Publications by authors named "Rahel Sollmann"

24 Publications

  • Page 1 of 1

Vital rates of two small populations of brown bears in Canada and range-wide relationship between population size and trend.

Ecol Evol 2021 Apr 10;11(7):3422-3434. Epub 2021 Mar 10.

School of Biological Sciences Victoria University of Wellington Wellington New Zealand.

Identifying mechanisms of population change is fundamental for conserving small and declining populations and determining effective management strategies. Few studies, however, have measured the demographic components of population change for small populations of mammals (<50 individuals). We estimated vital rates and trends in two adjacent but genetically distinct, threatened brown bear () populations in British Columbia, Canada, following the cessation of hunting. One population had approximately 45 resident bears but had some genetic and geographic connectivity to neighboring populations, while the other population had <25 individuals and was isolated. We estimated population-specific vital rates by monitoring survival and reproduction of telemetered female bears and their dependent offspring from 2005 to 2018. In the larger, connected population, independent female survival was 1.00 (95% CI: 0.96-1.00) and the survival of cubs in their first year was 0.85 (95% CI: 0.62-0.95). In the smaller, isolated population, independent female survival was 0.81 (95% CI: 0.64-0.93) and first-year cub survival was 0.33 (95% CI: 0.11-0.67). Reproductive rates did not differ between populations. The large differences in age-specific survival estimates resulted in a projected population increase in the larger population ( = 1.09; 95% CI: 1.04-1.13) and population decrease in the smaller population ( = 0.84; 95% CI: 0.72-0.95). Low female survival in the smaller population was the result of both continued human-caused mortality and an unusually high rate of natural mortality. Low cub survival may have been due to inbreeding and the loss of genetic diversity common in small populations, or to limited resources. In a systematic literature review, we compared our population trend estimates with those reported for other small populations (<300 individuals) of brown bears. Results suggest that once brown bear populations become small and isolated, populations rarely increase and, even with intensive management, recovery remains challenging.
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http://dx.doi.org/10.1002/ece3.7301DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8019027PMC
April 2021

A Bayesian Dirichlet process community occupancy model to estimate community structure and species similarity.

Ecol Appl 2021 03 6;31(2):e02249. Epub 2021 Jan 6.

Alaska Fisheries Science Center, National Marine Fisheries Service, NOAA, Seattle, Washington, 98115, USA.

Community occupancy models estimate species-specific parameters while sharing information across species by treating parameters as sampled from a common distribution. When communities consist of discrete groups, shrinkage of estimates toward the community mean can mask differences among groups. Infinite-mixture models using a Dirichlet process (DP) distribution, in which the number of latent groups is estimated from the data, have been proposed as a solution. In addition to community structure, these models estimate species similarity, which allows testing hypotheses about whether traits drive species response to environmental conditions. We develop a community occupancy model (COM) using a DP distribution to model species-level parameters. Because clustering algorithms are sensitive to dimensionality and distinctiveness of clusters, we conducted a simulation study to explore performance of the DP-COM with different dimensions (i.e., different numbers of model parameters with species-level DP random effects) and under varying cluster differences. Because the DP-COM is computationally expensive, we compared its estimates to a COM with a normal random species effect. We further applied the DP-COM model to a bird data set from Uganda. Estimates of the number of clusters and species cluster identity improved with increasing difference among clusters and increasing dimensions of the DP; but the number of clusters was always overestimated. Estimates of number of sites occupied and species and community-level covariate coefficients on occupancy probability were generally unbiased with (near-) nominal 95% Bayesian Credible Interval coverage. Accuracy of estimates from the normal and the DP-COM was similar. The DP-COM clustered 166 bird species into 27 clusters regarding their affiliation with open or woodland habitat and distance to oil wells. Estimates of covariate coefficients were similar between a normal and the DP-COM. Except sunbirds, species within a family were not more similar in their response to these covariates than the overall community. Given that estimates were consistent between the normal and the DP-COM, and considering the computational burden for the DP models, we recommend using the DP-COM only when the analysis focuses on community structure and species similarity, as these quantities can only be obtained under the DP-COM.
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http://dx.doi.org/10.1002/eap.2249DOI Listing
March 2021

Wild dogs at stake: deforestation threatens the only Amazon endemic canid, the short-eared dog ().

R Soc Open Sci 2020 Apr 22;7(4):190717. Epub 2020 Apr 22.

Laboratório de Biodoversidade Animal, Universidade Federal de Jataí, Jataí, GO, Brazil.

