On January 8, 2017, an eight-year-old boy named Dante de Kort spotted a dead collared peccary near his home in central Arizona. For his school science fair project, he set up a motion-activated camera—a birthday present from his grandparents—next to the corpse.

Little did he know that his school project would offer an invaluable glimpse at how these animals respond to death.

At a regional science fair with her daughter in February, Prescott College biologist Mariana Altrichter was immediately struck by de Kort's videos. Having studied the social, pig-like mammals for years, Altrichter knew how tightly bonded peccaries could be. But she'd never witnessed herd members return to a body repeatedly. (Read: "Where Peccaries Wallow, Other Animals Follow.")

“It was pretty amazing because it wasn’t just an immediate reaction and then they moved on—it went on for 10 days,” says Altrichter, chair of the International Union for Conservation of Nature’s Peccary Specialist Group.

Dealing With Death

Accounts of death rituals have been written for a variety of animals, including elephants, primates, dolphins, and birds such as ravens. Elephants, for instance, have been seen standing over a deceased herd member for days, rocking back and forth, and pulling the lifeless body in what some experts believe is an expression of grief. (Related: "Whales Mourn Their Dead, Just Like Us.")

Elephants in Mourning A herd of elephants stumble on some elephant bones and mourn the loss of fallen relatives.

But no one had ever observed a death response in any of the three peccary species, which live throughout the Americas and tend to travel in herds of varying size.

In the videos, the peccaries pay close attention to the body, nuzzling, biting, sniffing, and staring at it. They slept next to the carcass, and even tried to lift it by wedging their snouts under the body and pushing upward.

And when a pack of coyotes approached their fallen peer, the herd chased them away. “It really surprised me that they would stand up to the coyotes,” says de Kort, noting the peccaries were outnumbered. (Learn if crows hold "funerals" for their dead.)

On the tenth day, the coyotes finally demolished the rotting remains, and that’s when the herd stopped visiting. De Kort and Altrichter described the series of intriguing events in a paper published December 5 in the journal Ethology.

But was it mourning? It's hard to be certain based on the footage alone, although Altrichter is confident the behavior meets the scientific definition: Actions that an animal takes to deal with a loss.

Whether feelings of grief accompanied those actions is unclear, she notes.

Emotional Animals

Barbara J. King, an emeritus professor of Anthropology at the College of William and Mary and author of How Animals Grieve, objects to the distinction between mourning and grief.

She cites “the solid, widespread evidence for emotional responses [to death] in surviving animals, ranging from depressed social withdrawal to evident distress in body posture and vocalization.”

Still, King acknowledges the possibility that the animals in the videos were neither grieving nor mourning. (See pictures: "Gorilla Mother 'Mourns' Dead Baby.")

In her opinion, the strongest evidence for grief was the act of sleeping beside the body—a behavior that can’t simply be chalked up to curiosity, territoriality, or other alternatives. It's quite plausible that peccaries would grieve, given the growing body of research detailing animals’ emotional responses to death, she adds.

Further research on peccaries could answer these lingering questions, and de Kort hopes to be part of it. (See National Geographic users' photos of peccaries, also called javelina.)

“Most people think they’re just animals," says the fourth-grader, "but they actually are pretty smart, and they have some human instincts too.”