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The most threatened mammal group on Earth, Madagascar's five endemic lemur families (lemurs are found nowhere else) (1), represent more than 20% of the world's primate species and 30% of family-level diversity. This combination of diversity and uniqueness is unmatched by any other country—remarkable considering that Madagascar is only 1.3 to 2.9% the size of the Neotropics, Africa, or Asia, the other three landmasses where nonhuman primates occur. But lemurs face extinction risks driven by human disturbance of for-est habitats. We discuss these challenges and reasons for hope in light of site-specific, local actions proposed in an emergency con-servation action plan (2). Political Crisis, Remarkable Threat An International Union for Conservation of Nature (IUCN) Species Survival Commission (SSC) Red List reassessment found that 94% of lemur species are threatened (2) (Fig. S1 and Table S1), up from 74% in 2008, which makes lemurs the most imperiled group of large vertebrates. Although other large mammals are also under pres-sure, for the vast majority of taxa in an entire infraorder (Lemuriformes) to be threatened is new, notable, and disturbing. This reevaluation has resulted from both the deterioration of habitat and the recent application of genetic data to phylogenetic analyses (increasing the number of extant lemur species from 43 to 101) (3), revealing more species with smaller ranges. This unique primate diversity relies on for-est habitats that are shrinking under persistent anthropogenic destruction and disturbance. Remaining intact forest habitat was estimated to cover 92,200 km 2 in 2010, only 10 to 20% of Madagascar's original forest cover and down from 106,600 km 2 in 1990 (4); much of this habitat is inadequately or not at all protected. Habitat and lemur conservation are interdependent: Lemurs have important ecological roles and are essential to maintaining the island's unique forests. Their loss would likely trigger extinction cascades (5). Challenges to in situ lemur conservation are immense. Madagascar is one of the poor-est countries in the world; more than 92% of Malagasy live on less than U.S. $2/day (6). Although there is a paucity of published data compared to other lemur-related subjects, lemur poaching for bushmeat has drastically increased since the onset of the political crisis in 2009 (7, 8). Illegal logging of rosewood and ebony, mining, and slash-and-burn agriculture are all causing lemur population declines, by habitat loss, fragmentation, and alteration. Protected areas have not been spared; for example, armed timber poachers extracting valuable hardwoods targeted Masoala and Marojejy National Parks in the northeast once local law enforcement broke down (9). Foreign demand, as well as political turmoil and corruption, drive these
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... We estimated the proportion of habitat area that is too small to host viable populations for 157 nonvolant terrestrial mammals of Madagascar. Madagascar is a biodiversity hotspot that has seen extensive habitat destruction over the last decades (Harper et al., 2007;Vieilledent et al., 2018) and hosts a large number of endemic species persisting in small fragments (Myers et al., 2000;Goodman & Benstead, 2005;Schwitzer et al., 2014). We therefore expected large time-lagged effects of habitat fragmentation on Malagasy mammals. ...
... These results are concerning because Madagascar's biodiversity is already severely threatened by habitat loss without considering time-lagged effects of habitat fragmentation (e.g. Schwitzer et al., 2014;Vieilledent et al., 2018;Habel et al., 2019;Morelli et al., 2020). For example, the critically endangered northern sportive lemur (Lepilemur septentrionalis) and crowned sifaka (Propithecus coronatus) have lost over 80% of their individuals to habitat loss during their last 3 generations (IUCN, 2021). ...
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Biodiversity is severely threatened by habitat destruction. As a consquence of habitat destruction, the remaining habitat becomes more fragmented. This results in time-lagged population extirpations in remaining fragments when these are too small to support populations in the long term. If these time-lagged effects are ignored, the long-term impacts of habitat loss and fragmentation will be underestimated. We quantified the magnitude of time-lagged effects of habitat fragmentation for 157 nonvolant terrestrial mammal species in Madagascar, one of the biodiversity hotspots with the highest rates of habitat loss and fragmentation. We refined species’ geographic ranges based on habitat preferences and elevation limits and then estimated which habitat fragments were too small to support a population for at least 100 years given stochastic population fluctuations. We also evaluated whether time-lagged effects would change the threat status of species according to the International Union for the Conservation of Nature Red List assessment framework. We used allometric relationships to obtain the population parameters required to simulate the population dynamics of each species, and we quantified the consequences of uncertainty in these parameter estimates by repeating the analyses with a range of plausible parameter values. Based on the median outcomes, we found that for 34 species (22% of the 157 species) at least 10% of their current habitat contained unviable populations. Eight species (5%) had a higher threat status when accounting for time-lagged effects. Based on 0.95-quantile values, following a precautionary principle, for 108 species (69%) at least 10% of their habitat contained unviable populations, and 51 species (32%) had a higher threat status. Our results highlight the need to preserve continuous habitat and improve connectivity between habitat fragments. Moreover, our findings may help to identify species for which time-lagged effects are most severe and which may thus benefit the most from conservation actions.
