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Durbach, I., Borchers, D., Sutherland, C., Sharma, K. (2020). Fast, flexible alternatives to regular grid designs for spatial
capture–recapture..
Abstract: Spatial capture–recapture (SCR) methods use the location of
detectors (camera traps, hair snares and live-capture traps) and the
locations at which animals were detected (their spatial capture
histories) to estimate animal density. Despite the often large expense
and effort involved in placing detectors in a landscape, there has been
relatively little work on how detectors should be located. A natural
criterion is to place traps so as to maximize the precision of density
estimators, but the lack of a closed-form expression for precision has
made optimizing this criterion computationally demanding. 2. Recent
results by Efford and Boulanger (2019) show that precision can be well
approximated by a function of the expected number of detected
individuals and expected number of recapture events, both of which can
be evaluated at low computational cost. We use these results to develop
a method for obtaining survey designs that optimize this approximate
precision for SCR studies using count or binary proximity detectors, or
multi-catch traps. 3. We show how the basic design protocol can be
extended to incorporate spatially varying distributions of activity
centres and animal detectability. We illustrate our approach by
simulating from a camera trap study of snow leopards in Mongolia and
comparing estimates from our designs to those generated by regular or
optimized grid designs. Optimizing detector placement increased the
number of detected individuals and recaptures, but this did not always
lead to more precise density estimators due to less precise estimation
of the effective sampling area. In most cases, the precision of density
estimators was comparable to that obtained with grid designs, with
improvement in some scenarios where approximate CV(¬D) < 20% and density
varied spatially. 4. Designs generated using our approach are
transparent and statistically grounded. They can be produced for survey
regions of any shape, adapt to known information about animal density
and detectability, and are potentially easier and less costly to
implement. We recommend their use as good, flexible candidate designs
for SCR surveys when reasonable knowledge of model parameters exists. We
provide software for researchers to construct their own designs, in the
form of updates to design functions in the r package oSCR.
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Nawaz, M. A., Khan, B. U., Mahmood, A., Younas, M., Din, J. U, Sutherland, C. (2021). An empirical demonstration of the effect of study design on density estimations. Nature, 11(13104), 1–9.
Abstract: The simultaneous development of technology (e.g. camera traps) and statistical methods, particularly spatially capture–recapture (SCR), has improved monitoring of large mammals in recent years. SCR estimates are known to be sensitive to sampling design, yet existing recommendations about trap spacing and coverage are often not achieved, particularly for sampling wide-ranging and rare species in landscapes that allow for limited accessibility. Consequently, most camera trap studies on large wide-ranging carnivores relies on convenience or judgmental sampling, and often yields compromised results. This study attempts to highlight the importance of carefully considered sampling design for large carnivores that, because of low densities and elusive behavior, are challenging to monitor. As a motivating example, we use two years of snow leopard camera trapping data from the same areas in the high mountains of Pakistan but with vastly different camera configurations, to demonstrate that estimates of density and space use are indeed sensitive to the trapping array. A compact design, one in which cameras were placed much closer together than generally recommended and therefore have lower spatial coverage, resulted in fewer individuals observed, but more recaptures, and estimates of density and space use were inconsistent with expectations for the region. In contrast, a diffuse design, one with larger spacing and spatial coverage and more consistent with general recommendations, detected more individuals, had fewer recaptures, but generated estimates of density and space use that were in line with expectations. Researchers often opt for compact camera configurations while monitoring wide-ranging and rare species, in an attempt to maximize the encounter probabilities. We empirically demonstrate the potential for biases when sampling a small area approximately the size of a single home range—this arises from exposing fewer individuals than deemed sufficient for estimation. The smaller trapping array may also underestimate density by significantly inflating ?. On the other hand, larger trapping array with fewer detectors and poor design induces uncertainties in the estimates. We conclude that existing design recommendations have limited utility on practical grounds for devising feasible sampling designs for large ranging species, and more research on SCR designs is required that allows for integrating biological and habitat traits of large carnivores in sampling framework. We also suggest that caution should be exercised when there is a reliance on convenience sampling.
