Predation by mammalian carnivores on nocturnal primates: is the lack of evidence support for the effectiveness of nocturnality as an antipredator strategy?

Female Dispersion Is Necessary, but Not Sufficient, for Pairbonded Monogamy in Mammals

Explanations for the evolution of social monogamy in mammals typically emphasise one of two possibilities: females are overdispersed (such that males cannot defend access to more than one female at a time) or males provide a service to the female. However, the first claim has never been formally tested. I test it directly at three levels using population-level data from primates and ungulates. First, I show that the females of monogamous genera do not have territories that are significantly larger, either absolutely or relatively, than those of polygynous genera. Second, using two indices of territorial defendability, I show that, given their typical day journey lengths, males of most monogamous species could easily defend an area large enough to allow them to monopolise as many as 5–10 females if they ranged solitarily. Finally, I use a model of male mate searching strategies to show that the opportunity cost incurred by pairbonded males is typically 5–10 times the reproductive success they actually obtain by being obligately monogamous. This suggests that the selection pressure dissuading them from pursuing a roving male strategy must be very considerable. At present, the evidence is undecided as to whether mitigating predation or infanticide risk is the primary function, but estimates of their impacts suggest that both are in fact plausible.

Slow loris density in a fragmented, disturbed dry forest, north-east Thailand

Primate survival in disturbed forests can be governed by a complex of forest variables. For nocturnal arboreal primates, determining these ecological features is notoriously difficult but is critically important for their conservation. Here we assessed the effects of forest type, food availability, human disturbance, and forest structure on the nocturnal Bengal slow loris (Nycticebus bengalensis) in Sakaerat Biosphere, north-east Thailand, a small disturbed fragment containing dry evergreen, dry dipterocarp, and plantation forests. Distance sampling revealed plantation forest had the highest density estimate (27 loris/km² ) followed by dry evergreen forest (17 loris/km² ), while dry dipterocarp forest only had four detections. Based on forest type selection analyses, loris had a positive association with sap and fruit-flower productivity which was highest in plantation forest compared to the natural dry evergreen or dry dipterocarp forests. Furthermore, forest structure selection analysis indicated loris preferred denser canopies. Loris presence was positively associated with canopy height, canopy connections, tree trunk vegetation cover, and canopy density. The higher loris density found in the plantations, as also reported by other studies, was associated with dense vegetation structure and higher food productivity, particularly sap. However, the important structural features found in the plantation forest are strongly dependent on forest maturity, and the reduced longevity of such exotic tree species may limit the conservation importance of plantation forest, merely acting as a short-term alternative to natural habitat.

Assessing the spatiotemporal interactions of mesopredators in Sumatra's tropical rainforest

Co-occurrence between mesopredators can be achieved by differentiation of prey, temporal activity, and spatial habitat use. The study of mesopredator interactions is a growing area of research in tropical forests and shedding new light on inter-guild competition between threatened vertebrate species that were previously little understood. Here, we investigate sympatry between the Sunda clouded leopard (Neofelis diardi) and Asiatic golden cat (Pardofelis temminckii) living in the Sumatran rainforests of Indonesia. We investigate: i) spatial overlap of predator-prey species using a combination of single-species occupancy modelling and Bayesian two-species modelling, while controlling for the possible influence of several confounding landscape variables; and, ii) temporal overlap between mesopredators and their shared prey through calculating their kernel density estimate associations. From four study areas, representing lowland, hill, sub-montane and montane forest, 28,404 camera trap nights were sampled. Clouded leopard and golden cat were respectively detected in 24.3% and 22.6% of the 292 sampling sites (camera stations) and co-occurred in 29.6% of the sites where they were detected. Golden cat occupancy was highest in the study area where clouded leopard occupancy was lowest and conversely lowest in the study area where clouded leopard occupancy was highest. However, our fine-scale (camera trap site) analyses found no evidence of avoidance between these two felid species. While both mesopredators exhibited highest spatial overlap with the larger-bodied prey species, temporal niche separation was also found. Clouded leopard was more nocturnal and, consequently, had higher temporal overlap with the more nocturnal prey species, such as porcupine and mouse deer, whereas the more diurnal golden cat had higher overlap with the strictly diurnal great argus pheasant. The Bayesian two species occupancy modelling approach applied in our study fills several important knowledge gaps of Sumatra’s lesser known mesopredators and provides a replicable methodology for studying interspecific competition for other small-medium sized carnivore species in the tropics.

Down from the treetops: red langur (Presbytis rubicunda) terrestrial behavior

Using direct observations and camera traps at eight sites across Indonesian Borneo we show how red langurs (Presbytis rubicunda) are more terrestrial than previously believed, regularly coming to the ground. This unusual behavior has been found at six of the eight sites surveyed. We find that red langurs come to the ground more frequently in disturbed forests, specifically ones which have been impacted by logging, fire, and hunting, though more data are needed to confirm this as a direct correlation. We also found a trend towards decreased ground use with increased elevation of the habitat. When on the ground, red langurs are predominantly engaged in feeding (50% direct observations, 61% camera traps) and traveling (29% direct observations, 13% camera traps). Red langurs are found on the ground throughout the day, at similar times to activity periods of the apex predator, the Sunda clouded leopard (Neofelis diardi). We suggest that ground use by red langurs could be an adaptation to disturbed forest to exploit additional food sources and to facilitate travel.