The persistent high deforestation rate and fragmentation of the Amazon forests are the main threats to their biodiversity. To anticipate and mitigate these threats, it is important to understand and predict how species respond to the rapidly changing landscape. The short-eared dog is the only Amazon-endemic canid and one of the most understudied wild dogs worldwide. We investigated short-eared dog habitat associations on two spatial scales. First, we used the largest record database ever compiled for short-eared dogs in combination with species distribution models to map species habitat suitability, estimate its distribution range and predict shifts in species distribution in response to predicted deforestation across the entire Amazon (regional scale). Second, we used systematic camera trap surveys and occupancy models to investigate how forest cover and forest fragmentation affect the space use of this species in the Southern Brazilian Amazon (local scale). Species distribution models suggested that the short-eared dog potentially occurs over an extensive and continuous area, through most of the Amazon region south of the Amazon River. However, approximately 30% of the short-eared dog's current distribution is expected to be lost or suffer sharp declines in habitat suitability by 2027 (within three generations) due to forest loss. This proportion might reach 40% of the species distribution in unprotected areas and exceed 60% in some interfluves (i.e. portions of land separated by large rivers) of the Amazon basin. Our local-scale analysis indicated that the presence of forest positively affected short-eared dog space use, while the density of forest edges had a negative effect. Beyond shedding light on the ecology of the short-eared dog and refining its distribution range, our results stress that forest loss poses a serious threat to the conservation of the species in a short time frame. Hence, we propose a re-assessment of the short-eared dog's current IUCN Red List status (Near Threatened) based on findings presented here. Our study exemplifies how data can be integrated across sources and modelling procedures to improve our knowledge of relatively understudied species.
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http://dx.doi.org/10.1098/rsos.190717DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7211836PMC
April 2020

Habitat degradation and indiscriminate hunting differentially impact faunal communities in the Southeast Asian tropical biodiversity hotspot.

Commun Biol 2019 30;2:396. Epub 2019 Oct 30.

1Department of Ecological Dynamics, Leibniz Institute for Zoo and Wildlife Research, Berlin, 10315 Germany.

Habitat degradation and hunting have caused the widespread loss of larger vertebrate species (defaunation) from tropical biodiversity hotspots. However, these defaunation drivers impact vertebrate biodiversity in different ways and, therefore, require different conservation interventions. We conducted landscape-scale camera-trap surveys across six study sites in Southeast Asia to assess how moderate degradation and intensive, indiscriminate hunting differentially impact tropical terrestrial mammals and birds. We found that functional extinction rates were higher in hunted compared to degraded sites. Species found in both sites had lower occupancies in the hunted sites. Canopy closure was the main predictor of occurrence in the degraded sites, while village density primarily influenced occurrence in the hunted sites. Our findings suggest that intensive, indiscriminate hunting may be a more immediate threat than moderate habitat degradation for tropical faunal communities, and that conservation stakeholders should focus as much on overhunting as on habitat conservation to address the defaunation crisis.
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http://dx.doi.org/10.1038/s42003-019-0640-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6821809PMC
April 2020

A new mark-recapture approach for abundance estimation of social species.

PLoS One 2018 20;13(12):e0208726. Epub 2018 Dec 20.

Department of Wildlife, Fish, and Conservation Biology, University of California Davis, Davis, CA, United States of America.

Accurate estimates of population abundance are a critical component of species conservation efforts in order to monitor the potential recovery of populations. Capture-mark-recapture (CMR) is a widely used approach to estimate population abundance, yet social species moving in groups violate the assumption of CMR approaches that all individuals in the population are detected independently. We developed a closed CMR model that addresses an important characteristic of group-living species-that individual-detection probability typically is conditional on group detection. Henceforth termed the Two-Step model, this approach first estimates group-detection probability and then-conditional on group detection-estimates individual-detection probability for individuals within detected groups. Overall abundance is estimated assuming that undetected groups have the same average group size as detected groups. We compared the performance of this Two-Step CMR model to a conventional (One-Step) closed CMR model that ignored group structure. We assessed model sensitivity to variation in both group- and individual-detection probability. Both models returned overall unbiased estimates of abundance, but the One-Step model returned deceptively narrow Bayesian confidence intervals (BCI) that failed to encompass the correct population abundance an average 52% of the time. Contrary, under the Two-Step model, CI coverage was on average 96%. Both models had similar root mean squared errors (RMSE), except for scenarios with low group detection probability, where the Two-Step model had much lower RMSE. For illustration with a real data set, we applied the Two-Step and regular model to non-invasive genetic capture-recapture data of mountain gorillas (Gorilla beringei beringei). As with simulations, abundance estimates under both models were similar, but the Two-Step model estimate had a wider confidence interval. Results support using the Two-Step model for species living in constant groups, particularly when group detection probability is low, to reduce risk of bias and adequately portray uncertainty in abundance estimates. Important sources of variation in detection need to be incorporated into the Two-Step model when applying it to field data.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0208726PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6301682PMC
May 2019

Use of RFID technology to characterize feeder visitations and contact network of hummingbirds in urban habitats.

