No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Every flight is a surprise: first records of the southern maned three-toed sloth (Bradypus crinitus: Bradypodidae) through drones
Mammalia
Abstract
Every flight is a surprise: first records of the southern maned three-toed sloth (Bradypus crinitus: Bradypodidae) through drones Abstract: Drones (unmanned aerial vehicles, UAVs), are an advanced technology that allows the collection of large amounts of data in a short amount of time, including the detection of cryptic and arboreal animals. Here, we report the first records of the southern maned sloth Bradypus crinitus obtained with thermal cameras from a drone. As far as we know, this is the first time a sloth has been observed by a drone. We recorded four individuals of B. crinitus in the Brazilian Atlantic Forest, plus first records of Procyon cancrivorus, which were all resting in the forest canopy. The individuals' thermal responses demonstrate that the use of drones for research on these species may be a viable option to study still unexplored aspects of their ecology or conservation.
... A utilização de novas tecnologias de biomonitoramento, como DNA ambiental (Sales et al. 2020), armadilhas fotográficas no dossel (Kaizer et al. 2022), gravadores acústicos passivos (Duarte et al. 2018, Mancini et al. 2022), e drone com câmera termal (Melo 2021;Santos et al. 2023), podem oferecer dados confiáveis e uma melhor compreensão dos mamíferos em escala espacial e temporal na região, em especial para aquelas espécies raras, arborícolas ou de hábitos crípticos, que muitas vezes não são detectadas pelos métodos tradicionais de estudo (Santos et al. 2016). Feijó, A., et al. (2022). ...
Resumo Identificar e analisar as lacunas de biodiversidade é fundamental para elencar e priorizar áreas para pesquisa, manejo e conservação. A região Central Serrana do Espírito Santo possui uma inegável importância para a conservação da biodiversidade, porém ainda são necessárias pesquisas indicando a distribuição dos registros de espécies e a riqueza da região. Assim, este estudo visou iden-tificar áreas importantes para a conservação por meio da análise de lacunas. Compilamos registros de mamíferos para a região, provenientes de diferentes bases de dados e publicações. A partir desse conjunto atualizado de dados, realizamos análises espaciais de densidade de kernel e de riqueza. Também identificamos o avanço temporal dos registros, assim como verificamos os registros em áreas protegidas e fora delas. Ao todo, nossa base reuniu 2.798 registros considerados potencialmente seguros, englobando 121 espécies de mamíferos silvestres. O município de Santa Teresa concentra a maioria dos registros, localizados, principalmente, em suas áreas protegidas. Já o município de Itarana abrange um menor número de registros. Essa desproporcionalidade na distribuição dos registros certamente está relacionada a um viés amostral, mas também pode refletir uma maior riqueza nas áreas protegidas. De modo geral, a região Central Serrana do Espírito Santo apresenta uma alta represen-tatividade em termos de riqueza, sendo um importante refúgio para diversas espécies ameaçadas de mamíferos.
... A utilização de drones com sensores térmicos para estudos de conservação ainda é algo que precisa ser meticulosamente avaliada, pois se trata de uma tecnologia cara, tornandoa bastante inacessível para muitos pesquisadores (SANTOS et al., 2023). Além disso, é essencial investir em cursos preparatórios específicos para o uso de drones, com foco nos drones térmicos, considerando que os voos serão realizados à noite, o que exige um cuidado ainda maior durante os voos. ...
Technological advances have enabled new methods for surveying fauna, such as the use of drones. This study aimed to evaluate the effectiveness of drones with thermal sensors in detecting Coendou baturitensis, an arboreal rodent popularly known as porcupine. Carried out in the municipality of Mulungu, in a fragment of the Atlantic Forest located in the Caatinga biome, the study involved three night flights, totaling 43 minutes (0.7 hours) of flight time. During this period, three individuals of Coendou baturitensis were recorded, with an encounter rate of 4.28 individuals per hour. The results demonstrate the efficiency of thermal drones for detecting and monitoring this species. Despite its proven effectiveness, we recommend conducting comparative studies with other fauna monitoring methods to validate and improve this technique.
... Taxonomic revisions are also important given its distribution has expanded significantly, which may indicate we are dealing with a different species, as was recently discovered for sloths of genus Bradypus (Miranda et al., 2023). Therefore, it is essential to promote more studies on the little-known arboreal mammal diversity of the central-southern Amazon, especially research employing new techniques of biodiversity survey, such as drones equipped with thermal cameras (Melo, 2021;Santos et al., 2023), canopy camera trapping (Kaizer et al., 2022), and environmental DNA metabarcoding (Sales et al., 2020), which can help detecting cryptic species such as sloths. ...
