A groundbreaking study was just released in the journal Biological Conservation. Written by Thinley et al. (2018), it deals with the ecosystem services provided by tigers (Panthera tigris) to villagers in Bhutan. The authors found strong evidence that the presence of tigers near villages can limit both crop and livestock losses.
At its core, this study is about how different “guilds” (sizes) of predators interact with one another. Thinley et al.’s (2018) study area consisted of Jigme Dorji National Park (JDNP) in Northwestern Bhutan. This ecologically rich landscape contains multiple species of predator, including: leopards (Panthera pardus), dholes (Cuon alpinus), and tigers.
Both leopards and dholes (a type of wild dog) are considered to be medium-sized predators within JDNP. As such, they are both less dominant than the much larger tigers. This is a key element in Thinley et al.’s (2018) findings.
To obtain their results, Thinley et al. (2018) instructed villagers to report all crop and livestock losses to the local authorities. At the same time, the researchers used a variety of methods to survey for predators in and around villages. They found several interesting patterns.
When a tiger was present near a village, it tended to favor the thicker forests on the outskirts of the settlement. This pushed leopards and dholes closer to the village, in an attempt to avoid the tiger. This was important for two primary reasons.
Having leopards and dholes near villages was good for crops, since they preyed on the herbivores that were responsible for most crop losses. Perhaps unexpectedly, it was also good for livestock.
Villagers in and around JDNP usually allowed their livestock to graze unattended in the forests outside villages – where the tigers were. While tigers did prey on livestock, they did so less frequently than leopards and dholes. So by keeping the latter two mesopredators (medium-sized predators) away from livestock, tigers actually performed a valuable service for local villagers.
This service was not insignificant. Thinley et al. (2018) estimated that having tigers around could save villagers up to US $1,570 every year. Based on 2014 figures, “This represents a very substantial rural household saving in Bhutan which is 70% of the average per capita income” (Thinley et al., 2018, p. 124).
Thinley et al.’s (2018) findings have important implications. They suggest that in addition to having immense cultural value and helping to regulate ecosystem functions, the presence of tigers can have economic benefits for rural villagers in Bhutan. I wonder if the same is true for other areas, and for more species than tigers? Could the presence of wolves (Canis lupus), for example, exert similar pressures on coyotes (Canis latrans) as tigers did on leopards and dholes?
Regardless of the answer to my musings, Thinley et. al’s (2018) study is most fascinating. I have included a link to the study in the “Further Reading” section below, along with a detailed news article about it.
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 – Phuntsho Thinley et al.
The Surprising Ways Tigers Benefit Farmers and Livestock Owners – John R. Platt