PLoS One 2018 12;13(12):e0208057. Epub 2018 Dec 12.

Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California Davis, Davis, California, United States of America.

Despite the popular use of hummingbird feeders, there are limited studies evaluating the effects of congregation, sharing food resources and increased contact when hummingbirds visit feeders in urban landscapes. To evaluate behavioral interactions occurring at feeders, we tagged 230 individuals of two species, Anna's and Allen's Hummingbirds, with passive integrated transponder tags and recorded their visits with RFID transceivers at feeders. For detecting the presence of tagged birds, we developed an RFID equipped feeding station using a commercially available antenna and RFID transceiver. Data recorded included the number of feeder visits, time spent at the feeder, simultaneous feeder visitation by different individuals, and identifying which feeders were most commonly visited by tagged birds. For the study period (September 2016 to March 2018), 118,017 detections were recorded at seven feeding stations located at three California sites. The rate of tagged birds returning to RFID equipped feeders at least once was 61.3% (141/230 birds). Females stayed at feeders longer than males per visit. We identified primary, secondary and tertiary feeders at Sites 2 and 3, according to the frequency of visitation to them, with a mean percentage of 86.9% (SD±19.13) visits to a primary feeder for each tagged hummingbird. During spring and summer, hummingbirds visited feeders most often in morning and evening hours. Feeder visits by males overlapped in time with other males more frequently than other females. The analysis of the contact network at the feeders did not distinguish any significant differences between age or sex. Although most hummingbirds visited the feeders during the daytime, our system recorded night feeder visitations (n = 7 hummingbirds) at one site. This efficient use of RFID technology to characterize feeder visitations and contact networks of hummingbirds in urban habitats could be used in the future to elucidate behaviors, population dynamics and community structure of hummingbirds visiting feeders.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0208057PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6291107PMC
June 2019

State space and movement specification in open population spatial capture-recapture models.

Ecol Evol 2018 Oct 27;8(20):10336-10344. Epub 2018 Sep 27.

Centre for Wildlife Studies Bangalore Karnataka India.

With continued global changes, such as climate change, biodiversity loss, and habitat fragmentation, the need for assessment of long-term population dynamics and population monitoring of threatened species is growing. One powerful way to estimate population size and dynamics is through capture-recapture methods. Spatial capture (SCR) models for open populations make efficient use of capture-recapture data, while being robust to design changes. Relatively few studies have implemented open SCR models, and to date, very few have explored potential issues in defining these models. We develop a series of simulation studies to examine the effects of the state-space definition and between-primary-period movement models on demographic parameter estimation. We demonstrate the implications on a 10-year camera-trap study of tigers in India. The results of our simulation study show that movement biases survival estimates in open SCR models when little is known about between-primary-period movements of animals. The size of the state-space delineation can also bias the estimates of survival in certain cases.We found that both the state-space definition and the between-primary-period movement specification affected survival estimates in the analysis of the tiger dataset (posterior mean estimates of survival ranged from 0.71 to 0.89). In general, we suggest that open SCR models can provide an efficient and flexible framework for long-term monitoring of populations; however, in many cases, realistic modeling of between-primary-period movements is crucial for unbiased estimates of survival and density.
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http://dx.doi.org/10.1002/ece3.4509DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6206188PMC
October 2018

First detection of feline hemoplasmas in free-ranging jaguars (Panthera onca).

Vet Microbiol 2018 Feb 18;214:75-80. Epub 2017 Dec 18.

Departamento de Medicina Veterinária Preventiva e Saúde Animal, Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, Av. Prof. Dr. Orlando Marques de Paiva, 87, 05508-000, São Paulo-SP, Brazil.

Species of hemoplasmas have been described worldwide, but little information is available for wild felids. Between February 2000 and January 2010, blood samples were collected from 30 jaguars (Panthera onca) and 22 domestic cats (Felis catus) from the Cerrado, Pantanal and Amazon biomes of Brazil. In all samples molecular tests were performed for Mycoplasma haemofelis/Mycoplasma haemocanis (Mhf/Mhc), 'Candidatus Mycoplasma haemominutum' (CMhm) and 'Candidatus Mycoplasma turicensis' (CMt). Twenty-two (73.4%) jaguars and four domestic cats (18.2%) tested positive for infection with at least one feline hemoplasma: 73.4% jaguars from the three areas were positive for CMhm, 13.6% jaguars from the Pantanal and 50.0% from the Amazon were positive for Mhf/Mhc, and 9.1% of individuals from the Pantanal tested positive for CMt. Domestic cats from the Cerrado (28.6%) and the Pantanal (30.0%) were positive for feline hemoplasma. All but one jaguar from the three sites are healthy. One female adult jaguar showed low body weight and dehydration. This is the first record of feline hemoplasmas in free-ranging jaguars. The high prevalence of CMhm suggest the participation of jaguars in the maintenance of this hemoplasma in nature. Although susceptible to Mhf/Mhc and CMt, jaguars did not appear to participate in the maintenance of these agents in the environment. The involvement of domestic cats in the transmission of any of these hemoplasmas cannot be excluded.
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http://dx.doi.org/10.1016/j.vetmic.2017.12.009DOI Listing
February 2018

Genetic sampling for estimating density of common species.

