In the face of increased defaunation in tropical regions, embracing the complexity of wildlife population trends is important to guide the development of effective conservation and restoration strategies. Here, based on a case study in Democratic Republic of the Congo, we use an ethnozoological approach, with a protocol that captures spatially explicit and temporal ecological knowledge on defaunation. Our case study evidences the overall depletion profile for the majority of mammal species in the whole landscape and particularly for red colobus, orycterope, and chimpanzee. The elephant has already disappeared locally, and okapi and forest buffalo only persist in the northern part of the landscape. On the other hand, postdepletion sustainability seems to characterize Yangambi Reserve, with more stable populations of fast-reproducing/small-sized species. Local extinctions or sharp declines in mammal populations in our landscape are either the direct consequence of conflict or the result of cascading effects that have their origins in the rebellions between 1996 and 2002. From a conservation perspective, the challenge is to understand how the depletion process can be reversed in a postconflict context and to identify the levers that can inverse the cascading effect to allow species recovery. We encourage the use of our methodology in regions that are regularly used by a significant number of observers. The proposed methodology provides cost-effective, reliable, and spatially explicit data on population trends, covering for a wide range of species and allows to understand the historical pattern of defaunation as well the wider context in which changes occurred.
Tag: mammals
Integrating ecosystem management, protected areas and mammal conservation in the Brazilian Amazon
The Amazon forest has been converted to a matrix of pristine and modified habitats. Landscape-scale biodiversity conservation requires an understanding of species’ distributions over this matrix to guarantee both effective protection and use for present and future generations. In this study, we evaluated how much of the existing and future planned protected areas (PAs) would be contributing to the conservation of Brazilian Amazon mammals (N = 399), including threatened species (N = 51). Currently, almost 37% of Brazilian Amazon is protected and that may increase to 46% if planned PAs are implemented. In the current PA system, 22% are indigenous land and 11% are sustainable use units, e.g., production forests. Only one-fifth of the whole range of mammal species occurring in Brazilian Amazon is actually protected by Brazilian PAs. However, considering only the part of the ranges within the Brazilian Amazon, and therefore under the scope of Brazilian actions, Brazilian PAs assume an important role in the protection of 39% of mammal distribution ranges, particularly the threatened species (39%). These results suggest that an integrated network of protected areas among Amazon countries would be necessary to increase their efficiency in mammal conservation. The need for strengthening of the forest sector and good management practices in Brazil appears critical for the maintenance of large extents of forest and species conservation. Under such a scenario, the contribution of developed nations and international agencies must assume an important role for the maintenance and enlargement of the protected area network in Amazon region.
Sustainable Palm Oil Certification: Do Forest Reserves Designated using “High Carbon Stock” Approaches within Palm Oil Plantations Support Mammal Conservation?
Studies to date indicate that palm oil plantations support a lower diversity of wildlife compared to other land uses. Programs for certified palm oil have been established in order to increase environmental sustainability of palm oil production, reduce adverse environmental effects, and encourage “wildlife friendly” palm oil plantations. Certification requires palm oil companies to set aside forest reserves based on High Conservation Value (HCV). A High Carbon Stock (HCS) approach also has been used voluntarily by some palm oil companies to prioritize their designated forest reserves. We use camera trapping to investigate mammalian occupancy and diversity in oil palm plantations and HCS and HCV forest reserves in West Kalimantan, Indonesia. We found significantly lower mammalian species richness in plantations relative to forest reserves, and the differences between mammal communities in palm oil and forest were much stronger in this study than in previous studies. None-the-less, within forest reserves, most mammalian species were found in low abundance. No correlation was found between mammal abundance and carbon stocks in forest reserves, but there was a significant correlation between mammal abundance and forest reserve size. Size of remnant forest fragments was the most important variable explaining the presence of large mammals. Our results suggest that designating forest reserves based on carbon stocks alone will not be sufficient to conserve mammalian biodiversity in palm oil landscapes. In contrast, the size of the forest patch should be considered when designating forest reserves. In my study area, most forest reserves currently are small and have poor long-term prospects for maintaining large mammals.
