Research Article:

Wikramanayake, E. D., Dinerstein, E., Robinson, J. G., Karanth, U., Rabinowitz, A., Olson, D., Mathew, T., Hedao, P., Conner, M., Hemley, G., & Bolze, D. (1998). An ecology-based method for defining priorities for large mammal conservation: The tiger as case study. Conservation Biology, 12(4), 865–878.

Blog Author: Arjun Menon and Malavika Jayachandran

Key highlights: 

  • A study was conducted to understand the decline of carnivores in Asia due to habitat loss and poaching.
  • The study identified 159 Tiger Conservation Units across Asia, of which 25 were good habitats with low levels of threat, 21 were moderate habitats with manageable levels of threat, and 97 were fragmented habitats with high levels of threat.
  • To improve tiger conservation, researchers highlighted the need for more protected areas linked via natural corridors, as many of Asia’s wildlife reserves were highly fragmented.
  • The study recommended protected areas beyond international borders, citing the need for transboundary collaboration to improve tiger populations.

The disappearance of large mammals due to human-induced causes has been well-known around the world. Historically, habitat loss and poaching have been among the greatest threats to their survival. In 1998, scientists got together to address this issue, taking the tiger as an example. Tigers play an important role in ecosystems across their range. They also act as an umbrella species in the habitats they occur in, and their protection enables the conservation of a much larger area, and all the associated species within their range. The tiger was chosen as a focal species for this study as it faced rapid population declines from poaching, habitat degradation, and prey loss in vast Asian ecosystems. Understanding the threats tigers faced would paint a better picture for researchers to understand the conservation of other large carnivores.

This study divided the range of tigers into various bioregions such as the Indian subcontinent, Indochina, Southeast Asia etc, and distinguished them based on habitat types i.e. alluvial grasslands, subtropical moist deciduous forests, temperate upland forests, mangroves etc. Then, they were further divided into Tiger Conservation Units (TCUs). A TCU was defined as a landscape-scale area that could support interacting populations of tigers—often spanning multiple protected and non-protected lands.

Researchers identified 159 TCU’s and ranked them based on habitat integrity, poaching pressure, and population trends. They demarcated the TCU’s into 3 levels, with level I being large habitats with low poaching, level II being sizable habitats with manageable poaching, and level III being small/fragmented habitats with high threats.​

On the other hand, striped hyenas occupied about 52% of the district, while sloth bears were present across roughly 26%. Both species were closely tied to rocky and scrubby ONEs, which provided denning sites and daytime refuge from human activity. A surprising finding was that longer road networks did not negatively impact the presence of the two species, though further evidence is required to understand how traffic, surroundings, and other road characteristics impact the species. 

In total, they found 25 good habitats with low levels of threat (level I), 21 habitats with manageable levels of threat (level II), and 97 habitats that were fragmented with high levels of threat (level III). In the Indian subcontinent they identified 59 TCUs, of which only 11 habitats in regions like the Western Ghats and Deccan Plateau fell under level I. In Indochina, 69 TCUs were identified with only 10 falling under level I. Some of these included the Huay Kha Khaeng-Thung Yai Naresuan region in Thailand and Pegu Yomas in Burma. In Southeast Asia, 31 TCUs were identified with only 4 being classified as level I in parts of Sumatra, Malaysia and Thailand.

The shortage of high quality habitats for the species highlighted the need for improving habitat quality in Asia, with a key focus on anti-poaching, habitat linkage, and transboundary collaborations between countries to establish tiger reserves. With tigers being a flagship driving megafauna recovery across Asia, this study provides an adaptable, ecology-based framework to work towards resilient landscapes.

You can access the original article here.

Keywords: Large mammal conservation, Tigers, Asia, South-east Asia, Conservation priorities, Anti-poaching, Habitat Study