were actually sighted were identified to species, red or blue. However, on some occasions, duikers were detected by alarm calls and/or movements as they fled; these were simply recorded as duikers. Duiker abundance, regardless of species or mode of detection, was higher in colonizing forest 2 than colonizing forest 1 and the old growth forest. However, when the analysis was restricted only to duikers that were sighted, and hence identified to species, red duiker abundance was highest in colonizing forest 2 followed by the old growth forest and was lowest in colonizing forest 1; all these differences were significant. Blue duiker abundance was lowest in the old growth forest despite its proximity to the research camp; however, this was only significantly lower than in colonizing forest 2. Apart from colonizing forest 1, red duikers were significantly more abundant than blue duikers in the other two forest sections. This study suggests that forests colonizing anthropogenic grasslands may support more duikers than old growth forests; poaching in colonizing forest 1 has a severe impact on the duiker population and, red duikers are affected more severely by poaching than blue duikers.     

Night and day: evaluating transect methodologies to monitor duikers in the Dzanga‐Sangha Protected Areas,Central African Republic

Across the Congo Basin, human hunting pressure poses the biggest threat to small‐ and medium‐bodied forest ungulates (genus Philantomba and Cephalophus, commonly known as duikers). The exploitation of these species has cascading effects on larger ecosystem processes, as well as on human subsistence practices. This study compares encounter rates and estimated population densities of duiker species, specifically Philantomba monticola (blue duiker) in the Dzanga‐Sangha Protected Areas (APDS), Central African Republic (CAR). Data were collected using direct observations of individual animals during diurnal (135 km) and nocturnal (150 km) transects in the APDS, with abundance estimates produced using DISTANCE software. Transect data demonstrate that within hunted forests similar to APDS, nocturnal rather than diurnal transects yield more individual observations of ungulates. Despite hunting pressure in the region, estimates presented for APDS suggest some of the highest density estimates reported for blue duikers in western and central Africa (58.6 blue duikers per km²). This study directly contributes current regional data on the status of duiker populations at APDS and in the larger Sangha Trinational Landscape (TNS, UNESCO). More broadly, we highlight the potential importance of nocturnal transect data to the development of adaptive management regimes in hunted forests.     

Distinguishing dung from blue, red and yellow-backed duikers through noninvasive genetic techniques

Dung counts have been widely used to estimate duiker abundance and densities in tropical African forests. However, one of the major limitations of this method is that species' identification of dung based on morphological characteristics is extremely difficult in most cases. Some authors made the assumption that dung pellets could at least be distinguishable between the blue duiker, the red duikers and the yellow-backed duiker. However, this study is the first attempt to test the reliability of field identification. In this study, we suggest a method based on a noninvasive genetic protocol to identify duiker species. The comparison of field and genetic identifications shows that only dung from Cephalophus silvicultor was identified in the field without error. The rate of error for red duikers and the blue duiker is high and any attempt to distinguish among those species will result in wrong estimations for each species. We recommend the use of DNA tests to ensure reliable species' identification when duiker censuses based on dung counts are used. This methodological input will probably strengthen the dung count technique and increase its reliability for duiker species abundance estimations and spatial distribution studies.     

Co-existence and niche segregation of three small bovid species in southern Mozambique

Niche segregation among three small antelopes – red duiker, common duiker and suni – was investigated in a coastal savanna woodland/forest mosaic. It was expected that these similar‐sized concentrate selectors would show differentiation in diet choice to decrease competition. Diet composition did not vary significantly among the different vegetation types. For all three antelope species, the number of dietary items was large, with a minimum of 70 different food items per species. Dietary specialization was low, with only 10% of the food items being exclusively used by each of the species. The ranks of food items were positively correlated among species in the wet season, but not in the dry season. Diet breadth significantly decreased in the dry season. The use of exclusive species was significantly larger in the dry season with lowest values recorded for the common duiker. Diet overlap in the wet season was considerable, but significantly decreased in the dry season, the time of food scarcity. The dry season data showed evidence for niche segregation, although this was not based on displacement. As niche segregation in the dry season was coupled to a random apportionment of diet items among antelope species, it cannot be interpreted as the result of competitive displacement.     