Ecol Evol 2017 08 3;7(16):6210-6219. Epub 2017 Jul 3.

Wildlife Biology Program and Office of the Vice President for Research and Creative Scholarship University of Montana Missoula MT USA.

Understanding population dynamics requires reliable estimates of population density, yet this basic information is often surprisingly difficult to obtain. With rare or difficult-to-capture species, genetic surveys from noninvasive collection of hair or scat has proved cost-efficient for estimating densities. Here, we explored whether noninvasive genetic sampling (NGS) also offers promise for sampling a relatively common species, the snowshoe hare ( Erxleben, 1777), in comparison with traditional live trapping. We optimized a protocol for single-session NGS sampling of hares. We compared spatial capture-recapture population estimates from live trapping to estimates derived from NGS, and assessed NGS costs. NGS provided population estimates similar to those derived from live trapping, but a higher density of sampling plots was required for NGS. The optimal NGS protocol for our study entailed deploying 160 sampling plots for 4 days and genotyping one pellet per plot. NGS laboratory costs ranged from approximately $670 to $3000 USD per field site. While live trapping does not incur laboratory costs, its field costs can be considerably higher than for NGS, especially when study sites are difficult to access. We conclude that NGS can work for common species, but that it will require field and laboratory pilot testing to develop cost-effective sampling protocols.
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http://dx.doi.org/10.1002/ece3.3137DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5574800PMC
August 2017

Connecting Earth observation to high-throughput biodiversity data.

Nat Ecol Evol 2017 Jun 22;1(7):176. Epub 2017 Jun 22.

Department of Geography, King's College London, Strand Campus, London WC2R 2LS, UK.

Understandably, given the fast pace of biodiversity loss, there is much interest in using Earth observation technology to track biodiversity, ecosystem functions and ecosystem services. However, because most biodiversity is invisible to Earth observation, indicators based on Earth observation could be misleading and reduce the effectiveness of nature conservation and even unintentionally decrease conservation effort. We describe an approach that combines automated recording devices, high-throughput DNA sequencing and modern ecological modelling to extract much more of the information available in Earth observation data. This approach is achievable now, offering efficient and near-real-time monitoring of management impacts on biodiversity and its functions and services.
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http://dx.doi.org/10.1038/s41559-017-0176DOI Listing
June 2017

Hepatozoon SPP. Infect Free-Ranging Jaguars (Panthera onca) in Brazil.

J Parasitol 2017 06 16;103(3):243-250. Epub 2017 Feb 16.

*   Jaguar Conservation Fund/Instituto Onça-Pintada, Caixa Postal 193, 75830-000, Mineiros-GO, Brazil.

This study investigated the presence of Hepatozoon spp. in jaguars ( Panthera onca ) and domestic animals in the Cerrado, Amazon, and Pantanal biomes of Brazil. Between February 2000 and January 2010, blood samples were collected from 30 jaguars, 129 domestic dogs ( Canis lupus familiaris), and 22 domestic cats ( Felis catus ) for molecular tests. All of the jaguars from the Pantanal (n = 22) and Cerrado (n = 4) and 3 of 4 jaguars from the Amazon were positive for Hepatozoon spp. Domestic dogs (62.8%) and cats (31.8%) were also positive for the agent. Hepatozoon nucleotide sequences from jaguars and domestic cats grouped with other Hepatozoon felis, whereas Hepatozoon from domestic dogs showed high similarity to Hepatozoon canis. Different species of Amblyomma were identified as parasitizing the jaguars and may act as vectors for Hepatozoon spp. Jaguars from the 3 sites were healthy and did not seem to be threatened by the hemoparasite within its population or environments. Most likely, jaguars play an important role in the maintenance of Hepatozoon spp. in nature.
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http://dx.doi.org/10.1645/16-99DOI Listing
June 2017

Is the free-ranging jaguar (Panthera onca) a reservoir for Cytauxzoon felis in Brazil?

Ticks Tick Borne Dis 2017 06 6;8(4):470-476. Epub 2017 Feb 6.

Departamento de Medicina Veterinária Preventiva e Saúde Animal, Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, Av. Prof. Dr. Orlando Marques de Paiva, 87, 05508-000, São Paulo, SP, Brazil.

