Introduction
Squirrel monkeys are one of the most well-known and well-studied primate species originally discovered in South America. Their natural area of inhabitance includes Amazon forests in Peru, Ecuador, Colombia, Venezuela, Guyana, and Suriname (Campelo et al. 174). According to biological classification, squirrel monkeys belong to the Saimiriinae subfamily within the Cebidae family (Suárez-Bonnet et al. 1). As such, the closest primates who share many similar physical characteristics with the latter are capuchins (Cebinae subfamily) and tamarins (Callitrichinae subfamily) (Suárez-Bonnet et al. 1). There are five species of squirrel monkeys, namely the common squirrel monkey, black-capped squirrel monkey, bare-eared squirrel monkey, black squirrel monkey, and Central American squirrel monkey (Haines). Among them, only the latter two are considered vulnerable due to increasing human agricultural and deforestation activities (Haines; The IUCN Red List of Threatened Species). The current paper aims to discuss the biological structure and behavior of squirrel monkeys based on the analysis of academic and popular literature and personal observations.
Primate Research
Biological Structure
Squirrel monkeys are relatively small-sized and light weighted animals compared to other primates. Their body length varies from 9-14 inches (22-36 cm), whereas the tail can reach 14-17 inches (36-42 cm) (Haines). A grown squirrel monkey can weigh from 500 to 750 grams if it is a female and from 750 to 1100 grams if it is a male. While the primate’s body is covered with a short light brown and yellowish fur, the ‘hair’ color around the eyes and mouth is different being white and black accordingly.
Squirrel monkeys’ average lifespan varies significantly in the wilderness and in captivity. If the animal normally lives for 15 years in its natural inhabitance, in captivity, its lifespan increases to approximately 20 years (Conservation Society of California). In its diet, the primate has a strong preference for eating different fruits, nuts, and seeds but can sometimes consume insects. Lastly, female monkeys reach reproductive maturity by the age of 2.5, whereas males become sexually active by the age of four.
Behavior
Squirrel monkeys are social animals and live in large groups with multiple males and females. For this reason, in order to communicate effectively with each other, these primates have a sophisticated vocalization system (Campelo et al. 175). In addition, they use urine to mark their domain of control and inhabitance (Conservation Society of California). Males generally exhibit more dominant and aggressive behavior than females and, thus, have the role of territory protectors. As for reproductive behavior, squirrel monkeys mate during autumn, and both sexes would normally mate with several partners. When babies are born, mothers generally raise them without the help of fathers (Conservation Society of California). Nevertheless, the latter’s behavior would still change and become more aggressive in order to protect the newborns from the potential threat.
Personal Observations
My personal observations suggest that squirrel monkeys are quite active and alert. They usually stay close to each other, but it seems that grooming does not occur frequently. However, the younger monkeys were play fighting almost 30-40% of the observation time. The older ones spent most of their time (around 70%) eating fruits. Additionally, I noticed that these primates could jump the distances that exceed their body length for more than 5-6 times and do not use their tail to grip branches.
Conclusion
Overall, the current paper presented the results of my personal observation of squirrel monkeys and further research of academic and popular literature. It was found that these primates’ natural area of inhabitance includes the northern part of South America. Moreover, the investigation revealed that among five species, only two, namely the black squirrel monkey and Central American squirrel monkey, were under the threat of extinction due to unsustainable human activity. Furthermore, the biological structure of squirrel monkeys was presented, including the average size, weight, fur color and type, lifespan, and diet. Finally, the behavioral patterns such as grooming, play, dominance and aggression display, vocalizing, and overall activity were analyzed.
Works Cited
Campelo, Anielise C., et al. “Home Sweet Home? Adjustments in the Ecology, Behaviour and Vocalisations of Amazonian Squirrel Monkeys Inhabiting an Atlantic Forest Fragment.” Ethology Ecology & Evolution, vol. 31, no. 2, 2019, pp. 173-197.
Conservation Society of California. “Squirrel Monkey.”Oakland Zoo.
Haines, Bryan. “35 Squirrel Monkey Facts: All 5 Saimiri Species (Plus 8 Subspecies).”Storyteller.Travel, 2021.
Suárez-Bonnet, Alejandro, et al. “Scent (Apocrine) Gland Adenocarcinoma in a Wedge-Capped Capuchin Monkey (Cebus olivaceus): Histological and Immunohistochemical Features.” Journal of Comparative Pathology, vol. 179, 2020, pp. 1-6.
The IUCN Red List of Threatened Species. The Red List, 2022.