We documented new records of Choloepus didactylus extending up to 820 km south of its current geographic distribution. These records, and others found in literature for the central‐southern Amazon, evidence a southern expansion of about 30% of the known species' area of occurrence and help shedding light on decades of uncertainties about its real distribution.
Abstract in Portuguese is available with online material.
Tree kangaroos (Dendrolagus spp.) are poorly studied owing to their elusive arboreal nature, which makes detection difficult using traditional methods such as spotlighting and hand-held thermal cameras. This note documents the first successful detection of Bennett’s tree kangaroos (D. bennettianus) using thermal drones in tropical rainforest at Cape Tribulation, Australia. In less than an hour, six individuals were observed across 17 ha. The method proved minimally invasive and highly effective in rainforest environments despite dense vegetation and high temperatures, demonstrating both the unexpected abundance of this species and the utility of thermal drones for monitoring tropical arboreal fauna.
The Atlantic Forest of South America supports a rich terrestrial biodiversity but has been reduced to only a small extent of its original forest cover. It hosts a large number of endemic mammalian species but our knowledge of arboreal mammal ecology and conservation has been limited because of the challenges of observing arboreal species from ground level. Camera trapping has proven to be an effective tool in terrestrial mammal monitoring but the technique has rarely been used for arboreal species. For the first time in the Atlantic Forest, we obtained data on the arboreal mammal community using arboreal camera trapping, focusing on Caparaó National Park, Brazil. We placed 24 infrared camera traps in the forest canopy in seven areas within the Park, operating them continuously during January 2017–June 2019. During this period the camera traps accumulated 4,736 camera-days of footage and generated a total of 2,256 photographs and 30-s videos of vertebrates. The arboreal camera traps were able to detect arboreal mammals of a range of body sizes. The mammal assemblage comprised 15 identifiable species, including the Critically Endangered northern muriqui Brachyteles hypoxanthus and buffy-headed marmoset Callithrix flaviceps as well as other rare, nocturnal and inconspicuous species. We confirmed for the first time the occurrence of the thin-spined porcupine Chaetomys subspinosus in the Park. Species richness varied across survey areas and forest types. Our findings demonstrate the potential of arboreal camera trapping to inform conservation strategies.
Abstract Drones and machine learning‐based automated detection methods are being used by ecologists to conduct wildlife surveys with increasing frequency. When traditional survey methods have been evaluated, a range of factors have been found to influence detection probabilities, including individual differences among conspecific animals, which can thus introduce biases into survey counts. There has been no such evaluation of drone‐based surveys using automated detection in a natural setting. This is important to establish since any biases in counts made using these methods will need to be accounted for, to provide accurate data and improve decision‐making for threatened species. In this study, a rare opportunity to survey a ground‐truthed, individually marked population of 48 koalas in their natural habitat allowed for direct comparison of the factors impacting detection probability in both ground observation and drone surveys with manual and automated detection. We found that sex and host tree preferences impacted detection in ground surveys and in manual analysis of drone imagery with female koalas likely to be under‐represented, and koalas higher in taller trees detected less frequently when present. Tree species composition of a forest stand also impacted on detections. In contrast, none of these factors impacted on automated detection. This suggests that the combination of drone‐captured imagery and machine learning does not suffer from the same biases that affect conventional ground surveys. This provides further evidence that drones and machine learning are promising tools for gathering reliable detection data to better inform the management of threatened populations.
Accurate and precise population estimates form the basis of conservation action but are lacking for many arboreal species due to the high costs and difficulty in surveying these species. Recently, researchers have started to use drones to obtain data on animal distribution and density. In this study, we compared ground and drone counts for spider monkeys (Ateles geoffroyi) at their sleeping sites using a custom-built drone fitted with a thermal infrared (TIR) camera. We demonstrated that a drone with a TIR camera can be successfully employed to determine the presence and count the number of spider monkeys in a forested area. Using a concordance analysis, we found high agreement between ground and drone counts for small monkey subgroups (<10 individuals), indicating that the methods do not differ when surveying small subgroups. However, we found low agreement between methods for larger subgroups (>10 individuals), with drone counts being higher than the corresponding ground counts in 83% of surveys. We could identify additional individuals from TIR drone footage due to a greater area covered compared to ground surveys. We recommend using TIR drones for surveys of spider monkey sleeping sites and discuss current challenges to implementation.
