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Comparison of species richness and detection between line transects, ground camera traps, and arboreal camera traps
Abstract
Monitoring trends in the occurrence of species over time is important for informing conservation plans and concurrent management actions. Understanding the effectiveness of field methodologies for collecting accurate and precise data is crucial for optimizing allocation of sampling effort and resources. In this study, we compared mammalian species richness and detection probabilities between three field methodologies: line transects, ground camera traps and arboreal camera traps in Nyungwe National Park, Rwanda. Arboreal camera traps may be suitable for monitoring mammal communities with arboreal species, but their relative effectiveness compared to the more common field methods, line transects and ground camera traps, is relatively unknown. Using single‐season occupancy models with multi‐species data and single‐species multi‐method occupancy models, we estimated mammalian species richness and detection probability for each method and combination of methods. In addition, we estimated single‐species occupancy and detection probability by method for six diurnal primate species. And, we tested for the effect of height on a tree on estimated occupancy probability and detection probability for arboreal camera traps. Overall, for all species the combination of ground and arboreal cameras was the most effective methodology in terms of highest estimates of occupancy and detection coupled with highest precision. However, for the six primate species the most effective method differed between species. The height of the arboreal camera trap in the tree did not significantly affect estimates of occupancy or detection. We suggest using all three field methods concurrently to maximize detection of all species; however, if only two methods can be deployed combining arboreal and ground cameras provided the highest and most precise estimates of occupancy and detection. The addition of arboreal camera traps could improve detection of species and improve future species monitoring programs. Understanding the effectiveness of field methodologies for collecting accurate and precise data is crucial for optimizing allocation of sampling effort and resources within species monitoring programs. In this study, we compared mammalian species richness and detection probabilities between three field methodologies: line transects, ground camera traps and arboreal camera traps in Nyungwe National Park, Rwanda. Overall we found that for all species, the combination of ground and arboreal cameras was the most effective methodology in terms of highest estimates of occupancy and detection coupled with highest precision.
... For example, the availability of foliage, branches, cavities, epiphytes and physical conditions such as solar radiation, moisture and temperature vary at different heights from the ground (Hallé et al., 2012;Jung et al., 2012;Shaw, 2004). Therefore, wildlife sampling conducted from the ground could lead to strong biases in the estimations of abundance, occupancy, home-range size and activity patterns of species that use the vertical profile of the forests (Azcarraga et al., 2020;Bowler et al., 2017;Hongo et al., 2020;Moore et al., 2020;Rader and Krockenberger, 2006). Despite the recognition of the importance of habitat structure (Ferreira de Camargo et al., 2018;Oliveira and Scheffers, 2018;Pearson, 1975;Seidl et al., 2020), the vertical structuring in the use of space by wildlife has been less addressed, especially in temperate ecosystems. ...
... In forest ecosystems, most occupancy studies have been conducted from the ground (e.g., Guzy et al., 2019;Morante-Filho et al., 2021;Thornton et al., 2011), despite the important proportion of animals that use the canopy. A recent review of surveys with arboreal camera traps (Moore et al., 2021) found only three studies (see Bowler et al., 2017;Moore et al., 2020;Whitworth et al., 2019) that addressed occupancy of arboreal species, all of them focused on mammals. Authors attributed the scarcity of studies to the logistic difficulties of obtaining an appropriate sample size in the forest canopies. ...
... Authors attributed the scarcity of studies to the logistic difficulties of obtaining an appropriate sample size in the forest canopies. Among these studies, only one compared between ground and canopy, finding that probability of detection was higher at ground for some and at canopy for other primate species (Moore et al., 2020). Then, for species that preferentially use the upper forest canopy, it is possible to expect larger biases from groundbased occupancy estimation. ...
Habitat use is how animals use the physical and biological components of the environment. Studies relating habitat and wildlife in forest ecosystems have typically been conducted from the ground, even though most wildlife use the three-dimensional space. The objective of our study was to understand how wildlife uses the whole vertical profile of the forest and to analyze possible associations between different species and vertical forest strata, using camera traps and occupancy models. We defined four strata (forest floor, understory, lower canopy, and upper canopy) that range from 0 to 32 m from the ground. We installed 16 camera-traps per stratum (n = 64), and we analyzed the use of each stratum by seven taxa using occupancy models. We detected 24 wildlife taxa, including 17 birds, six mammalian taxa and one reptile. Occupancy models showed that rodents and two bird species were associated either to the forest floor or to the lower strata (understory and ground), whereas one furnariid bird and one marsupial used the vertical profile more frequent than the forest floor. Finally, the lizard and a furnariid bird preferentially used the lower and upper canopy. For all but one of the species, activity patterns were similar between the upper and lower strata of the forest. Our study shows that wildlife species differ in the use of the vertical profile of the forest and suggests that occupancy of species that select the canopy can be largely underestimated from ground-based surveys affecting management decisions.
... Combining data obtained using different methods for modelling species distributions has increased substantially in recent years (Fletcher et al., 2019). However, studies that assess simultaneously the accuracy of method combinations compared to each single method and their associated economic costs are infrequent, although they are essential for selecting the most cost-effective method(s) for a particular species (Long et al., 2007;Moore et al., 2020). This kind of studies is particularly scarce for species of mesocarnivores, singularly in the south of Europe, where the communities of mesocarnivores are highly diverse (e.g. ...
... Our results show that combining different methods can overcome the disadvantages of each single method used alone (high bias, low detection) for detecting an expanding carnivore species such as the Egyptian mongoose. These results agree with the findings of recent studies pointing out that the combination of survey methods allows optimizing the detection probability of different carnivore species (Clare et al., 2017;Bowler et al., 2019;Moore et al., 2020). However, our study is one of the first of this kind performed in Europe since previous studies were performed in other continents. ...
... Camera-trapping was the top-ranked single method, with a medium detection probability, low coefficient of variation and low bias (Table 1). Moore et al., (2020) showed that the combination of camera-traps and line transects was more effective and provided higher occupancy estimates for mammal species than each single method used independently. Nevertheless, they recommended using camera-traps if only one method could be used. ...
Knowing the distribution of expanding carnivore species is paramount for identifying and addressing potential human–wildlife conflicts. Occupancy models are useful tools to estimate the distribution and the probability of detection of wildlife species. In this study, we used these models with an empirical dataset to compare different survey methods and their combinations in order to optimize the estimated distribution in central Iberian Peninsula of the Egyptian mongoose ( Herpestes ichneumon ), the only Herpestidae species occurring in Europe. In particular, we aimed to identify the most cost‐effective (most accurate, with the lowest bias and cost) method or combination of methods. Sign surveys along transects on foot, hair‐traps (baited and unbaited) and camera‐traps were used as detection methods. We replicated these methods in 10 sampling units within four study zones in which the species was known to occur. We employed occupancy models to estimate the detection probability for each method in each zone, using covariates exclusively for detection probability, and made combinations of all methods. Camera‐trapping was the most precise and least biased single method, followed by transects on foot. In contrast, both baited and unbaited hair‐traps produced biased estimates of occupancy. However, camera‐traps was the most costly method, whereas single unbaited hair‐traps had the lowest cost. Our results demonstrate that the combination of several methods provides more precise and unbiased estimates of occupancy than those obtained from single methods. Even so, a biased method could contribute to improve the estimates if combined with other unbiased and precise methods. We recommend considering not only the precision and bias, but also the cost and effort required by each method to achieve the most cost‐effective results in distribution studies of carnivore species.
... Traditionally, arboreal mammals have been sampled using ground-based visual surveys, but these tend to be biased towards larger-bodied, diurnal species that can be readily observed and identified from below, and show some degree of tolerance to people (Whitworth et al., 2016;Bowler et al., 2017;Moore et al., 2020). Moreover, the heights at which arboreal species are detected present significant challenges for accurate identification from the ground (Jayasekara et al., 2007;Gregory et al., 2014;Whitworth et al., 2016). ...
... To date, applications of camera-trapping in the canopy have focused mainly on documenting animal presence (e.g., Suzuki and Ando, 2019), behaviour (e.g., Godoy-Guinao et al., 2018), or activity in relation to particular habitat features such as fruiting trees (e.g., Jayasekara et al., 2007) or canopy bridges (e.g., Gregory et al., 2017) (see also Supplementary Table 1). Published inventories of arboreal mammal communities based on camera-trap data are limited to five sites (Whitworth et al., 2016(Whitworth et al., , 2019aBowler et al., 2017;Hongo et al., 2020;Moore et al., 2020), all in the Neotropics or Africa, and with four of five focusing on medium-and largebodied mammals. Only three of these studies compared canopy inventories to those generated from camera-traps on the ground (Whitworth et al., 2019a;Hongo et al., 2020;Moore et al., 2020), limiting the inferences that can be made when describing arboreal versus terrestrial communities. ...
... Published inventories of arboreal mammal communities based on camera-trap data are limited to five sites (Whitworth et al., 2016(Whitworth et al., , 2019aBowler et al., 2017;Hongo et al., 2020;Moore et al., 2020), all in the Neotropics or Africa, and with four of five focusing on medium-and largebodied mammals. Only three of these studies compared canopy inventories to those generated from camera-traps on the ground (Whitworth et al., 2019a;Hongo et al., 2020;Moore et al., 2020), limiting the inferences that can be made when describing arboreal versus terrestrial communities. Further, almost half of all published canopy-based camera-trap studies that recorded camera-trap height (26 of 54, Supplementary Table 1) placed camera-traps ≤ 10 m above the ground, missing a large portion of the vertical space from their sampling. ...
Arboreal mammals form a diverse group providing ecologically important functions such as predation, pollination and seed dispersal. However, their cryptic and elusive nature, and the heights at which they live, makes studying these species challenging. Consequently, our knowledge of rainforest mammals is heavily biased towards terrestrial species, limiting our understanding of overall community structure and the possible impacts of human-induced disturbance. We undertook the first in-depth appraisal of an arboreal mammal community in Southeast Asia, using camera-traps set in unlogged and logged tropical rainforest in Sabah, Borneo. Using paired canopy and terrestrial camera-traps at 50 locations (25 in unlogged forest, 25 in logged), we assessed the effectiveness of camera-trapping at characterising the arboreal versus terrestrial community, and tested the influence of strata and forest type on community structure and composition. The paired design detected 55 mammal species across 15,817 camera-trap nights (CTNs), and additional canopy sampling in a subset of trees added a further two arboreal species to the inventory. In total, thirty species were detected exclusively by terrestrial camera-traps, eighteen exclusively by canopy camera-traps, and nine by units set at both heights, demonstrating significant differences between arboreal and terrestrial communities. This pattern was strongest in unlogged forest, reflecting greater structural diversity of this habitat, but held in logged forest as well. Species accumulation curves revealed that canopy camera-trapping significantly boosted species inventories compared to terrestrial-only sampling, and was particularly effective at detecting gliding mammals, rodents and primates. Canopy inventories took longer to reach an asymptote, suggesting that a greater sampling effort is required when deploying canopy camera-traps compared to those set on the ground. We demonstrate that arboreal mammals in Borneo’s rainforest form a diverse and distinct community, and can be sampled effectively using canopy camera-traps. However, the additional costs incurred by sampling in the canopy can be substantial. We provide recommendations to maximise sampling effectiveness, while bringing down costs, to help encourage further study into one of the last frontiers of tropical forest research.
... About three quarters of terrestrial forest vertebrates in the tropics, including a great diversity of mammals, are strictly or partially restricted to the arboreal realm (Eisenberg & Thorington, 1973;Kays & Allison, 2001). For many years, tropical arboreal mammals were traditionally inventoried and observed through ground-based methods, which often missed cryptic, fast-moving and nocturnal species (Lowman & Moffett, 1993;Kays & Allison, 2001;Whitworth et al., 2016;Bowler et al., 2017;Moore et al., 2020). These methods are also extremely difficult to implement in remote areas and on a large scale. ...
... While camera traps have become a ubiquitous method in ecological studies and conservation programs of terrestrial mammals (Glover-Kapfer et al., 2019), with great potential for global network monitoring (Ahumada et al., 2011;Steenweg et al., 2017). It is only recently that this method has started to be applied to survey arboreal mammals in tropical forest canopies (Olson et al., 2012;Gregory et al., 2014;Whitworth et al., 2016;Bowler et al., 2017;Kaizer, 2019;Hongo et al., 2020;Moore et al., 2020). Here we provide the first study using canopy camera trapping to survey arboreal mammals in the Atlantic Forest. ...
