If your family went missing, and you didn’t know what had happened to them, how would you react? A new study, “Return or roam? Trapping-induced social disruption reshapes movement behavior allocation in wild pigs,” asked if pigs who experience the traumatic loss of family members flee in fear or hunker down for safety? The study is full of euphemisms (“trapping-induced isolation”, “loss of social cohesion”), but also hints at the emotional lives of pigs.
Wild pigs often travel in groups of 6-10 related pigs called sounders. Sounders are important for finding food, protection from predators, and for social reasons.
Capturing an entire sounder at once is more effective in reducing a wild pig population than targeting individual animals. But as you can imagine, it’s not easy to do. The study determined to find out what could be expected to happen to pigs who avoid the trap.
Using a large corral trap, a sounder was trapped and then one adult female pig, randomly selected, was fitted with a GPS collar and released. This was repeated until researchers had 18 collared pigs.
Curiously, researchers waited until the lucky pig had fled the area before the other members of the sounder were killed, in order to reduce the chances that witnessing the killing would influence “post-release behavior.” Would witnessing the death of family members change how she reacted in the coming days and weeks? The study doesn’t say more.
Some animals widely disperse following a traumatic event, but not pigs. Immediately after “isolation”, the study found, surviving pigs were cautious and stayed near the area where the group had been disrupted. But after about two weeks, pigs began to venture out in search of food and water, or perhaps after abandoning efforts “to reestablish contact” with family. Behaviors returned to normal around day 19, the study concluded.
The researchers stressed that the study results– pigs remain near familiar areas– was behavior motivated by safety (avoiding risk), but they included the possibility that pigs may have also been “waiting for opportunities to rejoin conspecifics.”
It seems obvious– of course, pigs experience grief and loneliness after the loss of family– but it is still rare for studies in scientific journals to acknowledge the emotions and social bonds of wild animals.