The proliferation of relatively affordable off-the-shelf drones offers great opportunities for wildlife monitoring and conservation. Similarly the recent reduction in cost of thermal infrared cameras also offers new promise in this field, as they have the advantage over conventional RGB cameras of being able to distinguish animals based on their body heat and being able to detect animals at night. However, the use of drone-mounted thermal infrared cameras comes with several technical challenges. In this paper we address some of these issues, namely thermal contrast problems due to heat from the ground, absorption and emission of thermal infrared radiation by the atmosphere, obscuration by vegetation, and optimizing the flying height of drones for a best balance between covering a large area and being able to accurately image and identify animals of interest. We demonstrate the application of these methods with a case study using field data, and make the first ever detection of the critically endangered riverine rabbit (Bunolagus monticularis) in thermal infrared data. We provide a web-tool so that the community can easily apply these techniques to other studies
Animals of the rainforest canopies are often endangered by deforestation or hunting but are difficult to survey and study because of the inaccessibility of the treetops, combined with the visual camouflage of many species. Drone-based thermal sensors have the potential to overcome these hurdles by rapidly scanning large forested areas from above, detecting and mapping wildlife based on the contrast between their warm body temperatures and the cool tree canopies. We tested this concept by flying a drone-mounted thermal infrared radiometric sensor over the wildlife-rich rainforests of Barro Colorado Island, Panama. Arboreal mammals had body temperatures around 27°C and were conspicuous in the thermal infrared imagery at night and early morning when the forest canopy was cool (23–25°C), but were difficult to detect by mid-morning, by which time the direct sunshine had heated up canopy vegetation to over 30°C. Species were difficult to identify from thermal infrared imagery alone, but could be recognized from synchronized visual images taken during the daytime. Simultaneous drone and ground-based surveys of the same area proved that the aerial thermal camera did detect high-canopy species missed by the terrestrial observer, but that substantially more animals were detected by the human than by the drone. Because animal detection was so much better at night, when species ID was difficult, we suggest that future work could combine automated detection of animals from thermal infrared imagery with flash photography or IR illumination to enable species ID during nocturnal surveys. We conclude by discussing various logistical challenges that limit the utility of drone-based thermal infrared today, but that could be overcome by continued improvement of technology and collaboration with permitting agencies.
Attitudes among conservation biologists towards technological innovations and solutions have changed over the years from mistrusting and dismissive to widely accepting. However, the time has come for the conservation community to move from being technology consumers to become innovation leaders and to actively seek to create novel technologies to provide conservation tools and solutions. This challenging but critical mind‐set change requires thinking outside the box to establish and support the necessary bridges between the conservation community, technologists in both the public and the private sectors, and policy makers. The ingredients already exist, but success hinges on an open mind to new types of interactions, and bold but coordinated movements to nurture the organisational ecosystem in which such collaborations can thrive and be funded.
This article is protected by copyright. All rights reserved
Tropical deforestation continues to be a major driver of biodiversity loss and greenhouse gas emissions. Remote sensing technology is increasingly used to assess changes in forest cover, species distributions and carbon stocks. However, satellite and airborne sensors can be prohibitively costly and inaccessible for researchers in developing countries. Here, we describe the development and use of an inexpensive (<$2,000) unmanned aerial vehicle for surveying and mapping forests and biodiversity (referred to as ‘Conservation Drone’ hereafter). Our prototype drone is able to fly pre-programmed missions autonomously for a total flight time of ~25 minutes and over a distance of ~15 km. Non-technical operators can program each mission by defining waypoints along a flight path using an open-source software. This drone can record videos at up to 1080 pixel resolution (high definition), and acquire aerial photographs of <10 cm pixel resolution. Aerial photographs can be stitched together to produce real-time geo-referenced land use/cover maps of surveyed areas. We evaluate the performance of this prototype Conservation Drone based on a series of test flights in Aras Napal, Sumatra, Indonesia. We discuss the further development of Conservation Drone 2.0, which will have a bigger payload and longer range. Initial tests suggest a flight time of ~50 minutes and a range of ~25 km. Finally, we highlight the potential of this system for environmental and conservation applications, which include near real-time mapping of local land cover, monitoring of illegal forest activities, and surveying of large animal species.
