[Commentary] Estimating population of world’s snow leopards

A snow leopard captured by a camera trap in the Western Himalaya. Photo by Rishi Kumar Sharma/NCF/HPFD

A snow leopard captured by a camera trap in the Western Himalaya. Photo by Rishi Kumar Sharma/NCF/HPFD

  • Despite several decades of research on snow leopards, reliable estimates of their population density are scarce.
  • Accessibility to the habitat, funding and sensitive international borders are some of the challenges in studying the snow leopard.
  • The commitment of snow leopard range countries to protect the animal and the willingness of the conservation organisations to take on conservation challenges is an opportunity that can shape conservation of snow leopards in the decades to come, writes Rishi K. Sharma in this commentary.
  • The views expressed in this commentary are that of the author.

The status and distribution over time of large carnivore populations are of enduring interest to biologists and conservation managers. Carnivore populations and distribution can decline due to a range of factors such as habitat loss and fragmentation, change in land-use practices, poaching, a decline of wild ungulate populations and increased competition with other predators such as the free-ranging dogs and disease like the canine distemper virus (CDV). Carnivore densities in a landscape can also vary as a function of anthropogenic land-use factors such as the intensity of livestock grazing, human-wildlife conflict, the natural topographical features of the landscape and distribution and abundance of wild prey.

Landscapes, especially the multiple-use areas, have tremendous natural heterogeneity and type of human land use can induce or reduce that heterogeneity. Human-induced homogeneity (e.g. monoculture plantations or commercial livestock production) or loss of natural variation in a landscape can adversely impact biodiversity.

Large carnivores such as snow leopards are umbrella species and indicative of the health of an ecosystem. Understanding what drives the variation in population-density as the most important determinant of population estimates, given fixed or reducing land areas, can help devise appropriate management actions. Despite the apparent importance of reliable estimates of snow leopard populations, determining population size and monitoring snow leopards is difficult due to their natural rarity, the remote, rugged and challenging terrain they inhabit, and lack of adequate resources required for large scale monitoring programs. Politicians and policymakers often want to know how many animals are there, where they are, and how are their populations and habitats changing? In the absence of such information, it is hard to draw political attention towards the plight of a species and influence policy decisions.

What do we know so far?

Despite several decades of research on snow leopards, reliable estimates of their population density are scarce. Currently, less than four percent of the snow leopard range globally has been covered using reliable methods that provide accurate data on their distribution and abundance. The absence of reliable estimates makes it hard for biologists and managers to make informed decisions and recommendations to policymakers. The global estimates of snow leopard numbers are essentially based on expert opinion and guesstimates. Both the estimates of snow leopard range and snow leopard number vary depending on whom you ask! The snow leopard distribution range estimates vary from 1.2 to 3 million square kilometers while the estimates of population size vary from a minimum of 3,920 to a maximum of 10,000. The wide variation in the current estimates at the global and country levels itself makes them much less useful for a meaningful conservation programme or evaluation of conservation interventions.

Himal-rakshaks (the mountain guardians), members from the local community inspecting snow leopard signs on a rocky outcrop in West Sikkim. Photo by Rohan Pandit/WWF-India
Himal-rakshaks (the mountain guardians), members from the local community inspecting snow leopard signs on a rocky outcrop in West Sikkim. Photo by Rohan Pandit/WWF-India.

From the existing radio telemetry studies in Mongolia, we know that snow leopards have large home ranges of about 200 sq. km for males and 125 sq. km for females. However, home range size as large as 1590 sq. km have been reported. Unfortunately, only the long-term studies in Mongolia have provided robust information on the home range size and movement patterns of snow leopards and there is little information on whether snow leopard home range is similar or different in other parts of its range. Studies on the species’ population density show that snow leopard density on an average is 1 animal per 100 sq. km, though densities as high as four snow leopards per 100 sq. km have been reported. We also know that there might be considerable variation in the density of snow leopards in a landscape in response to factors such as anthropogenic pressures such as livestock grazing, poaching of snow leopards and wild ungulates, the density of the wild ungulates and natural topographical features of a landscape.

Why is it so difficult?

The approximate 1.8 million square kilometers of snow leopard habitat is spread across 12 countries in Central and South Asia. The snow leopard range encompasses some of the highest and coldest mountain ranges of the world, often inaccessible due to their sheer remoteness. The accessibility issues mean the logistical challenges of conducting a snow leopard survey can be a nightmare. Even when logistical and accessibility challenges are overcome, the snow leopard habitats are not particularly hospitable to humans due to severe cold, high winds, and low oxygen levels.

One might be tempted to think that tiger numbers can be estimated at large scale why cannot it be done for snow leopards? Everything else being constant, a snow leopard population estimation survey, can be far more difficult by several magnitude orders. Only the most intrepid and committed researchers embrace the hardships that come with studying snow leopards. The funding needed for snow leopard research can be prohibitive, and sensitive International Borders can stall even ongoing projects. Far more cooperation between researchers, managers and a range of government institutions is needed including securing adequate financial resources for large-scale monitoring programs.