This study investigated the occurrence of Cytauxzoon felis and Babesia spp. in free-ranging jaguars (Panthera onca), domestic dogs (Canis lupus familiaris) and domestic cats (Felis catus) from the Cerrado, Amazon and Pantanal biomes of Brazil. Blood samples were collected from 30 jaguars, 129 dogs and 22 cats for detection of the 18S rRNA genes of piroplasmids. All of the jaguars from the Pantanal (n=22) and Cerrado (n=4) and three of four jaguars from the Amazon were positive for C. felis, but no dogs or cats were positive for the agent. All of the jaguars and domestic cats were negative for Babesia spp., while dogs from the Cerrado (7.9%; 5/63) and Amazon (10.6%; 5/47) biomes tested positive for the hemoparasite. Cytauxzoon nucleotide sequences detected were closely related to C. felis; and Babesia nucleotide sequences showed 100% of identity with Babesia vogeli. Although the pathogenicity of Cytauxzoon spp. genotypes that circulate in Brazil is still unknown, free-ranging jaguars probably play an important role in the maintenance of C. felis in nature. In addition, even though there is no evidence of the circulation of Babesia spp. between jaguars and dogs, the presence of this hemoparasite should be monitored in jaguar populations.
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http://dx.doi.org/10.1016/j.ttbdis.2017.02.005DOI Listing
June 2017

Predicting the offshore distribution and abundance of marine birds with a hierarchical community distance sampling model.

Ecol Appl 2016 Sep;26(6):1797-1815

Biodiversity Research Institute, Portland, Maine, 04103, USA.

Proposed offshore wind energy development on the Atlantic Outer Continental Shelf has brought attention to the need for baseline studies of the distribution and abundance of marine birds. We compiled line transect data from 15 shipboard surveys (June 2012-April 2014), along with associated remotely sensed habitat data, in the lower Mid-Atlantic Bight off the coast of Delaware, Maryland, and Virginia, USA. We implemented a recently developed hierarchical community distance sampling model to estimate the seasonal abundance of 40 observed marine bird species. Treating each season separately, we included six oceanographic parameters to estimate seabird abundance: three static (distance to shore, slope, sediment grain size) and three dynamic covariates (sea surface temperature [SST], salinity, primary productivity). We expected that avian bottom-feeders would respond primarily to static covariates that characterize seafloor variability, and that surface-feeders would respond more to dynamic covariates that quantify surface productivity. We compared the variation in species-specific and community-level responses to these habitat features, including for rare species, and we predicted species abundance across the study area. While several protected species used the study area in summer during their breeding season, estimated abundance and observed diversity were highest for nonbreeding species in winter. Distance to shore was the most common significant predictor of abundance, and thus useful in estimating the potential exposure of marine birds to offshore development. In many cases, our expectations based on feeding ecology were confirmed, such as in the first winter season, when bottom-feeders associated significantly with the three static covariates (distance to shore, slope, and sediment grain size), and surface-feeders associated significantly with two dynamic covariates (SST, primary productivity). However, other cases revealed significant relationships between static covariates and surface-feeders (e.g., distance to shore) and between dynamic covariates and bottom-feeders (e.g., primary productivity during that same winter). More generally, we found wide interannual, seasonal, and interspecies variation in habitat relationships with abundance. These results show the importance of quantifying detection and determining the ecological drivers of a community's distribution and abundance, within and among species, for evaluating the potential exposure of marine birds to offshore development.
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http://dx.doi.org/10.1890/15-1955.1DOI Listing
September 2016

Ocelot (Leopardus pardalis) Density in Central Amazonia.

PLoS One 2016 18;11(5):e0154624. Epub 2016 May 18.

Wildlife Conservation Research Unit, Department of Zoology, University of Oxford, Tubney, United Kingdom.

Ocelots (Leopardus pardalis) are presumed to be the most abundant of the wild cats throughout their distribution range and to play an important role in the dynamics of sympatric small-felid populations. However, ocelot ecological information is limited, particularly for the Amazon. We conducted three camera-trap surveys during three consecutive dry seasons to estimate ocelot density in Amanã Reserve, Central Amazonia, Brazil. We implemented a spatial capture-recapture (SCR) model that shared detection parameters among surveys. A total effort of 7020 camera-trap days resulted in 93 independent ocelot records. The estimate of ocelot density in Amanã Reserve (24.84 ± SE 6.27 ocelots per 100 km2) was lower than at other sites in the Amazon and also lower than that expected from a correlation of density with latitude and rainfall. We also discuss the importance of using common parameters for survey scenarios with low recapture rates. This is the first density estimate for ocelots in the Brazilian Amazon, which is an important stronghold for the species.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0154624PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4871438PMC
July 2017

Serosurvey of Smooth Brucella, Leptospira spp. and Toxoplasma gondii in Free-Ranging Jaguars (Panthera onca) and Domestic Animals from Brazil.