The transformation of natural landscapes in extensive anthropogenic areas has significantly affected ecological processes, and studies that evaluate such changes are essential for the definition of conservation strategies. In this study, we sought to identify the variables influencing the occupancy of Atlantic forest fragments by the endemic and endangered maned sloth. We selected 33 sampling stations, distributed at least 500 m apart throughout the municipality of Santa Maria de Jetibá—ES, Brazil. We sampled each station five times to verify the presence or absence of the species and to collect local variables. Using GIS tools, we defined a buffer of 200 m around each fragment and calculated the landscape metrics. After analysis of collinearity, we selected six variables – three local variables, two at patch level and one at landscape level – to assess their effect on the occupancy and detection probabilities. We selected models using AICc and calculated the weight of evidence and ratio of the models as well as the cumulative weight of each predictor variable. We detected the sloth in 48% of the stations. Its occupation was positively correlated to two variables on the local scale: Important Feeding Trees and Canopy height. Our results show that the maned sloth respond to fine local scale variables, but not to landscape structure. This is probably associated with the relatively high proportion of forest cover in the study area, but it also indicates the maned sloth flexibility to occupy fragmented landscape. Based on our results, we reinforce the unquestionable importance of local variables for species occupancy within fragmented landscapes, such as those related with the forest structure, and it is particularly important for strictly arboreal species.
To conserve biodiversity scientists monitor wildlife populations and their habitats. Current methods have constraints such as the costs of ground or aerial surveys, limited resolution of freely-available satellite images, and expensive high resolution satellite images. Recently researchers started to use unmanned aerial vehicles (aka UAVs or drones) for wildlife and habitat monitoring. Here we tested whether we could detect nests of the critically endangered Sumatran orang-utan on imagery acquired from camera mounted drone to determine distribution and density. Our results show that the distribution of nests compares well between aerial and ground based surveys and that relative density (nest/km) shows a significant correlation between these two survey types. The results also indicate that both methods can be used to detect significant differences in relative density between previously degraded reforested and enriched areas. We conclude that orang-utan nest surveys from drones are a promising survey method to determine distribution and (relative) density of this and perhaps other ape species.
Technologies to identify individual animals, follow their movements, identify and locate animal and plant species, and assess the status of their habitats remotely have become better, faster, and cheaper as threats to the survival of species are increasing. New technologies alone do not save species, and new data create new problems. For example, improving technologies alone cannot prevent poaching: solutions require providing appropriate tools to the right people. Habitat loss is another driver: the challenge here is to connect existing sophisticated remote sensing with species occurrence data to predict where species remain. Other challenges include assembling a wider public to crowdsource data, managing the massive quantities of data generated, and developing solutions to rapidly emerging threats.
Three-toed sloths (Bradypus) are heterothermic, and ambient temperature may have a direct effect on their activity levels. Our goal was to describe the time budget, pattern and rhythm of activity of the maned sloth, Bradypus torquatus (Xenarthra: Bradypodidae), and to evaluate the effect of ambient temperature on its activity. We hypothesized that (1) sloth activity increases with ambient temperature, fluctuating with the circadian temperature cycle, and (2) sloths are more active in the diurnal period during colder seasons than warm seasons due to constraints or avoidance of the colder times within a 24-h cycle. Nine radio-collared individuals were followed in forest remnants in southern Bahia, Brazil from March 2003 to April 2014. Behavior data of 8 sloths were collected during the diurnal period by direct visualization (608 h of record), and the activities of 4 sloths were recorded by an automated system during continuous hours (744 h of record). The maned sloths exhibited low activity levels, resting 77% of a 24-h period. In general, they were cathemeral, although they were twice as active in the diurnal phase (active 32% of the time) compared with the nocturnal phase (15%). The ambient temperature had a significant positive effect on activity levels. The rhythm of activity was circadian and synchronized with the ambient temperature. No difference was detected in the diurnal activity between hotter and colder seasons, most likely reflecting the low fluctuations in climatic conditions of this tropical forest. The narrow relationship between the circadian activity pattern of maned sloths and the ambient temperature cycle highlights their poor thermoregulatory ability. The lower activity levels exhibited during colder times may represent a behavioral adaptation that reduces heat loss, enhances body temperature control and optimizes energetic benefits, a key feature for a species relying on a low energetic diet.
The maned sloth Bradypus torquatus (Pilosa, Bradypodidae) is endemic to a small area in the Atlantic Forest of coastal Brazil.