... However, Madagascar is also one of the hotspots with highest deforestation rates: the island has lost around 44% of its forest cover in the last 60 years and many endemic species are forest dependent (Goodman & Benstead, 2003;Myers et al., 2000;Vieilledent et al., 2018). The International Union for Conservation of Nature's (IUCN) Red List considers about 98% of all lemur species as threatened, and about 30% as critically endangered, due to habitat loss and hunting (IUCN, 2021;Schwitzer et al., 2014). Delineating protected areas has been one of the government's main strategies to halt deforestation and to protect flora and fauna (Rakotomanana et al., 2013;Virah-Sawmy et al., 2014). ...
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In the eastern rainforests of Madagascar, rainfed swidden rice cultivation remains prevalent despite efforts to encourage uptake of irrigated systems to reduce deforestation. We used agricultural surveys with a stratified sample of 171 households to investigate constraints on and productivity of irrigated and rainfed rice perceived by farmers, and actual rice yields. Irrigated rice plots had higher median yields (1.72 t/ha compared to 0.62 t/ha), but farmers perceived the type of rice cultivation they practised themselves as more productive, possibly reflecting differences in the land suitability, farmers experience, and other constraints. While some factors, such as pests and water, were mentioned to limit yields, access to fertiliser was not frequently mentioned by smallholders. Higher food security was related to irrigated rice farming, higher rice yields, and owning more livestock. Conservation initiatives need to target households with and without access to irrigable land to improve food security and reduce deforestation, as exclusively promoting a cessation of swidden agriculture is neglecting its cultural value and the scarcity of irrigable land in the region.
... Indeed, out of the 107 lemur species assessed by the IUCN in Madagascar, 103 were considered to be threatened, with 33 of them being listed as critically endangered, making lemurs the most threatened vertebrate taxon in Madagascar (IUCN, 2021). The drivers causing the decline of lemurs can act synergistically, although habitat loss because of cultivation and timber harvesting is the major contributor (Irwine et al., 2010;Schwitzer et al., 2014), which is amplified by the negative impact of anthropogenic disturbance on the physiology and health of primates (Junge et al., 2011;Schwitzer et al., 2011;Bublitz et al., 2015). The response of species to habitat disturbance has shown to be mixed and species-trait dependent, e.g., small-bodied and mixed folivorous/frugivorous primates show a higher resilience compared with large bodied species and those with a more specialized diet (Eppley et al., 2020). ...
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Increasing anthropogenic disturbances in Madagascar are exerting constrains on endemic Malagasy lemurs and their habitats, with possible effects on their health and survival. An important component of health is the gut microbiome, which might be disrupted by various stressors associated with environmental change. We have studied the gut microbiome of grey-brown mouse lemurs (Microcebus griseorufus), one of the smallest Malagasy primates and an important model of the convergent evolution of diseases. We sampled two sites: one situated in a national park and the other consisting of a more disturbed site around human settlement. We found that more intense anthropogenic disturbances indeed disrupted the gut microbiome of this lemur species marked by a reduction in bacterial diversity and a shift in microbial community composition. Interestingly, we noted a decrease in beneficial bacteria (i.e. members of the Bacteroidaceae family) together with a slight increase in disease-associated bacteria (i.e. members of the Veillonellaceae family), and alterations in microbial metabolic functions. Because of the crucial services provided by the microbiome to pathogen resistance and host health, such negative alterations in the gut microbiome of mouse lemurs inhabiting anthropogenically disturbed habitats might render them susceptible to diseases and ultimately affecting their survival in the shrinking biodiversity seen in Madagascar. Gut microbiome analyses might thus serve as an early warning signal for pending threats to lemur populations.
... Perturbed microbiota are increasingly recognized as culprits of obesity, gastrointestinal distress, and even associated mortality in captive animals [79,[126][127][128]. Given that lemurs are among the most endangered mammals on the planet [129], maintaining populations of healthy animals in captivity is an important 'safety net' that augments in-vivo conservation efforts [130,131]. We suggest that environmental acquisition may be a key component of 'rewilding' or 'bioaugmenting' captive animal gut microbiota, a process by which gut consortia can be reshaped to better promote host-microbe symbiosis [26,130,132]. ...