... To date, most of the studies reporting arboreal mammal assemblage in remnants of the Atlantic Forest have been based on ground-based surveys. Our findings demonstrate the potential of arboreal camera trapping to register rare, nocturnal and cryptic species that are prone to false negatives obtained by ground-based methods (Olson et al., 2012;Whitworth et al., 2016;Bowler et al., 2017;Moore et al., 2020). Considering the habits of some scansorial and terrestrial species, we suggest that arboreal camera traps should be paired with terrestrial cameras, which would reduce the likelihood of failing to detect these species. ...
The Atlantic Forest of South America supports some of the greatest terrestrial biodiversity on our planet but is now reduced to only a small extent of its original forest cover. It hosts a large number of endemic mammalian species but our knowledge on arboreal mammal ecology and conservation has been hindered by 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. Here we generated data on the arboreal mammal community based on canopy camera trapping for the first time in the Atlantic Forest, focusing on Caparaó National Park, Brazil. We placed 24 infrared camera traps in the forest canopy distributed in seven areas within the Park, operating continuously from January 2017 to June 2019. In this time, they accumulated 4,736 camera-days and generated 2,256 sets of pictures and 30 second videos of vertebrates. Canopy camera traps were able to detect arboreal mammals spanning a wide variety of body sizes. The local mammal assemblage comprised of 15 identifiable species, including the critically endangered northern muriqui (Brachyteles hypoxanthus) and the buffy-headed marmoset (Callithrix flaviceps), and other rare, nocturnal and inconspicuous species. For the first time, we confirmed the occurrence of the thin-spined porcupine (Chaetomys subspinosus) in the Park. Species richness varied across sampling areas and forest types. Our findings demonstrate the potential of canopy camera trapping for future surveying efforts to better inform conservation strategies for mammals.
... Camera trapping (use of automated cameras to capture animal incidences) is a well-documented and preferred method of non-invasively assessing terrestrial mammal populations (Tobler et al., 2008;Rovero & Marshall, 2009;Gregory et al., 2014), but novel studies have shown that arboreal camera traps can also be useful in detecting species not observed by traditional ground-based techniques (e.g. Whitworth et al., 2016;Bowler et al., 2017;Moore & Niyigaba, 2018;Moore et al., 2020). However, there is still much to be learned on how to appropriately design arboreal camera trapping studies for maximizing detections (Moore et al., 2021). ...
... Standardized detection is a key requirement in occupancy modeling. As arboreal detection rates are typically much lower than terrestrial detection rates (Whitworth et al., 2016;Moore et al., 2020;Haysom et al., 2021), arboreal data is likely to be more sparse and thus less conducive to complex models with many covariates. Identifying forest and focal limb characteristics which maximize detections in a particular region or habitat will allow future studies to standardize arboreal camera placement and focus on variables affecting occupancy. ...
Tropical forests are the most species‐rich biomes in the world but suffer high rates of logging and conversion. Tropical tree‐dwelling (arboreal and semi‐arboreal) mesomammals reliant on old‐growth forest structures are especially vulnerable. The degree of behavioral arboreality of semi‐arboreal mammals can be related to forest structure and perceived terrestrial threats. Paired arboreal and terrestrial camera traps are a promising new method for estimating the arboreality of cryptic and nocturnal species. Our study aimed to (1) model the effects of forest structure and anthropogenic disturbance on the detection and occurrence of arboreal and semi‐arboreal mesomammals and (2) evaluate differences in occurrence and detection between paired arboreal and terrestrial camera trap sites for semi‐arboreal mammals while estimating the degree of arboreality. We set 20 terrestrial and arboreal camera trap pairs in eastern Cat Tien National Park (Nam Cat Tien), Vietnam, from June 2019 to September 2020. We evaluated the effects of forest structure and proximity to roads on nine arboreal mesomammal species using single‐season occupancy models. We used multi‐scale occupancy modeling to estimate the degree of arboreality for four semi‐arboreal mammals. All models were fit using hierarchical Bayesian modeling and compared using WAIC. We detected most arboreal and terrestrial mesomammal species currently known to inhabit Nam Cat Tien, including rare and cryptic species. Canopy connectivity and other mature forest characteristics were important for explaining the detection and occurrence of highly arboreal species, while the effect of a tree and focal limb characteristics on detection was species‐specific. All semi‐arboreal species had a greater probability of terrestrial station use than arboreal, suggesting a greater vulnerability to terrestrial threats, though the degree of arboreality varied by species. Using one sampling method underestimated occupancy for most semi‐arboreal species. Multi‐method sampling designs with multi‐scale occupancy modeling can improve estimates of species distribution and habitat use for guiding management and conservation decisions. We conducted a rigorous quantitative empirical study using arboreal camera trapping in southern Vietnam to (1) model the effects of forest structure and anthropogenic disturbance on the detection and occurrence of arboreal and semi‐arboreal mesomammals and (2) evaluate differences in occurrence and detection between paired arboreal and terrestrial camera trap sites for semi‐arboreal mammals. We provide new methods for defining and estimating the degree of arboreality from presence‐absence data for semi‐arboreal species, to evaluate vulnerability to terrestrial‐ and arboreal‐specific threats. We also demonstrate how multi‐method occupancy designs can be used to improve estimates of species distribution and habitat use for guiding management and conservation decisions.
... In some instances (n = 8), for example, because wildlife are known to use human trails and roads for travel 5,35 cameras were placed near or in the direction of recreational dirt roads and old overgrown conservation roads that are occasionally utilized by vehicles. Cameras were strapped 0.5 m 40 above the base of trees ± 30° of north to reduce direct sunlight 41 , and when possible, along linear features (e.g., river, trail, etc.) with no addition of bait or lure. Camera settings were chosen to increase the probability of capturing and accurately identifying www.nature.com/scientificreports/ ...
... Camera settings were chosen to increase the probability of capturing and accurately identifying www.nature.com/scientificreports/ fast-moving carnivores, thus cameras recorded multiple photographs per trigger, at a rate of 1 frame per second, re-triggering immediately if the animal was still in view 5,41,42 . We exchanged SD cards every 2-3 months, except during winter when many cameras were not accessible. ...
Protected areas serve an important role in wildlife conservation, yet most wildlife occur outside these areas, subject to varying degrees of human disturbance. In the Upper Peninsula of Michigan, American black bears (Ursus americanus), a highly mobile, opportunistic species, are common despite an extensive outdoor recreation industry with the potential to affect black bear spatial and temporal activity. We investigated how environmental and anthropogenic factors influence black bear occupancy, detection, and diel activity patterns across the anthropogenic–wildland interface before and after hibernation. Using 30 camera traps deployed across a rural–wildland interface, we captured black bears at 23 camera sites (~ 77%), which exhibited co-occurrence with humans at 10 sites (~ 33%), revealing that human presence and human population density exert negative effects on black bear seasonal occupancy. Bears were more nocturnal during the hunting season, before hibernation. Human recreational activity increased ~ 38% after hibernation, but bear diurnal activity also increased ~ 36%, except when cubs were present. Our results suggest bears prioritize avoiding humans spatially, rather than temporally, except during the hunting season and when cubs are present. Understanding black bear responses to human recreation patterns and environmental variation is essential for minimizing human-mediated disturbance, and fueling conservation efforts of large, charismatic carnivores.
... So far, most of the camera-trap studies have been carried out on terrestrial mammal communities, using camera traps at ground level (O'Connell et al. 2011;Rovero et al. 2010). However, camera traps situated at ground level are not efficient at photographing canopy obligate mammals, which rarely or never descend to the ground, and may thus be missed from mammal surveys (Moore et al. 2020;Whitworth et al. 2016). This limitation has started to be overcome with the implementation of canopy camera trapping, a technology with great potential for surveying arboreal mammals Moore et al. 2021). ...
... Arboreal camera trapping has been implemented successfully to obtain information about mammal community diversity (Bowler et al. 2017), individual behavior (Bezerra et al. 2014;LaFleur et al. 2014;Oliveira-Santos et al. 2008), as well as monitoring the effectiveness of canopy bridges or rope overpasses to restore habitat connectivity (Gregory et al. 2017;Teixeira et al. 2013). In addition, comparisons between arboreal and ground-level camera trapping, as well as between arboreal camera trapping and more traditional census transects, have revealed greater effectiveness of the former for surveying canopy wildlife, especially due to its effectiveness in recording nocturnal or cryptic arboreal mammal species (Bowler et al. 2017;Haysom et al. 2021;Moore et al. 2020;Whitworth et al. 2016). Its main limitations are associated with the greater difficulty of setting cameras high in the canopy branches, the higher risk of injury, and the challenge to locate cameras avoiding high sunlight exposure and wind that may trigger the camera almost continuously during the day, leading to a high number of false-positive shots (Gregory et al. 2014). ...
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.
... Data from different sources can be complementary [94]: a camera trap (proximal sensor) might take a picture of a buffalo on the ground, while a satellite (remote sensor) with a high-resolution camera might take an overhead picture of the same animal. The two sources can be combined for a more comprehensive buffalo census than either source independently would allow. ...
In this white paper, we synthesize key points made during presentations and discussions from the AI-Assisted Decision Making for Conservation workshop, hosted by the Center for Research on Computation and Society at Harvard University on October 20-21, 2022. We identify key open research questions in resource allocation, planning, and interventions for biodiversity conservation, highlighting conservation challenges that not only require AI solutions, but also require novel methodological advances. In addition to providing a summary of the workshop talks and discussions, we hope this document serves as a call-to-action to orient the expansion of algorithmic decision-making approaches to prioritize real-world conservation challenges, through collaborative efforts of ecologists, conservation decision-makers, and AI researchers.
... Here we found that camera traps positively supported data collection for Zone A and B, by adding more species and increasing abundance observations for each zone. Although use of camera traps has been found to get higher detection probability of group-living vs solitary species (Treves et al., 2010;Moore et al., 2020), here camera traps did register more solitary than group-living species. In contrary, null species observations were obtained with the camera trap used for Zone C, but supplemented with the sightings gathered by trail walks. ...
Introduction: Change of natural land use has become major a driver of biodiversity loss around the world. Mammals are important components of forests because they affect forest structure and composition, but few studies have compared mammals in tropical areas with different levels of human disturbance. Objective: To do a rapid assessment of non-flying mammals in Hacienda Barú National Wildlife Refuge, Costa Rica, in three zones with different levels of human disturbance. Methods: On July 18-21, 2019, we identified non-flying mammals with trail walk sightings, camera traps, and Sherman traps. Results: We identified 17 species but no differences among zones. The most common were Cebus imitador and Pecari tajacu, the most used plant was Mangifera indica. Conclusion: This brief study identified 17 non-flying mammals in this reserve.
... La comunidad de mamíferos arbóreos en la EBCC y su estratificación vertical ha sido descrita hace varias décadas (Janson y Emmons 1990); sin embargo, solo se han realizado muestreos de mamíferos desde el suelo. Las nuevas tecnologías y métodos de monitoreo, como el uso de cámaras trampa en el dosel, permiten estudios más efectivos, y registrar especies que no tienden a ser observadas en transectos lineales (Bowler et al. 2016;Debruille et al. 2020;Fang et al. 2020;Moore et al. 2020Moore et al. , 2021Whitworth et al. 2016), ya que estos dispositivos funcionan continuamente durante el día y la noche. ...
Cocha Cashu Biological Station has been studied for more than 50 years; however, a study had not been conducted in the canopy with camera traps. The objective of this research was to monitor the arboreal mammal community with this equipment in order to characterize their richness, generate new records and differentiate their activity in two strata of the canopy, during different periods of the day. Sixty camera traps were installed at 30 points separated by 1.5 km, forming a grid, one in the high canopy (25m+) and the other in the low canopy (15-25m high), for a period of 6861 camera-days covering the dry and rainy seasons. Twenty-seven species of arboreal mammals were recorded, one of which, the dwarf porcupine Coendou cf. ichillus, is a possible new record for Manu National Park. The arboreal mammal community presented a marked temporal stratification between day and night, while twilight was a transition period with no significant difference to the other periods. It was also determined that the body mass and trophic group of the species influenced their temporal activity and their use of the different canopy strata.
... We overcome the low detection probability expected when studying mostly arboreal marbled cats using ground-based cameras with our immense trapping effort. Furthermore ground-based camera traps have been previously shown to record the majority of arboreal mammals at the area of deployment (Moore et al., 2020), including primates and squirrels, which are thought to be marbled cat prey. To satisfy the requirement of spatial independence of our camera traps, we resampled all new camera trapping data into 3.45 km 2 hexagonal grid cells with an apothem of 1 km, defined as our sampling units. ...