It has been listed as a threatened species because of its restricted geographic range, habitat loss and fragmentation, and
declining populations. The major objectives of this study were to estimate its potential geographic distribution, the climatic
conditions across its distributional range, and to identify suitable areas and potential species strongholds. We developed a
model of habitat suitability for the maned sloth using two methods, Maxent and Mahalanobis Distance, based on 42
occurrence points. We evaluated environmental variable importance and the predictive ability of the generated distribution
models. Our results suggest that the species distribution could be strongly influenced by environmental factors, mainly
temperature seasonality. The modeled distribution of the maned sloth included known areas of occurrence in the Atlantic
Forest (Sergipe, Bahia, Espı´rito Santo, and Rio de Janeiro), but did not match the observed distributional gaps in northern
Rio de Janeiro, northern Espı´rito Santo or southern Bahia. Rather, the model showed that these areas are climatically
suitable for the maned sloth, and thus suggests that factors other than climate might be responsible for the absence of
species. Suitable areas for maned sloth were located mainly in the mountainous region of central Rio de Janeiro throughout
Espı´rito Santo and to the coastal region of southern Bahia. We indicate 17 stronghold areas and recommended survey areas
for the maned sloth. In addition, we highlight specific areas for conservation, including the current network protected areas.
Our results can be applied for novel surveys and discovery of unknown populations, and help the selection of priority areas
for management and conservation planning, especially of rare and relatively cryptic species directed associated with
forested habitats.
Ecologists require spatially explicit data to relate structure to function. To date, heavy reliance has been placed on obtaining such data from remote-sensing instruments mounted on spacecraft or manned aircraft, although the spatial and temporal resolutions of the data are often not suited to local-scale ecological investigations. Recent technological innovations have led to an upsurge in the availability of unmanned aerial vehicles (UAVs) – aircraft remotely operated from the ground – and there are now many lightweight UAVs on offer at reasonable costs. Flying low and slow, UAVs offer ecologists new opportunities for scale-appropriate measurements of ecological phenomena. Equipped with capable sensors, UAVs can deliver fine spatial resolution data at temporal resolutions defined by the end user. Recent innovations in UAV platform design have been accompanied by improvements in navigation and the miniaturization of measurement technologies, allowing the study of individual organisms and their spatiotemporal dynamics at close range.
Read More: http://www.esajournals.org/doi/abs/10.1890/120150
Unmanned Aircraft Systems (UAS) have evolved rapidly over the past decade driven primarily by military uses, and have begun finding application among civilian users for earth sensing reconnaissance and scientific data collection purposes. Among UAS, promising characteristics are long flight duration, improved mission safety, flight repeatability due to improving autopilots, and reduced operational costs when compared to manned aircraft. The potential advantages of an unmanned platform, however, depend on many factors, such as aircraft, sensor types, mission objectives, and the current UAS regulatory requirements for operations of the particular platform. The regulations concerning UAS operation are still in the early development stages and currently present significant barriers to entry for scientific users. In this article we describe a variety of platforms, as well as sensor capabilities, and identify advantages of each as relevant to the demands of users in the scientific research sector. We also briefly discuss the current state of regulations affecting UAS operations, with the purpose of informing the scientific community about this developing technology whose potential for revolutionizing natural science observations is similar to those transformations that GIS and GPS brought to the community two decades ago.
A meeting on Biodiversity Technologies was held by the Biodiversity Institute, Oxford on the 27-28 of September 2012 at the Department of Zoology, University of Oxford. The symposium brought together 36 speakers from North America, Australia and across Europe, presenting the latest research on emerging technologies in biodiversity science and conservation. Here we present a perspective on the general trends emerging from the symposium. © 2012 The Author(s) Published by the Royal Society. All rights reserved.
1. Structural diversity and niche differences within habitats are important for stabilizing species coexistence. However, land-use change leading to environmental homogenization is a major cause for the dramatic decline of biodiversity under global change. The difficulty in assessing large-scale biodiversity losses urgently requires new technological advances to evaluate land-use impact on diversity timely and efficiently across space.
2. While cost-effective aerial images have been suggested for potential biodiversity assessments in forests, correlation of canopy object variables such as gaps with plant or animal diversity has so far not been demonstrated using these images.
