• An inexpensive and open-source method to study large terrestrial animal diet and behaviour using time-lapse video and GPS

      de la Rosa, Carlos A. (2019)
      The behaviour of free-ranging animals is difficult to study, especially on the large spatial and temporal scales relevant to long-lived large species. Animal-borne video and environmental data collection systems (AVEDs) record behaviour and other data in real time as animals conduct daily activities....
    • Do responsibly managed logging concessions adequately protect jaguars and other large and medium-sized mammals? Two case studies from Guatemala and Peru

      Tobler, Mathias W.; Garcia Anleu, Rony; Carrillo-Percastegui, Samia E.; Ponce Santizo, Gabriela; Polisar, John; Zuñiga Hartley, Alfonso; Goldstein, Isaac (2018)
      Large areas of tropical forest have been designated for timber production but logging practices vary widely. Reduced-impact logging is considered best practice and third-party certification aims to ensure that strict standards are met....
    • Estimating jaguar densities with camera traps: Problems with current designs and recommendations for future studies

      Tobler, Mathias W.; Powell, G.V.N. (2013)
      Camera traps have become the main method for estimating jaguar (Panthera onca) densities. Over 74 studies have been carried out throughout the species range following standard design recommendations. We reviewed the study designs used by these studies and the results obtained. Using simulated data we evaluated the performance of different statistical methods for estimating density from camera trap data including the closed-population capture–recapture models Mo and Mh with a buffer of ½ and the full mean maximum distance moved (MMDM) and spatially explicit capture–recapture (SECR) models under different study designs and scenarios….
    • Estimating mammalian species richness and occupancy in tropical forest canopies with arboreal camera traps

      Bowler, Mark; Tobler, Mathias W.; Endress, Bryan A.; Gilmore, Michael P.; Anderson, Matthew J. (2017)
      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.
    • First video footage of the elusive Ebo gorillas in Cameroon

      Mfossa, D.; Ndimbe, M.; Abwe, Ekwoge E.; Morgan, Bethan J. (2019)
    • High jaguar densities and large population sizes in the core habitat of the southwestern Amazon

      Tobler, Mathias W.; Carrillo-Percastegui, S.E.; Zúñiga Hartley, A.; Powell, G.V.N. (2013)
      Over 80% of the currently occupied range of the jaguar (Panthera onca) lies in the Amazon. However, few density estimates exist for this habitat. Between 2005 and 2010 we carried out six camera trap surveys at three different sites in the department of Madre de Dios in the Peruvian Amazon….
    • Hot monkey, cold reality: surveying rainforest canopy mammals using drone-mounted thermal infrared sensors

      Kays, Roland; Sheppard, James; Mclean, Kevin; Welch, Charlie; Paunescu, Cris; Wang, Victor; Kravit, Greg; Crofoot, Meg (2018)
      Animals of the rainforest canopies are often endangered by deforestation or hunting but are difficult to survey and study because of the inaccessibility of the treetops, combined with the visual camouflage of many species. Drone-based thermal sensors have the potential to overcome these hurdles by rapidly scanning large forested areas from above, detecting and mapping wildlife based on the contrast between their warm body temperatures and the cool tree canopies....
    • Human visual identification of individual Andean bears Tremarctos ornatus

      Van Horn, Russell C.; Zug, Becky; LaCombe, Corrin; Velez-Liendo, Ximena; Paisley, Susanna (2014)
      It is often challenging to use invasive methods of individual animal identification for population estimation, demographic analyses, and other ecological and behavioral analyses focused on individual-level processes. Recent improvements in camera traps make it possible to collect many photographic samples yet most investigators either leap from photographic sampling to assignment of individual identity without considering identification errors, or else to avoid those errors they develop computerized methods that produce accurate data with the unintended cost of excluding participation by local citizens. To assess human ability to visually identify Andean bears Tremarctos ornatus from their pelage markings we used surveys and experimental testing of 381 observers viewing photographs of 70 Andean bears of known identity. Neither observer experience nor confidence predicted their initial success rate at identifying individuals. However, after gaining experience observers were able to achieve an average success at identifying adult bears of 73.2%, and brief simple training further improved the ability of observers such that 24.8% of them achieved 100% success. Interestingly, observers who were initially more likely to falsely identify two photos of the same bear as two different bears than vice versa were likely to continue making errors and their bias became stronger, not weaker. Such biases would lead to inaccurate population estimates, invalid assessments of the bears involved in conflict situations, and underestimates of bear movements. We thus illustrate that in some systems accurate data on individual identity can be generated without the use of computerized algorithms, allowing for community engagement and citizen science. In addition, we show that when using observers to collect data on animal identity it is important to consider not only the overall frequency of observer error, but also observer biases and error types, which are rarely reported in field studies.
    • Individual identification of wild giant pandas from camera trap photos – a systematic and hierarchical approach

      Zheng, X.; Owen, Megan A.; Nie, Y.; Hu, Y.; Swaisgood, Ronald R.; Yan, L.; Wei, F. (2016)
      ...Here we tested the utility of an approach to individually identify wild giant pandas Ailuropoda melanoleuca from camera trap images, by cataloguing and careful scrutiny of numerous traits. We developed our identification strategy first by analyzing images of known (captive) individuals (N = 7). We then deployed camera traps at 23 control sites and at seven camera trap arrays ‘baited’ with conspecific decoys, in Foping Nature Reserve, China….
    • Into the night: camera traps reveal nocturnal activity in a presumptive diurnal primate, (Rhinopithecus brelichi)