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Nawaz, M. A., Khan, B. U., Mahmood, A., Younas, M., Din, J. U, Sutherland, C. (2021). An empirical demonstration of the effect of study design on density estimations. Nature, 11(13104), 1–9.
Abstract: The simultaneous development of technology (e.g. camera traps) and statistical methods, particularly spatially capture–recapture (SCR), has improved monitoring of large mammals in recent years. SCR estimates are known to be sensitive to sampling design, yet existing recommendations about trap spacing and coverage are often not achieved, particularly for sampling wide-ranging and rare species in landscapes that allow for limited accessibility. Consequently, most camera trap studies on large wide-ranging carnivores relies on convenience or judgmental sampling, and often yields compromised results. This study attempts to highlight the importance of carefully considered sampling design for large carnivores that, because of low densities and elusive behavior, are challenging to monitor. As a motivating example, we use two years of snow leopard camera trapping data from the same areas in the high mountains of Pakistan but with vastly different camera configurations, to demonstrate that estimates of density and space use are indeed sensitive to the trapping array. A compact design, one in which cameras were placed much closer together than generally recommended and therefore have lower spatial coverage, resulted in fewer individuals observed, but more recaptures, and estimates of density and space use were inconsistent with expectations for the region. In contrast, a diffuse design, one with larger spacing and spatial coverage and more consistent with general recommendations, detected more individuals, had fewer recaptures, but generated estimates of density and space use that were in line with expectations. Researchers often opt for compact camera configurations while monitoring wide-ranging and rare species, in an attempt to maximize the encounter probabilities. We empirically demonstrate the potential for biases when sampling a small area approximately the size of a single home range—this arises from exposing fewer individuals than deemed sufficient for estimation. The smaller trapping array may also underestimate density by significantly inflating
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Din, J. U., Bari, F., Ali, H., Rehman, E. U., Adli, D. S. H., Abdullah, N. A., Norma-Rashid, Y., Kabir, M., Hameed, S., Nawaz, D. A., Nawaz, M. A. (2022). Drivers of snow leopard poaching and trade in Pakistan and implications for management. Nature Conservation, 46, 49–62.
Abstract: The snow leopard is one of the highly valued species from high-altitude mountain ecosystems of Central and Southeast Asia, including Pakistan. This keystone species is facing a myriad of conventional and emerging threats, including poaching and trade, that are poorly documented in Pakistan. To understand the dynamics and drivers of the poaching and trading of snow leopards in Pakistan, we investigated the issue in depth through a multifaceted survey in the snow leopard range of the country. We recorded 101 snow leopard poaching incidences from 11 districts during 2005–2017. The reported poaching incidences varied spatially (‒x = 9 ± 2.6 [95% Cl: 3–15]) and temporally (‒x = 7.8 ± 1.09) and accounted for 2–4% annual population loss (n = 200–420) in a period of 13 years. Poaching and trade together constituted 89% of the total incidence reported and animals were mostly shot (66%), poisoned (12%), snared (12%) and captured (4%), respectively. Only a fraction (3%) of the incidences were reported to the relevant law enforcement agencies. Trade routes included large cities and neighbouring countries, even the Middle East and Europe. The average base and end prices for each item were 245 ± 36 USD and 1,736 ± 520 USD, respectively, while maximum monetary fines set as per the law were 275 USD. Our results establish the need for developing multi-stakeholder coordination mechanisms at regional, national and international levels and information sharing to curb this menace. Improving the existing laws and surveillance system, while taking the local communities onboard, will further help to this end.
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Johansson, O., Mishra, C., Chapron, G., Samelius, G., Lkhagvajav, P., McCarthy, T., Low, M. (2022). Seasonal variation in daily activity patterns of snow leopards and their prey. Nature Portfolio, 12(21681), 1–11.
