Cephalophus ogilbyi crusalbum Grubb 1978, described from coastal Gabon, is quite common in the Forêt des Abeilles, Central Gabon

La nouvelle forme de céphalophe (Cephalophus ogilbyi crusalbum) décrite en 1978 par Grubb à partir de quelques spécimens de musée était supposée avoir une distribution limitée à la zone côtière du Gabon. De ce fait, elle fut classée comme rare et comme faisant partie des espèces nécessitant des mesures de protection urgentes. De récentes observations effectuées sur le site d'étude du Camp de la Makandé (Forêt des Abeilles) montrent que cette espèce est en fait commune dans cette région où elle est régulièrement observée. Les jarrets blancs qui la caractérisent constituent un critère d'identification aisé. Des observations complémentaires faites dans la réserve de la Lopé confirment que C. o. crusalbum est également présent sur la rive gauche de l'Offou

Forest structure and fruit availability as complementary factors influencing habitat use by a troop of monkeys (Cercopithecus cephus)

Ce travail analyse l'influence relative de la structure de la forêt et de la disponibilité en fruits sur les modes d'utilisation de l'habitat par une troupe de Cercopithecus cephus. Il montre que : 1/ La structure de la végétation est le facteur déterminant de l'utilisation de l'habitat pendant la période journalière de moindre activité et durant la nuit. Pour l'établissement de leur site de sommeil, les singes choisissent une forêt haute au sousbois clair, tandis qu'une forêt basse et un couvert dense sont significativement recherchés pour le repos journalier. 2/ Que la disponibilité en fruits influence l'utilisation de l'habitat pendant les deux courtes périodes matinale et vespérale pendant lesquelles la collecte et l'ingestion de fruits par les animaux sont maximales. Quand la diversité des espèces fructifiant est faible, l'utilisation du domaine vital est déterminée par la distribution des deux espèces végétales les plus abondantes (s aison sèche). Au contraire, quand cette diversité augmente (saison humide), les singes visitent les parties de leur domaine qui comprennent plusieurs espèces appétentes, même si leur densité spécifique est faible. 3/ En dépit de variations saisonnières de la disponibilité en fruits, les mouvements journaliers et la surface prospectée chaque jour par la troupe ne varient pas sensiblement d'une saison à l'autre. Ceci peut s'expliquer par le fait que cette surface correspond au compromis optimal d'un point de vue énergétique. On montre en effet que, quelle que soit la saison, les animaux devraient considérablement augmenter la surface visitée pour accroître sensiblement leurs rencontres avec de nouvelles espèces végéta les (en raison de leur faible densité). Il en résulte qu'en saison sèche, pendant laquelle un nombre réduit d'espèces fructifient, le facteur limitant pourrait être la faible diversité spécifique conduisant les animaux à un régime mal équilibré. 4/ La disponibilité en fruits n'a d'influence sur l'utilisation de l'habitat que si la structure de celui-ci convient aux animaux. On montre, en effet, que l'utilisation de la forêt haute au sousbois clair, n'est pas accrue quand sa richesse en fruits augmente, tandis que, lorsque la forêt la plus dense devient aussi riche que les autres, elle est significativement la plus utilisée quelles que soit l'heure de la journée et l'activité en cours. 5/ La recherche et la capture des proies s'effectue tout au long de la journée (sauf aux heures de moindre luminosité) et dans la forêt claire comme dans la forêt dense ; elles ne semblent donc pas être déterminantes dans le choix de l'habitat. 6/ La sélection par C. cephus d'habitats de structure différente selon la pério de du cycle nycthéméral est interprétée en termes de stratégie anti-prédation. Pendant la nuit, les singes font face à la prédation qu'exercent des prédateurs non volants et venant du sol (pythons, panthères), en choisissant une forêt haute au sous-bois dégagé, qui comporte peu de supports permettant aux prédateurs d'atteindre la couronne des arbres où dorment leurs proies. Au contraire, pendant le jour, les singes choisissent les niveaux peu élevés d'une forêt au sous-bois encombré qui les dissimulent le mieux au prédateur diurne essentiel qu'est l'Aigle des singes (Staephanoetus coronatus

Primate-plant mutualisms : is there evidence for primate fruit syndromes?

For over thirty years, researchers have identified the traits of “primate fruits” (fruits that are exclusively or primarily dispersed by primates). This book chapter reviews the primate fruit syndrome hypothesis in the history of primate seed dispersal studies. It addresses whether primate fruit syndromes exist in alignment with primates exerting sufficient selective pressure on plants via seed dispersal that alters the evolutionary trajectories of those plants. Because of recent technological advances that allow for the quantification of fruit traits, along with the importance of primates as seed dispersers, the fruit syndrome hypothesis can be tested.Canada Research Chairs ProgramNatural Science and Engineering Research Council of CanadaFonds Québécois de la Recherche sur la Nature et les Technologie

Vigilance of mustached tamarins in single-species and mixed-species groups—the influence of group composition

Species that participate in mixed-species groups (MSG) may have complementary roles in antipredator strategies. We studied vigilance in mustached tamarins (Saguinus mystax), small arboreal primates that form stable mixed-species groups with saddleback tamarins (Saguinus fuscicollis), in order to examine how the direction of vigilance changes with different species group compositions and whether the division of labor between the two species can be confirmed. We did so by comparing quantitative and qualitative differences in vigilance behavior between same individuals in and out of association (case A); MSG and single-species groups of the same total group size from two different populations (case B); and MSG of the same group size but with a different ratio of conspecifics to heterospecifics (case C). We predicted that individuals would increase downward scanning when heterospecifics are absent or their percentage is low, but total vigilance would increase only in case A due to the group size effect. However, mustached tamarins increased total vigilance due to horizontal scanning in cases A and C, and the predictions were confirmed only in small-sized groups in case B. Thus, we found indications that associating tamarin species in MSG might complement each other in the direction of vigilance, but the division of labor alone does not satisfactorily explain all the findings. There appear to be other mechanisms at work that define how direction of vigilance changes with group size and species composition. Complementarity of species probably occurs due to species vertical stratification rather than differences in the direction of vigilance