Southeast Asia supports the greatest diversity of felids globally, but this diversity is threatened by the severe forest loss and degradation occurring in the region. The response of felids to disturbances appears to differ depending on their ecology. For example, the largely terrestrial and nocturnal leopard cat (Prionailurus bengalensis) thrives near forest edges and in oil palm plantations where it hunts rodents (Muridae) at night, thereby avoiding human activity peaks. Conversely, we hypothesized that the sympatric and similar‐sized marbled cat (Pardofelis marmorata) would respond negatively to edges and relatively open oil palm plantations as they are more arboreal than leopard cats, rely on tree connectivity for hunting, and are diurnal so have less potential to temporally avoid humans. We used camera trapping from Southeast Asia to test habitat associations at multiple spatial scales using zero‐inflated Poisson generalized linear mixed models and hierarchical occupancy modeling. We found that marbled cats were positively associated with large intact forests and, in contrast to leopard cats, negatively associated with oil palm plantations. Furthermore, we found preliminary evidence suggesting marbled cats may adapt their diel activity to become more crepuscular in degraded forests, likely shifting their activity to avoid humans. These findings suggest that the marbled cat's International Union for Conservation of Nature (IUCN) Red List conservation status should potentially be upgraded from Near Threatened to Vulnerable, matching other forest‐dependent felids in the region. We posit our findings may be generalizable such that semi‐arboreal and diurnal felids could face greater threats from habitat degradation than their terrestrial and nocturnal relatives.
... As a result, the survey methods suitable for a species in a given habitat, may not provide accurate or precise density estimates in other contexts. To overcome the complexity of surveying arboreal primates in the wild, depending on the habitat and species of interest, recent methods suggested the application of acoustic playback (Gestich et al. 2017), passive acoustic monitoring (Kalan et al. 2015), camera traps (Bessone et al. 2020;Moore et al. 2020), and drones (Semel et al. 2020;Spaan et al. 2019). However, these novel techniques are still under development and cannot be applied to all species (e.g., acoustic methods can only be used for highly vocal species), leaving line transect distance sampling (LTDS) as the method of choice for surveying primates (Buckland et al. 2001;Plumptre et al. 2013). ...
Habitat destruction and over-hunting are increasingly threatening the arboreal primates of Central Africa. To establish effective conservation strategies, accurate assessments of primate density, abundance, and spatial distribution are required. To date, the method of choice for primate density estimation is line transect distance sampling. However, primates fleeing human observers violate methodological assumptions, biasing the accuracy of resulting estimates. In this study, we used line transect distance sampling to study five primate species along 378 km of transects in Salonga National Park, Democratic Republic of the Congo. We tested the effect of different levels of survey-inherent disturbance (i.e., cutting) on the number of observed (i) primate groups, and (ii) individuals within groups, by counting groups at three different time lags after disturbance of the transect, (i) a minimum of 3 h, (ii) 24 h, (iii) a minimum of 3 days. We found that survey-inherent disturbance led to underestimated densities, affecting both the number of encountered groups and of observed individuals. However, the response varied between species due to species-specific ecological and behavioral features. Piliocolobus tholloni and Colobus angolenis resumed an unaltered behavior only 24 h after disturbance, while Lophocebus aterrimus, Cercopithecus ascanius, and Cercopithecus wolfi required a minimum of 10 days. To minimize bias in density estimates, future surveys using line transect distance sampling should be designed considering survey-inherent disturbance. We recommend evaluating the factors driving primate response, including habitat type, niche occupation, and hunting pressure, peculiar to the survey-specific area and primate community under study.
... The estimated occupancy of Eastern chimpanzee in Gishwati Forest was 0.31 (range: 0.15-0.54; Table 3) which was well below that established for neighbouring Nyungwe NP (0.69; Moore et al. 2020) or that reported from the Taï NP in Ivory Coast (0.5-1.0; Kalan et al. 2015). The detectability and occupancy of chimpanzees were not affected by any environmental or anthropogenic variable, indicating that chimpanzees were widely and equally distributed across Gishwati Forest, despite a strong human impact on other wildlife species. ...
In conservation biology, flagship species are defined as species that can raise support for biodiversity conservation in a given place or social context. In the newly established Gishwati–Mukura National Park in Rwanda, the Eastern chimpanzee was considered such an ambassador. To test whether the flagship species concept was effective in the park, we studied species richness, relative abundance, and species distribution (occupancy) of medium- to large-sized, ground-dwelling mammals using camera trapping technology. The impact of three environmental and three anthropogenic variables on species distribution was investigated and the ecological diversity of the fauna in the national park assessed. Over a period of 9 months, two 4 × 4 camera trapping grids were deployed in Gishwati and Mukura Forest. Sampling effort in each forest equated to 32 and 29 camera trapping locations, yielding 258 and 242 independent photographic events of eight and six species, respectively. In both forests, the Emin's giant poached rat was the most frequently encountered species, while all other species showed high relative abundance only in Gishwati Forest. The relative abundance of the endangered Eastern chimpanzee in Gishwati Forest was 0.54, the estimated occupancy was 0.31. Single-species, single-season occupancy models revealed that forest cover, altitude and distance to forest edge influenced the detectability of L'Hoest's monkey and squirrel species, while no effect was found on their occupancy. Notably, no larger herbivore or carnivore species were observed in the park, while the flagship species, i.e., the Eastern chimpanzee, was relatively abundant. Moreover, in both forests, all detected carnivores were small- to medium-sized, suggesting a meso-predator release phenomenon, i.e., populations of medium-sized predators increased after the removal of larger, top carnivores, due to relaxed competition. It appears that the prioritization of the flagship species resulted in the neglect of other mammalian species, leading eventually into the demise of entire functional guilds. Based on these results, the Gishwati–Mukura NP was categorized as a ‘depleted forest’. We, therefore, strongly object chimpanzees as a suitable flagship species—at least in the Gishwati–Mukura NP—and recommend collating more knowledge on the release of meso-predators and the loss of forest ungulates to improve their future conservation in Afro-montane forest habitats.
... Il fototrappolaggio risulta un valido strumento per analizzare i ritmi di attività, il comportamento (cf. Bridges e Noss, 2011) ma anche eventi più rari come l'arrivo di grandi carnivori (Wearn e Glover -Kapfer, 2019), recando un disturbo minimo alla fauna Moore, 2020). Uno dei maggiori vantaggi, rispetto ad altri metodi di campionamento quali osservazione diretta, cattura o monitoraggio, è dato dalla capacità di raccogliere informazioni accurate e standardizzate per lunghi periodi (nell'ordine di mesi, se necessario), con un impegno minimo da parte degli operatori (Wearn e Glover -Kapfer 2019). ...
... An exception was observed for arboreal and scansorial species from the Afrotropical and Indo-Malayan regions, where larger species had higher detection probability than smaller species. The Afrotropics support a greater proportion of species adapted to open and fragmented forests [68] and it appears that many larger arboreal and scansorial species such as chimpanzees (Pan troglodytes) spend considerable time on the ground [69]. Processes operating on these detection probabilities in the Indo-Malayan region likely relate to anthropogenic activities and impacts. ...
The structure of forest mammal communities appears surprisingly consistent across the continental tropics, presumably due to convergent evolution in similar environments. Whether such consistency extends to mammal occupancy, despite variation in species characteristics and context, remains unclear. Here we ask whether we can predict occupancy patterns and, if so, whether these relationships are consistent across biogeographic regions. Specifically, we assessed how mammal feeding guild, body mass and ecological specialization relate to occupancy in protected forests across the tropics. We used standardized camera-trap data (1002 camera-trap locations and 2-10 years of data) and a hierarchical Bayesian occupancy model. We found that occupancy varied by regions, and certain species characteristics explained much of this variation. Herbivores consistently had the highest occupancy. However, only in the Neotropics did we detect a significant effect of body mass on occupancy: large mammals had lowest occupancy. Importantly, habitat specialists generally had higher occupancy than gener-alists, though this was reversed in the Indo-Malayan sites. We conclude that habitat specialization is key for understanding variation in mammal occupancy across regions, and that habitat specialists often benefit more from protected areas, than do generalists. The contrasting examples seen in the Indo-Mala-yan region probably reflect distinct anthropogenic pressures.
... In some cases, arboreal deployments have targeted particular primate species (e.g., Prolemur simus) and shown that, in some areas, arboreally deployed cameras have higher detection rates than subcanopy cameras (Olson et al. 2012). More recent studies have focused on extracting CT data for building occupancy models and revealing species richness (Chen et al. 2021;Johnson et al. 2020;Moore et al. 2020). ...
Observing and quantifying primate behavior in the wild is challenging. Human presence affects primate behavior and habituation of new, especially terrestrial, individuals is a time-intensive process that carries with it ethical and health concerns, especially during the recent pandemic when primates are at even greater risk than usual. As a result, wildlife researchers, including primatologists, have increasingly turned to new technologies to answer questions and provide important data related to primate conservation. Tools and methods should be chosen carefully to maximize and improve the data that will be used to answer the research questions. We review here the role of four indirect methods—camera traps, acoustic monitoring, drones, and portable field labs—and improvements in machine learning that offer rapid, reliable means of combing through large datasets that these methods generate. We describe key applications and limitations of each tool in primate conservation, and where we anticipate primate conservation technology moving forward in the coming years.
... The undetected fast-moving, diurnal mongoose species were therefore likely to be less detectable by the cameras compared to analogous nocturnal mammals because of the comparatively high background surface temperatures during the day. Another potential reason for the mongooses undetection may be that these two species may have low detection probabilities as well as low abundances or patchy distribution in MWR, as has been found in similar studies for other mongoose species (Fuda et al., 2018;Moore et al., 2020). ...
Biological monitoring in protected areas is essential for making management decisions, especially in small (<1000 km ² ), fenced reserves which require intensive intervention to maintain core habitat characteristics. Estimates of species richness and community structure provide important information for planning and evaluating conservation strategies. Majete Wildlife Reserve (MWR) is a small (691 km ² ), isolated reserve in southern Malawi in the Miombo Woodland Ecoregion. We investigated species richness and community structure of the terrestrial medium and large mammals at MWR through a standardised camera trap survey. During the 2018 dry season, 140 camera locations were sampled for 40 days each. Thirty‐five mammal species were detected and Chao 2, ICE and Jackknife 1 and 2 richness estimators indicated between 36–41 species present which aligns closely with historic accounts. Non‐detection of some species is attributed to species specialised habitat requirements not catered for in the systematic camera trap survey design. Mammal community structure, calculated from the camera detected species’ relative abundance indices (RAI), was atypical for Miombo woodland, with an underrepresentation of elephants. Camera trap‐derived RAI was positively related with 2018 aerial census species encounter data. These results can assist management in refining survey techniques and act as a baseline to monitor conservation efforts.
... However, this methodological combination may result in underestimates of cryptic and nocturnal species in the arboreal habitats. Perhaps a sampling method that combines camera trapping both at ground and arboreal level is a viable solution (Tongkok et al., 2020), because it has the potential to detect all species (Moore et al., 2020). ...
Abstract Although arboreal camera trapping is a growing field, it has rarely been used for monitoring plant‐frugivore interactions in the trees. Frugivore foraging behavior generally occurs in trees, hence arboreal camera trapping can be a potentially useful tool for frugivory research. We developed a camera trap sampling method to monitor plant‐frugivore interactions during mature fruiting periods. We used this method to monitor 318 individuals (camera sites) of 18 fleshy‐fruit plant species on 22 subtropical land‐bridge islands in the Thousand Island Lake, China. We recorded a total of at least 52 frugivorous animals, including a ground‐foraging bird species (Lophura nycthemera) and several mammals with foraging behaviors in the trees. We also recorded 4399 independent interaction events, including 275 unique plant‐bird interactions. We proposed a framework to classify interaction types and performed a sampling completeness test. We found that a sampling strategy that covered approximately a third of the fruit maturation period when most fruits were ripe was sufficient to sample plant‐frugivore interactions. Our results demonstrated that our sampling method with camera transects is reliable to monitor plant‐frugivore interactions in a fragmented landscape. This study helps to lay the methodological foundation for building networks of plant‐frugivore interactions with arboreal camera trapping on large spatial/temporal scales. As a non‐invasive, labor‐saving, and largely unbiased sampling method, the field application of arboreal camera trapping in different regions can advance the technology of biodiversity monitoring and lead to more accurate biodiversity inventories in arboreal environments.
... Se instalaron 146 cámaras trampa en el suelo (~ 30 cm de altura), las cuales sumaron un esfuerzo de 977 días/cámaras-trampa. El método de cámara trampa es muy útil y complementario con transectos, que permite registrar la mayor cantidad de especies, incluyendo animales crípticos, ariscos y que viven en baja densidad (Pérez-Peña et al., 2019a;Moore et al., 2020). ...