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Background Inter-population variation in host-associated microbiota reflects differences in the hosts’ environments, but this characterization is typically based on studies comparing few populations. The diversity of natural habitats and captivity conditions occupied by any given host species has not been captured in these comparisons. Moreover, intraspecific variation in gut microbiota, generally attributed to diet, may also stem from differential acquisition of environmental microbes—an understudied mechanism by which host microbiomes are directly shaped by environmental microbes. To more comprehensively characterize gut microbiota in an ecologically flexible host, the ring-tailed lemur ( Lemur catta ; n = 209), while also investigating the role of environmental acquisition, we used 16S rRNA sequencing of lemur gut and soil microbiota sampled from up to 13 settings, eight in the wilderness of Madagascar and five in captivity in Madagascar or the U.S. Based on matched fecal and soil samples, we used microbial source tracking to examine covariation between the two types of consortia. Results The diversity of lemur gut microbes varied markedly within and between settings. Microbial diversity was not consistently greater in wild than in captive lemurs, indicating that this metric is not necessarily an indicator of host habitat or environmental condition. Variation in microbial composition was inconsistent both with a single, representative gut community for wild conspecifics and with a universal ‘signal of captivity’ that homogenizes the gut consortia of captive animals. Despite the similar, commercial diets of captive lemurs on both continents, lemur gut microbiomes within Madagascar were compositionally most similar, suggesting that non-dietary factors govern some of the variability. In particular, soil microbial communities varied across geographic locations, with the few samples from different continents being the most distinct, and there was significant and context-specific covariation between gut and soil microbiota. Conclusions As one of the broadest, single-species investigations of primate microbiota, our study highlights that gut consortia are sensitive to multiple scales of environmental differences. This finding begs a reevaluation of the simple ‘captive vs. wild’ dichotomy. Beyond the important implications for animal care, health, and conservation, our finding that environmental acquisition may mediate aspects of host-associated consortia further expands the framework for how host-associated and environmental microbes interact across different microbial landscapes.
... Vocalizations have long been used to assist assessments of presence/absence or abundance of some primate species, such as gibbons or titi monkeys (Brockelman & Srikosamatara, 1993;Kidney et al., 2016;Gestich et al., 2017). Therefore, using PAM to assist conservation practice in Madagascar's lemurs is especially interesting as the lemurs are one of the most endangered groups of mammals (Schwitzer et al., 2014). New methods for cost-effective monitoring of lemur populations are essential to assess ongoing conservation efforts and for their future survival (Schwitzer et al., 2013). ...
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Developing new cost-effective methods for monitoring the distribution and abundance of species is essential for conservation biology. Passive acoustic monitoring (PAM) has long been used in marine mammals and has recently been postulated to be a promising method to improve monitoring of terrestrial wildlife as well. Because Madagascar’s lemurs are among the globally most threatened taxa, this study was designed to assess the applicability of an affordable and open-source PAM device to estimate the density of pale fork-marked lemurs (Phaner pallescens). Using 12 playback experiments and one fixed transect of four automated acoustic recorders during one night of the dry season in Kirindy Forest, we experimentally estimated the detection space for Phaner and other lemur vocalizations. Furthermore, we manually annotated more than 10,000 vocalizations of Phaner from a single location and used bout rates from previous studies to estimate density within the detection space. To truncate detections beyond 150 m, we applied a sound pressure level (SPL) threshold filtering out vocalizations below SPL 50 (dB re 20 μPa). During the dry season, vocalizations of Phaner can be detected with confidence beyond 150 m by a human listener. Within our fixed truncated detection area corresponding to an area of 0.07 km2 (detection radius of 150 m), we estimated 10.5 bouts per hour corresponding to a density of Phaner of 38.6 individuals/km2. Our density estimates are in line with previous estimates based on individually marked animals conducted in the same area. Our findings suggest that PAM also could be combined with distance sampling methods to estimate densities. We conclude that PAM is a promising method to improve the monitoring and conservation of Phaner and many other vocally active primates.
... Lemurs across Madagascar face extinction risks driven by human disturbance of forest habitats and they are considered to be the most threatened mammal group on earth . Nocturnal lemurs in particular are highly threatened due to habitat loss and illegal bushmeat hunting (Fa and Brown, 2009;Schwitzer et al., 2014). This applies also to the nocturnal lemurs within the Alaotra-Mangoro region . ...