PLoS One 2015 25;10(11):e0143816. Epub 2015 Nov 25.

Departamento de Medicina Veterinária Preventiva e Saúde Animal, Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, São Paulo, São Paulo, Brasil.

This study investigated the exposure of jaguar populations and domestic animals to smooth Brucella, Leptospira spp. and Toxoplasma gondii in the Cerrado, Pantanal and Amazon biomes of Brazil. Between February 2000 and January 2010, serum samples from 31 jaguars (Panthera onca), 1,245 cattle (Bos taurus), 168 domestic dogs (Canis lupus familiaris) and 29 domestic cats (Felis catus) were collected and analysed by rose bengal test for smooth Brucella, microscopic agglutination test for Leptospira spp. and modified agglutination test for T. gondii. Cattle populations from all sites (9.88%) were exposed to smooth Brucella, but only one jaguar from Cerrado was exposed to this agent. Jaguars captured in the Cerrado (60.0%) and in the Pantanal (45.5%) were seropositive for different serovars of Leptospira spp., cattle (72.18%) and domestic dogs (13.1%) from the three sites and one domestic cat from Pantanal were also seropositive for the agent. The most prevalent serotype of Leptospira spp. identified in jaguars from the Cerrado (Grippotyphosa) and the Pantanal (Pomona) biomes were distinct from those found in the domestic animals sampled. Jaguars (100%), domestic dogs (38.28%) and domestic cats (82.76%) from the three areas were exposed to T. gondii. Our results show that brucellosis and leptospirosis could have been transmitted to jaguars by domestic animals; and jaguars probably play an important role in the maintenance of T. gondii in nature.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0143816PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4659634PMC
June 2016

Defining habitat covariates in camera-trap based occupancy studies.

Sci Rep 2015 Nov 24;5:17041. Epub 2015 Nov 24.

Leibniz Institute for Zoo and Wildlife Research, Alfred-Kowalke-Str. 17, 10315 Berlin, Germany.

In species-habitat association studies, both the type and spatial scale of habitat covariates need to match the ecology of the focal species. We assessed the potential of high-resolution satellite imagery for generating habitat covariates using camera-trapping data from Sabah, Malaysian Borneo, within an occupancy framework. We tested the predictive power of covariates generated from satellite imagery at different resolutions and extents (focal patch sizes, 10-500 m around sample points) on estimates of occupancy patterns of six small to medium sized mammal species/species groups. High-resolution land cover information had considerably more model support for small, patchily distributed habitat features, whereas it had no advantage for large, homogeneous habitat features. A comparison of different focal patch sizes including remote sensing data and an in-situ measure showed that patches with a 50-m radius had most support for the target species. Thus, high-resolution satellite imagery proved to be particularly useful in heterogeneous landscapes, and can be used as a surrogate for certain in-situ measures, reducing field effort in logistically challenging environments. Additionally, remote sensed data provide more flexibility in defining appropriate spatial scales, which we show to impact estimates of wildlife-habitat associations.
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http://dx.doi.org/10.1038/srep17041DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4657010PMC
November 2015

iDNA from terrestrial haematophagous leeches as a wildlife surveying and monitoring tool - prospects, pitfalls and avenues to be developed.

Front Zool 2015 1;12:24. Epub 2015 Oct 1.

Centre for GeoGenetics, Natural History Museum of Denmark, University of Copenhagen, Copenhagen, Denmark ; Trace and Environmental DNA Laboratory, Department of Environment and Agriculture, Curtin University, Perth, Western Australia Australia.

Invertebrate-derived DNA (iDNA) from terrestrial haematophagous leeches has recently been proposed as a powerful non-invasive tool with which to detect vertebrate species and thus to survey their populations. However, to date little attention has been given to whether and how this, or indeed any other iDNA-derived data, can be combined with state-of-the-art analytical tools to estimate wildlife abundances, population dynamics and distributions. In this review, we discuss the challenges that face the application of existing analytical methods such as site-occupancy and spatial capture-recapture (SCR) models to terrestrial leech iDNA, in particular, possible violations of key assumptions arising from factors intrinsic to invertebrate parasite biology. Specifically, we review the advantages and disadvantages of terrestrial leeches as a source of iDNA and summarize the utility of leeches for presence, occupancy, and spatial capture-recapture models. The main source of uncertainty that attends species detections derived from leech gut contents is attributable to uncertainty about the spatio-temporal sampling frame, since leeches retain host-blood for months and can move after feeding. Subsequently, we briefly address how the analytical challenges associated with leeches may apply to other sources of iDNA. Our review highlights that despite the considerable potential of leech (and indeed any) iDNA as a new survey tool, further pilot studies are needed to assess how analytical methods can overcome or not the potential biases and assumption violations of the new field of iDNA. Specifically we argue that studies to compare iDNA sampling with standard survey methods such as camera trapping, and those to improve our knowledge on leech (and other invertebrate parasite) physiology, taxonomy, and ecology will be of immense future value.
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http://dx.doi.org/10.1186/s12983-015-0115-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4589908PMC
October 2015

An open-population hierarchical distance sampling model.