RESUMEN Los mamíferos mantienen la estructura del bosque y son importantes como fuente proteica y económica para las comunidades amazónicas. Para conocer la diversidad de mamíferos (excepto murciélagos, roedores pequeños y marsupiales) en los hábitats del interfluvio Putumayo-Napo-Amazonas, se recorrieron 1908,1 km de transectos lineales en donde se avistaron y registraron huellas, 146 cámaras trampa fueron instaladas y se tuvo 977 días/ cámaras trampa, se buscaron madrigueras en 118,4 km de transectos. Además, se recopiló información de 13 publicaciones desde 2004 hasta 2020 para conocer la diversidad en el interfluvio. La diversidad fue tomada como riqueza de especies registradas, mientras que la riqueza esperada fue estimada con Chao 1 y la similitud entre hábitats fue analizada con el índice de Morisita. La riqueza fue alta, se registraron 56 especies de 26 familias y 9 órdenes, y fue similar en colina baja, terraza alta, terraza media y aguajal mixto, pero fue muy bajo en el varillal pantanoso y en el bosque de orilla. Los hábitats de terraza media y aguajal mixto fueron muy similares, así como el de terraza alta con colina baja. Los primates Leontocebus nigricollis, Pithecia hirsuta y Cheracebus lucifer, Lagothrix lagothricha lagothricha están restringidas a este interfluvio y las especies con mayor amenaza fueron Pteronura brasiliensis y L. lagothricha. Las amenazas antropogénicas más frecuentes fueron, sobre caza, tala selectiva y deforestación. Este interfluvio tiene una enorme diversidad de mamíferos que
... Kamerafeller med tilhørende bildeprosessering og maskinlaering er i dag den mest avanserte metoden som blir brukt for å registrere mellomstore til store pattedyr (> 1 kg) (Rovero & Zimmermann 2016). Nylige modifikasjoner gjør det også mulig å bruke kamerafeller til å kartlegge smågnagere (Mos & Hofmeester 2020) og trelevende arter (Moore et al. 2020). Den store fordelen med kamerafeller er at hvert enkelt kamera kan ta tusenvis av bilder i månedsvis i strekk gjennom hele året (inkludert perioder med snødekke), og de er derfor spesielt egnet for arter med lav tetthet og/eller svaert mobile arter. ...
Surveying and monitoring biodiversity using new technology: eDNA and camera trapping. NINA Report 1962. Norwegian Institute for Nature Research.
Norway has committed to halting the loss of biodiversity. However, preserving biodiversity requires knowledge about species distributions. For some species we have good knowledge of distribution and population size, but the vast majority of species are poorly known. For instance, this is the case for species found in soil and dead wood, and mobile species with low population densities. New technologies have emerged recently, such as the use of environmental DNA (eDNA) and camera traps, which provide many opportunities for the detection of “hidden” biodiversity as well as cost-effective mapping of other species groups.
To be able to exploit new technology in mapping and monitoring of biodiversity, it is necessary to identify the best and most cost-effective methods. We have therefore tested different technologies for surveying terrestrial biodiversity in Norway. This includes surveying biodiversity in soil and dead wood using eDNA, and diversity and phenology of mammals using camera traps.
We show that analyses of eDNA in relatively simple soil and wood samples is a potentially useful tool for mapping and monitoring of biodiversity. We confirm the utility of genetic markers for plants, fungi and annelids in soil as well as fungi in dead wood. For these species groups we found that the method is robust and can detect important differences in community structure between habitat and substrate types independent of sampling and DNA extraction methods. The probability of detecting species was also consistent across methodologies. We can therefore recommend using the simplest and most cost-effective methods. The results for plants were comparable to those of traditional ANO surveys. Preliminary testing of markers for collembola, nematodes, arachnids, insects and vertebrates resulted in relatively few species. Our findings suggest that if the goal is to monitor species richness or composition in general, eDNA can be suitable. However, if the aim is to detect all species, especially red-listed species, a combination of traditional methods and eDNA is probably the best.
Our studies with camera traps shows that the method is suitable for mapping and monitoring the presence and relative densities of medium to large mammals, the distribution of both native and alien species, community structure as well as the presence of certain diseases and the timing of life history events (phenology) like winter dormancy of badgers, winter coats in mountain hare and antler cycles in roe deer. This demonstrates that the remotely collected images obtained from camera traps can provide insights into many ecosystem parameters beyond presence. Analyses of eDNA did not capture the mammal species recorded using camera traps.
This report provides new insights into the way that new technologies can contribute to monitoring the biodiversity associated with Norwegian nature. Further work with eDNA should focus on ex-ploring how field sampling methods, choice of sequence depth and marker selection can be optimized. For camera traps, future work should explore how different deployments of cameras influence the stability of abundance indices, and how modified cameras can be used to monitor small mammals. The results clearly show that a combination of many different methods will be needed to effectively monitor biodiversity.
https://brage.nina.no/nina-xmlui/handle/11250/2733422
... On a positive note, our photo capture of the wild dog (Lycaon pictus) confirms the presence of this endangered species in the study area [32,64]. These comparisons underline the general consensus that a combination of multiple survey methods is necessary to capture an entire mammal community in a given area [77]. An added benefit of using camera traps is the ability to identify animals to the species level in almost all cases. ...
In many regions of sub Saharan Africa large mammals occur in human-dominated areas, yet their community composition and abundance have rarely been described in areas occupied by traditional hunter-gatherers and pastoralists. Surveys of mammal populations in such areas provide important measures of biodiversity and provide ecological context for understanding hunting practices. Using a sampling grid centered on a Hadza hunter-gatherer camp and covering 36 km ² of semi-arid savannah in northern Tanzania, we assessed mammals using camera traps (n = 19 stations) for c. 5 months (2,182 trap nights). In the study area ( Tli’ika in the Hadza language), we recorded 36 wild mammal species. Rarefaction curves suggest that sampling effort was sufficient to capture mammal species richness, yet some species known to occur at low densities in the wider area (e.g. African lions, wildebeest) were not detected. Relative abundance indices of wildlife species varied by c. three orders of magnitude, from a mean of 0.04 (African wild dog) to 20.34 capture events per 100 trap-nights (Kirk’s dik dik). To contextualize the relative abundance of wildlife in the study area, we compared our study’s data to comparable camera trap data collected in a fully protected area of northern Tanzania with similar rainfall (Lake Manyara National Park). Raw data and negative binomial regression analyses show that wild herbivores and wild carnivores were generally detected in the national park at higher rates than in the Hadza-occupied region. Livestock were notably absent from the national park, but were detected at high levels in Tli’ika, and cattle was the second most frequently detected species in the Hadza-used area. We discuss how these data inform current conservation efforts, studies of Hadza hunting, and models of hunter-gatherer foraging ecology and diet.
... However, arboreal camera trapping can operate remotely 24 hours a Plant-frugivore interactions revealed by arboreal camera trapping Camera trapping technology -which allows images of organisms to be obtained remotely from the field -has advanced rapidly in recent decades, and its infrared capability has become a standard tool in wildlife monitoring, especially for detecting ground-dwelling endothermic animals (O'Connell et al. 2011). However, the activities of animals in arboreal habitats (including the forest canopy) are still poorly known (Gregory et al. 2014;Moore et al. 2020), and to date, no studies have used arboreal camera trapping to monitor plant-frugivore networks over an extensive area. ...
... At the same time, recent technological improvements in monitoring systems now enable the collection of a wide range of ecological data for terrestrial wildlife. For instance, camera traps have proved to be a useful, cost-effective, and relatively low-effort technique (Gregory et al., 2014;Moore et al., 2020). Furthermore, the development of automated radio-tracking systems (Gottwald et al., 2019) will likely allow us to determine the vertical movement patterns even of small animals (see Ripperger et al., 2020) in the near future and thus will provide an increasingly detailed view of vertical movements of individual animals. ...
Vertical stratification (VS) is a widespread phenomenon in plant and animal communities in forests and a key factor for structuring their species richness and biodiversity, particularly in tropical forests. The organisms composing forest communities adjust and shape the complex three-dimensional structure of their environment and inhabit a large variety of niches along the vertical gradient of the forest. Even though the degree of VS varies among different vertebrate groups, patterns of compositional stratification can be observed across taxa. Communities of birds, bats, primates, and non-flying small mammals are vertically stratified in terms of abundance, species richness, diversity, and community composition. Frugivorous members of these taxa play important roles as seed dispersers and forage on fruit resources that, in turn, vary in quantity and nutritional value along the vertical gradient. As a consequence, plant-seed disperser interaction networks differ among strata, which is manifested in differences in interaction frequencies and the degree of mutual specialization. In general, the canopy stratum is composed of strong links and generalized associations, while the lower strata comprise weaker links and more specialized interactions. Investigating the VS of communities can provide us with a better understanding of species habitat restrictions, resource use, spatial movement, and species interactions. Especially in the face of global change, this knowledge will be important as these characteristics can imply different responses of species and taxa at a fine spatial scale.
... This tool is already widely used for monitoring larger terrestrial mammals and birds [12], and is increasingly being applied with some degree of success to arboreal species (e.g. Ref. [13]), smaller mammals (e.g. Ref. [14]), lizards and snakes (e.g. ...
Evidence-based decision-making in natural resource management and conservation is often constrained by lack of robust biodiversity data. Technology offers opportunities for enhanced data collection through a range of satellite-based and Earth-based sensors and techniques. This paper reviews lessons learned from the application of four key technological monitoring solutions (satellite-based remote sensing, cameras, acoustic recording devices and environmental DNA) to identify factors affecting their relevance and applicability. Most tools, if relevant to local user needs and integrated into goal-based monitoring schemes, can contribute to creating the enabling conditions necessary for effective biodiversity monitoring, improving data availability and quality for various taxa when compared with traditional observer-based methods. However, until the tools become cheap enough and easy enough for widespread use (especially in biodiversity-rich countries), and until they can be more inclusive in their taxonomic coverage, technological solutions will still need to be complemented with traditional observer-based methods for the foreseeable future.
... One needs to monitor a large area to study community-level land use, since some species have large home ranges. Camera trapping enables simultaneous monitoring of multiple locations in a large area, and the combination of terrestrial and arboreal camera trapping can provide a more robust method of estimating species occurrence than traditional line transect surveys (Moore et al., 2020). However, it is still difficult to know abundance patterns using camera trapping, in particular for arboreal primates. ...
Knowledge of niche partitioning with respect to habitat is indispensable to understand the mechanism of coexistence of multiple species. Among primates, however, data are still deficient because repeated survey for a sufficiently long time, covering seasonal changes over a large area, is the only way to clarify habitat segregation within a seasonally fluctuating environment. Southeast Asia is particularly interesting because of the supra-annual, highly unpredictable seasonality in fruiting known as mast fruiting. We conducted repeated route census, habitat monitoring, and group tracking for 25 months in two study sites (ca. 10 km apart) in the largely primary lowland dipterocarp forest of the Danum Valley Conservation Area, eastern Sabah, northern Borneo, Malaysia. The five species of diurnal primates (Bornean orangutan Pongo pygmaeus, Müeller's gibbon Hylobates muelleri, red leaf monkey Presbytis rubicunda, long-tailed macaque Macaca fascicularis, and southern pig-tailed macaque M. nemestrina) did not show horizontal spatial segregation. Red leaf monkeys showed preferences for places with short tree height, but their distribution was not confined to such places. In response to the fruiting peak observed once during the study period, orangutans increased their numbers simultaneously in the two study sites. The average tree height used by the five species was different, but their range overlapped substantially. Compared with other primate communities, the lack of horizontal spatial segregation and the suggested long-distance movement of orangutans seem to be unique characteristics in Borneo, although the use of different forest strata is a widespread phenomenon among primate communities throughout the world.
Animal activity is driven by the environmental conditions and physical structure of a habitat, and the need to interact with, or avoid, other animals. Knowledge of the proportion of the 24‐hour cycle spent active (activity level), and the time/s of day in which activity is concentrated (activity pattern), informs our understanding of species' ecology and community dynamics. In multidimensional habitats such as tropical rainforests, arboreal (canopy‐dwelling) taxa comprise up to three‐quarters of vertebrate assemblages; yet, wildlife surveys are typically limited to ground level. Terrestrial‐only sampling can result in activity metrics that do not take account of species' full use of horizontal and vertical habitat space. We paired ground‐ and canopy‐level camera traps to characterize mammal activity across vertical strata in Borneo. Additionally, we sampled unlogged and recovering‐logged rainforest to evaluate whether this activity was impacted by logging. Activity across vertical strata varied substantially among 37 species. Arboreal mammals were predominantly nocturnal or diurnal but never cathemeral, terrestrial mammals were mostly nocturnal or cathemeral, and semi‐arboreal mammals appeared to fill the temporal niches under‐utilized by other groups. Differences in activity between unlogged and recovering‐logged forest were minimal, with 92% of species found in both forest types retaining the same activity pattern. Our study demonstrates that the inclusion of canopy‐based sampling provides much greater insights into overall rainforest mammal activity than terrestrial sampling alone. Our results suggest that the varying opportunities and constraints of each stratum act in concert to influence the diel patterns of tropical mammals.
