CONSERVATION STATUS
Tigers (Panthera tigris), which historically occurred across Asia, have suffered large contractions in range and population over the past century. As human populations continue to expand, refugia for tigers are becoming increasingly scarce and fragmented. This is compounded by poaching and other threats, jeopardizing long-term population persistence. This is particularly evident in Southeast Asia which is home to the Indochinese tiger (Panthera tigris corbetti) of which potentially fewer than 200 remain. Severe reductions in the tiger’s range in the region have occurred at a time where national and transnational economic strategies have necessitated monumental investments in infrastructure and transformative land use change. With this critically endangered subspecies of tiger in Southeast Asia seemingly at a crossroads, understanding the effects of these potential threats to tiger population persistence is crucial for developing effective conservation and management strategies.
WILDCRU APPROACH
WildCRU’s approach includes surveys from vast arrays of camera trapping grids in nine countries across Southeast Asia (India, Nepal, Myanmar, Thailand, Laos, Vietnam, Cambodia, Malaysia and Indonesia). In a long-term collaboration with the Department of Forests and Park Services of Bhutan, early research contributed to human tiger conflict mitigation in rural communities and latterly mapping conflict risk. Leveraging Bhutan’s national survey of Bengal tigers (Panthera tigris tigris), our research on density estimation and community ecology contributed to the Tiger Action Plan for Bhutan 2024-2033. Our current focus with partners in Bhutan is on connectivity modelling and the potential impacts of future landscape change on tigers. We are partners in the Satpuda Landscape Tiger Partnership, the largest NGO alliance working to protect tigers in India.
For Indochinese tigers, in partnership with Thailand’s Department of National Parks, Wildlife and Plant Conservation (DNP), Freeland Foundation and Panthera, our research has focussed on the critically important breeding population in Thailand’s Dong Phayayen-Khao Yai Forest complex (DPKY), a group of five protected areas and UNESCO World Heritage Site. We have developed modelling to investigate current and future potential connectivity of remaining populations of Indochinese tigers in Thailand, Myanmar, Lao PDR, Cambodia, and Vietnam to provide a basis for broad-scale population recovery.
TIGER RESEARCH AND CONSERVATION IMPACT HIGHLIGHTS
Long-term collaborations with the Department of Forests and Park Services of Bhutan involving 3 PhD students and 2 Diploma students
Identifying umbrella and indicator species to support multispecies population connectivity in a Himalayan biodiversity hotspot
Documenting the demise of tiger and leopard, and the status of other carnivores and prey, in Lao PDR’s protected area: Nam Et – Phou Louey
WildCRU currently has one programme focused on tiger research:
Key WildCRU publications relating to tigers:
Female-biased introductions produce higher predicted population size and genetic diversity in simulations of a small, isolated tiger (Panthera tigris) population
Tigers on the edge: mortality and landscape change dominate individual-based spatially-explicit simulations of a small tiger population
Estimating the density of a globally important tiger (Panthera tigris) population: Using simulations to evaluate survey design in Eastern Thailand
Scale dependence of felid predation risk: identifying predictors of livestock kills by tiger and leopard in Bhutan
Understanding the environmental and anthropogenic correlates of tiger presence in a montane conservation landscape
Feeding habits and niche partitioning in a predator guild composed of tigers, leopards and dholes in a temperate ecosystem in central Bhutan
Female-biased introductions produce higher predicted population size and genetic diversity in simulations of a small, isolated tiger (Panthera tigris) population
Isolation of wildlife populations represents a key conservation challenge in the twenty-first century. This may necessitate consideration of translocations to ensure population viability. We investigated the potential population and genetic trajectory of a small, isolated tiger (Panthera tigris) population in Thailand’s Dong Phayayen-Khao Yai forest complex across a range of scenarios. Using an individual-based, spatially-explicit population modelling approach, we simulate population and genetic trajectories and evaluate the relative impact of translocations from a related population. Population and genetic trajectories in our study were most sensitive to sex and number of individuals translocated and translocation frequency. Translocation of females produced consistently higher population, allelic richness, and heterozygosity compared to equal numbers of males. Despite population increases, declines in allelic richness and heterozygosity across simulations were stark, with simulations predicting a mean decline of allelic richness and heterozygosity of 46.5% and 53.5% without intervention, respectively. Translocations of four females every generation or every other generation were required to prevent substantial heterozygosity declines. While translocations could increase population size, they may fail to prevent long-term loss of genetic diversity in small populations unless applied frequently. This reinforces the importance of incorporating realistic processes of genetic inheritance and gene flow in modelling small populations.
Tigers on the edge: mortality and landscape change dominate individual-based spatially-explicit simulations of a small tiger population
Context Reductions in the tiger’s (Panthera tigris) range in Southeast Asia have been concurrent with large infrastructure expansion and landscape change. Thailand’s Dong Phayayen-Khao Yai Forest Complex (DPKY), a landscape of tiger conservation priority, may be particularly vulnerable to such changes, necessitating investigations into effects on population dynamics.
Objectives Evaluate relative effects of landscape change scenarios on the probability of tiger persistence in DPKY and sensitivity of predictions to spatially-explicit mortality risk, landscape resistance, and tiger population density.
Methods We utilize individual-based, spatially-explicit population modelling to evaluate the trajectory of tiger population dynamics across 11 landscape change scenarios. Concurrently, we evaluate sensitivity of predictions to landscape resistance transformation, maximum population density, and spatially-explicit mortality across 20 generations.
Results Spatially-explicit mortality risk dominated predictions of population persistence, frequently resulting in population declines/extinction. Adjustment of moderate mortality risk to slightly convex and concave forms shifted extinction rates from 46% to 12% and 85%, respectively. Holding mortality constant at moderate levels, strong negative effects were predicted in landscape change scenarios incorporating road expansion (46%-74% extinction) and construction of dams (52%). Strong negative effects of combined development persisted even when habitat restoration measures were applied (96% extinction). Adjusting resistance and maximum population density had marginal effects.
Conclusions The high sensitivity and variability of predictions to spatial patterns of mortality risk suggest a population on a proverbial knife’s edge. Our results underscore the importance of incorporating spatial patterns of mortality risk in population modelling, highlighting their potentially dominating influence on population dynamics and extinction risk.