First report of prey capture from human laid snare-traps by wild chimpanzees

Chimpanzees regularly hunt for meat in the wild, including both solo and group hunting; however, theft of prey from non-chimpanzee hunters, or scavenging of carcasses is extremely rare. Here we report the first observations of a novel prey capture technique by the chimpanzees in two adjacent communities in the Budongo Conservation Field Station, Uganda. In both cases blue duikers were found caught in human laid snare traps, and then retrieved by the chimpanzees. In one case the duiker was still alive when retrieved and subsequently fully consumed by the chimpanzees. In the other, the chimpanzees encountered the duiker while alive, but retrieved it soon after its death; here only a small portion was consumed. These observations are discussed in comparison to observations of chimpanzee hunting, scavenging, and their exploitation of an environment increasingly modified by human activity.     

The significance of chicory to the diet of common duiker at Grants valley, Eastern Cape Province, South Africa

South Africa is considered one of the top four chicory (Chichorium intybus) producing countries of the world and commercial growing of the plant in the country is restricted to a small area in three districts of the Eastern Cape Province. Faecal analysis technique was used to study the diet of common duiker (Sylvicapra grimmia Linnaeus, 1758) in a chicory growing region at Grants valley. One of the principal items in the diet of these antelopes was chicory and the crop provided more than one third (35.6%) of the winter diet and a substantial proportion (14.4%) of the spring diet of common duiker. These findings confirmed earlier reports of common duiker feeding on cultivated crops and may have profound implications for the South African chicory industry. The study also confirmed earlier findings that common duiker are selective feeders and predominantly browsers, consuming only a very small proportion of monocotyledonous plants.     

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.     

Local depletion of two larger Duikers in the Oban Hills Region,Nigeria

Across West and Central Africa, duikers are important for trade and consumption; their populations are expected to become depleted. Reliable data on their status are scanty in Nigeria. We assessed duiker populations in the Oban Sector of Cross River National Park through diurnal and nocturnal surveys along 32 transects of 2 km each. After 508‐km survey effort, only Ogilby's duiker (Cephalophus ogilbyi) and blue duiker (Philantomba monticola) were recorded. Using habitat as a covariate in modelling detection probability in DISTANCE 6.0, we estimated densities for the blue duiker ranging from 15.5 (95% CI: 7.8–30.9) in the core, 5.8 (CI: 2.6–12.9) in the buffer and 0.9 (CI: 0.09–10.1) km² in farm fallow to no duikers in the plantation. For Ogilby's duiker, densities ranged from 1.6 (95% CI: 0.7–3.7) km² in the core, 2.0 (CI: 0.8–5.1) in buffer to no duikers in farm fallow and plantation. The apparent absence of yellow‐backed and Bay duikers may indicate local depletion. We call on all stakeholders to rise up to the challenge of rescuing this biological hotspot in Nigeria from further degradation and species loss through improved funding for well‐equipped field staff and institutionalized community wildlife management.     

Methods of estimating ungulate populations in tropical forests

Pellet group counts, drive counts and track counts were used to estimate population abundances of one small and four large species of duiker (Cephalophus sp.) in a moist evergreen forest in northeastern Zaire. Procedures to develop estimates based on line transect counts of pellet groups are described. The Fourier Series estimator proved to be useful for estimating densities of pellet groups. Comparisons were made between population abundance in heavily and lightly hunted areas, and between small and large species. The three census methods were consistent in showing no significant difference between animal abundance in the hunted populations or between abundances of the smaller species relative to the larger species. All methods showed potential as population indices for assessing trends of rare and elusive species in forest environments. Drive counts and pellet group counts may also be useful for estimating densities.     

Chimpanzee predation in the Mahale mountains from August 1979 to May 1982

Fifty-four episodes of predatory behavior of wild chimpanzees were recorded in Mahale, western Tanzania, from August 1979 to May 1982. The chimpanzees most frequently hunt in two seasons, during May, and from August to December. Longer-term fecal analysis indicates that predation frequency is significantly higher in the dry than in the rainy season. The seasonality of predation might be the result of the sum of various ecological factors, at least one of which is the birth season of the prey species. Most of the prey are juvenile blue duiker, bushbuck, bushpig, red colobus, and red-tailed monkeys. Sex difference is recognized in the prey selection and in the hunting method employed. Apparent local difference in the predatory behavior between Mahale and Combe chimpanzees (in Mahale,females hunt more frequently, and blue duiker is the most frequent prey) can be understood in terms of the difference either in the observation methods or in the faunal diversity and density. Other aspects of predatory behavior also are reported.     

