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"Spalton, Andrew"
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Searching for spots: a comprehensive survey for the Arabian leopard Panthera pardus nimr in Saudi Arabia
The Arabian leopard Panthera pardus nimr is categorized as Critically Endangered, with < 200 individuals estimated to remain in the wild. Historically the species ranged over an extensive area of western Saudi Arabia but, with no confirmed sightings since 2014, investigating potential continued presence and distribution is of critical conservation importance. We present the results of a comprehensive survey designed to detect any remaining Arabian leopard populations in Saudi Arabia. We conducted 14 surveys, deploying 586 camera-trap stations at 13 sites, totalling 82,075 trap-nights. Questionnaire surveys were conducted with 843 members of local communities across the Arabian leopard's historical range to assess the presence of leopards, other predators and prey species. Predator scats were collected ad hoc by field teams and we used mitochondrial DNA analysis to identify the originating species. We obtained 62,948 independent photographs of animals and people, but none were of Arabian leopards. Other carnivores appeared widespread and domestic animals were numerous, but wild prey were comparatively scarce. Three questionnaire respondents reported sightings of leopards within the previous year, but targeted camera-trap surveys in these areas did not yield evidence of leopards. Of the 143 scats sent for analysis, no DNA was conclusively identified as that of the leopard. From this extensive study, we conclude there are probably no surviving, sustainable populations of Arabian leopards in Saudi Arabia. Individual leopards might be present but were not confirmed. Any future Arabian leopard conservation in Saudi Arabia will probably require reintroduction of captive-bred leopards.
Journal Article
Coupled Spatiotemporal Characterization of Monsoon Cloud Cover and Vegetation Phenology
In monsoonal ecosystems, vegetation phenology is generally modulated by the timing and intensity of seasonal precipitation. Seasonal precipitation is often characterized by substantial interannual variability in both space and time. A rigorous quantitative understanding of the ecology of the landscape requires spatially explicit information regarding the strength of the relationship between seasonal precipitation and vegetation phenology, as well as the interannual variability of the system. For this information to be accurately estimated, it must be based on spatially and temporally consistent measurements. The optical satellite image archive can provide these measurements. Satellite imagery offers observations of both a) atmospheric parameters such as the timing and spatial extent of monsoon cloud cover; and, b) phenological parameters, such as the timing and spatial extent of vegetation green-up and senescence. This work presents a method to capture both atmospheric and phenological parameters from an optical image time series. The method uses Empirical Orthogonal Function (EOF) analysis of a single spectral index for unified characterization of the spatiotemporal dynamics of both monsoon cloud cover and vegetation phenology. This is made possible by leveraging well-understood differences in the visible and near infrared reflectance of green vegetation, soil, and clouds. Image time series are transformed into a temporal feature space (TFS) that is comprised of low-order Principal Components. The structure of the temporal feature space reveals spatiotemporally distinct annual cycles of both cloud cover and vegetation phenology. In order to illustrate this technique, we apply it to the retrospective analysis of a seasonal cloud forest in the Dhofar Mountains of the southern Arabian Peninsula. Our results quantify known (but previously unmapped) local gradients in monsoon duration and vegetation community response. Individual ecological subsystems are also clearly distinguishable from each other, and consistent elevation gradients emerge within each subsystem. Novel observations also emerge, such as regreening/early greening events and spatial patterns in cloud duration. The method is conceptually straightforward and could be applied to characterize other monsoon environments anywhere on Earth.
Journal Article
Can genetic rescue help save Arabia's last big cat?
Genetic diversity underpins evolutionary potential that is essential for the long‐term viability of wildlife populations. Captive populations harbor genetic diversity potentially lost in the wild, which could be valuable for release programs and genetic rescue. The Critically Endangered Arabian leopard (Panthera pardus nimr) has disappeared from most of its former range across the Arabian Peninsula, with fewer than 120 individuals left in the wild, and an additional 64 leopards in captivity. We (i) examine genetic diversity in the wild and captive populations to identify global patterns of genetic diversity and structure; (ii) estimate the size of the remaining leopard population across the Dhofar mountains of Oman using spatially explicit capture–recapture models on DNA and camera trap data, and (iii) explore the impact of genetic rescue using three complementary computer modeling approaches. We estimated a population size of 51 (95% CI 32–79) in the Dhofar mountains and found that 8 out of 25 microsatellite alleles present in eight loci in captive leopards were undetected in the wild. This includes two alleles present only in captive founders known to have been wild‐sourced from Yemen, which suggests that this captive population represents an important source for genetic rescue. We then assessed the benefits of reintroducing novel genetic diversity into the wild population as well as the risks of elevating the genetic load through the release of captive‐bred individuals. Simulations indicate that genetic rescue can improve the long‐term viability of the wild population by reducing its genetic load and realized load. The model also suggests that the genetic load has been partly purged in the captive population, potentially making it a valuable source population for genetic rescue. However, the greater loss of its genetic diversity could exacerbate genomic erosion of the wild population during a rescue program, and these risks and benefits should be carefully evaluated. An important next step in the recovery of the Arabian leopard is to empirically validate these conclusions, implement and monitor a genomics‐informed management plan, and optimize a strategy for genetic rescue as a tool to recover Arabia's last big cat.