Landscape-level human disturbance results in loss and contraction of mammalian populations in tropical forests
Tropical forests hold most of Earth’s biodiversity and a higher concentration of threatened mammals than other biomes. As a result, some mammal species persist almost exclusively in protected areas, often within extensively transformed and heavily populated landscapes. Other species depend on remaining remote forested areas with sparse human populations. However, it remains unclear how mammalian communities in tropical forests respond to anthropogenic pressures in the broader landscape in which they are embedded. As governments commit to increasing the extent of global protected areas to prevent further biodiversity loss, identifying the landscape-level conditions supporting wildlife has become essential. Here, we assessed the relationship between mammal communities and anthropogenic threats in the broader landscape. We simultaneously modeled species richness and community occupancy as complementary metrics of community structure, using a state-of-the-art community model parameterized with a standardized pan-tropical data set of 239 mammal species from 37 forests across 3 continents. Forest loss and fragmentation within a 50-km buffer were associated with reduced occupancy in monitored communities, while species richness was unaffected by them. In contrast, landscape-scale human density was associated with reduced mammal richness but not occupancy, suggesting that sensitive species have been extirpated, while remaining taxa are relatively unaffected. Taken together, these results provide evidence of extinction filtering within tropical forests triggered by anthropogenic pressure occurring in the broader landscape. Therefore, existing and new reserves may not achieve the desired biodiversity outcomes without concurrent investment in addressing landscape-scale threats.
Environmental variation is a major predictor of global trait turnover in mammals
Assessment of small mammal diversity in coffee agroforestry in the Western Ghats, India
Coffee agroforestry is a conservation strategy that has shown promise to support the diversity of bird, bat, and insect communities, but few studies have focused on non-volant mammals in coffee farms. We assessed mammal diversity within coffee agroforestry systems in Kodagu, India and investigated the impacts of the non-native shade tree species, Grevillea robusta, on mammal diversity. Twenty farms, with varying amounts of G. robusta planted within the coffee farm, were sampled throughout three rainfall zones during the 4-month study period. We captured six species of small mammals, with indirect methods yielding an additional five species, totaling 11 mammal species. Contrary to current ecological thought, we found that increased amounts of G. robusta did not have a negative impact on either abundance or richness of mammals. Small mammal abundances were higher at farms with greater amounts of herbaceous ground cover and larger, mature shade trees, while small mammal species richness was found to increase with an increase in tree species richness as well as greater amounts of herbaceous ground cover. Additionally, small mammal abundance was higher at coffee farms closer to forested areas. Based on these findings, we suggest the maintenance or cultivation of shade tree richness, mature shade trees, and herbaceous ground cover within coffee farms and preservation of forested areas within the landscape to enhance coffee agroforestry habitat for non-volant mammals. We hope that these habitat requirements will be incorporated into conservation strategies for the promotion of biodiversity within coffee agroforestry systems.
Consistent diel activity patterns of forest mammals among tropical regions
An animal’s daily use of time (their “diel activity”) reflects their adaptations, requirements, and interactions, yet we know little about the underlying processes governing diel activity within and among communities. Here we examine whether community-level activity patterns differ among biogeographic regions, and explore the roles of top-down versus bottom-up processes and thermoregulatory constraints. Using data from systematic camera-trap networks in 16 protected forests across the tropics, we examine the relationships of mammals’ diel activity to body mass and trophic guild. Also, we assess the activity relationships within and among guilds. Apart from Neotropical insectivores, guilds exhibited consistent cross-regional activity in relation to body mass. Results indicate that thermoregulation constrains herbivore and insectivore activity (e.g., larger Afrotropical herbivores are ~7 times more likely to be nocturnal than smaller herbivores), while bottom-up processes constrain the activity of carnivores in relation to herbivores, and top-down processes constrain the activity of small omnivores and insectivores in relation to large carnivores’ activity. Overall, diel activity of tropical mammal communities appears shaped by similar processes and constraints among regions reflecting body mass and trophic guilds.