Habitat fragmentation influences nestling growth in Mediterranean blue and great tits

In patchy forest areas, the size of the forest patch where birds breed has a strong influence on their breeding success. However, the proximate effects contributing to lowering the breeding success in small forest patches remain unclear; and a shortage of crucial resources in those forest patches has been suggested to account in some degree for this failure. With the aim to further investigate this issue, we have monitored the breeding cycle of blue and great tits in three ‘large’ forest patches (ranging between 26.5 and 29.6 ha) and twelve ‘small’ forest patches (ranging between 1.1 and 2.1 ha) in a Mediterranean area in central Spain, during three years (2011–2013). We also recorded the nestling diet inside the nest-boxes with the aid of handy-cams. Only males significantly differed between forest patch size categories; being on average younger and with better body condition in small patches for great and blue tits respectively. Reproductive traits did not vary between forest patch size categories, but the body condition of blue tit nestlings and the size of great tit nestlings did, being significantly better and larger respectively in large forest patches. The recruitment rate of blue tit nestlings was also higher in large patches. Regarding nestling diet, blue tits did not differ but great tits did, delivering a larger amount of caterpillars in large forest patches. Most variation in the reproductive traits occurred between years, probably due to annual differences in environmental conditions. This study suggests that food supply could be limiting the breeding success of birds above all in small patches, but also in large patches under particular environmental conditions.     

Duiker demography and dispersal under hunting in Northern Congo

Duikers are the most heavily hunted species across forested Central and West Africa. Although these species form a vital food resource for people, little is known about their ecology and demography. The information available to date was collected from populations protected from hunting. However, hunting can profoundly alter demography and behaviour, such as dispersal, which in turn determine the sustainability of harvest. To address this research gap, I used radiotelemetry to examine duiker demography under hunting in Congo-Brazzaville. Among blue duikers ( Philantoba monticola , n = 17) I found annual survival rates (0.94), immature dispersal rates (0.25), and average home ranges (5.5 ha) that largely coincided with previous research from unhunted regions. Neighbouring animals all showed some home range overlap, in contrast to previous studies which found blue duikers to be strictly territorial. Although limited by sample size, immature animals' dispersal distances were relatively high (1.5 km, n = 2). Animals' dispersal rates do not appear to be greatly increased by hunting pressure, although source-sink theory depends upon high rates of dispersal to maintain the elevated and localized hunting offtakes observed around settlements. Building a fuller understanding of duiker demography under hunting, including dispersal, will be essential for conservation and management efforts.     

A new antelope from Gabon

A new subspecies Cephalophus ogilbyi crusalbum , of Ogilby's duiker, is described from Gabon. It is the only duiker with white legs and is isolated from previously described subspecies of C. ogilbyi.     

Differential response of seven duiker species to human activities in Taï National Park,Côte d'Ivoire

African rainforest is severely impacted by human activities, ranging from resource collection, selective logging to fragmentation and scale deforestation. Consequently, large mammal communities occurring therein are strongly modified. Here, we present a study conducted in Taï National Park (TNP), which characterises the spatial distribution and differential response of seven duiker species to human activities. Based on extensive survey data recorded between 2005 and 2015, we used a maximum entropy modelling approach for predicting duiker species distribution and a hierarchical clustering approach to identify potential subgroups in the duiker community. The seven duiker species clearly differed in their spatial distribution, with Cephalophus dorsalis and Philantomba maxwellii being the most common and widely distributed with no clear response towards gradients of impact from human activities. In contrast, Cephalophus ogilbyi, Cephalophus jentinki, Cephalophus sylvicultor and Cephalophus zebra showed increasing responses towards anthropogenic impact gradients, with the latter two being particularly sensitive. These duikers are not found in areas of illegal human activities. The restricted distribution of Cephalophus niger seems artificial and may indicate species misidentification. The strong spatial signature of human activities in the duiker community of TNP is of concern. Effective park management, including extensive ranger patrols, is vital for ensuring the persistence of this unique duiker community in West Africa.     