Abstract in Malay is available with online material.
The persistence of seed-dispersing animals in degraded habitats could be critical for ensuring the long-term conservation value and restoration of forests. This is particularly important in Southeast Asia, where > 70% of the remaining forest areas are within 1 km of a forest edge, and many are degraded (e.g. logged). We synthesized information on the habitat associations of the binturong Arctictis binturong, a large, semi-arboreal, frugivorous civet and one of the most important seed dispersers in the region, especially for figs (Ficus spp). We adopted a multiscale approach by employing ensemble species distribution modelling from presence-only records, assessing landscape-scale variation in detection rates in published camera-trap studies and using hierarchical occupancy modelling to assess local (i.e. within-landscape) patterns observed from 20 new camera-trap surveys. Contrary to prior reports that binturongs are strongly associated with intact forests, the species was equally present in degraded forests and near forest edges where sufficient forest cover was maintained (> 40% forest cover within a 20-km radius). The species also tolerates moderate incursions of oil palm plantations (< 20% of the area within a 20-km radius covered by oil palm plantations). The relative resilience of binturongs to habitat degradation could be in part because of behavioural adaptations towards increased nocturnal activity. These results support the notion that key seed dispersers can persist and maintain their ecological function in degraded forests.
In West Africa, high deforestation rates and poaching have induced dramatic declines of mammal’s populations and local extinctions. Due to their isolation, island species are more vulnerable than mainland species. The premises of that scenario are perceptible in the Ehotilé Islands National Park, south-eastern Côte d’Ivoire, but have not been documented. This study aimed to update the diversity and conservation status of medium and large mammals in that protected area. Several surveys were conducted between 2019 and 2021, using ethno-zoological interviews and individual surveys with local populations, as well as reconnaissance walks and camera trapping to collect data on the presence or absence of mammals. From interviews with local populations and literature review, a list of 27 species of mammals that were potentially present in the park in the past was established. Most “lost” species are large mammals, especially primates that are globally threatened. A total of 11 species were pictorially identified, including two Near threatened species ( Aonyx capensis and Hydrictis maculicollis ) and one Vulnerable species ( Cercopithecus lowei ). The study confirms a trend of population decline and the erosion of mammal diversity in the park, hence highlighting the need for urgent conservation actions.
Many tropical biosphere reserves face the problem of overexploiting biological resources, which is a major cause of biodiversity loss. We used an integrative approach, combining camera trapping and bat trapping in diverse habitats over multiple surveys in Yangambi Biosphere Reserve, Democratic Republic of the Congo. We investigated whether species-level traits of volant and nonvolant mammals, as well as key features of their habitats, can predict effects on species detectability and occupancy, and thus on community-level species richness. We applied single-season occupancy models using multi-species data for camera trap and bat trap datasets. We found a positive effect of denser woodlands on occupancy estimates over 6480 camera-days. Average adult body weight and whether species were group-living negatively influenced species detection estimates. Species richness and body size assemblages approximated marginal rainforest diversity. This included small-bodied, generally high-hunting-resilient arboreal and terrestrial species. During 324 trap-nights, site location was the main determinant of habitat occupancy at the community level. Occupancy estimates were not, however, directly linked to variables measured in different stands. This may be a consequence of habitat patterns at larger spatial scales, which require additional data to clarify. Species-level characteristics that might influence detection estimates were not, however, included in the parsimonious output of the model used. Our findings indicate specific mechanisms triggering mammalian impoverishment above a critical size that may drive ecological changes. Thanks to certain life-history traits, bats can compensate for some of the lost services previously provided by large mammals, thus contributing to the maintenance of biodiversity dynamics.
Camera traps have been used increasingly as a research tool to monitor wildlife globally, and have become more advanced, thereby improving their performance and lowering costs. Their use has allowed researchers to study a range of species, including rare and elusive species, particularly in remote areas, in a non-invasive, reliable and cost-effective way. In this review, we sought to document the camera trapping research on terrestrial wildlife conducted in Africa, identifying countries and habitat types of focus, and how these camera trap research trends in Africa could be improved in the future. Through a systematic literature search, we found 408 peer-reviewed publications using camera traps to study terrestrial wildlife in Africa, with the first being in 2005 and up to 2021. Although camera trap studies were conducted in 38 African countries, most were in South Africa (28.9%). Most studies assessed the occupancy of species (41.4%). The studies covered a range of taxa, with mammals being the most popular. The majority of research focussed on large carnivores (24.8%), with a particular focus on leopards (Panthera pardus) (60 studies). Most studies (43.9%) focused on a single species, with forests (174 studies, 42.6%) and savannah/bushveld (145 studies, 35.5%) being the habitat type of focus. There was also a strong preference for camera trap studies to be conducted in protected areas (68.9%). The camera trap methods used varied considerably between studies, which included: the number of camera trap stations, survey length, trap effort, camera trap make and model, camera trap flash type, interval delay, camera multishot, height of camera trap placement, camera trap layout method and whether the camera trap was baited. These variations are expected because of the difference in research goals posed by each study. However, studies with similar objectives and/or focus still display a clear lack of standardisation (studies do not conform to a specific standard), which could negatively impact the results obtained, as inappropriate camera trap protocols could affect the detectability of certain species. Future camera trap studies will hopefully extend to countries and taxa that have received little attention, with further research informing appropriate conservation strategies that could reduce the threats to biodiversity.
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.
Forest-agricultural mosaics are now considered critical for biodiversity. Within these landscapes, the type of land use surrounding remnant forests influences the ability of arboreal non-flying wildlife to travel, disperse and ultimately survive, making arboreal species disproportionally impacted from habitat change. To inform land management strategies we must first understand how wildlife, including arboreal taxa, respond to heterogeneous landscapes.
Here, we examine the occurrence patterns of four arboreal and three semi-terrestrial primate species in response to agroforest landscape characteristics in southern Guinea-Bissau, West Africa.
We combine results from arboreal and terrestrial camera traps across Cantanhez National Park (1067 km2). We fit occupancy models using anthropogenic and environmental covariates generated via remote sensing and in-situ vegetation surveys.
Arboreal camera traps (N = 38 locations, 1922 camera trap days) detected all seven primate species, terrestrial camera traps (N = 62 locations, 3113 camera trap days) detected five. Arboreal red colobus (Piliocolobus badius) and semi-terrestrial Guinea baboon (Papio papio) were the only species not detected at all outside forest blocks. Occupancy of semi-terrestrial chimpanzee (Pan troglodytes) increased nearer villages, whereas that of arboreal king colobus (Colobus polykomos) and Demidoff's galago (Galagoides demidoff) decreased. Our models also suggest that semi-arboreal Campbell's monkeys (Cercopithecus campbelli) increase arboreality nearer villages.
We demonstrate heterogeneous spatial responses amongst primates across the agroforest landscape. The lack of distinct patterns between groups (arboreal vs. semi-terrestrial primates) is likely due to species-specific human-induced anti-predator strategies and hunting preferences. Our results highlight the contribution of arboreal camera traps to community-based landscape-scale studies in anthropogenic environments.
Spatial partitioning in ecological communities has predominantly been described in two dimensions, yet habitat is complex and 3D. Complex space use mediates community structure and interaction strength by expanding spatial, temporal, and dietary dimensions. Vertical stratification of resources provides opportunities for novel specializations, creating a 3D niche. Competition and predation are mediated by 3D space use, as individuals use the vertical axis to access prey, flee predators, or avoid competitors. The 3D niche is important for long-term conservation strategies as species must navigate tradeoffs in habitat use between strata-specific threats and suboptimal habitat patches. Ultimately, elucidating the 3D niche has implications for protected area management and corridor design that directly influence species persistence and ecosystem function in a rapidly changing world.
Wildlife monitoring is essential for conservation science and data‐driven decision‐making. Tropical forests pose a particularly challenging environment for monitoring wildlife due to the dense vegetation, and diverse and cryptic species with relatively low abundances. The most commonly used monitoring methods in tropical forests are observations made by humans (visual or acoustic), camera traps, or passive acoustic sensors. These methods come with trade‐offs in terms of species coverage, accuracy and precision of population metrics, available technical expertise, and costs. Yet, there are no reviews that compare the characteristics of these methods in detail. Here, we comprehensively review the advantages and limitations of the three mentioned methods, by asking four key questions that are always important in relation to wildlife monitoring: (1) What are the target species?; (2) Which population metrics are desirable and attainable?; (3) What expertise, tools, and effort are required for species identification?; and (4) Which financial and human resources are required for data collection and processing? Given the diversity of monitoring objectives and circumstances, we do not aim to conclusively prescribe particular methods for all situations. Neither do we claim that any one method is superior to others. Rather, our review aims to support scientists and conservation practitioners in understanding the options and criteria that must be considered in choosing the appropriate method, given the objectives of their wildlife monitoring efforts and resources available. We focus on tropical forests because of their high conservation priority, although the information put forward is also relevant for other biomes. Wildlife monitoring is essential for conservation science and data‐driven decision‐making. We compare three commonly used monitoring methods by following four questions that are always important in relation to wildlife monitoring.
Arboreal camera trapping is a burgeoning method providing a novel and effective technique to answer research questions across a variety of ecosystems, and it has the capacity to improve our understanding of a wide range of taxa. However, while terrestrial camera trapping has received much attention, there is little guidance for dealing with the unique challenges of working in the arboreal realm.
Our review draws on the expertise of researchers from six continents and the broader literature to investigate the advantages and disadvantages of arboreal camera trapping, and challenges to consider when using this technology. We also include mini‐guides with detailed information on the current arboreal camera trap literature, mounts used to install arboreal cameras, tree climbing pointers and safety tips, methods for deploying cameras without climbing, and tips for managing interference with camera function.
We find that arboreal camera traps have been most commonly used in the study of mammals in forests; however, there is potential for this method to be applied to a broad range of habitats including urban areas, and taxa such as birds, amphibians, invertebrates, and plants. Methods in arboreal camera trapping could be improved by developing a greater understanding of the factors affecting detection of species. The most common challenges of arboreal camera trapping are camera placement and camera site access. These can be overcome by understanding correct camera orientation, managing potential sources of interference in front of cameras, utilizing appropriate cameras mounts and training researchers properly.
Given the benefits and opportunities presented by arboreal camera trapping, it is likely to become an ever‐more popular method of studying arboreal species and systems. The information synthesized in this review provides guidance for future studies to help direct more reliable and robust ecological inferences from arboreal camera trapping.
Primate species face growing risks of extinction throughout the world. To better protect their populations, effective monitoring techniques are needed. The goal of this study was to evaluate the use of arboreal camera traps and occupancy modeling as conservation tools for threatened lemur species. This project aimed to (1) estimate the occupancy and detection probabilities of lemur species, (2) investigate factors potentially affecting lemur habitat use, and (3) determine whether ground or arboreal cameras are better for surveying lemur assemblages. We conducted camera trapping research in five forest fragments (total trap nights = 1770; 900 arboreal trap nights (134 photo events); 870 ground trap nights (2 photo events)) and reforestation areas (total trap nights = 608; 1 photo event) in Kianjavato, Madagascar from May to September 2019. We used arboreal trap data from fragments to estimate occupancy for five species: the red-fronted brown lemur (Eulemur rufifrons; ψ = 0.54 ± SD 0.03), Jolly's mouse lemur (Microcebus jollyae; ψ = 0.14 ± 0.17), the greater dwarf lemur (Cheirogaleus major; ψ = 0.42 ± 0.30), the red-bellied lemur (Eulemur rubriventer; ψ = 0.24 ± 0.03), and the black-and-white ruffed lemur (Varecia variegata; ψ = 0.24 ± 0.08). Tree diameter, elevation, distance to village, and canopy connectivity were important predictors of occupancy, while camera height, canopy connectivity, fragment ID, and fragment size predicted detection. Arboreal cameras recorded significantly higher species richness compared with ground cameras. We suggest expanded application of arboreal camera traps in future research, but we recommend longer trapping periods to better sample rarer species. Overall, arboreal camera trapping combined with occupancy modeling can be a highly efficient and useful approach for monitoring and predicting the occurrence of elusive lemur species and has the potential to be effective for other arboreal primates and canopy taxa across the globe.