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In April 2000, the Masoala forest was devastated by a very intense category 4 cyclone, called Hudah. Studies were carried out on the impacts of this natural disaster on the population of the diurnal lemur Varecia rubra which were carried out one year (2001) and four years (2004) after its passage in a site named Antsahamanara, located on the east coast of the Masoala peninsula, the region most affected by this cyclone. This study is conducted in 2018 at the same site, during the same season and applying the same data collection methods as those used during the previous studies. It consists in determining the variations on the demographic and habitat parameters, the time budget and the availability of food eighteen years after the passage of Hurricane Hudah. From this study, changes in these parameters were reported suggesting an adaptation strategy of Varecia rubra to the degradation of its habitat despite its vulnerability.
... The impact can be all the stronger as the natural regeneration of forests in Madagascar appears slowed down by the slow growth rate of trees, the washing of soils due to erosion, and relatively inefficient pioneer plant species and secondary vegetation (Koechlin et al., 1974;Ganzhorn, 1988;Wright, 1999;Leigh et al., 2007). Together with illegal hunting and organized timber trade, deforestation and forest fragmentation have resulted in the loss of large mammals, including primates and less emblematic animals (Schwitzer et al., 2014;Eppley et al., 2020). However, more positive perspectives for maintaining biodiversity can be expected in some places (Cormier-Salem, 2006;Aubertin and Rodary, 2009;Méral et al., 2009), for instance where human conceptions about nature are favorable to biological conservation and deserve to be supported at national and international level beyond traditional representations. ...
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Biological conservation projects conducted in inhabited areas are often based on the combination of ecological diagnostics and study of practices and use of the environment by local communities. They less frequently integrate the influence of the perception and representation of nature on these practices, while these should also be taken into account in the initiation of sustainable conservation actions. We carried out a long-term study combining biological and social science approaches in North-western Madagascar in the Antrema protected area (with dry forest/savannah/coastal ecosystems), including an analysis of the use and perception of nature by its inhabitants. Together with the study of tree diversity, forest structure and biomass in 7 forest fragments, we estimated population densities of whole communities of diurnal and nocturnal lemurs, one of which is considered sacred. We interviewed local resource users from several villages using classical methods of social anthropology supplemented with perception tests derived from sensory evaluation methods. The structure of forest fragments as well as their basal area and richness in tree species varied with human pressure on specific plants (timber extraction) or with historical changes in pasture management (forest regrowth). Lemurs were generally abundant, with a high total biomass compared to other dry forests. Although the inhabitants of Antrema (Sakalava, Tsimihety, and Betsileo) still strongly adhered to local use rights and shared deeply rooted knowledge about the forest, the use and perception of nature (e.g., regarding the sacred lemur Propithecus coronatus ) have changed since the Antrema protection project in 2000. The results suggest that local communities tend to integrate traditional rules about nature with international environmental regulation, perhaps a sign of a new ecological awareness. However, in the new management mode accompanying this transition, it can also be a means of local empowerment that takes advantage of a program supporting pro-environmental management of the Antrema area.
... Lemurs are the most threatened group of mammals in the world (C. Schwitzer et al., 2014). These arboreal primates are all threatened by forest loss, fragmentation, and degradation, but individual species respond differently to changing habitat Irwin et al., 2010;Lehman, 2007). ...
Article
Madagascar's lemurs are threatened by forest loss, fragmentation, and degradation. Many species use flexible behaviors to survive in degraded habitat, but their ability to persist in very small areas may be limited. Insular lemurs, like those found on Nosy Be, an island off the northwestern coast of Madagascar, are at heightened risk of sudden population declines and extirpation. Nosy Be is home to two Critically Endangered species-the endemic Nosy Be sportive lemur (Lepilemur tymerlachsoni) and Claire's mouse lemur (Microcebus mamiratra)-as well as the Endangered black lemur (Eulemur macaco). Most of the remaining forest on Nosy Be is protected by the 862-ha Lokobe National Park. To document how Nosy Be lemurs use their restricted habitat, we conducted vegetation and reconnaissance surveys on 53 transects in and around Lokobe. We collected data on tree size, canopy cover, understory visibility, and elevation for 248 lemur sightings. We used a spatially explicit, multi-species occupancy model to investigate which forest-structure variables are important to lemurs. Our results represent some of the first data on habitat use by insular lemurs. Black lemurs preferred significantly larger trees and areas with less dense understory. They also occurred significantly less outside of Lokobe National Park, even when accounting for sampling effort and geography. The distributions of the sportive and mouse lemurs were not related to the forest structure variables we documented, but they did negatively predict each other-perhaps because their habitat requirements differ. These results also underscore the importance of the national park to protecting the black lemur population on Nosy Be and raise questions about what factors do influence the distribution of Nosy Be's smaller lemurs. Close monitoring is needed to prevent these populations and the ecosystem services they provide from disappearing, as have other island lemurs.