3. Here, we show that aerial images of canopy gaps can be used to assess floristic biodiversity of the forest understorey. This approach is made possible because we employed cutting-edge unmanned aerial vehicles and very high-resolution images (7 cm pixel−1) of the canopy properties. We demonstrate that detailed, spatially implicit information on gap shape metrics is sufficient to reveal strong dependency between disturbance patterns and plant diversity (R2 up to 0·74). This is feasible because opposing disturbance patterns such as aggregated and dispersed tree retention directly correspond to different functional and dispersal traits of species and ultimately to different species diversities.
4. Our findings can be used as a coarse-filter approach to conservation in forests wherever light strongly limits regeneration and biodiversity.
Tropical deforestation continues to be a major driver of biodiversity loss and greenhouse gas emissions. Remote sensing technology is increasingly used to assess changes in forest cover, species distributions and carbon stocks. However, satellite and airborne sensors can be prohibitively costly and inaccessible for researchers in developing countries. Here, we describe the development and use of an inexpensive (<$2,000) unmanned aerial vehicle for surveying and mapping forests and biodiversity (referred to as 'Conservation Drone' hereafter). Our prototype drone is able to fly pre-programmed missions autonomously for a total flight time of ~25 minutes and over a distance of ~15 km. Non-technical operators can program each mission by defining waypoints along a flight path using an open-source software. This drone can record videos at up to 1080 pixel resolution (high definition), and acquire aerial photographs of <10 cm pixel resolution. Aerial photographs can be stitched together to produce real-time geo-referenced land use/cover maps of surveyed areas. We evaluate the performance of this prototype Conservation Drone based on a series of test flights in Aras Napal, Sumatra, Indonesia. We discuss the further development of Conservation Drone 2.0, which will have a bigger payload and longer range. Initial tests suggest a flight time of ~50 minutes and a range of ~25 km. Finally, we highlight the potential of this system for environmental and conservation applications, which include near real-time mapping of local land cover, monitoring of illegal forest activities, and surveying of large animal species.
Climate change and habitat loss have been identified as the main causes of species extinction. Forest regeneration and protected areas are essential to buffer climate change impacts and to ensure quality habitats for threatened species. We assessed the current and future environmental suitability for the maned sloth, Bradypus torquatus, under both future climate and forest restoration scenarios, using ecological niche modeling. We compared environmental suitability for two Evolutionarily Significant Units (ESUnorth and ESUsouth) using two climate change scenarios for 2070, and three potential forest regeneration scenarios. Likewise, we evaluated the protection degree of the suitable areas resulting from the models, according to Brazilian law: PA—Protected Areas; PPA—Permanent Protection Areas (environmentally sensitive areas in private properties); and LR—Legal Reserves (natural vegetation areas in private properties). Finally, we calculated the deficit of PPA and LR in each ESU, considering the current forest cover. Forest regeneration might mitigate the deleterious effects of climate change by maintaining and increasing environmental suitability in future scenarios. The ESUnorth contains more suitable areas (21,570 km²) than the ESUsouth (12,386 km²), with an increase in all future scenarios (up to 45,648 km² of new suitable areas), while ESUsouth might have a significant decrease (up to 7,546 km² less). Suitable areas are mostly unprotected (ESUnorth—65.5% and ESUsouth—58.3%). Therefore, PPA and PA can maintain only a small portion of current and future suitable areas. Both ESUs present a high deficit of PPA and LR, highlighting the necessity to act in the recovery of these areas to accomplish a large-scale restoration, mitigate climate change effects, and achieve, at least, a minimum forested area to safeguard the species. Notwithstanding, a long-term conservation of B. torquatus will benefit from forest regeneration besides those minimum requirements, allied to the protection of forest areas.
We present a taxonomic revision of maned sloths, subgenus Bradypus (Scaeopus), a taxon endemic to the Brazilian Atlantic Forest and currently composed of a single species, the vulnerable Bradypus torquatus. Our review is based on coalescent species delimitation analyses using mitochondrial and nuclear DNA, morphological analyses, and field observations. Our integrative approach demonstrates that two species of maned sloth can be recognized: the northern maned sloth (Bradypus torquatus Illiger, 1811) occurring in the Brazilian states of Bahia and Sergipe, and the southern maned sloth (Bradypus crinitus Gray, 1850), occurring in Rio de Janeiro and Espirito Santo states. The two species diverged in the Early Pliocene and are allopatrically distributed. We discuss the biogeographic pattern of the two maned sloth species, comparing it with other Atlantic Forest mammals. We also suggest that the conservation status of both maned sloths needs to be reassessed after this taxonomic rearrangement.
