Dataset Information

Estimating large carnivore populations at global scale based on spatial predictions of density and distribution - Application to the jaguar (Panthera onca).

ABSTRACT: Broad scale population estimates of declining species are desired for conservation efforts. However, for many secretive species including large carnivores, such estimates are often difficult. Based on published density estimates obtained through camera trapping, presence/absence data, and globally available predictive variables derived from satellite imagery, we modelled density and occurrence of a large carnivore, the jaguar, across the species' entire range. We then combined these models in a hierarchical framework to estimate the total population. Our models indicate that potential jaguar density is best predicted by measures of primary productivity, with the highest densities in the most productive tropical habitats and a clear declining gradient with distance from the equator. Jaguar distribution, in contrast, is determined by the combined effects of human impacts and environmental factors: probability of jaguar occurrence increased with forest cover, mean temperature, and annual precipitation and declined with increases in human foot print index and human density. Probability of occurrence was also significantly higher for protected areas than outside of them. We estimated the world's jaguar population at 173,000 (95% CI: 138,000-208,000) individuals, mostly concentrated in the Amazon Basin; elsewhere, populations tend to be small and fragmented. The high number of jaguars results from the large total area still occupied (almost 9 million km2) and low human densities (< 1 person/km2) coinciding with high primary productivity in the core area of jaguar range. Our results show the importance of protected areas for jaguar persistence. We conclude that combining modelling of density and distribution can reveal ecological patterns and processes at global scales, can provide robust estimates for use in species assessments, and can guide broad-scale conservation actions.

SUBMITTER: Jedrzejewski W

PROVIDER: S-EPMC5868828 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

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Estimating large carnivore populations at global scale based on spatial predictions of density and distribution - Application to the jaguar (Panthera onca).

Jędrzejewski Włodzimierz W Robinson Hugh S HS Abarca Maria M Zeller Katherine A KA Velasquez Grisel G Paemelaere Evi A D EAD Goldberg Joshua F JF Payan Esteban E Hoogesteijn Rafael R Boede Ernesto O EO Schmidt Krzysztof K Lampo Margarita M Viloria Ángel L ÁL Carreño Rafael R Robinson Nathaniel N Lukacs Paul M PM Nowak J Joshua JJ Salom-Pérez Roberto R Castañeda Franklin F Boron Valeria V Quigley Howard H

PloS one 20180326 3

Broad scale population estimates of declining species are desired for conservation efforts. However, for many secretive species including large carnivores, such estimates are often difficult. Based on published density estimates obtained through camera trapping, presence/absence data, and globally available predictive variables derived from satellite imagery, we modelled density and occurrence of a large carnivore, the jaguar, across the species' entire range. We then combined these models in a ...[more]

PMID: 29579129

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Project description:We estimated jaguar density and tenure, and investigated ranging behavior, using camera traps across the Maya Forest Corridor, a human-influenced landscape in central Belize that forms the only remaining connection for jaguar populations inhabiting two regional forest blocks: the Selva Maya and the Maya Mountain Massif. Jaguars were ubiquitous across the study area. Similar to the neighboring Selva Maya, mean density ranged from 1.5 to 3.1 jaguars per 100 km2, estimated by spatial capture-recapture models. Cameras detected almost twice as many males as females, probably reflecting detection bias, and males ranged more widely than females within the camera grid. Both sexes crossed two major rivers, while highway crossings were rare and male-biased, raising concern that the highway could prevent female movement if traffic increases. Jaguars were more transient where the landscape was fragmented with settlements and agriculture than in contiguous forest. Compared with jaguars in the protected forests of the Maya Mountains, jaguars in central Belize displayed a lower potential for investment in intraspecific communication, indicative of a lower quality landscape; however, we did detect mating behavior and juveniles. Tenure of individuals was shorter than in the protected forests, with a higher turnover rate for males than females. At least three-quarters of reported jaguar deaths caused by people were male jaguars, and the majority was retaliation for livestock predation. Jaguars seem relatively tolerant to the human-influenced landscape of central Belize. However, intensification of game hunting and lethal control of predators would threaten population persistence, while increased highway traffic and clear-cutting riparian forest would severely limit the corridor function. Our results show that the viability of the corridor, and thus the long-term survival of jaguar populations in this region, will depend on appropriate land-use planning, nonlethal control of livestock predators, enforcement of game hunting regulations, and wildlife-friendly features in future road developments.

