Protecting the world’s endangered species from poachers is dangerous business.

Over the past decade, more than 1,000 rangers have died in the line of duty, according to statistics released last week for World Ranger Day. Some deaths were caused by accidents or animals. Most, however, were murders committed by heavily armed poachers who enter national parks and other protected areas in search of species such as tigers, rhinos, and elephants.

At the same time, rangers have killed hundreds of poachers, often spurred by the shoot on sight policies that have become the norm in several parks. The numbers add up: Between 2011 and 2015, rangers at South Africa’s Kruger National Park alone reportedly killed nearly 500 poachers.

While these rangers are undoubtedly heroes who all too often lay down their lives to protect the animals in their care, some organizations have begun to raise questions about the retaliatory bloodshed, asking if it is ethical or moral for rangers to kill suspected poachers without arrest or trial. The issue came to bear most recently last month after a guard in India’s Kaziranga National Park, which has a shoot-to-kill policy, critically wounded a seven-year-old boy from a tribe that lives around the park.

“We’re pretty horrified by the situation,” said Sophie Grig, senior campaigner at Survival International, a tribal rights organization that has criticized the recent Kaziranga shooting and shoot-to-kill policies in general. “It seems to us a very worrying trend that is bad for both local people who get caught in the crossfire and for conservation.”

Grig also wonders if shooting poachers even solves the larger problem. “If you were arresting those people and then investigating them, you could trace back and work out who the kingpins are,” she said. “If you shoot them dead, you can’t ask them any questions.”

Annette Hübschle, who recently authored a report on rhino poaching for the Global Initiative Against Transnational Organized Crime, echoed those sentiments. She said the “current militarized approach” is pushing people away from any chance they might have to participate in conservation. “There should be a greater focus on investigating the transporters and buyers, prosecuting organized criminals such as kingpins and smugglers, ‘follow the money’ approaches, and seizing assets of criminals,” she said.

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Aside from legal strategies, the issue of whether or not poachers should be killed brings up several potential lines of ethical thought, said Anna Peterson, a professor in the department of religion at the University of Florida and the author of Being Animal: Beasts and Boundaries in Nature Ethics.

One way of thinking about it, she said, is to ask if individual sentient beings have value and if there is a difference in that value between a human life and that of a rhinoceros. She pointed to ethicist Tom Regan’s test, which asked if you would throw a dog out of a lifeboat to save yourself. “Essentially, Regan said you would always throw out the dog on the basis of complexity and what would be lost by a human’s death rather than a dog’s death,” she said.

More broadly, Peterson said, you could ask if a species is rare and significant and if its ecosystem would suffer in its absence. This ecological perspective could come into play when discussing species such as rhinos, tigers, and elephants. “We have that debate here about Florida panthers, which are both rare and important predators,” she said.

Finally, Peterson looked at the question from the field of ethics known as war theory. “The just war theory,” she said, “lays out a series of criteria, such as do you have a just cause and have you tried to fix this peacefully?” If we consider preserving ecosystems to be a just cause, then killing could be justified. Similarly, so could looking at poaching as an economic issue, as it threatens tourism, or as a national security issue, an important consideration involving organized crime, smuggling, national borders, and related crimes such as drugs and weapons.

No one has easy answers. “Rangers are doing difficult jobs in difficult circumstances,” Grig said. She added, though, that the often public enthusiasm for killing poachers seems contrary to the call to protect human rights in just about any other crime. “I think this is something we need to be discussing,” she said.