Canopy camera trapping is being increasingly used to characterize assemblages of arboreal mammals. In this study we compared, for the first time, the assemblage of arboreal mammals of the Atlantic Forest, surveyed using canopy camera trapping at two protected areas of Mis-iones, Argentina: Piñalito (11 camera-trap stations) and Cruce Caballero (9 stations), with the assemblage recorded at ground-level with a camera-trapping survey conducted at another protected area, the nearby private reserve Valle del Alegría (18 stations). We calculated the number of independent photo-events for each species and site, and we built species rank abundance curves to compare the recorded species diversity among sites. We recorded six mammal species at Piñalito and Cruce Caballero, and 23 at Valle del Alegría. Canopy-survey sites showed lower diversity but a different and non-nested species composition when compared to the ground-level survey. One of the most frequently recorded species in the canopy, the brown-eared woolly opossum, Caluromys lanatus, categorized as Vulnerable in Argentina, has not been photographed in ground-level camera-trap surveys in Misiones before. Our results suggest that canopy camera trapping represents a robust method to sample arboreal species that are missed in ground-level camera-trap surveys, thus improving forest species inventories.
Habitat loss and the isolation of remaining habitats are undoubtedly the two greatest threats to biodiversity conservation, especially for the maned sloth, due to its ecological restrictions. In this study, we identified a critical threshold of forest cover for maned sloth occurrence and explored the effects of other local and landscape variables. We sampled 68 sites, where we searched for the maned sloth and collected local habitat variables. We calculated the percentage of forest cover and open areas, assessing the appropriated scale through model selection. We used occupancy models and model selection methods to identify the threshold and assess occupancy and detection probabilities. The occupancy probability of the maned sloth is 0.97, but it decreases abruptly at 35% of forest cover, reaching zero in areas with less than 20% of forest cover. The two landscape variables are the most important predictors of sloth occupancy, based on the cumulative weight of evidence, were: Forest cover (78%) and Open areas cover (46%); the latter influencing negatively maned sloth occupancy. This is the first attempt to identify the habitat requirements of the threatened maned sloth in a fragmented area using landscape and local variables. Our results imply that conservation of maned sloth will benefit from an increase in the amount of native forest at the landscape scale. Given difficulties in the creation of new public protected areas, this improvement could be achieved via the recovery of areas located in private properties that are protected by the Brazilian Forest Code.
The proliferation of relatively affordable off-the-shelf drones offers great opportunities for wildlife monitoring and conservation. Similarly the recent reduction in the cost of thermal infrared cameras also offers new promise in this field, as they have the advantage over conventional RGB cameras of being able to distinguish animals based on their body heat and being able to detect animals at night. However, the use of drone-mounted thermal infrared cameras comes with several technical challenges. In this article, we address some of these issues, namely thermal contrast problems due to heat from the ground, absorption and emission of thermal infrared radiation by the atmosphere, obscuration by vegetation, and optimizing the flying height of drones for a best balance between covering a large area and being able to accurately image and identify animals of interest. We demonstrate the application of these methods with a case study using field data and make the first ever detection of the critically endangered riverine rabbit (Bunolagus monticularis) in thermal infrared data. We provide a web-tool so that the community can easily apply these techniques to other studies (http://www.astro.ljmu.ac.uk/aricburk/uav_calc/).
Integration of multiple technologies greatly increases the spatial and temporal scales over which ecological patterns and processes can be studied, and threats to protected ecosystems can be identified and mitigated. A range of technology options relevant to ecologists and conservation practitioners are described, including ways they can be linked to increase the dimensionality of data collection efforts. Remote sensing, ground-based, and data fusion technologies are broadly discussed in the context of ecological research and conservation efforts. Examples of technology integration across all of these domains are provided for large-scale protected area management and investigation of ecological dynamics. Most technologies are low-cost or open-source, and when deployed can reach economies of scale that reduce per-area costs dramatically. The large-scale, long-term data collection efforts presented here can generate new spatio-temporal understanding of threats faced by natural ecosystems and endangered species, leading to more effective conservation strategies.
