Understanding & addressing wildlife poisoning in Northern Cambodia

Emiel de Lange

https://doi.org/10.1017/S0030605319001492

ដើម្បីអានអត្ថបទនេះជាភាសាខ្មែរសូមចូលទៅកាន់:

 https://doi.org/10.6084/m9.figshare.12146181.v1

The coronavirus pandemic is likely to have a variety of unforeseen implications for people and wildlife. One early trend is a reported increase in waterhole poisonings in Cambodia's Northern Plains. This is concerning for both conservation and human health reasons. Preah Vihear province in northern Cambodia is home to the largest remaining fragments of Southeast Asia’s deciduous woodlands. These woodlands, which once carpeted mainland Southeast Asia, have disappeared elsewhere. As such, Cambodia’s Northern Plains are stronghold for some unique and threatened wildlife species. For example, the area is home to the Giant Ibis – Cambodia’s national bird, which was thought extinct until it was re-discovered in 1993. Unfortunately, three Giant Ibis (representing over 1% of the global population) have been poisoned in recent months. These poisonings can also harm farmers and their livestock, who depend on the waterholes as a critical water source.

So why might we be seeing this worrying spike in waterhole poisoning? Research conducted in 2017, by ICCS’s Emiel de Lange and two Cambodian students, Yim Vichet and Leang Chantheavy, may help to provide some answers. The study is forthcoming in the journal Oryx (watch this space!)

Figure 1:  The critically endangered Giant Ibis, sitting near a waterhole in Preah Vihear province, Cambodia
Figure 1:  The critically endangered Giant Ibis, sitting near a waterhole in Preah Vihear province, Cambodia

The first documented carbofuran poisonings in Preah Vihear: a problem for people and wildlife

In 2016, in the heat of the dry season, cows in Preah Vihear province were dying seemingly without reason and farmers were complaining of diarrhoea and stomach pains. When government officials investigated they found troubling scenes: at five vital life-giving waterholes, strange purple gravel was strewn at their edges, and dead and dying animals were scattered nearby. A slender-billed vulture, one of less than 100 individuals left in Southeast Asia, was found struggling in the grass and rushed to a vet.

The bird did not survive. However, by examining the contents of its stomach in a laboratory, vets discovered that it had been poisoned by a pesticide called carbofuran. This was even more troubling, as carbofuran is extremely toxic to birds, and was banned internationally, under the Rotterdam convention, following a massacre of Europe’s farmland birds in 1998. Such poisonings not only represented a significant public health danger to farmers and their livestock; they also threatened the rare wildlife which depend on the waterholes for their survival.

At the time, conservationists could only speculate as to the causes for these events. Was it an accidental consequence of pesticide use in agriculture? Was it an intentional attack, perhaps intended to kill a cow in retaliation for a land dispute? Or a protest against conservation rules? To address this problem, we would first need to understand the root causes.

Understanding the root causes of waterhole poisonings

Emiel and his team interviewed local residents and organised group discussions in ten villages in the area, to get a broader sense of how people perceived poisoning, and to attempt to measure its prevalence. Given the sensitive nature of the behaviour, they used a mixed methods approach drawing on theory from social psychology, sensitive questioning techniques, and triangulating multiple data sources. Their conclusions have important implications for managing poisoning in Preah Vihear province, and for studying sensitive behaviours in other contexts.

1. The who, what, where, when, and why, of wildlife poisoning

“In the dry season, when the waterholes are dry, I put the poison in a coconut shell. It is a powder which I dissolve in the water and put in the shell […]. Using this poison, I used to catch a lot of birds, maybe five or six each time, and I would try three times in one season.”

This description is typical of practices documented in eight of the ten villages visited during the study. It is a method used to harvest wild meat, which is primarily consumed at home. It is considered extremely efficient, and easy to learn compared to methods such as setting traps or using guns. In the dry season, a lot of wildlife concentrates at waterholes which makes them easy targets. However, from a conservation perspective, this indiscriminate killing is concerning and witnesses reported that many important species have been affected. It is usually young men, perhaps up to the age of 30, who are using poisons, but we also heard about children playing with poisons and catching animals too. They might learn this from relatives in the village or from shopkeepers, who sometimes sell the poison repackaged in clear plastic bags for ~$0.25.

We might assume that the poorest households are using poison because of food insecurity, but the evidence for this was not clear in 2017. A more important factor in deciding whether to use poison or not seems to be how health risks are perceived. This is one of the key factors that may have changed following the outbreak of COVID-19, as migrant workers are forced to return home and no longer have employment opportunities.