      Tan, Chia L.; Yang, Yeqin; Niu, Kefeng (2013)
      Most living primates exhibit a daytime or nighttime activity pattern. Strict diurnality is thought to be the rule among anthropoids except for owl monkeys. Here we report the diel activity pattern of an Asian colobine, the Guizhou snub-nosed monkey Rhinopithecus brelichi, based on a methodology that relied on using 24-h continuously operating camera traps. We conducted the study in Fanjingshan National Nature Reserve in Guizhou, China from March 22 to May 19 and from June 17 to October 14, 2011. After standardizing all time elements to a meridian-based time according to the geographic coordinates of the study site, we showed unequivocally that the monkeys, though predominantly diurnal, exhibited activity beyond daylight hours throughout the study. Specifically, their activity at night and during twilight periods suggests a complex interplay of behavioral adaptations, among others, to living in a temperate environment where day length and food resources fluctuate substantially across seasons. We contend that, under prevailing ecological conditions, so-called strictly diurnal primates may adjust their activity schedule opportunistically in order to increase energy intake. We also discuss the advantages of using camera traps in primate studies, and how the standardized use of meridian-based time by researchers would benefit comparisons of diel activity patterns among primates.
    • Multi-species occupancy modelling of a carnivore guild in wildlife management areas in the Kalahari

      Van der Weyde, Leanne K.; Mbisana, Christopher; Klein, Rebecca (Elsevier BV, 2018)
      It was hypothesised that land use type surrounding WMAs, human settlements and prey availability might affect carnivore distribution patterns. We conducted a camera-trap study with 96 stations in two WMAs in the Ghanzi district and used a Royles-Nichol multi-species occupancy model to test which factors influenced habitat use for nine carnivore species....
    • Photos provide information on age, but not kinship, of Andean bear

      Van Horn, Russell C.; Zug, Becky; Appleton, Robyn D.; Velez-Liendo, Ximena; Paisley, Susanna; LaCombe, Corrin (2015)
      Using photos of captive Andean bears of known age and pedigree, and photos of wild Andean bear cubs <6 months old, we evaluated the degree to which visual information may be used to estimate bears’ ages and assess their kinship. We demonstrate that the ages of Andean bear cubs ≤6 months old may be estimated from their size relative to their mothers with an average error of <0.01 ± 13.2 days (SD; n = 14), and that ages of adults ≥10 years old may be estimated from the proportion of their nose that is pink with an average error of <0.01 ± 3.5 years (n = 41). We also show that similarity among the bears’ natural markings, as perceived by humans, is not associated with pedigree kinship among the bears (R2 < 0.001, N = 1,043, p = 0.499). Thus, researchers may use photos of wild Andean bears to estimate the ages of young cubs and older adults, but not to infer their kinship. Given that camera trap photos are one of the most readily available sources of information on large cryptic mammals, we suggest that similar methods be tested for use in other poorly understood species.
    • Recommended guiding principles for reporting on camera trapping research

      Meek, P. D.; Ballard, G.; Claridge, A.; Kays, R.; Moseby, K.; O’Brien, T.; O’Connell, A.; Sanderson, J.; Swann, D. E.; Tobler, Mathias W.; et al. (2014)
      …Here we propose a series of guiding principles for reporting methods and results obtained using camera traps. Attributes of camera trapping we cover include: (i) specifying the model(s) of camera traps(s) used, (ii) mode of deployment, (iii) camera settings, and (iv) study design….
    • Spatial and temporal response of wildlife to recreational activities in the San Francisco Bay ecoregion

      Reilly, M. L.; Tobler, Mathias W.; Sonderegger, D. L.; Beier, P. (2017)
      Non-motorized human recreation may displace animals from otherwise suitable habitat; in addition, animals may alter their activity patterns to reduce (or increase) interactions with recreationists. We investigated how hiking, mountain biking, equestrians, and recreationists with domestic dogs affected habitat use and diel activity patterns of ten species of medium and large-sized mammals in the San Francisco Bay ecoregion....
    • Spatiotemporal hierarchical modelling of species richness and occupancy using camera trap data

      Tobler, Mathias W.; Zúñiga Hartley, Alfonso; Carrillo-Percastegui, Samia E.; Powell, George V. N. (2015)
      * 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. * 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. * We applied both models to data from eight camera trap surveys from south-eastern 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. * 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. * Synthesis and applications. Our multi-session multi-species occupancy model provides improved estimates for species richness and occupancy for a large data set. Our model is ideally suited for integrating large numbers of camera trap data sets 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.
    • Sumatran tiger survival threatened by deforestation despite increasing densities in parks

      Luskin, Matthew Scott; Albert, Wido Rizki; Tobler, Mathias W. (2017)
      The continuing development of improved capture–recapture (CR) modeling techniques used to study apex predators has also limited robust temporal and cross-site analyses due to different methods employed. We develop an approach to standardize older non-spatial CR and newer spatial CR density estimates and examine trends for critically endangered Sumatran tigers (Panthera tigris sumatrae) using a meta-regression of 17 existing densities and new estimates from our own fieldwork. We find that tiger densities were 47% higher in primary versus degraded forests and, unexpectedly, increased 4.9% per yr from 1996 to 2014, likely indicating a recovery from earlier poaching. However, while tiger numbers may have temporarily risen, the total potential island-wide population declined by 16.6% from 2000 to 2012 due to forest loss and degradation and subpopulations are significantly more fragmented. Thus, despite increasing densities in smaller parks, we conclude that there are only two robust populations left with >30 breeding females, indicating Sumatran tigers still face a high risk of extinction unless deforestation can be controlled.