Abstract: The daily and seasonal activity patterns of snow leopards (Panthera uncia) are poorly understood, limiting our ecological understanding and hampering our ability to mitigate threats such as climate change and retaliatory killing in response to livestock predation. We fitted GPS-collars with activity loggers to snow leopards, Siberian ibex (Capra sibirica: their main prey), and domestic goats (Capra hircus: common livestock prey) in Mongolia between 2009 and 2020. Snow leopards were facultatively nocturnal with season-specific crepuscular activity peaks: seasonal activity shifted towards night- sunrise during summer, and day-sunset in winter. Snow leopard activity was in contrast to their prey, which were consistently diurnal. We interpret these results in relation to: (1) darkness as concealment for snow leopards when stalking in an open landscape (nocturnal activity), (2) low-intermediate light preferred for predatory ambush in steep rocky terrain (dawn and dusk activity), and (3) seasonal activity adjustments to facilitate thermoregulation in an extreme environment. These patterns suggest that to minimise human-wildlife conflict, livestock should be corralled at night and dawn in summer, and dusk in winter. It is likely that climate change will intensify seasonal effects on the snow leopard’s daily temporal niche for thermoregulation in the future.
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Shrestha, B., Kindlmann, P. (2020). Implications of landscape genetics and connectivity of snow
leopard in the Nepalese Himalayas for its conservation. (Vol. 10).
Abstract: The snow leopard is one of the most endangered large mammals.
Its population, already low, is declining, most likely due to the
consequences of human activity, including a reduction in the size and
number of suitable habitats. With climate change, habitat loss may
escalate, because of an upward shift in the tree line and concomitant
loss of the alpine zone, where the snow leopard lives. Migration between
suitable areas, therefore, is important because a decline in abundance
in these areas may result in inbreeding, fragmentation of populations,
reduction in genetic variation due to habitat fragmentation, loss of
connectivity, bottlenecks or genetic drift. Here we use our data
collected in Nepal to determine the areas suitable for snow leopards, by
using habitat suitability maps, and describe the genetic structure of
the snow leopard within and between these areas. We also determine the
influence of landscape features on the genetic structure of its
populations and reveal corridors connecting suitable areas. We conclude
that it is necessary to protect these natural corridors to maintain the
possibility of snow leopards' migration between suitable areas, which
will enable gene flow between the diminishing populations and thus
maintain a viable metapopulation of snow leopards.
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Nature Conservation Division, Department of Forests and Park Services, Ministry of Energy and Natural Resources, & Royal Government of Bhutan. (2023). Snow Leopard Status in Bhutan – National Snow Leopard Survey Report 2022-2023.
Abstract: The National Snow Leopard Survey (NSLS) report 2022-2023 provides an updated status of the snow leopard in Bhutan. The report is an outcome of the camera trapping survey spanning five protected areas namely Jigme Khesar Strict Nature Reserve, Jigme Dorji National Park, Wangchuck Centennial National Park, Bumdeling Wildlife Sanctuary and Jigme Singye Wangchuck National Park and two Divisional Forest Offices of Paro and Thimphu. A total of 310 camera stations were setup across the field sites that accumulated a survey effort of 22,636 trap nights, with over 10,000 images of snow leopards captured. A careful review of 476 images identified 96 adult individuals and 10 cubs across the landscape. Bayesian-based Spatially Explicit Capture Recapture (SECR) modelling estimated 134 snow leopards, as compared to the 2016 baseline of 96 individuals. Snow leopard density was estimated at 1.34 snow leopards per 100 km2 with the possibility of higher density in western Bhutan than in central and eastern Bhutan. Habitat distribution modeling also suggests more suitable habitats in western Bhutan as compared to other regions.