Our woodpecker study on the buffer effect of floaters by reinforcing colonisation has been published by Animal Conservation. Here the cover page and issue information
Large and medium-bodied rainforest canopy mammals are typically surveyed using line transects, but these are labour intensive and usually ignore nocturnal species. Camera traps have become the preferred tool for assessing terrestrial mammal communities, but have rarely been used for arboreal species. Here, we compare the efficiency of arboreal camera trapping with line transects for inventorying medium and large-sized arboreal mammals, and assess the viability of using camera traps in trees to model habitat occupancy. We installed 42 camera traps, spaced 2 km apart, in the canopy of the Maijuna-Kichwa Regional Conservation Area, Peru and walked 2014 km of diurnal line transects on 22 trails at the same site. We compared the efficiency of each method using species accumulation curves. We applied a multi-species occupancy model, while examining the effect of camera height on detection probabilities, including the distance from a village and from a river as covariates to examine variability in habitat occupancy. In 3147 camera days, 18 species of arboreal medium and large-sized mammals were detected by cameras, while 11 species were recorded on line transects. Ten of these species were detected by both methods. Diurnal species were detected more quickly and with less effort using arboreal camera trapping than using diurnal line transects at the same site, although some species were more easily detected during line transects. Habitat occupancy was positively correlated with distance from the village for two species, and negatively correlated with distance from the river for one. Detection probabilities increased modestly with camera height. Practical limitations of arboreal camera trapping include the requirement for specialized climbing techniques, as well as increased potential for false triggers, requiring extended processing time. Arboreal camera trapping is an efficient method for inventorying arboreal mammals and a viable option for studying their distribution relative to environmental or anthropogenic variables when abundance or density estimates are not required.
Traditionally, arboreal rainforest mammals have been inventoried using ground-based survey techniques. However, given the success of camera traps in detecting secretive terrestrial rainforest mammals, camera trapping could also be a valuable tool for inventorying arboreal species. Here we assess, for the first time, the effectiveness of arboreal camera traps for inventorying arboreal rainforest mammals and compare the results with those from other methodologies. We do so in one of the world's most biodiverse conservation areas, the Manu Biosphere Reserve, Peru. We accumulated 1201 records of 24 arboreal mammal species. Eighteen species were detected by arboreal cameras, seven by diurnal line transects, six by nocturnal transects and eighteen through incidental observations. Six species were only detected using arboreal camera traps. Comparing arboreal camera traps with traditional ground-based techniques suggests camera traps are an effective tool for inventorying arboreal rainforest mammal communities. They also detected more cryptic species compared with other methodologies. Daily detection frequency patterns were found to differ between ground-based techniques and arboreal cameras. A cost-effort analysis indicated that despite greater upfront costs in equipment and training for arboreal camera trapping, when accounting for the additional survey hours required to provide similar numbers of records using ground-based methods, overall costs were similar. Our work demonstrates that arboreal camera trapping is likely to be a powerful technique for inventorying canopy mammals. The method has considerable potential for the study of charismatic and threatened arboreal mammal species that may otherwise remain largely unknown and could quietly disappear from the world's tropical forests.
Long-term monitoring and research projects are essential to understand ecological change and the effectiveness of management activities. An inherent characteristic of long-term projects is the need for consistent data collection over time, requiring rigorous attention to data management and quality assurance. Recent papers have provided broad recommendations for data management; however, practitioners need more detailed guidance and examples. We present general yet detailed guidance for the development of comprehensive, concise, and effective data management for monitoring projects. The guidance is presented as a graded approach, matching the scale of data management to the needs of the organization and the complexity of the project. We address the following topics: roles and responsibilities; consistent and precise data collection; calibration of field crews and instrumentation; management of tabular, photographic, video, and sound data; data completeness and quality; development of metadata; archiving data; and evaluation of existing data from other sources. This guidance will help practitioners execute effective data management, thereby, improving the quality and usability of data for meeting project objectives as well as broader meta-analysis and macrosystem ecology research. © 2015 The Wildlife Society.
1.Over the last two decades a large number of camera trap surveys have been carried out around the world and camera traps have been proposed as an ideal tool for inventorying and monitoring medium to large-sized terrestrial vertebrates. However, few studies have analysed camera trap data at the community level.2.We developed a multi-session multi-species occupancy model that allows us to obtain estimates for species richness and occupancy combining data from multiple camera trap surveys (sessions). By estimating species presence at the session level and modelling detection probability and occupancy for each species and sessions as nested random effects we could improve parameter estimates for each session, especially for species with sparse data. We developed two variants of our model: one was a binary latent states model while the other used a Royle–Nichols formulation for the relationship between detection probability and abundance.3.We applied both models to data from eight camera trap surveys from southeastern Peru including six study sites, 263 camera stations, and 17,423 camera days. Sites covered protected areas, a logging concession, and Brazil nut concessions. We included habitat (terra firme vs. floodplain) as a covariate for occupancy, and trail vs. off-trail as a covariate for detection.4.Among-camera heterogeneity was a serious problem for our data and the Royle–Nichols variant of our model had a much better fit than the binary-state variant. Both models resulted in similar species richness estimates showing that most of the sites contained intact large mammal communities. Detection probabilities and occupancy values were more variable across species than across sessions within species. Three species showed a habitat preference and four species showed preference or avoidance of trails.5.Synthesis and applications. Our multi-session multi-species occupancy model provides improved estimates for species richness and occupancy for a large dataset. Our model is ideally suited for integrating large numbers of camera trap datasets to investigate regional and/or temporal patterns in the distribution and composition of mammal communities in relation to natural or anthropogenic factors or to monitor mammal communities over time.This article is protected by copyright. All rights reserved.
1.Although camera trapping has been shown to be a highly effective non-invasive tool for wildlife monitoring, the technique has not yet been widely applied to studies of arboreal species. Despite the unique challenges that camera trapping in the canopy poses, its versatility and relatively non-invasive nature, combined with recent technological improvements on the cameras themselves, make camera trapping a highly useful tool for arboreal research. 2.We present data on the methodology and effectiveness of arboreal camera trapping during the first six months of a year-long study in the Lower Urubamba Region of Peru investigating animal use of natural crossing points (i.e., branches) over a natural gas pipeline clearing. We placed Reconyx PC800 Hyperfire cameras in 25 crossing points of 13 distinct natural canopy “bridges” at a mean height of 26.8m. 3.After six months of data collection, we logged 1,522 photo events, recording 20 mammal, 23 bird, and four reptile species. An analysis of animal passing events in front of the cameras over time did not suggest any negative response to camera presence. While we found that cameras in the canopy are triggered more frequently by non-target stimuli (e.g., leaves) than cameras on the ground, we demonstrated significantly reduced false triggering following leaf removal within 1.5 meters of the camera. 4.Our results suggest that arboreal camera trapping can provide robust documentation of a diversity of vertebrate species engaged in a variety of activities, and we provide recommendations for other researchers interested in using in this method. This is the most extensive arboreal camera trapping study to date in terms of the length of the study period, the number of cameras being used, and the height of the cameras in the trees. Therefore, lessons provided from this experience can be used to improve the design of future arboreal camera trap studies. This article is protected by copyright. All rights reserved.
Context. There is an increasing reliance on the use of camera-trap technologies for surveys of medium to large terrestrial mammals. Camera trapping may, however, also have significant applications for broad-scale surveys of small mammals. Aims. The present study aims to compare results from camera-trapping surveys to those of the more traditional live-trapping techniques. Specifically, it aims to test the effectiveness of the techniques for detecting species, and the cost effectiveness of both approaches. Methods. Surveys were conducted across 36 sites in the Grampians National Park, Victoria, Australia, between April and July 2009. At each site, independent surveys were conducted for small mammals by using a combination of Elliot and cage trapping, then camera trapping. Results for the two different approaches were compared for both their ability to generate small-mammal presence data and their cost effectiveness. Key results. Camera-trapping surveys of 36 sites in the Grampians National Park compared favourably with those of live-trapping surveys. Similar species were detected across the sites, and camera trapping was a considerably more cost effective than live trapping. Conclusions. Camera-trapping surveys of small terrestrial mammals may provide a new and cost-effective technique for surveying terrestrial small mammals. This is particularly the case when presence data are the main requirement of the survey, with no requirement to capture and tag animals. Implications. Given the cost-effective nature of camera trapping, there is potential to use this approach to increase the level of replication and spatial coverage of small-mammal surveys. Improving the replication and spatial coverage of studies has the potential to significantly increase the scope of research questions that can be asked, thus providing the potential to improve wildlife management. © CSIRO 2010.
The emerging field of climate-change adaptation has experienced a dramatic increase in attention as the impacts of climate change on biodiversity and ecosystems have become more evident. Preparing for and addressing these changes are now prominent themes in conservation and natural resource policy and practice. Adaptation increasingly is viewed as a way of managing change, rather than just maintaining existing conditions. There is also increasing recognition of the need not only to adjust management strategies in light of climate shifts, but to reassess and, as needed, modify underlying conservation goals. Major advances in the development of climate-adaptation principles, strategies, and planning processes have occurred over the past few years, although implementation of adaptation plans continues to lag. With ecosystems expected to undergo continuing climate-mediated changes for years to come, adaptation can best be thought of as an ongoing process, rather than as a fixed endpoint.
Although highly diverse (Fonseca et al . 1996), the Atlantic forest mammal fauna is still poorly known, with very few sites exhaustively inventoried or subjected to long-term studies (Passamani et al . 2000). Although the first surveys using camera traps were carried out in the 1920s (e.g. Chapman 1927), most studies are rather recent (Karanth & Nichols 1998). This is not different in Brazil, where few studies have been published (Marques & Ramos 2001, Santos-Filho & Silva 2002, Silveira et al . 2003, Trolle 2003, Trolle & Kéry 2003). Given this, the objective of this paper is to assess the efficiency of camera trapping as an inventory technique for Neotropical forests in general and Atlantic forest in particular. The study was conducted at the Santa Lúcia Biological Station (SLBS), a biologically rich Atlantic Forest preserve located in south-eastern Brazil (Mendes & Padovan 2000) where mammals have been intensively live-trapped, observed from line-transects or had indirect evidence of their presence (faeces, footprints, scratches, etc.) recorded in earlier years (Passamani et al . 2000).
1. Line transect survey techniques have been used to estimate population density for a variety of mammal species in tropical forests. In many cases indirect methods, surveying signs of animals such as counts of dung or nests, have been used because of the poor visibility in these forests. The estimates of the production and decomposition rates of these signs each have their associated errors; however, for the majority of published studies these errors have not been incorporated into the estimate of the standard errors or confidence limits of the density estimate. An equation is given showing how this should be done.
Nondetection of a species at a site does not imply that the species is absent unless the probability of detection is 1. We propose a model and likelihood-based method for estimating site occupancy rates when detection probabilities are 1. The model provides a flexible framework enabling covariate information to be included and allowing for missing observations. Via computer simulation, we found that the model provides good estimates of the occupancy rates, generally unbiased for moderate detection probabilities (0.3). We estimated site occupancy rates for two anuran species at 32 wetland sites in Maryland, USA, from data collected during 2000 as part of an amphibian monitoring program, Frog-watch USA. Site occupancy rates were estimated as 0.49 for American toads (Bufo amer-icanus), a 44% increase over the proportion of sites at which they were actually observed, and as 0.85 for spring peepers (Pseudacris crucifer), slightly above the observed proportion of 0.83.
Mammal inventories in tropical forests are often difficult to carry out, and many elusive species are missed or only reported from interviews with local people. Camera traps offer a new tool for conducting inventories of large- and medium-sized terrestrial mammals. We evaluated the efficiency of camera traps based on data from two surveys carried out at a single site during 2 consecutive years. The survey efforts were 1440 and 2340 camera days, and 75 and 86% of the 28 large- and medium-sized terrestrial mammal species known to occur at the site were recorded. Capture frequencies for different species were highly correlated between the surveys, and the capture probability for animals that passed in front of the cameras decreased with decreasing size of the species. Camera spacing and total survey area had little influence on the number of species recorded, with survey effort being the main factor determining the number of recorded species. Using a model we demonstrated the exponential increase in survey effort required to record the most elusive species. We evaluated the performance of different species richness estimators on this dataset and found the Jackknife estimators generally to perform best. We give recommendations on how to increase efficiency of camera trap surveys exclusively targeted at species inventories.
1.Distance sampling is a widely used technique for estimating the size or density of biological populations. Many distance sampling designs and most analyses use the software Distance.