Why there is so much attention on snow leopard numbers?

In 2017, the International Union for Conservation of Nature (IUCN) down-listed the snow leopard from the endangered to vulnerable status. The decision evoked strong criticism from some of the conservationists who questioned the evidence used for the move.  Conservationists opposing the IUCN decision argued that reliable estimates of snow leopard population do not exist across the larger part of its range and the demographic modeling actually favours the “endangered” categorisation. Conservationists favouring the IUCN decision contend that IUCN used the best available data and that snow leopard numbers might be far higher than previously thought. The number game is, however, fraught with problems. For one, there is no robust baseline of snow leopard abundance to infer an increase or decrease in their population. Secondly, there is no monitoring system either that can help determine trends in snow leopard populations. Therefore, claims of an increase or decrease in snow leopard numbers are mostly based on expert opinion and remain questionable.

Ibex, an important wild prey species for snow leopards. Photo Rishi Kumar Sharma/WWF-India
Ibex, an important wild prey species for snow leopards. Photo Rishi Kumar Sharma/WWF-India.

The Global Snow Leopard Ecosystem Protection Program (GSLEP) launched a global effort to estimate population of snow leopards in the world. Population Assessment of World’s Snow Leopards (PAWS) launched in 2018 aims to address the critical issue of lack of robust estimates of snow leopard numbers through a multi-country and multi-institutional collaborative effort. Many snow leopard range countries, including Bhutan, Mongolia, Russia, Nepal and India have already launched ambitious National Level Snow Leopard Population Assessments.. Most of these countries are at different stages of achieving the goal of their National Level Population Assessment and are committed to make it happen. Once the estimates from these large-scale population surveys from the range countries emerge, there should be far less uncertainty about the population size of snow leopards in each of the range countries.

China alone contains more than 60 percent of the snow leopard habitat of the world and conservation efforts in China alone can have a major influence on snow leopard conservation. Many of the snow leopard range countries share sensitive and disputed borders and trans-boundary collaboration and cooperation between the range countries is essential for long term conservation of snow leopards. Co-operation towards snow leopard conservation between Russia and Mongolia is an excellent example of two snow leopard range countries partnering for the cause of conservation. Many more of such partnerships are needed as snow leopards range far and wide and do not recognise the political boundaries.

Read more: Scientific survey maps 73 snow leopards in Himachal Pradesh

An opportunity for snow leopard science and conservation

Often the goal of population estimation of a species is to establish benchmarks to evaluate whether species conservation efforts are yielding desired results such as an increase in the population of a species. A single population estimate, or a population estimate of a species in isolation cannot help conservation. The robust estimates of population size need to be accompanied with an equally rigorous assessment of impacts of threats such as poaching, habitat degradation and loss and effects of climate change on the species. Similarly, conservation interventions need to be rigorously evaluated to provide evidence that they work and have the intended impact requiring repeat population estimates over time. Since a large part of the snow leopard range is outside of the protected areas, what is also needed is understanding the opportunities and challenges for the conservation of snow leopards in complex multiple-use landscapes.

Therefore, establishing a clear goal for the National Level Population Assessments and a clear roadmap to achieve that should be prioritised. For instance, which landscapes will be surveyed and monitored for the long run, how often the monitoring exercise will be carried out and what other information should be collected as a part of the monitoring program needs to be thought through and spelled out clearly. Snow leopards are amongst the least studied of the big cats, so any information from any survey may add value to the existing knowledge on the species. Indeed, new surveys in areas previously not surveyed add valuable new information on the species and should be encouraged. IUCN’s decision to down-list the snow leopards and the disagreements in the conservation community on the snow leopard population estimates may have spurred the ambitious exercise to estimate the population of the snow leopards in the world. But it will be a lost opportunity if this exercise is not tied to clearly defined conservation goals if it does not improve the knowledge on snow leopards especially the spatial ecology, and if it does not engage and foster a genuine partnership of local communities in snow leopard conservation and falls short of finding solution towards co-existence of people and snow leopards.

The commitment of the snow leopard range country governments to protect snow leopards and the willingness of the conservation organisations to take on the complex conservation challenges is a unique opportunity that can shape the conservation of the snow leopards in the decades to come. Using the momentum behind the global assessment of snow leopard abundance to infuse rigour in the science of snow leopard conservation, foster collaborations and partnerships between countries and institutions and genuine involvement of local communities in the production of knowledge and conservation decision making will have a lasting impact on the people and snow leopards that inhabit the formidable mountains of Asia.

Dr. Rishi K. Sharma is the Lead, Science and Policy, Snow Leopard Conservation Programme at WWF India and WWF International.

Banner image: A snow leopard captured by a camera trap in the Western Himalaya. Photo by Rishi Kumar Sharma/NCF/HPFD.

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