ENVIRONMENT

A recent study finds that the often-feared big cats actually help keep crops and domesticated animals safe from other threats. (Scientific American)

Zoom in on the dwindling range of the biggest of the big cats with today’s MapMaker Interactive map.

Teachers, scroll down for a quick list of key resources in our Teachers Toolkit.

Discussion Ideas

• New research investigates “ecosystem services” offered by tigers in rural Bhutan. What are ecosystem services?
  • Ecosystem services describe the many benefits humans and human communities receive from healthy, functioning natural ecosystems.
  • Ecosystem services are often divided into four categories:
    • regulating services. Regulating services are those that regulate natural cycles, such as climate, carbon cycle, and the water cycle.
    • provisioning services. Provisioning services describe the ways in which natural ecosystems provide products for human use, from seafood to timber.
    • cultural services. Cultural services describe the benefits human communities receive from the educational, scientific, spiritual, intellectual, and recreational aspects of natural ecosystems.
    • support services. Support services describe ecological processes that allow other ecosystem services to function. Perhaps the most important of these is the functioning of primary producers—the way that plants, bacteria, and other organisms generate organic matter and oxygen through processes such as photosynthesis and chemosynthesis.

• What sort of ecosystem services are the tigers of rural Bhutan providing nearby human communities?
  • The presence of tigers is supporting a provisioning service by indirectly contributing the development of crops and livestock.

• Read through the short Scientific American article. How does tiger habitat contribute to ecosystem services described in the article?
  • Tigers are apex predators that “tend to live in the deepest, most pristine habitats they can find.” This has a ripple effect on other animals in the ecosystem.
    • First, other predators shift their range to the edge of the “deepest, most pristine habitat” to avoid the tiger. In Bhutan, the predators pushed to the edge of the ecosystem were leopards and dholes (a type of wild dog.)
    • In the second part of the ripple, the slightly displaced leopards and dholes do not prey on local livestock, however. Instead, they prey on herbivore “crop raiders” that would otherwise harm local crops. The primary species of herbivore hunted by leopards and dholes in Bhutan is the wild boar.

• The Scientific American article reports that the “domesticated animals raised by pastoralists in Bhutan tend to range relatively unattended and often graze in the forests surrounding villages.” So why aren’t tigers, leopards, and dholes preying on livestock?
  • The presence of a small, healthy tiger population has allowed the livestock and predators to switch places in the ecosystem.
    • Livestock are present in forested tiger habitat, but tigers are an endangered species. (Only 3,800 remain.) Their population simply isn’t large enough to pose a significant threat to free-range livestock.
    • Tiger populations have pushed leopard and dhole populations from deep forests to cropland, where the predators are more likely to encounter “crop raiders” than livestock.

• The study authors say “conservation of large apex predators can be better justified by their ecosystem services instead of their iconic status.” How did the study quantify “ecosystem benefits”?
  • Scientists put a financial value on the presence of tigers. They determined “that the presence of a tiger would reduce so much herbivore crop damage it would be like putting an extra $450 a year in each family’s pockets. Livestock losses would also be reduced by an average of 2.4 animals per farm, the equivalent of saving $1,120 a year. Considering the per capita income of Bhutan is just about $2,200, that’s a potential economic windfall—all thanks to tigers.”

• Take a look at today’s MapMaker Interactive map comparing tiger ranges, land use, and national borders. What obstacles might complicate applying the conservation lessons learned in Bhutan to other regions in the tiger’s range?
  • politics. Some nations, such as Bhutan, China, and Russia, have very strong federal government policies that could determine conservation strategy for the entire nation. Other nations, such as India and Indonesia, have more decentralized governments in which regional entities (such as states) may have differing conservation policies.
  • population. The region studied in Bhutan is sparsely populated. In more densely populated areas, the tiger’s habitat is much more fragmented; livestock is less likely to be free-range; and predators such as tigers, leopards, and dholes have likely adapted in different ways to domesticated animals, feral animals, and human settlements. (Not always in negative ways! Read this terrific article to understand how leopards a regulating service—health—by preying on rabid dogs on the outskirts of Mumbai, India.)
  • land use. The Bhutan study researches the impact of tigers on rural agricultural communities. The ecosystem benefits have little relevance to regions where the human footprint is more dramatic: urban or suburban areas, industrial areas, sites with infrastructure such as airports or shipping yards.
  • agricultural methods. Most industrialized regions do not practice pastoralist, free-range agriculture studied in Bhutan. This changes the “trickle-down” ecosystem benefits offered by tiger populations.

TEACHERS TOOLKIT

Scientific American: The Surprising Ways Tigers Benefit Farmers and Livestock Owners

Nat Geo: Where might tigers benefit farmers and ranchers? map

(extra credit!) Biological Conservation: The ecological benefit of tigers (Panthera tigris) to farmers in reducing crop and livestock losses in the eastern Himalayas: Implications for conservation of large apex predators