Journal Article
Distribution of bat species in Western Asia: Occurrence records from the Western Asia Bat Research Network (WAB-Net) project
Western Asia represents a mixing pot of diverse bat species with distributions spanning across other geographic regions. Yet, relative to other regions, there is a significant gap in coordinated bat research in Western Asia, thereby resulting in a relatively limited number of curated occurrence records. The Western Asia Bat Research Network (WAB-Net) project was created to strengthen research capacity and knowledge of the diversity and distribution of bat species in a little-studied region, as well as to collect data to characterise the diversity and prevalence of coronaviruses in diverse bat species. Over a four-year period (2018–2022), we documented 4,278 individual records for 41 bat species using a cross-sectional survey approach at 50 sites in seven Western Asian countries, specifically Armenia, Azerbaijan, Georgia, Jordan, Oman, Pakistan and Turkiye. At each site, we captured, on average, 90 individual bats (range: 9-131) over multiple consecutive nights and used standardised methods to collect demographic and morphological data from captured individuals. We additionally completed a systematic evaluation of environmental characterisation and human-bat interactions at all 50 sites. Here, we report individual occurrence records and site conditions from this multi-country, multi-year sampling effort.
Journal Article
Contemporary Pastoralism in the Dhofar Mountains of Oman
In the Dhofar Mountains of Oman stakeholders are concerned about the social and ecological sustainability of pastoralism. In this study we used interviews with pastoralists to examine the prevailing drivers of pastoralism and how they are changing. We find that people are committed to pastoralism for sociocultural reasons but also that this commitment is under pressure because of husbandry costs and changing values. We find that capital investment in feedstuff enables pastoralists to overcome the density-dependent regulation of livestock populations. However, high production costs deter investment in marketing and commercialization, and there is little off take of local livestock. Our study reveals how pastoral values, passed down within households, motivate pastoralists in the face of high husbandry costs, modernization and social change.
Journal Article
Big cats in borderlands: challenges and implications for transboundary conservation of Asian leopards
Large carnivores have extensive spatial requirements, with ranges that often span geopolitical borders. Consequently, management of transboundary populations is subject to several political jurisdictions, often with heterogeneity in conservation challenges. In continental Asia there are four threatened leopard subspecies with transboundary populations spanning 23 countries: the Persian Panthera pardus saxicolor, Indochinese P. pardus delacouri, Arabian P. pardus nimr and Amur P. pardus orientalis leopards. We reviewed the status of these subspecies and examined the challenges to, and opportunities for, their conservation. The Amur and Indochinese leopards have the majority (58–100%) of their remaining range in borderlands, and the Persian and Arabian leopards have 23–26% of their remaining ranges in borderlands. Overall, in 18 of 23 countries the majority of the remaining leopard range is in borderlands, and thus in most countries conservation of these subspecies is dependent on transboundary collaboration. However, we found only two transboundary initiatives for Asian leopards. Overall, we highlighted three key transboundary landscapes in regions that are of high importance for the survival of these subspecies. Recent listing of the leopard in the Bonn Convention on the Conservation of Migratory Species of Wild Animals is important, but more international collaboration is needed to conserve these subspecies. We provide a spatial framework with which range countries and international agencies could establish transboundary cooperation for conserving threatened leopards in Asia.
Journal Article
Critically Endangered Arabian leopards Panthera pardus nimr persist in the Jabal Samhan Nature Reserve, Oman
Between 1997 and 2000 a survey of the Arabian subspecies of leopard Panthera pardus nimr was conducted in the little known Jabal Samhan Nature Reserve in southern Oman. Using camera-traps 251 photographic records were obtained of 17 individual leopards; nine females, five males, two adults of unknown sex and one cub. Leopards were usually solitary and trail use and movements suggested large ranges characterized by spatial sharing but little temporal overlap. More active by day than night in undisturbed areas, overall the leopards exhibited two peaks in activity, morning and evening. The survey also provided records of leopard prey species and first records of nine Red List mammal species previously unrecorded in Jabal Samhan. Although people are mostly absent from the Reserve there is some conflict between leopards and shepherds who live outside the Reserve. The numbers and activities of frankincense harvesters in the Reserve need to be managed to safeguard the leopard and its habitat. The main challenge for the future is to find ways whereby local communities can benefit from the presence of the Reserve and from the leopards that the Reserve seeks to safeguard.
Journal Article