The Influence of Hunting on Antipredator Behavior in Central African Monkeys and Duikers

Many animals can adjust their behavioral strategies to reduce predation risk. We investigated whether rain forest monkeys and duikers alter their antipredatory behavior in response to hunting by humans in southwestern Gabon. We compared monkey and duiker responses to human observers in an area where hunting is prohibited, to those in a nearby area where hunting pressure is moderate but spatially variable. The results of our study indicate that monkeys become more secretive when hunted, commencing alarm calls only when at a certain distance (typically > 50 m) from humans. We found no difference in monkey group size between hunted and no-hunting areas. In no-hunting areas, duikers often freeze in response to approaching observers, but in hunted areas they abandon this strategy and rapidly flee from humans. Duikers also whistle more often in areas where they are hunted frequently. Our findings have at least two important implications. First, behavioral observations of monkeys and duikers may be useful in gauging local hunting intensity in African rain forests. Second, duiker densities are likely to be overestimated in hunted areas, where they more readily flee and whistle, and underestimated in no-hunting areas, where they rely on freezing behavior to avoid detection. Because behavioral adaptations to hunting vary both among species and localities, these differences should be considered when attempting to derive population-density estimates for forest wildlife.     

A multi-locus species phylogeny of African forest duikers in the subfamily Cephalophinae: evidence for a recent radiation in the Pleistocene

ABSTRACT: BACKGROUND: Duikers in the subfamily Cephalophinae are a group of tropical forest mammals believed to have first originated during the late Miocene. However, knowledge of phylogenetic relationships, pattern and timing of their subsequent radiation is poorly understood. Here we present the first multi-locus phylogeny of this threatened group of tropical artiodactyls and use a Bayesian uncorrelated molecular clock to estimate divergence times. RESULTS: A total of 4152 bp of sequence data was obtained from two mitochondrial genes and four nuclear introns. Phylogenies were estimated using maximum parsimony, maximum likelihood, and Bayesian analysis of concatenated mitochondrial, nuclear and combined datasets. A relaxed molecular clock with two fossil calibration points was used to estimate divergence times. The first was based on the age of the split between the two oldest subfamilies within the Bovidae whereas the second was based on the earliest known fossil appearance of the Cephalophinae and molecular divergence time estimates for the oldest lineages within this group. Findings indicate strong support for four major lineages within the subfamily, all of which date to the late Miocene/early Pliocene. The first of these to diverge was the dwarf duiker genus Philantomba, followed by the giant, eastern and western red duiker lineages, all within the genus Cephalophus. While these results uphold the recognition of Philantomba, they do not support the monotypic savanna-specialist genus Sylvicapra, which as sister to the giant duikers leaves Cephalophus paraphyletic. BEAST analyses indicate that most sister species pairs originated during the Pleistocene, suggesting that repeated glacial cycling may have played an important role in the recent diversification of this group. Furthermore, several red duiker sister species pairs appear to be either paraphyletic (C.callipygus/C. ogilbyi and C. harveyi/C. natalensis) or exhibit evidence of mitochondrial admixture (C. nigrifrons and C. rufilatus), consistent with their recent divergence and/or possible hybridization with each other. CONCLUSIONS: Molecular phylogenetic analyses suggest that Pleistocene-era climatic oscillations have played an important role in the speciation of this largely forest-dwelling group. Our results also reveal the most well supported species phylogeny for the subfamily to date, but also highlight several areas of inconsistency between our current understanding of duiker taxonomy and the evolutionary relationships depicted here. These findings may therefore prove particularly relevant to future conservation efforts, given that many species are presently regulated under the Convention for Trade in Endangered Species.     

Evidence of a specific nidation site in ruminants

The site of umbilical cord attachment in ruminants indicates the limited segment of the uterus where the blastocyst attachment occurs and could have potential significance for locating presumptive nidation sites. Measurements of the site of cord attachment were made on impala (Aepyceros melampus) and common duiker (Sylvicapra grimmia) at several stages of gestation. Both implant only in the right uterine horn although they ovulate from either ovary. Relative to uterine length, cord attachment in impala is somewhat closer to the cervix than it is in common duiker. As pregnancy advances in common duiker, the relative position of cord attachment becomes closer to the tubal end. This relationship was not seen in impala and may perhaps to be attributed inadequate data. Upon extrapolation of the data from common duiker, a presumptive attachment area is suggested for this species. This region is located at about 41% of the distance from the internal cervical os to the uterotubal junction. Similar cord attachment data could be used in any ruminant species to indicate the existence and location of a specific nidation site.