2.We briefly review distance sampling and its assumptions, outline the history, structure and capabilities of Distance, and provide hints on its use.
3.Good survey design is a crucial prerequisite for obtaining reliable results. Distance has a survey design engine, with a built-in geographic information system, that allows properties of different proposed designs to be examined via simulation, and survey plans to be generated.
4.A first step in analysis of distance sampling data is modelling the probability of detection. Distance contains three increasingly sophisticated analysis engines for this: conventional distance sampling, which models detection probability as a function of distance from the transect and assumes all objects at zero distance are detected; multiple-covariate distance sampling, which allows covariates in addition to distance; and mark–recapture distance sampling, which relaxes the assumption of certain detection at zero distance.
5.All three engines allow estimation of density or abundance, stratified if required, with associated measures of precision calculated either analytically or via the bootstrap.
6.Advanced analysis topics covered include the use of multipliers to allow analysis of indirect surveys (such as dung or nest surveys), the density surface modelling analysis engine for spatial and habitat modelling, and information about accessing the analysis engines directly from other software.
7.Synthesis and applications. Distance sampling is a key method for producing abundance and density estimates in challenging field conditions. The theory underlying the methods continues to expand to cope with realistic estimation situations. In step with theoretical developments, state-of-the-art software that implements these methods is described that makes the methods accessible to practising ecologists.
Line transect sampling is widely used for estimating abundance of primate populations. Researchers commonly use animal-to-observer
distances (AODs) in analysis, in preference to perpendicular distances from the line, which is in marked contrast with standard
practice for other applications of line transect sampling. We formalize the mathematical shortcomings of approaches based
on AODs, and show that they are likely to give strongly biased estimates of density. We review papers that claim good performance
for the method, and explore this performance through simulations. These confirm strong bias in estimates of density using
AODs. We conclude that AOD methods are conceptually flawed, and that they cannot in general provide valid estimates of density.
Keywordsanimal-to-observer distances-distance sampling-estimating primate density-Kelker strip-modified Kelker method-primate surveys
Activities involving fauna monitoring are usually limited by the lack of resources; therefore, the choice of a proper and efficient methodology is fundamental to maximize the cost–benefit ratio. Both direct and indirect methods can be used to survey mammals, but the latter are preferred due to the difficulty to come in sight of and/or to capture the individuals, besides being cheaper. We compared the performance of two methods to survey medium and large-sized mammal: track plot recording and camera trapping, and their costs were assessed. At Jataí Ecological Station (S21°31'15"–W47°34'42"-Brazil) we installed ten camera traps along a dirt road directly in front of ten track plots, and monitored them for 10 days. We cleaned the plots, adjusted the cameras, and noted down the recorded species daily. Records taken by both methods showed they sample the local richness in different ways (Wilcoxon, T = 231; p ;; 0.01). The track plot method performed better on registering individuals whereas camera trapping provided records which permitted more accurate species identification. The type of infra-red sensor camera used showed a strong bias towards individual body mass (R
2 = 0.70; p = 0.017), and the variable expenses of this method in a 10-day survey were estimated about 2.04 times higher compared to track plot method; however, in a long run camera trapping becomes cheaper than track plot recording. Concluding, track plot recording is good enough for quick surveys under a limited budget, and camera trapping is best for precise species identification and the investigation of species details, performing better for large animals. When used together, these methods can be complementary.
Protected areas (PAs) are a cornerstone of global efforts to shield wildlife from anthropogenic impacts, yet their effectiveness at protecting wide-ranging species prone to human conflict--notably mammalian carnivores--is increasingly in question. An understanding of carnivore responses to human-induced and natural changes in and around PAs is critical not only to the conservation of threatened carnivore populations, but also to the effective protection of ecosystems in which they play key functional roles. However, an important challenge to assessing carnivore communities is the often infrequent and imperfect nature of survey detections. We applied a novel hierarchical multi-species occupancy model that accounted for detectability and spatial autocorrelation to data from 224 camera trap stations (sampled between October 2006 and January 2009) in order to test hypotheses about extrinsic influences on carnivore community dynamics in a West African protected area (Mole National Park, Ghana). We developed spatially explicit indices of illegal hunting activity, law enforcement patrol effort, prey biomass, and habitat productivity across the park, and used a Bayesian model selection framework to identify predictors of site occurrence for individual species and the entire carnivore community. Contrary to our expectation, hunting pressure and edge proximity did not have consistent, negative effects on occurrence across the nine carnivore species detected. Occurrence patterns for most species were positively associated with small prey biomass, and several species had either positive or negative associations with riverine forest (but not with other habitat descriptors). Influences of sampling design on carnivore detectability were also identified and addressed within our modeling framework (e.g., road and observer effects), and the multi-species approach facilitated inference on even the rarest carnivore species in the park. Our study provides insight for the conservation of these regionally significant carnivore populations, and our approach is broadly applicable to the robust assessment of communities of rare and elusive species subject to environmental change.
Camera traps are increasingly used to estimate relative abundance and distribution of wildlife. These methods are powerful and efficient ways to inventory multiple species simultaneously and count rare, secretive individuals across landscapes. However the estimation methods demand assumptions about relative capture probability that may not hold well for gregarious animals. We present results from the first systematic, camera-trap study in forest–woodland, western Uganda. Within a landscape of seven protected areas with globally important biodiversity, we detected >36 species of large mammals and birds in 8841 camera-trap days. Species photographed in groups of two or more individuals produced higher estimates of relative abundance and wider distribution than species photographed as single individuals. We propose these findings reflect higher detectability for animals that forage or travel in groups. We discuss how capture–recapture theory should be adapted to account for both non-independence among individuals in groups and for the interaction between individual and temporal variation in capture probability. We also identify several species that deserve greater conservation attention in Uganda and beyond. Among them, leopards were unexpectedly rare, especially when compared to the sympatric African golden cat. We recommend against a recent policy on leopard trophy hunting, at least in western Uganda.
The Albertine Rift is one of the most important regions for conservation in Africa. It contains more vertebrate species than any other region on the continent and contains more endemic species of vertebrate than any other region on mainland Africa. This paper compiles all currently known species distribution information for plants, endemic butterfly species and four vertebrate taxa from the Albertine Rift. The literature on fish species richness and endemism is also reviewed to assess the importance of the larger lakes in the Rift for conservation. We use data from 38 protected and unprotected areas to prioritise sites within the Albertine Rift for conservation based upon their numbers of endemic and globally threatened species. Virunga and Kahuzi Biega National Parks and Itombwe Massif in Democratic Republic of Congo, Bwindi Impenetrable and Kibale National Parks in Uganda, and Nyungwe National Park in Rwanda rank highest in terms of numbers of both endemic and globally threatened species. Six conservation landscapes are described that include most of these sites and it is argued that a focus on these landscapes may be a more holistic method to ensure the safety of the priority areas of the Albertine Rift.
Density estimation is of fundamental importance in wildlife management. The use of camera traps to estimate animal density has so far been restricted to capture2013recapture analysis of species with individually identifiable markings. This study developed a method that eliminates the requirement for individual recognition of animals by modelling the underlying process of contact between animals and cameras. The model provides a factor that linearly scales trapping rate with density, depending on two key biological variables (average animal group size and day range) and two characteristics of the camera sensor (distance and angle within which it detects animals). We tested the approach in an enclosed animal park with known abundances of four species, obtaining accurate estimates in three out of four cases. Inaccuracy in the fourth species was because of biased placement of cameras with respect to the distribution of this species. Synthesis and applications. Subject to unbiased camera placement and accurate measurement of model parameters, this method opens the possibility of reduced labour costs for estimating wildlife density and may make estimation possible where it has not been previously. We provide guidelines on the trapping effort required to obtain reasonably precise estimates.
Analyses of life-history, ecological, and geographic trait differences among species, their causes, correlates, and likely consequences are increasingly important for understanding and conserving biodiversity in the face of rapid global change. Assembling multispecies trait data from diverse literature sources into a single comprehensive data set requires detailed consideration of methods to reliably compile data for particular species, and to derive single estimates from multiple sources based on different techniques and definitions. Here we describe PanTHERIA, a species-level data set compiled for analysis of life history, ecology, and geography of all known extant and recently extinct mammals. PanTHERIA is derived from a database capable of holding multiple geo-referenced values for variables within a species containing 100?740 lines of biological data for extant and recently extinct mammalian species, collected over a period of three years by 20 individuals. PanTHERIA also includes spatial databases of mammalian geographic ranges and global climatic and anthropogenic variables. Here we detail how the data fields are extracted and defined for PanTHERIA using a customized data input format (MammalForm); how data were collected from the literature, species names and sources tracked, error-checking and validation procedures applied, and how data were consolidated into species-level values for each variable. Tables of the consolidated species-level values are made available for each of two recent species-level taxonomic classifications of mammals, as well as associated taxonomic synonymy conversion and data-input files. This study provides a useful guide to prospective researchers on how to structure and codify life-history, ecological, geographic, and taxonomic data and methods to extract meaningful species-level traits. It also provides comprehensive information on traits like size, diet, environmental conditions, and ecology to permit macroecological and macroevolutionary analyses of this important clade. The complete data sets corresponding to abstracts published in the Data Papers section of the journal are published electronically in Ecological Archives at ?http://esapubs.org/archive?. (The accession number for each Data Paper is given directly beneath the title.)
Monitoring is an integral part of species conservation. Monitoring programs must take imperfect detection of species into account in order to be reliable. Theory suggests that detection probability may be determined by population size but this relationship has not yet been assessed empirically. Population size is particularly important because it may induce heterogeneity in detection probability and thereby cause bias in estimates of biodiversity. We used a site occupancy model to analyse data from a volunteer-based amphibian monitoring program to assess how well different variables explain variation in detection probability. An index to population size best explained detection probabilities for four out of six species (to avoid circular reasoning, we used the count of individuals at a previous site visit as an index to current population size). The relationship between the population index and detection probability was positive. Commonly used weather variables best explained detection probabilities for two out of six species. Estimates of site occupancy probabilities differed depending on whether the population index was or was not used to model detection probability. The relationship between the population index and detectability has implications for the design of monitoring and species conservation. Most importantly, because many small populations are likely to be overlooked, monitoring programs should be designed in such a way that small populations are not overlooked. The results also imply that methods cannot be standardized in such a way that detection probabilities are constant. As we have shown here, one can easily account for variation in population size in the analysis of data from long-term monitoring programs by using counts of individuals from surveys at the same site in previous years. Accounting for variation in population size is important because it can affect the results of long-term monitoring programs and ultimately the conservation of imperiled species.
Terrestrial mammals are a key component of tropical forest communities as indicators of ecosystem health and providers of important ecosystem services. However, there is little quantitative information about how they change with local, regional and global threats. In this paper, the first standardized pantropical forest terrestrial mammal community study, we examine several aspects of terrestrial mammal species and community diversity (species richness, species diversity, evenness, dominance, functional diversity and community structure) at seven sites around the globe using a single standardized camera trapping methodology approach. The sites-located in Uganda, Tanzania, Indonesia, Lao PDR, Suriname, Brazil and Costa Rica-are surrounded by different landscape configurations, from continuous forests to highly fragmented forests. We obtained more than 51 000 images and detected 105 species of mammals with a total sampling effort of 12 687 camera trap days. We find that mammal communities from highly fragmented sites have lower species richness, species diversity, functional diversity and higher dominance when compared with sites in partially fragmented and continuous forest. We emphasize the importance of standardized camera trapping approaches for obtaining baselines for monitoring forest mammal communities so as to adequately understand the effect of global, regional and local threats and appropriately inform conservation actions.
We review the four major contemporary methods for estimating density of group-living animals from line-transect sampling: perpendicular modelling of group centers, perpendicular modelling of center of measurable individuals, strip transects and animal-observer distance. The efficacy of each method is evaluated to produce a simple selection guide. We review the literature and use field data from the Udzungwa Mountains, Tanzania. The review is relevant to all group-living animals; however, examples are drawn from the primates. Perpendicular methods have better mathematical justification than non-perpendicular methods. For perpendicular methods using detection function models, it is preferable to measure group location using center of measurable individuals, as group centers are hard to estimate. The assumptions of detection function models are often broken in poor visibility habitats or with unhabituated animals. Alternatively strip transects may be used where there are reliable data on group spread and/or visibility. Strip transects are also the most practical, along with the animal-observer method; however, the latter lacks mathematical justification. We conclude that there are arguments for continued use of all four methods. In certain situations the use of raw encounter rates may also be considered. The appropriate method is determined by minimizing bias and considering time, resources and field conditions.
