Anthropologists from Tulane University have captured incredible footage of capuchin monkeys teaming up to rescue one of their own from the strangling clutches of a Boa constrictor. The video, along with the scientists' description of the incident, were recently published in the journal Scientific Reports.
In the summer of 2019, Professor of Anthropology Dr. Katharine M. Jack and her colleagues were following a group of 25 white-faced capuchin monkeys in Sector Santa Rosa of the Area de Conservación in Guanacaste, Costa Rica. A few of the juveniles were enjoying a light-hearted play session when the attack occurred. The terrifying ordeal abruptly begins roughly 28 seconds into the video below and lasts just 19 seconds.
Around 28 seconds in, you can hear the victim, a 6-year-old juvenile, start to scream as the two meter-long Boa constrictor begins its suffocating embrace. A second later, a subordinate adult male sounds the snake alarm call to rouse the rest of the group. Just four seconds afterwards, the group's alpha male charges toward the snake and starts to furiously bite and scratch it, drawing blood. Soon afterward, two older females join the alpha male in attacking the Boa while also attempting to pry the juvenile from its clutches. They succeed after a few seconds, ending the attack and scurrying away at about the 47-second mark.
While predation events like these occur frequently, they are rarely observed by scientists. According to the researchers, the swift, heroic actions of the capuchin group "clearly support the hypothesis that predation has been a strong selective force driving sociality in primates." A tight social bond can be the difference between life and death for an individual within a group. And direct kinship is not required. In this case, the group's alpha male risked his life to save the juvenile even though he was not actually related to the young monkey.
"The threat of constricting snakes may have been a particularly strong selective force in early primate evolution when primates were small bodied and, therefore, more susceptible to fall prey to constricting snakes," the researchers conclude.
Source: Jack, K.M., Brown, M.R., Buehler, M.S. et al. Cooperative rescue of a juvenile capuchin (Cebus imitator) from a Boa constrictor. Sci Rep 10, 16814 (2020). https://doi.org/10.1038/s41598-020-73476-4