Project description:BACKGROUND:Connectivity among jaguar (Panthera onca) populations will ensure natural gene flow and the long-term survival of the species throughout its range. Jaguar conservation efforts have focused primarily on connecting suitable habitat in a broad-scale. Accelerated habitat reduction, human-wildlife conflict, limited funding, and the complexity of jaguar behaviour have proven challenging to maintain connectivity between populations effectively. Here, we used non-invasive genetic sampling and individual-based conservation genetic analyses to assess genetic diversity and levels of genetic connectivity between individuals in the Cockscomb Basin Wildlife Sanctuary and the Maya Forest Corridor. We used expert knowledge and scientific literature to develop models of landscape permeability based on circuit theory with fine-scale landscape features as ecosystem types, distance to human settlements and roads to predict the most probable jaguar movement across central Belize. RESULTS:We used 12 highly polymorphic microsatellite loci to identify 50 individual jaguars. We detected high levels of genetic diversity across loci (HE =?0.61, HO =?0.55, and NA =?9.33). Using Bayesian clustering and multivariate models to assess gene flow and genetic structure, we identified one single group of jaguars (K?=?1). We identified critical areas for jaguar movement that fall outside the boundaries of current protected areas in central Belize. We detected two main areas of high landscape permeability in a stretch of approximately 18?km between Sittee River Forest Reserve and Manatee Forest Reserve that may increase functional connectivity and facilitate jaguar dispersal from and to Cockscomb Basin Wildlife Sanctuary. Our analysis provides important insights on fine-scale genetic and landscape connectivity of jaguars in central Belize, an area of conservation concern. CONCLUSIONS:The results of our study demonstrate high levels of relatively recent gene flow for jaguars between two study sites in central Belize. Our landscape analysis detected corridors of expected jaguar movement between the Cockscomb Basin Wildlife Sanctuary and the Maya Forest Corridor. We highlight the importance of maintaining already established corridors and consolidating new areas that further promote jaguar movement across suitable habitat beyond the boundaries of currently protected areas. Continued conservation efforts within identified corridors will further maintain and increase genetic connectivity in central Belize.

Project description:Camera trapping is the standard field method of monitoring cryptic, low-density mammal populations. Typically, researchers run camera surveys for 60 to 90 days and estimate density using closed population spatially explicit capture-recapture (SCR) models. The SCR models estimate density, capture probability (g0), and a scale parameter (?) that reflects ranging behaviour. We used a year of camera data from 20 camera stations to estimate the density of male jaguars (Panthera onca) in the Cockscomb Basin Wildlife Sanctuary in Belize, using closed population SCR models. We subsampled the dataset into 276 90-day sessions and 186 180-day sessions. Estimated density fluctuated from 0.51 to 5.30 male jaguars / 100 km2 between the 90-day sessions, with comparatively robust and precise estimates for the 180-day sessions (0.73 to 3.75 male jaguars / 100 km2). We explain the variation in density estimates from the 90-day sessions in terms of temporal variation in social behaviour, specifically male competition and mating events during the three-month wet season. Density estimates from the 90-day sessions varied with ?, but not with the number of individuals detected, suggesting that variation in density was almost fully attributable to changes in estimated ranging behaviour. We found that the models overestimated ? when compared to the mean ranging distance derived from GPS tracking data from two collared individuals in the camera grid. Overestimation of ? when compared to GPS collar data was more pronounced for the 180-day sessions than the 90-day sessions. We conclude that one-off ('snap-shot') short-term, small-scale camera trap surveys do not sufficiently sample wide-ranging large carnivores. When using SCR models to estimate the density from these data, we caution against the use of poor sampling designs and/or misinterpretation of scope of inference. Although the density estimates from one-off, short-term, small-scale camera trap surveys may be statistically accurate within each short-term sampling period, the variation between density estimates from multiple sessions throughout the year illustrate that the estimates obtained should be carefully interpreted and extrapolated, because different factors, such as temporal stochasticity in behaviour of a few individuals, may have strong repercussions on density estimates. Because of temporal variation in behaviour, reliable density estimates will require larger samples of individuals and spatial recaptures than those presented in this study (mean +/- SD = 14.2 +/- 1.2 individuals, 37.7 +/- 4.7 spatial recaptures, N = 276 sessions), which are representative of, or higher than published sample sizes. To satisfy the need for larger samples, camera surveys will need to be more expansive with a higher density of stations. In the absence of this, we advocate longer sampling periods and subsampling through time as a means of understanding and describing stability or variation between density estimates.

Dataset Information

Estimating large carnivore populations at global scale based on spatial predictions of density and distribution - Application to the jaguar (Panthera onca).

Publications

Estimating large carnivore populations at global scale based on spatial predictions of density and distribution - Application to the jaguar (Panthera onca).

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