Figure 2: a poisoned waterhole with a dead plaintive cuckoo. The purple carbofuran pesticide is visible on the tree trunk.
Figure 2: a poisoned waterhole with a dead plaintive cuckoo. The purple carbofuran pesticide is visible on the tree trunk.

2. Social norms and village reactions

“The villagers are all unhappy [about poisoning] […]. Last year I told everyone at a meeting to not do it and forbade the shopkeepers to sell the poison, […] but people continue to do it in secret.”

Social norms around wildlife poisoning are complex and differ from village to village. In one village, poisoning was a topic discussed freely and seemed to be quite common, while in others nobody had ever seen or heard about such a practice. Most villages lay somewhere in the middle: there were clearly groups of varying size who were using poison or who were accepting of it, while others disapproved strongly. In five villages, chiefs or other authority figures had attempted to prevent poisoning, because it destroys clean water sources and fish populations, risks people’s health, and has caused the deaths of beloved dogs, cows and chickens. They had made poisoners sign contracts promising to stop, or held village meetings to discuss the problem. One traditional doctor even suspected a young boy had been poisoned, but we couldn’t confirm this story. Many people also worry about the health effects of eating poisoned meat, and we recorded a long list of suspected symptoms. On the other hand, many believe that removing the internal organs of a poisoned animal makes the meat safe to eat.

3. The challenges of studying sensitive behaviour

“If people in the village knew this was happening, they would be unhappy as it could kill their cattle.”

Understandably, many people were reluctant to talk about poisoning. Many residents were unhappy about poisoning, and authorities have publicly acted against it in some villages. As such, those using poison may keep quiet about it to avoid social and legal repercussions. Some villages also benefit from conservation projects, such as community ecotourism businesses or organic farming projects, so village authorities may work closely with environment authorities to enforce conservation rules.

This situation raises challenges for researchers. Few people openly admitted to poisoning. Most accounts were indirect, or from those who had been negatively impacted by poisoning. Nevertheless, by carefully triangulating evidence from multiple sources, the study makes several robust qualitative conclusions, though trying to estimate prevalence of poison usage across the landscape has proved more difficult.

Figure 3: A summary of evidence collected for 9 hypotheses, showing how they vary across the 10 studied villages. Green triangles pointing upwards indicate that the hypothesis is supported, and purple triangles pointing downwards indicate it is not. The size of the shape indicates the strength of this evidence.
Figure 3: A summary of evidence collected for 9 hypotheses, showing how they vary across the 10 studied villages. Green triangles pointing upwards indicate that the hypothesis is supported, and purple triangles pointing downwards indicate it is not. The size of the shape indicates the strength of this evidence.

What does this mean for preventing waterhole poisoning in the future?

Despite the challenges of studying sensitive behaviours, the results of this study will be useful for planning interventions to reduce wildlife poisoning in the area. Local managers now understand the practices that lead to wildlife poisoning, the people involved, and their motivations. Importantly, the prevalence of this practice is now better understood, as well as the social norms and dynamics in each village, and previous efforts by local authorities to combat poisoning. All of this knowledge allows us to:

  1. Prioritise villages for intervention
  2. Identify target groups and plan how to reach them
  3. Identify potential allies to collaborate with, or use as key messengers
  4. Understand what sort of information might influence poisoners’ decision-making.

Based on the results of the study, Emiel and his collaborators at WCS Cambodia launched pilot interventions in early 2019. A full social marketing intervention has been conducted in one village, followed by extensive surveys to understand its effects. Watch this space for more news on its impact!

Finally, whether or not the recently observed increase in poisonings follows the trends described in this study remains to be seen. However, early evidence suggests that greater quantities of poison are being used than before. This might indicate that new actors with greater access to capital and commercial motivations are engaging in poisoning. A key component of our interventions to date has been to engage local communities in monitoring and reporting poisoning using a hotline, and this will continue to be critical for addressing this new challenge. High profile media coverage may also assist in encouraging greater control of trade in these deadly pesticides.

For more details, you can contact the lead author from University of Edinburgh, Emiel de Lange (e.delange@ed.ac.uk).

Emiel de Lange (@emiel_delange) is an environmental social scientist currently completing his PhD at the University of Edinburgh. For the past six years he has been working in Cambodia, designing and evaluating behavioral interventions with WCS Cambodia.