Primate Tales: The Story of Moth, a White-Faced Capuchin

August 3, 2017

Primate Tales

Primate Tales is a new blog series that explores the lives of individual apes and monkeys at research sites supported by The Leakey Foundation. The first installment of our Primate Tales series is the story of Moth, a male capuchin monkey that lives in Costa Rica. He is one of the monkeys studied by Leakey Foundation grantee Susan Perry as part of the Lomas Barbudal Monkey Project. These capuchins have become one of the most intensively studied wild monkey populations in the world.

By Susan Perry, Lomas Barbudal Monkey Project in Costa Rica

 

---

Moth was born into Rambo’s group in 1992. The circumstances of his birth were somewhat unusual, as he is one of very few individuals born into this population who was not sired by the alpha male. Moth was sired by Doble, the closest ally of the alpha male Pablo. Moth has always been an unusually large and greedy male.  He was always skilled at rough and tumble play and (later) at fighting. He is one of the two largest males in the history of the project.

When he was 7 years old, his mother (Keeda) left Rambo’s group with the rest of her matriline to form their own group (Splinter group). Moth chose to remain in his father’s group, where there were more young males to play with, but he no longer had any close matrilineal kin in the group. As we know from our long-term study, Moth’s decision was typical: Males of this species exhibit unusually strong loyalty to their fathers and also generally prefer to stay with male playmates rather than with their mothers during a fission.

Moth began leaving the group to visit neighboring groups when he was ten years old. He mainly did this in the company of his two closest playmates, Newman and Tranquilo. When he was 11 years old he successfully invaded the neighboring Abby’s group and became alpha male for a few weeks. As soon as he successfully invaded with the help of his ally Tranquilo, he turned on Tranquilo, evicting from the group. He killed the infant of one of the females there, and the group evicted him. (Perhaps he would have fared better had he retained his ally!)

Moth returned to his natal group and stayed there for the remainder of his life. This is where his odd circumstances of birth were of assistance to him. His own father left the group around this time, never to return, so he was no longer co-residing with either of his parents. Pablo (the alpha male of that group) had many adult daughters (and even granddaughters) because he had been alpha male for ~17 years. There is strong father-daughter inbreeding avoidance in capuchins, so Pablo couldn’t mate with his own female descendants. This meant that Moth, who was less related to these females than any other natal male, could breed while remaining in his natal group; he conceived seven offspring while living in Rambo’s group as a subordinate natal male. Moth, with his superior fighting skills, was effective in helping Pablo defend the group from would-be invaders.  They had what seemed to be almost a co-alpha arrangement in which the elderly Pablo (now in his late 20’s) contributed the political expertise and Moth (who was always more interested in eating than in socializing) contributed physical formidability.  They co-resided comfortably until 2008, when Moth fought Pablo and wounded him. Pablo stepped down as alpha male then and stopped siring offspring. Moth permitted Pablo to remain in the group as a subordinate male till his death nearly 2 years later, enabling Pablo to care for his children and grandchildren.

Moth permitted various other pairs of co-migrants to immigrate to his group and never seemed particularly concerned about these arrivals (which is unusual for an alpha male). The only time any of these migrants launched an attack on Moth was when he was handicapped for a while by breaking his leg. Two subordinate males took turns at being alpha male during the early stages of this injury, but Moth soon regained alpha status, ruling from the ground until his leg had fully healed. His many fans took to playing and socializing on the ground during his healing phase, so that they could be with him.

Rambo’s group fared well under Moth’s rule until 2014-15, when there was a major drought (caused by El Niño). Many members of the group died (apparently of hunger) during this time, bringing the group down in size from 23 to 10 members during the latter half of 2015. Moth, surprisingly, was one of the members who vanished despite his extreme skill in finding food. We don’t know what the cause of his death was, and in theory, he could have just migrated to a different group outside the study area. But he has not been seen in the past year, and it is rare for males to abandon their own offspring, so we think we can fairly safely conclude that this memorable male has completed his lifespan.

The Lomas Barbudal Monkey Project was founded in 1990 by Leakey Foundation grantee Susan Perry with the help of Joseph Manson and Julie Gros-Louis for the purpose of studying social intelligence in the white-faced capuchin, Cebus capucinus, and this population has been studied almost continuously ever since.

The Leakey Foundation is proud to support this and other long term primate research sites around the world. You can help support long term research by making a donation today!