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The birds (avian) in India are endemic to different hotspots play a vital role in balancing the ecosystem and its functions. They have a significant role in providing the pollination of various plant species. Eco-tourism plays a very important economic activity in any protected area and institution. Habitats disturbance has been shown to negatively impact avifauna nesting and foraging and also disturb the fledging times. The study was conducted to illustrate the fluctuation in the numbers of individuals of avifauna by daily vis-itor's entries in Forest Research Institute, Dehradun, In-dia. We observed daily tourists and some surrounding common species of avifauna in Forest Research Institute , Dehradun Campus. The objectives of this study are to find out the visitors' impacts on populations of birds species and habitat conservation and disruption. During the study, we found that the species which habitats are in near-human settled areas are the least influenced by visitors, and those species which habitats are generally natural forest types are effectively most. The finding shows that increasing numbers of visitors per day also impact the individual number of species. The study concludes an early warning alarm for the habitat perturbation as the number of visitors increases, the species populations are showing disturbed and the number of individuals appears less.
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Although many protected areas are foci for scientific research, they also face growing threats from illegal encroachment and overharvesting. Does the presence of field researchers help to limit such threats? Although evidence is largely anecdotal, researchers do appear to provide some protective effects, both actively (such as by deterring poachers) and passively (such as by benefiting local communities economically and thereby generating support for protected areas). However, much remains unknown about the generality and impacts of such benefits. A key priority is to develop a better understanding of the advantages and limitations of field research for aiding protected areas and their biodiversity.
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We sought to assess the role of lemurs for seed dispersal in the dry deciduous forest of western Madagascar and the possible consequences of the demise of lemurs for forest regeneration. Forest regeneration was studied in eight plots in two large blocks of primary forest and in seven fragments of primary forest (1 plot per fragment). In 4 of the 15 study plots, the abundance of saplings was negatively and significantly correlated (p < 0.05) with the abundance of mature individuals of the same tree species. In another 10 study plots there were negative correlations, although these were not significant on the community level. Second-order statistics were significant with p < 0.001 and indicated that seed dispersal away from the parent trees was important for successful establishment of saplings. Apart from possibly the bush pig (Potamochoerus larvatus), only one vertebrate species of the dry forest, the brown lemur (Eulemur fulvus), ingested seeds >11 mm long and passed them through its digestive tract unharmed. These results for lemurs were based on direct observations and fecal analyses. To evaluate the role of E. fulvus, we compared regeneration in forest plots with and without E. fulvus. In forest fragments without E. fulvus, fewer lemur-dispersed tree species regenerated than would be expected based on the presence of mature tree species that are lemur-dispersed (p < 0.05). No such effect was seen in primary forests with E. fulvus or for trees whose seeds can also be dispersed by other vertebrates. Thus, regeneration of the dry deciduous forest of western Madagascar with the complete set of primary forest tree species seems to depend upon the presence of E. fulvus.
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Understanding the patterns of wild meat consumption from tropical forests is important for designing approaches to address this major threat to biodiversity and mitigate potential pathways for transmission of emerging diseases. Bushmeat consumption has been particularly poorly studied in Madagascar, one of the world's hottest biodiversity hotspots. Studying bushmeat consumption is challenging as many species are protected and researchers must consider the incentives faced by informants. Using interviews with 1154 households in 12 communes in eastern Madagascar, as well as local monitoring data, we investigated the importance of socio-economic variables, taste preference and traditional taboos on consumption of 50 wild and domestic species. The majority of meals contain no animal protein. However, respondents consume a wide range of wild species and 95% of respondents have eaten at least one protected species (and nearly 45% have eaten more than 10). The rural/urban divide and wealth are important predictors of bushmeat consumption, but the magnitude and direction of the effect varies between species. Bushmeat species are not preferred and are considered inferior to fish and domestic animals. Taboos have provided protection to some species, particularly the Endangered Indri, but we present evidence that this taboo is rapidly eroding. By considering a variety of potential influences on consumption in a single study we have improved understanding of who is eating bushmeat and why. Evidence that bushmeat species are not generally preferred meats suggest that projects which increase the availability of domestic meat and fish may have success at reducing demand. We also suggest that enforcement of existing wildlife and firearm laws should be a priority, particularly in areas undergoing rapid social change. The issue of hunting as an important threat to biodiversity in Madagascar is only now being fully recognised. Urgent action is required to ensure that heavily hunted species are adequately protected.
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Predicted forest losses and a recent government ban on logging build support for trade protection of Malagasy rosewood.
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