Ecology 2015 Feb;96(2):325-31

Modeling population dynamics while accounting for imperfect detection is essential to monitoring programs. Distance sampling allows estimating population size while accounting for imperfect detection, but existing methods do not allow for estimation of demographic parameters. We develop a model that uses temporal correlation in abundance arising from underlying population dynamics to estimate demographic parameters from repeated distance sampling surveys. Using a simulation study motivated by designing a monitoring program for Island Scrub-Jays (Aphelocoma insularis), we investigated the power of this model to detect population trends. We generated temporally autocorrelated abundance and distance sampling data over six surveys, using population rates of change of 0.95 and 0.90. We fit the data generating Markovian model and a mis-specified model with a log-linear time effect on abundance, and derived post hoc trend estimates from a model estimating abundance for each survey separately. We performed these analyses for varying numbers of survey points. Power to detect population changes was consistently greater under the Markov model than under the alternatives, particularly for reduced numbers of survey points. The model can readily be extended to more complex demographic processes than considered in our simulations. This novel framework can be widely adopted for wildlife population monitoring.
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http://dx.doi.org/10.1890/14-1625.1DOI Listing
February 2015

Coming down from the trees: is terrestrial activity in Bornean orangutans natural or disturbance driven?

Sci Rep 2014 Feb 13;4:4024. Epub 2014 Feb 13.

Leibniz Institute for Zoo and Wildlife Research, Alfred-Kowalke-Straβe 17, 10315 Berlin, Germany.

The orangutan is the world's largest arboreal mammal, and images of the red ape moving through the tropical forest canopy symbolise its typical arboreal behaviour. Records of terrestrial behaviour are scarce and often associated with habitat disturbance. We conducted a large-scale species-level analysis of ground-based camera-trapping data to evaluate the extent to which Bornean orangutans Pongo pygmaeus come down from the trees to travel terrestrially, and whether they are indeed forced to the ground primarily by anthropogenic forest disturbances. Although the degree of forest disturbance and canopy gap size influenced terrestriality, orangutans were recorded on the ground as frequently in heavily degraded habitats as in primary forests. Furthermore, all age-sex classes were recorded on the ground (flanged males more often). This suggests that terrestrial locomotion is part of the Bornean orangutan's natural behavioural repertoire to a much greater extent than previously thought, and is only modified by habitat disturbance. The capacity of orangutans to come down from the trees may increase their ability to cope with at least smaller-scale forest fragmentation, and to cross moderately open spaces in mosaic landscapes, although the extent of this versatility remains to be investigated.
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http://dx.doi.org/10.1038/srep04024DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3923384PMC
February 2014

Serosurvey for selected viral infections in free-ranging jaguars (Panthera onca) and domestic carnivores in Brazilian Cerrado, Pantanal, and Amazon.

J Wildl Dis 2013 Jul;49(3):510-21

Jaguar Conservation Fund/Instituto Onça-Pintada, Caixa Postal 193, 75830-000, Mineiros-Goiás, Brazil.

We investigated the exposure of jaguar (Panthera onca) populations and domestic carnivores to selected viral infections in the Cerrado, Amazon, and Pantanal biomes of Brazil. Between February 2000 and January 2010, we collected serum samples from 31 jaguars, 174 dogs (Canis lupus familiaris), and 35 domestic cats (Felis catus). Serologic analyses for antibodies to rabies virus, canine distemper virus (CDV), feline immunodeficiency virus (FIV), and for feline leukemia virus (FeLV) antigen were conducted. The jaguars from Cerrado and Pantantal were exposed to rabies virus, while the jaguars from the Pantanal and the dogs from all three areas were exposed to CDV. Two cats from the Amazonian site were antigen-positive for FeLV, but no jaguars had FeLV antigen or FIV antibody. Canine distemper and rabies viruses should be carefully monitored and considered potential threats to these jaguar populations. Currently FIV and FeLV do not appear to represent a health threat for jaguar populations in this area. Domestic dogs and cats in these areas should be vaccinated, and the movement of domestic animals around protected areas should be restricted.
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http://dx.doi.org/10.7589/2012-02-056DOI Listing
July 2013

A spatial mark--resight model augmented with telemetry data.

