A new scientific survey provides evidence of breeding tiger populations in eastern Thailand’s Dong Phayayen-Khao Yai forest complex, one of the last stands of the Indochinese population.

The outcome is the result of a decade-long program to protect tigers in this area.

Researchers deployed an unconventional survey design for this study, investigating the reliability of previous methods of estimating wildlife populations.

Camera traps in eastern Thailand’s Dong Phayayen-Khao Yai (DPKY) forest complex have yielded photos of tiger cubs, providing long-awaited evidence that the big cat is breeding in this part of Southeast Asia.

Conservationists conducted the camera-trap survey in the Thap Lan-Pang Sida Tiger Conservation Landscape (TCL) of DPKY, where recent reports suggest a small, but vital, population of tigers (Panthera tigris) occurs. (There’s currently debate about whether Indochinese tigers constitute their own subspecies, P. t. corbetti, or are simply a population of mainland Asian tigers, P. t. tigris, that also include the larger Bengal and Siberian tigers.)

“Efforts to improve anti-poaching patrols and law enforcement efforts are critical to providing a safe area for tigers to breed,” said Supagit Vinitpornsawan, the former head of the DPKY Wildlife Research Station. “Recent results of our monitoring indicate these efforts may be paying off.”

Published in the journal Biological Conservation, the new scientific survey shows a glimmer of hope for a decade-old program known as the DPKY Tiger Recovery Project. Conservationists say they may even be on track to meet a goal of increasing Thailand’s tiger numbers by 50% by 2026. It may be that Thailand’s tigers can avoid the fate of those in other countries.

Currently, conservationists believe only 221 Indochinese tigers remain in two Asian countries, Thailand and Myanmar, after a camera trap study in 2019 revealed the last remaining populations in Laos had vanished. Populations in Vietnam and Cambodia are also believed to be locally extinct.

But the DPKY population has room to grow. The estimated population for the study area is around 20 individuals, with a minimum of 14 and a maximum of 33 tigers. The researchers estimate the population density is only 0.63 tigers per 100 square kilometers (39 square miles) — a much lower density than other habitats in the tiger’s current range. For example, in Huai Kha Khaeng, in Thailand’s Western Forest Complex (WEFCOM), a previous study estimated a density ranging from 1.27 to 2.09 tigers per 100 km2 from 2005 to 2012. Still, differences in study design make exact comparisons difficult.

Categorized as endangered on the IUCN Red List, Thailand’s tigers are imperiled by poaching for tiger parts, poaching of their prey, and illegal rosewood logging. All these threats are present in the forest complex where they reside.

“If we fail to contain [the illegal wildlife trade] it is likely we will see the extinction of the species in the wild in the not too distant future,” said Chris Hallam, a conservation scientist in charge of monitoring and operations for Panthera USA. Panthera, a global wild cat conservation organization, collaborated on the survey with Thailand’s Department of National Parks, Wildlife and Plant Conservation (DNP), the Freeland Foundation, and Oxford University’s Wildlife Conservation Research Unit (WildCRU).

Tiger numbers in the wild have dropped from 100,000 a century ago to around 3,900 today, most of which survive in India. There are more captive tigers in the U.S. than there are wild ones worldwide.

For this study, the researchers used spatially explicitly capture-recapture (SECR) sampling, a popular method of population estimation. However, with so few tigers out there, reliable results were difficult, and, in the end, they found non-regular survey designs more beneficial.

“In our study, we utilized computer simulations to investigate and evaluate how different camera-trap placements and survey duration effect population estimates,” said Eric Ash, lead author of the study and a researcher with WildCRU.

The paper questions previous methods of estimating wildlife populations, a potentially valuable step toward improving our understanding of tiger distribution across their range.

To avoid extirpations similar to those in Laos and Cambodia, “monitoring is critical for managers to evaluate populations over time and determine the efficacy of conservation actions. It can also determine areas of conservation priority in which protection efforts can be focused,” Ash said.

But even remote monitoring with camera traps can lead to harrowing moments. Hallam says his biggest thrill during the camera trapping was “coming across a fresh urine spray from a tiger while putting out cameras.”

He added, “With such thick habitat and low densities, seeing tigers is difficult in the DPKY, but knowing I was mere seconds from one was both terrifying, exhilarating and humbling all at once.”

Banner image: Two Indochinese tiger cubs in Thailand’s Dong Phayayen-Khao Yai forest complex cautiously inspecting a camera trap. Image by Freeland Foundation.

Citations:

Ash, E., Hallam, C., Prawatsart, C., Kaszta, Z., Macdonald, D. W., Rojanachinda, W., … Harihar, A. (2020). Estimating the density of a globally important tiger (Panthera tigris) population: Using simulations to evaluate survey design in Eastern Thailand. Biological Conservation, 241, 108349. doi:10.1016/j.biocon.2019.108349.

Gray, T. N. E., Hughes, A. C., Laurance, W. F., Long, B., Lynam, A. J., O’Kelly, H., … Wilkinson, N. M. (2018). The wildlife snaring crisis: an insidious and pervasive threat to biodiversity in Southeast Asia. Biodiversity and Conservation, 27(4), 1031-1037. doi:10.1007/s10531-017-1450-5.

Duangchantrasiri, S., Umponjan, M., Simcharoen, S., Pattanavibool, A., Chaiwattana, S., Maneerat, S., … Karanth, K.U. (2016). Dynamics of a low‐density tiger population in Southeast Asia in the context of improved law enforcement. Conservation Biology, 30(3), 639-648. doi:10.1111/cobi.12655