From elephants to chimpanzees, highly intelligent social animals have frequently been observed mourning the loss of their friends and group members. Now we can add peccaries, pig-like animals from South and Central America, to the list of animals that mourn their dead.

This latest discovery was actually made by an 8-year-old boy called Dante de Kort. He was watching a group of five peccaries (Pecari tajacu) that were living in his backyard in Arizona, when one female died of illness. Yet he noticed that the rest of the herd were still hanging around.

Intrigued, and with a school science fair coming up, he installed a camera trap to see what might be going on when the carcass was moved away from the house due to the growing pong. Over the next 10 days, de Kort captured the first ever evidence of peccaries behaving in a way that suggests they were mourning the death of their friend.

But it was only after de Kort showed his findings at his school fair that he realized the significance of what he had filmed, as attending that fair was Mariana Altrichter, who just so happens to be co-chair of the Peccary Specialist Group for the International Union for Conservation of Nature. She got in contact with de Kort and his mother, and said that she thought what he had recorded might be unique.

Altrichter then took on the project, and studied the 100 videos that de Kort had taken of the event. These have now been written up in a scientific paper and published in the journal Ethology, with de Kort as the study’s first author.

The paper documents how the animals tended to visit the corpse either on their own or in pairs, and continued to do so even after it was moved away from where the female initially died, showing that they were not simply returning to the place of death. What they did during their visits varied, including “pushing at the dead individual, staring at it, biting it, and trying to pick it up by putting their snout under the corpse and pushing it up,” write the authors.

The peccaries spent most of their time with the corpse at night, with some of them even sleeping next to it, cuddling up close. After a few weeks, a pack of coyotes moved in to try and feed, but even then the peccaries chased the predators away. Eventually, the coyotes won out, and the peccaries stopped returning to the carcass.

The authors suspect that this kind of behavior, particularly in highly social animals, is not unusual, it’s just that researchers rarely get to observe the natural death of individuals in the wild.