Spatial organization and activity patterns of the masked palm civet (Paguma larvata) in central-south China

Movement and activity patterns are important components of life history, being central to resource acquisition and defense, mating behavior, and individual survival and fitness. Here, we present results from the 1st systematic radiotracking study of the masked palm civet (Paguma larvata), a widespread viverrid found in subtropical and tropical forests of Asia. From June 2004 to November 2007, we radiotracked 12 masked palm civets (5 males and 7 females) in central-south China. Mean individual home-range size based on 95% minimum convex polygons was 192.6 ha ± 42.6 SE (range = 64-451 ha). Although males had larger mean home-range sizes than females (276.8 and 136.5 ha, respectively), these differences were not statistically significant. Males also exhibited greater daily movement distances and extents than females, but we found no evidence of sexual dimorphism in body size. Masked palm civets were predominantly nocturnal, but were active intermittently during the day. No significant seasonal (monthly) differences in daily activity patterns were apparent. We did, however, observe reduced hours of activity-but not continuous inactivity-during winter; consequently, we concluded that our study animals did not hibernate or semihibernate. We speculate that our observations of home-range overlap among individuals may indicate group living in the masked palm civet.

Mad, bad and dangerous to know: the biochemistry, ecology and evolution of slow loris venom

Only seven types of mammals are known to be venomous, including slow lorises (Nycticebus spp.). Despite the evolutionary significance of this unique adaptation amongst Nycticebus, the structure and function of slow loris venom is only just beginning to be understood. Here we review what is known about the chemical structure of slow loris venom. Research on a handful of captive samples from three of eight slow loris species reveals that the protein within slow loris venom resembles the disulphide-bridged heterodimeric structure of Fel-d1, more commonly known as cat allergen. In a comparison of N. pygmaeus and N. coucang, 212 and 68 compounds were found, respectively. Venom is activated by combining the oil from the brachial arm gland with saliva, and can cause death in small mammals and anaphylactic shock and death in humans. We examine four hypotheses for the function of slow loris venom. The least evidence is found for the hypothesis that loris venom evolved to kill prey. Although the venom's primary function in nature seems to be as a defense against parasites and conspecifics, it may also serve to thwart olfactory-orientated predators. Combined with numerous other serpentine features of slow lorises, including extra vertebra in the spine leading to snake-like movement, serpentine aggressive vocalisations, a long dark dorsal stripe and the venom itself, we propose that venom may have evolved to mimic cobras (Naja sp.). During the Miocene when both slow lorises and cobras migrated throughout Southeast Asia, the evolution of venom may have been an adaptive strategy against predators used by slow lorises as a form of Müllerian mimicry with spectacled cobras.

A problem shared is a problem reduced: seeking efficiency in the conservation of felids and primates

Threats faced by mammalian species can be grouped into one of a handful of categories, such as habitat loss, unsustainable hunting and persecution. Insofar as they face common threats, diverse species may benefit from the same conservation intervention, thereby offering efficiencies in conservation action. We explore this proposition for primates and felids by examining coarse scale overlaps in geographical distributions, using IUCN Red List assessments of the primary threats posed to each species. A global analysis of primates and felids that face common threats reveals the greatest overlap is in Central and South Asia, where up to 14 primates and felids co-occur. More than 80% of the land where at least 1 threatened species of either primate or felid occurs also contains at least one threatened species of the other taxon, yet over 60% of these grid cells containing both threatened primates and felids lie outside Conservation International's hot spots. A review of IUCN Action Plans of the threats to felids and primates strongly supports the hypothesis that they are often the same and occur in the same place. In principle, steps to conserve big cats have the potential to benefit several species of threatened primates, and vice versa.

Life and dinner under the shared umbrella: patterns in felid and primate communities

Sympatry between primates and felids is potentially relevant to both their behavioural ecology and their conservation. This paper briefly introduces felids and primates, for the purposes of assessing their interrelationships and the patterns in their spatial congruence using IUCN spatial data. First, we review evidence and opportunity for predator-prey interactions between the felids and primates. Second, we analyse the overlap between species of the two taxa to reveal the potential of particular felid species or guilds (unique combinations of 2 or more felids) to act as umbrellas for the conservation of co-occurring primates. Felid guilds vary in terms of their geographical ranges and numbers of members. Some felid species overlap the ranges of many primate species, and the most speciose felid guilds, while geographically limited in distribution, have the potential to act as protective umbrellas to large numbers of primate species. This prompts the hypothesis that threatened primates and felids are facing similar threats and might thus benefit from similar interventions, which is evaluated in a sister paper by Macdonald et al. in this special issue.