Exploring trends in species richness and the distribution of individual species over time as well as the factors affecting these trends informs conservation priorities in protecting species and ecosystems as a whole. We used data from 41 park‐wide line transect surveys in 2009 and 2014 and multi‐season occupancy models with multi‐species data to explore trends in species richness and distribution of individual species and factors affecting these trends in Nyungwe National Park (NNP), Rwanda. Mammalian species richness and the distributional range of 5 of the 7 species increased between 2009 and 2014 in NNP. The probability of colonization of a species into a new area in 2014, where it was not present in 2009, was highest in sites with a lower probability of poaching activity, close to tourist trails, and at lower elevations. The probability of colonization with no poaching activity was about 50% but dropped to about 10% with a 100% chance of poaching activity. Duiker species had the largest increase in distribution during the study, while there was a decrease in the distribution of the eastern chimpanzee and blue monkey. Our results suggest that increased patrols could be implemented in areas of the park with low species richness and areas with a low probability of occurrence for species of conservation concern to combat poaching activity and thus increase the probability of a species moving into a new area. Our use of a single multi‐season model for multiple species explicitly accounts for imperfect detection and species‐specific identities, while allowing for inferences to be made about rarely detected species by sharing covariates with common species. These results can be used to improve conservation planning in NNP for species management and ranger patrol protocols, and our modelling framework is broadly applicable to any protected area with presence/absence species field data.
Species richness and species-specific occupancy are key variables for biodiversity monitoring. While there are many field techniques to assess presence of mammalian species, their relative performance and cost effectiveness can be affected by biological variables that are related to availability (relative abundance, diurnal activity) or by traits that are related to visibility (body size, coloration, habitat selection) of a species. We conducted four transect surveys, driven during daytime hours and continuous monitoring with camera traps over a 16-week period in Lake Manyara National Park, Tanzania. Transect and camera-trap surveys yielded estimates of 20 and 38 mammalian species, respectively. In absolute terms, diurnal vehicle transects were less costly than camera trapping, but in relative terms (cost/species), camera trapping was more cost effective. Logistic regression showed that mammal species with reduced availability (low relative abundance and low proportion of diurnal activity) were less likely to be detected during diurnal line-transect surveys. Species-specific detection probabilities and occupancy estimates were lower during transect surveys compared to the camera-trap survey. Similar to differences in naive species occupancy, method-related differences in modeled detection probabilities were positively correlated with relative abundance. Results suggest that factors influencing availability of a species explain method-related differences in detection probabilities and species richness estimates.
Occupancy Estimation and Modeling: Inferring Patterns and Dynamics of Species Occurrence, Second Edition, provides a synthesis of model-based approaches for analyzing presence-absence data, allowing for imperfect detection. Beginning from the relatively simple case of estimating the proportion of area or sampling units occupied at the time of surveying, the authors describe a wide variety of extensions that have been developed since the early 2000s. This provides an improved insight about species and community ecology, including, detection heterogeneity; correlated detections; spatial autocorrelation; multiple states or classes of occupancy; changes in occupancy over time; species co-occurrence; community-level modeling, and more. Occupancy Estimation and Modeling: Inferring Patterns and Dynamics of Species Occurrence, Second Edition has been greatly expanded and detail is provided regarding the estimation methods and examples of their application are given. Important study design recommendations are also covered to give a well rounded view of modeling.
Monitoring has become fashionable. Business now talks about monitoring its activities, efficiency, costs and profits. The National Health Service is monitoring general practices and hospitals; it is keen to have more information about efficiency and the duration of stay of patients in different hospitals undergoing different types of treatment. These activities are usually carried out in relation to specific objectives with the aim of making activities more cost effective and competitive. Does the same apply in biology, ecology and nature conservation? Or, are we still enjoying conducting field surveys for the fun of it, at best with rather vague objectives and saying to our colleagues that we do our work because we need to know what is there? This book is an opportunity to consider some of the reasons why monitoring is important, how it differs from survey, how it may be able to answer specific questions and help with site management or problem solving. It will explore some of the taxa that are suitable for recording and how you may actually set about doing it. It is not intended as a catalogue of techniques but we will in each chapter give you sources of material so that with the minimum of effort you will be able to proceed with an efficient, relevant and not too time consuming monitoring programme. Some of the points that you need to consider before starting are also set down in the synthesis at the end of the book.
Despite Africa's rich biodiversity and the importance of its ecosystem services, it has relatively few collaborative, network-based studies that examine the ecological impacts of climate change. This book marks the beginning of such a collaboration. It covers ecological information that spans across five countries in the Albertine Rift region, reflects over 50 years of research, and includes contributions from 65 researchers who represent 44 organizations at work in 11 sites. It provides invaluable information about past and current trends in the status of species, ecosystems and associated threats, as well as recommendations for interventions. (Imprint: Nova Press).
Information about the magnitude and geographic distribution of mammalian diversity in Neotropical lowland rainforests is important for evaluating research and conservation priorities in Central and South America. Although relevant inventory data are rapidly accumulating in the literature, real site-to-site diversity differences are hard to identify because many confounding factors can affect the size and composition of faunal lists. Herein we assess the available information about Neotropical rainforest mammal diversity and suggest guidelines for future work by reviewing inventory methods, documenting and discussing faunal lists from ten localities, and summarizing geographic range data to predict diversity patterns that can be tested by field and museum research. All inventory methods are biased because each is suitable for collecting or observing only a fraction of the morphologically and behaviorally diverse mammalian fauna that inhabits Neotropical rainforests. Hence, many methods must be used in combination to census whole communities. Although no combination of methods can be guaranteed to produce complete inventories, the omission or nonintensive application of any of several essential methods probably guarantees incomplete results. We recommend nine methods that, used intensively and in combination, should maximize the efficiency of future inventory fieldwork. Ten rainforest mammal inventories selected as exemplars illustrate several common problems: sampling effort is highly variable from study to study, species accumulation curves are not asymptotic for any fauna, essential field methods were omitted in every case, and some localities were partially defaunated by hunters prior to inventory. Meaningful diversity comparisons are therefore impossible without a major investment in additional fieldwork at each site. Geographic range data provide an essential alternative source of diversity estimates. Comparisons of inventory results with geographic expectations (diversity predictions based on range data) suggest that all existing inventories are incomplete, that the degree of incompleteness is inversely correlated with inventory duration, and that special methods are required to add elusive species to faunal lists. The range data at hand also suggest several geographic patterns that should be tested with carefully focussed fieldwork. (1) Mammalian diversity in Amazonia is probably greatest in the western subregion (between the Rio Negro and the Rio Madeira, where over 200 species might be sympatric at some localities), least in the Guiana subregion (east of the Negro and north of the Amazon), and intermediate in southeastern Amazonia (east of the Madeira and south of the Amazon). (2) Geographic variation in Amazonian diversity chiefly involves marsupials, bats, primates, and rodents; by contrast, xenarthran, carnivore, and ungulate faunas are remarkably uniform across the entire region. (3) In Central American rainforests, a conspicuous and apparently monotonic diversity gradient extends from eastern Panama (where mammalian diversity is within the range of Amazonian values) to southern Mexico (where mammalian diversity may be less than anywhere else on the rainforested Neotropical mainland). Mammalian diversity in coastal Venezuelan and southeastern Brazilian rainforests is difficult to assess with existing literature and collection resources, but neither region is likely to be as diverse as Amazonia. Despite a few dissenting voices, the literature of New World mammalogy provides compelling evidence that mammalian diversity, as measured by sympatric species richness, is greatest in lowland tropical rainforests and decreases along gradients of increasing latitude, elevation, and aridity. Thus, the mammalian faunas of western Amazonia are the most diverse of any in the Americas and perhaps in the world. We briefly discuss the generality and causes of observed diversity patterns in terms of contemporary ecology and historical scenarios. Significant advances in understanding mammalian diversity patterns in Neotropical rainforests will require systematic revisions of many problematic genera and an aggressive program to inventory poorly sampled areas while opportunities to do so yet remain.
Rapid faunal assessments can use different methods depending on environmental conditions and costs. To compare the efficiency of three methods in detecting species richness and abundance, we tested them in the grasslands of Emas National Park, central Brazil. Track census was the most effective method for detecting richness, followed by camera-trapping and direct faunal counts. Track census reached an asymptote for number of species after only 12 days, but all methods converged on similar estimates of species richness after around 30 days. There was no significant spatial correlation for species richness or total abundance, between camera trap and tracks, across the 29 samples distributed in the park. However, for some species, abundance showed significant spatial correlation between methods. Also, these rates were significantly correlated across species and the spatial correlation between methods was significantly associated with log-transformed body mass across species. We conclude that, despite the high initial costs for camera-trapping, this method is the most appropriate for mammal inventory in all environmental conditions, allowing a rapid assessment of wildlife conservation status.
Biodiversity monitoring is important to identify biological units in need of conservation and to check the effectiveness of conservation actions. Programs generally monitor species richness and its changes (trend). Usually, no correction is made for imperfect species detectability. Instead, it is as- sumed that each species present has the same probability of being recorded and that there is no dif- ference in this detectability across space and time, e.g. among observers and habitats. Consequently, species richness is determined by enumeration as the sum of species recorded. In Switzerland, the federal government has recently launched a comprehensive program that aims at detecting changes in biodiversity at all levels of biological integration. Birds are an important part of that program. Since 1999, 2-3 visits per breeding season are made to each of >250 1 km 2 squares to map the terri- tories of all detected breeding bird species. Here, we analyse data from three squares to illustrate the use of capture-recapture models in monitoring to obtain detectability-corrected estimates of species richness and trend. Species detectability averaged only 85%. Hence an estimated 15% of species present remained overlooked even after three visits. Within a square, changes in detectability for dif- ferent years were of the same magnitude when surveys were conducted by the same observer as when they were by different observers. Estimates of trend were usually biased and community turnover was overestimated when based on enumeration. Here we use bird data as an illustration of methods. However, species detectability for any taxon is unlikely ever to be perfect or even constant across categories to be compared. Therefore, monitoring programs should correct for species de- tectability.
Plant and animal survey detection rates are important for ecological surveys, environmental impact assessment, inva-sive species monitoring, and modeling species distributions. Species can be difficult to detect when rare but, in general, how detection probabilities vary with abundance is unknown. We developed a new detectability model based on the time to detection of the first individual of a species. Based on this model, the predicted detection rate is proportional to a power function of abundance with a scaling exponent between zero and one that depends on clustering of individuals. We estimated the model parameters with data from three independent datasets: searches for chenopod shrub species and coins, experimental searches for planted seedlings, and frog surveys at multiple sites in sub-tropical forests of eastern Australia. Analyses based on the detection time and detection probability suggest that detection rate increases with abun-dance as predicted. The model provides a way to scale detection rates to cases of low abundance when direct estimation of detection rates is often impractical.
Summary • Occupancy estimation and modelling based on detection–nondetection data provide an effective way of exploring change in a species’ distribution across time and space in cases where the species is not always detected with certainty. Today, many monitoring programmes target multiple species, or life stages within a species, requiring the use of multiple detection methods. When multiple methods or devices are used at the same sample sites, animals can be detected by more than one method. • We develop occupancy models for multiple detection methods that permit simultaneous use of data from all methods for inference about method-specific detection probabilities. Moreover, the approach permits estimation of occupancy at two spatial scales: the larger scale corresponds to species’ use of a sample unit, whereas the smaller scale corresponds to presence of the species at the local sample station or site. • We apply the models to data collected on two different vertebrate species: striped skunks Mephitis mephitis and red salamanders Pseudotriton ruber. For striped skunks, large-scale occupancy estimates were consistent between two sampling seasons. Small-scale occupancy probabilities were slightly lower in the late winter/spring when skunks tend to conserve energy, and movements are limited to males in search of females for breeding. There was strong evidence of method-specific detection probabilities for skunks. As anticipated, large- and small-scale occupancy areas completely overlapped for red salamanders. The analyses provided weak evidence of method-specific detection probabilities for this species. • Synthesis and applications. Increasingly, many studies are utilizing multiple detection methods at sampling locations. The modelling approach presented here makes efficient use of detections from multiple methods to estimate occupancy probabilities at two spatial scales and to compare detection probabilities associated with different detection methods. The models can be viewed as another variation of Pollock's robust design and may be applicable to a wide variety of scenarios where species occur in an area but are not always near the sampled locations. The estimation approach is likely to be especially useful in multispecies conservation programmes by providing efficient estimates using multiple detection devices and by providing device-specific detection probability estimates for use in survey design.
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MacKenzie, D.I. & Hines, J.E. (2018). RPresence: R interface
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Wild.ID instruction manual version 0.9.29.Tropical Ecology Assessment and Monitoring Network
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