Comparative gastrointestinal organ lengths among Amazonian primates (Primates: Platyrrhini)
The morphological features of the gastrointestinal tract (GIT) in mammals reflect a species’ food niche breadth and dietary adaptations. For many wild mammals, the relationship between the structure of the GIT and diet is still poorly understood, for example, the GIT for frugivorous primates is usually classified as unspecialized and homogeneous. Here, we compare the GIT structure of 13 primate species from the three families of extant platyrrhines (Atelidae, Pitheciidae, and Cebidae) in Amazonia, and discuss possible evolutionary adaptations to different diets and trophic niches. We measured the length of the esophagus, stomach, small intestine, large intestine, cecum, colon, and rectum of the digestive tracts of 289 primate specimens. We determined the allometric relationships of the different tubular organs with the total length of the GIT as a proxy of specimen body size. Allometric parameters were used to establish the quotients of differentiation of every organ for each primate specimen. There was a high differentiation in structure of the digestive organs among genera. Alouatta specimens clearly separated from the other genera based on dissimilarities in gastric, colonic, and rectal quotients, likely linked to the fermentation of plant contents. In contrast, all cebines (Sapajus, Cebus, and Saimiri) and Cacajao species had similar small intestine quotients, which is expected due to their high rates of animal matter consumed. We show that diverse adaptations in digestive structure exist among frugivorous primates, which in turn reflect different dietary patterns within this group that may enable the geographic coexistence of different primate species.
Status of terrestrial mammals in the Yangambi Landscape, Democratic Republic of the Congo
In this study we provide the first comprehensive camera-trap assessment of terrestrial mammals in the Yangambi landscape, comprising the Yangambi Biosphere Reserve and a logging concession in the Democratic Republic of the Congo. The terrestrial mammal community in this area exhibits lower occupancy and species richness compared to other conservation areas in the Congo Basin. The community is dominated by four species: Emin’s pouched rat Cricetomys emini (1.3 kg), African brush-tailed porcupine Atherurus africanus (2.8 kg), blue duiker Philantomba monticola (5 kg) and bay duiker Cephalophus dorsalis (12 kg), which are known to be highly resilient. Large ungulates and medium-sized carnivores have particularly low abundances. Our study also confirmed the presence of four species categorized as threatened on the IUCN Red List: the chimpanzee Pan troglodytes, giant ground pangolin Smutsia gigantea, black-bellied pangolin Phataginus tetradactyla and white-bellied pangolin Phataginus tricuspis. Our findings highlight the need to consider wildlife conservation at the landscape level, including the logging concession, where species showed higher occupancy levels compared to the Biosphere Reserve, and highlighting the need for planning infrastructure construction and developing mitigation schemes, reducing forest degradation from logging and developing permanent cash crop agriculture. Landscape-level conservation will only be possible if a collaborative management model steered by local communities is developed with the participation of all constituencies.
Occurrence dynamics of mammals in protected tropical forests respond to human presence and activities
Protected areas (PAs) play a vital role in wildlife conservation. Nonetheless there is concern and uncertainty regarding how and at what spatial scales anthropogenic stressors influence the occurrence dynamics of wildlife populations inside PAs. Here we assessed how anthropogenic stressors influence occurrence dynamics of 159 mammal species in 16 tropical PAs from three biogeographic regions. We quantified these relationships for species groups (habitat specialists and generalists) and individual species. We used long-term camera-trap data (1,002 sites) and fitted Bayesian dynamic multispecies occupancy models to estimate local colonization (the probability that a previously empty site is colonized) and local survival (the probability that an occupied site remains occupied). Multiple covariates at both the local scale and landscape scale influenced mammal occurrence dynamics, although responses differed among species groups. Colonization by specialists increased with local-scale forest cover when landscape-scale fragmentation was low. Survival probability of generalists was higher near the edge than in the core of the PA when landscape-scale human population density was low but the opposite occurred when population density was high. We conclude that mammal occurrence dynamics are impacted by anthropogenic stressors acting at multiple scales including outside the PA itself.