Do Dispersing Monkeys Follow Kin? Evidence from Gray-cheeked Mangabeys (Lophocebus albigena)

Among social vertebrates, immigrants may incur a substantial fitness cost when they attempt to join a new group. Dispersers could reduce that cost, or increase their probability of mating via coalition formation, by immigrating into groups containing first- or second-degree relatives. We here examine whether dispersing males tend to move into groups containing fathers or brothers in gray-cheeked mangabeys (Lophocebus albigena) in Kibale National Park, Uganda. We sampled blood from 21 subadult and adult male mangabeys in 7 social groups and genotyped them at 17 microsatellite loci. Twelve genotyped males dispersed to groups containing other genotyped adult males during the study; in only 1 case did the group contain a probable male relative. Contrary to the prediction that dispersing males would follow kin, relatively few adult male dyads were likely first- or second-degree relatives; opportunities for kin-biased dispersal by mangabeys appear to be rare. During 4 yr of observation, adult brothers shared a group only once, and for only 6 wk. Mean relatedness among adult males sharing a group was lower than that among males in different groups. Randomization tests indicate that closely related males share groups no more often than expected by chance, although these tests had limited power. We suggest that the demographic conditions that allow kin-biased dispersal to evolve do not occur in mangabeys, may be unusual among primates, and are worth further attention

Time constraints do not limit group size in arboreal guenons but do explain community size and distribution patterns

To understand how species will respond to environmental changes, it is important to know how those changes will affect the ecological stress that animals experience. Time constraints can be used as indicators of ecological stress. Here we test whether time constraints can help us understand group sizes, distribution patterns and community sizes of forest guenons (Cercopithecus/Allochrocebus). Forest guenons typically live in small to medium sized one-male multi-female groups and often live in communities with multiple forest guenon species. We developed a time-budget model using published data on time budgets, diets, body sizes, climate, and group sizes to predict maximum ecologically tolerable group and community sizes of forest guenons across 202 sub-Saharan African locations. The model correctly predicted presence/absence at 83% of these locations. Feeding-foraging time (an indicator of competition) limited group sizes, while resting and moving time constraints shaped guenon biogeography. Predicted group sizes were greater than observed group sizes but comparable to community sizes, suggesting community sizes are set by competition among guenon individuals irrespective of species. We conclude that time constraints and intra-specific competition are unlikely to be the main determinants of relatively small group sizes in forest guenons. Body mass was negatively correlated with moving time, which may give larger bodied species an advantage over smaller bodied species under future conditions when greater fragmentation of forests is likely to lead to increased moving time. Resting time heavily depended on leaf consumption and is likely to increase under future climatic conditions when leaf quality is expected to decrease

The mammals of Angola

Scientific investigations on the mammals of Angola started over 150 years ago, but information remains scarce and scattered, with only one recent published account. Here we provide a synthesis of the mammals of Angola based on a thorough survey of primary and grey literature, as well as recent unpublished records. We present a short history of mammal research, and provide brief information on each species known to occur in the country. Particular attention is given to endemic and near endemic species. We also provide a zoogeographic outline and information on the conservation of Angolan mammals. We found confirmed records for 291 native species, most of which from the orders Rodentia (85), Chiroptera (73), Carnivora (39), and Cetartiodactyla (33). There is a large number of endemic and near endemic species, most of which are rodents or bats. The large diversity of species is favoured by the wide range of habitats with contrasting environmental conditions, while endemism tends to be associated with unique physiographic settings such as the Angolan Escarpment. The mammal fauna of Angola includes 2 Critically Endangered, 2 Endangered, 11 Vulnerable, and 14 Near-Threatened species at the global scale. There are also 12 data deficient species, most of which are endemics or near endemics to the countryinfo:eu-repo/semantics/publishedVersio

Seed Dispersal Anachronisms: Rethinking the Fruits Extinct Megafauna Ate

Background: Some neotropical, fleshy-fruited plants have fruits structurally similar to paleotropical fruits dispersed by megafauna (mammals.10 3 kg), yet these dispersers were extinct in South America 10–15 Kyr BP. Anachronic dispersal systems are best explained by interactions with extinct animals and show impaired dispersal resulting in altered seed dispersal dynamics. Methodology/Principal Findings: We introduce an operational definition of megafaunal fruits and perform a comparative analysis of 103 Neotropical fruit species fitting this dispersal mode. We define two megafaunal fruit types based on previous analyses of elephant fruits: fruits 4–10 cm in diameter with up to five large seeds, and fruits.10 cm diameter with numerous small seeds. Megafaunal fruits are well represented in unrelated families such as Sapotaceae, Fabaceae, Solanaceae, Apocynaceae, Malvaceae, Caryocaraceae, and Arecaceae and combine an overbuilt design (large fruit mass and size) with either a single or few (,3 seeds) extremely large seeds or many small seeds (usually.100 seeds). Within-family and within-genus contrasts between megafaunal and non-megafaunal groups of species indicate a marked difference in fruit diameter and fruit mass but less so for individual seed mass, with a significant trend for megafaunal fruits to have larger seeds and seediness. Conclusions/Significance: Megafaunal fruits allow plants to circumvent the trade-off between seed size and dispersal b