A picture of Spock resting in a big tree in 2007.

Today’s post is about a male of Colombian squirrel monkey who was first observed in 2005. At that time this male was one of the residents and dominant adult males in a Colombian squirrel monkey group of 42 individuals. He was a male of more than 8 years, probably 10 years in 2005, because of his body features and old scars. He was called Spock because he had a small cut in his right ear, which makes his ear pointed looking like the Start Wars character of that name.

Colombian squirrel monkey groups are composed of several females (5 – 8 females) and a few resident males (3 – 5 males), forming reproductive groups that move and forage together. Additional to this type of group, Colombian squirrel monkey males form groups of only males called bachelor males. Bachelor groups moves and forage independently of a group composed of both sexes and only during the reproductive season (August – September in the study area), bachelor groups are observed following reproductive groups. During these month males become more aggressive and their body accumulates fat on shoulders and thighs that make them look like an American football player.

Males of this species start their reproductive life once they leave their natal groups as solitary males or in small bachelor groups usually formed by a couple of adult males and a few subadult males who move and forage together. Males become resident males usually after several months in which they follow a reproductive group and challenge resident males. In some cases, resident males don’t tolerate them easily and they got back to their solitary life or join other bachelor groups. Although not very common they also can join reproductive groups in the company of an adult female, we only know one case in the study area.

Dominance between males also change and aggression became a tool for males to fight their access to reproductive females. Spock was one of the resident males and a dominant one in one of the reproductive groups in the study area. He was a successful reproductive male in the years 2005 and 2006 where we observed copulating with several females who later those years produce a new baby.

In 2005 – 2007, he remains as one of the dominant males in the group we were following and usually moving close to the females. Colombian squirrel monkey groups move as a group in which females moves in the core of the group with babies and juveniles, while the males move more toward the periphery of the group. Spock used to move close to the core or in the front of the group and always close to the adult females of the group.

Spock was one of the males who fist adapted to our presence following the group and low us to be close to him (3 -5 meter, when at a height of 5 -8 meter, which is close for a wild squirrel monkey). We observed him with the same group until 2009 when one of the students in this project found a dead squirrel monkey who was identified as Spock. He died at an age of around 14 years old. No apparent reason for his death was found, his body didn’t show any marks of predation and when he was found his body was relatively fresh. Although there is not much data on how long Colombian squirrel money males live in the wild, data from males observed in the study area have shown a span of around 24 years form another male from the same group who was last observed in 2017. This male, Van Gogh, was a bit older than Spock when he was first observed and he was one of the least dominant males of the group in 2005, always moving in the back and periphery of the reproductive group.

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