Three maned sloths were observed for a total of 680 h throughout 14 months in an Atlantic forest reserve of south-eastern Brazil. The study animals were located in the forest, monthly by radio-telemetry, and data on daily activity budgets were collected recording the actual time they spent in major activities. Individual home ranges were very small (0.5–6 ha, depending on the method used) and the sloths travelled an average of only 24 m during the 24 h period. A comparison between day- and night-range lengths suggests that maned sloths ranged more during daytime (17 m) than at night (5 m), indicating a predominantly diurnal period of activity. They rested, on average, for 74% of daytime, but a substantial variation was found between individuals (range 60–80%). Although a lack of synchrony was observed in activity pattern between study animals monitored simultaneously, all three sloths tended to start feeding and moving at the same time of the day (07:00–08:00), and the time that elapsed between the start of these activities on consecutive days was about 24 h, indicating a circadian rhythm of activity for the species. This finding contradicts previous studies on congeneric sloths, in which suggestions that Bradypus does not show cyclic patterns of activity were based on qualitative rather than quantitative data. Given the species' highly folivorous diet and the characteristic low basal rate of metabolism in this genus, the rather high levels of activity and the predominantly diurnal period of activity observed for maned sloths are probably related to the lower ambient temperatures found in the Atlantic forest when compared to other more equatorial localities of the Neotropics. Further studies with additional sloths are necessary, however, to ascertain the validity of this conclusion.
This work presents new data from 48 maned sloths Bradypus
torquatus captured between November 2002 and November 2003 in three regions of the Atlantic forest where the largest remnant populations of this species are found. Data from another long-term study, carried out from 1994 to 1996 and from 1999 to the present (n=14), were also used, making a total sample of 62 sloths. Average adult body weight is 6594±236 g and average head-body length is 66.5±0.8 cm (n=35), indicating that Bradypus
torquatus is the heaviest of all four Bradypus species. Individuals from lower-montane forests (600–1000 m a.s.l.) are significantly larger (head–body length; t-test; P=0.001) than individuals from the lowlands (<350 m a.s.l.), suggesting altitudinal differentiation between populations. Sexual dimorphism, here reported for the first time, was found in body length (females are significantly larger than males) and in other external characters, such as mane size and form (darker and larger in males), and size and shape of the external genitalia. Most differences between sexes are, however, only discernible in reproductively active individuals. Breeding is slightly seasonal; minimum observed interbirth interval was 1 year and litter size was always one. Infants stayed with their mothers until 8–11 months old; started feeding on solid food as early as 2 weeks old but continued suckling until c. 4 months of age. Age of sexual maturity was estimated at 2–3 years and the oldest captured maned sloth was a healthy male who was at least 12 years of age. Overall, results indicated that maned sloths are similar in these aspects to congeneric species. Information presented here significantly improves the current knowledge on this endangered sloth species and is useful for the proper planning and implementation of in
situ conservation strategies such as translocations and reintroductions.
The diet of maned sloths was studied throughout 14 months in an Atlantic forest reserve of south-eastern Brazil. Three adult sloths were observed for a total of 680 h and located monthly by radio-telemetry. Data were collected on diet, recording the actual time the sloths spent eating plant species. Overall, the diet was composed of 99% leaves, with young leaves (68%) preferred to mature ones (7%) throughout the year. A higher proportion of tree leaves (83%) than liana leaves (16%) were included in the diet. When analysed together, the diet of the three animals included a total of 21 plant species (16 tree and 5 liana), but each individual made up its diet with an even smaller number of species (7–12) and with a particular subset of the local flora. This is a very small portion of the total number of tree and liana species available to the sloths; furthermore, the top species consumed were present at very low population densities in the forest. Thus, B.
torquatus, like other congeneric species studied elsewhere in the Neotropics, is a strictly arboreal folivore with a highly selective diet, probably resulting from evolving physiological adaptations to cope with a smaller range of plant secondary compounds. This is possible for the species of this genus through a combination of low basal rates of metabolism, which enable the sloths to survive on an energy-poor diet, and a very long passage time of digesta, which, in turn, aids the digestion of a fibre-rich diet while possibly contributing to the degradation of secondary compounds.
Camera trapping arboreal mammals in Argentina’s Atlantic forest
- I. Agostini
- E. Pizzio
- D. Varela
- M.E. Iezzi
- P. Cruz
- A. Paviolo
- M. Di Betti
Reis, N.R., Peracchi, A.L., Pedro, W.A., Lima, I.P. (2006). . 1st ed. Londrina: Universidade Estadual de Londrina.
- N.R. Reis
- A.L. Peracchi
- W.A. Pedro
- I.P. Lima