Ecology 2013 Mar;94(3):553-9

North Carolina State University, Department of Forestry and Environmental Resources, Fisheries and Wildlife Program, 110 Brooks Avenue, Raleigh, North Carolina 27607, USA.

Abundance and population density are fundamental pieces of information for population ecology and species conservation, but they are difficult to estimate for rare and elusive species. Mark--resight models are popular for estimating population abundance because they are less invasive and expensive than traditional mark-recapture. However, density estimation using mark-resight is difficult because the area sampled must be explicitly defined, historically using ad hoc approaches. We developed a spatial mark--resight model for estimating population density that combines spatial resighting data and telemetry data. Incorporating telemetry data allows us to inform model parameters related to movement and individual location. Our model also allows <100% individual identification of marked individuals. We implemented the model in a Bayesian framework, using a custom-made Metropolis-within-Gibbs Markov chain Monte Carlo algorithm. As an example, we applied this model to a mark--resight study of raccoons (Procyon lotor) on South Core Banks, a barrier island in Cape Lookout National Seashore, North Carolina, USA. We estimated a population of 186.71 +/- 14.81 individuals, which translated to a density of 8.29 +/- 0.66 individuals/km2 (mean +/- SD). The model presented here will have widespread utility in future applications, especially for species that are not naturally marked.
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http://dx.doi.org/10.1890/12-1256.1DOI Listing
March 2013

High proportion of male faeces in jaguar populations.

PLoS One 2012 28;7(12):e52923. Epub 2012 Dec 28.

Department of Conservation Biology, Estación Biologica de Doñana, CSIC, Sevilla, Spain.

Faeces provide relevant biological information which includes, with the application of genetic techniques, the sex and identity of individuals that defecated, thus providing potentially useful data on the behaviour and ecology of individuals, as well as the dynamics and structure of populations. This paper presents estimates of the sex ratio of different felid species (jaguar, Panthera onca; puma, Puma concolor; and ocelot/margay, Leopardus pardalis/Leopardus wiedi) as observed in field collected faeces, and proposes several hypotheses that could explain the strikingly high proportion of faeces from male jaguars. The proportion of male and female faeces was estimated using a non-invasive faecal sampling method in 14 study areas in Mexico and Brazil. Faecal samples were genetically analysed to identify the species, the sex and the individual (the latter only for samples identified as belonging to jaguars). Considering the three species, 72.6% of faeces (n = 493) were from males; however, there were significant differences among them, with the proportion from males being higher for jaguars than for pumas and ocelots/margays. A male-bias was consistently observed in all study areas for jaguar faeces, but not for the other species. For jaguars the trend was the same when considering the number of individuals identified (n = 68), with an average of 4.2±0.56 faeces per male and 2.0±0.36 per female. The observed faecal marking patterns might be related to the behaviour of female jaguars directed toward protecting litters from males, and in both male and female pumas, to prevent interspecific aggressions from male jaguars. The hypothesis that there are effectively more males than females in jaguar populations cannot be discarded, which could be due to the fact that females are territorial and males are not, or a tendency for males to disperse into suboptimal areas for the species.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0052923PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3532461PMC
July 2013

How does spatial study design influence density estimates from spatial capture-recapture models?

PLoS One 2012 23;7(4):e34575. Epub 2012 Apr 23.

Department of Environmental Resources - Fisheries and Wildlife Program, North Carolina State University, Raleigh, North Carolina, United States of America.

When estimating population density from data collected on non-invasive detector arrays, recently developed spatial capture-recapture (SCR) models present an advance over non-spatial models by accounting for individual movement. While these models should be more robust to changes in trapping designs, they have not been well tested. Here we investigate how the spatial arrangement and size of the trapping array influence parameter estimates for SCR models. We analysed black bear data collected with 123 hair snares with an SCR model accounting for differences in detection and movement between sexes and across the trapping occasions. To see how the size of the trap array and trap dispersion influence parameter estimates, we repeated analysis for data from subsets of traps: 50% chosen at random, 50% in the centre of the array and 20% in the South of the array. Additionally, we simulated and analysed data under a suite of trap designs and home range sizes. In the black bear study, we found that results were similar across trap arrays, except when only 20% of the array was used. Black bear density was approximately 10 individuals per 100 km(2). Our simulation study showed that SCR models performed well as long as the extent of the trap array was similar to or larger than the extent of individual movement during the study period, and movement was at least half the distance between traps. SCR models performed well across a range of spatial trap setups and animal movements. Contrary to non-spatial capture-recapture models, they do not require the trapping grid to cover an area several times the average home range of the studied species. This renders SCR models more appropriate for the study of wide-ranging mammals and more flexible to design studies targeting multiple species.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0034575PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3335117PMC
September 2012