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Koju. N. P,, Bashyal, B., Pandey, B. P., Shah, S. N., Thami, S., Bleisch, W. V. (2020). First camera-trap record of the snow leopard Panthera uncia in Gaurishankar Conservation Area, Nepal. Oryx, , 1–4.
Abstract: The snow leopard Panthera uncia is the flagship species of the high mountains of the Himalayas. There is po- tentially continuous habitat for the snow leopard along the northern border of Nepal, but there is a gap in information about the snow leopard in Gaurishankar Conservation Area. Previous spatial analysis has suggested that the Lamabagar area in this Conservation Area could serve as a transbound- ary corridor for snow leopards, and that the area may con- nect local populations, creating a metapopulation. However, there has been no visual confirmation of the species in Lamabagar. We set !! infrared camera traps for " months in Lapchi Village of Gaurishankar Conservation Area, where blue sheep Pseudois nayaur, musk deer Moschus leucogaster and Himalayan tahr Hemitragus jemlahicus, all snow leopard prey species, had been observed. In November #$!% at &,!$$ m, ' km south-west of Lapchi Village, one camera recorded three images of a snow leopard, the first photographic evidence of the species in the Conservation Area. Sixteen other species of mammals were also recorded. Camera-trap records and sightings indicated a high abun- dance of Himalayan tahr, blue sheep and musk deer. Lapchi Village may be a potentially important corridor for snow leopard movement between the east and west of Nepal and northwards to Quomolongma National Park in China. However, plans for development in the region present in- creasing threats to this corridor. We recommend develop- ment of a transboundary conservation strategy for snow leopard conservation in this region, with participation of Nepal, China and international agencies.
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Moheb, Z., Rajabi, A. M., Jahed, N., Ostrowski, S., Zahler, P. I., Fuller, T. K. (2022). Using double-observer surveys to monitor urial and ibex populations in the Hindu Kush of Wakhan National Park, Afghanistan. Oryx, , 1–7.
Abstract: We surveyed the urial Ovis vignei and Siberian ibex Capra sibirica in the Hindu Kush mountain range of Wakhan National Park in north-eastern Afghanistan to determine their population status and identify potential drivers of population change. We conducted two double- observer ground surveys, in April–May 2015 and 2018, in 10 areas (total = 288 km2). Urial herds were mostly com- posed of both sexes (78% of observed herds), the mean adult sex ratio (females:males) was 100:70, and the mean female:juvenile ratio was 100:53. In 2018 we calculated a urial density of 35/100 km2, compared to 72/100 km2 in 2015. Ibex herds were mostly (79%) composed of both sexes, the mean adult sex ratio (females:males) was 100:103, and the mean female:juvenile ratio was 100:58. Ibex density estimates were similar in 2015 and 2018 (c. 250/100 km2). We discuss the usefulness of the double-observer methods for ungulate surveys, highlight the value of viewshed calculations and discuss the possible causes of urial population decline. To ensure the conservation of these ungulate populations, we recommend continued regular monitoring, measures to address poaching and research to clarify the taxonomical status of urials in Wakhan.
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Zhang, C., Ma, T., Ma, D. (2023). Status of the snow leopard Panthera uncia in the Qilian Mountains, Gansu Province, China. Oryx, , 1–6.
Abstract: Population density estimation is integral to the effective conservation and management of wildlife. The snow leopard Panthera uncia is categorized as Vulnerable on the IUCN Red List, and reliable information on its density is a prerequisite for its conservation and management. Little is known about the status of the snow leopard in the central and eastern Qilian Mountains, China. To address this, we estimated the population density of the snow leopard using a spatially explicit capture–recapture model based on camera trapping in Machang in the central and eastern Qilian Mountains during January–March 2019. We set up
40 camera traps and recorded 84 separate snow leopard captures over 3,024 trap-days. We identified 18 individual snow leopards and estimated their density to be 2.26/100 km. Our study provides baseline information on the snow leopard and the first population estimate for the species in the central and eastern Qilian Mountains.
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