Primate Update E-Newsletter, Vol. 2, Issue 4, Part 3

CONTINUING EDUCATION


Special Topic Robin- Feeding Behaviors in Spider Monkeys


Feeding Behaviors in Monkeys and Humans Have Ancient, Shared Roots,
Bolivian Rainforest Study Suggests

A recent study found, surprisingly, that spider monkeys control their diet in a similar way to humans, which is contrary to previous thought. Most monkeys are opportunistic feeders; this means that they will eat as much of a food resource as possible when they happen upon it (e.g. a mango tree full of mangos). Spider monkeys, however, have been found to tightly regulate their protein intake, regardless of seasonal food availability. This eating style has been linked with obesity in humans, and could prove a valuable finding in dealing with animals in captivity.

In this study, Dr. Annika Felton took detailed records of 15 individual monkeys’ movements and eating habits in the Bolivian rainforest. These types of studies are not usually done in such a thorough way; past studies usually collect averages for entire groups of animals. This means that Dr. Felton was able to collect more accurate data and get a clearer picture of the spider monkeys’ diets. Dr. Felton found that the pattern of nutrient intake by spider monkeys was almost identical to that of humans, even though spider monkeys are frugivorous and humans are omnivorous.

In humans, ingesting small amounts of protein and large amounts of carbohydrates and fats can cause obesity. Adjusting the diet can alleviate this condition, and would work the same way for animals in captivity. It is interesting that humans and spider monkeys were found to share similar nutritional intakes, as this would mean that the evolutionary origins of such patterns might be much older than previously thought (i.e. the Paleolithic Era, 2.4 million to 10,000 years ago), as humans and spider monkeys are not very closely related (New World Monkeys split from Old World Monkeys 40 million years ago). However, this might be due to convergent evolution, which means that each species developed the same trait independently of one another.

While figs made up the majority of the diet, the monkeys were found to eat 105 different fruits and vegetables, with the rare supplement of insects. Their protein intake remained constant regardless of the amount of food consumed, and the carbohydrate intake varied widely (if there was more sweet, ripe fruit, they would consume more in a day). To maintain a constant protein intake, the monkeys would eat more of a fruit if it was low in protein, and less of a fruit if it was high in protein. The detailed list of foods eaten that was gathered in this study will prove very valuable for the conservation of spider monkeys in the wild. This is important because the species of fig tree that makes up the majority of the monkeys’ diet is currently being cut down for timber. Because this information is now known, steps can be taken to conserve needed portions of forest for the spider monkeys.

-Oxford University Press (2009, May 20). Feeding Behaviors In Monkeys And Humans Have Ancient, Shared Roots, Bolivian Rainforest Study Suggests. ScienceDaily. Retrieved March 21, 2010, from http://www.sciencedaily.com/releases/2009/05/090519214940.htm

Special Topic-Erin: Species Spotlight


Black-handed Spider Monkeys (Ateles geoffroyi)

Spider Monkeys get their name from their appearance, with extremely long arms, legs and tails they resemble a spider. Pacific Primate Sanctuary is currently home to two Black-handed Spider Monkeys (Ateles geoffroyi). These lanky monkeys are one of the largest New World Primates, often weighing up to 20 pounds. They have tan to reddish bodies, with darker hands and feet and small heads. Their prehensile tail is quite impressive, with a palm like padded area for extra grip; their tails can easily support their entire body weight. While their feet are similar to most other primates with an opposable thumb, their hands are quite unique. Spider monkeys have four long fingers, and no thumb on their hands, which makes their hands hook-like. Their long arms, hook like hands, and flexible shoulder joints allow Spider Monkeys to brachiate, or move across branches and ropes by swinging arm over arm. Brachiation is a rare type of movement, seen only in Gibbons and Spider Monkeys.

Black-handed Spider Monkeys are found along the coasts of Mexico, through Central America and as far south as Northwestern Columbia. They live in mature rainforest and montane forests (forests at higher elevations). They are active during the day, and live in the trees. They spend the majority of their time in the upper levels of the forest, mainly in the canopy but will also use the middle and lower strata. They forage in the high canopy, but tend to travel lower down where the branches are thicker.

Spider Monkeys are highly social, living in groups of 20-30 individuals. These groups are multi-male and multi-female usually with more females in the group than males. Females will leave the group at puberty to find a new group, while the males generally stick together for their entire lives. This is very rare among primates. Another rare trait of Spider Monkeys is the presence of a Lead Female who directs the group, and is in charge of finding food and planning the foraging route each day. If there is not enough food for the entire group, they will split into smaller subgroups for foraging. Spider Monkeys are highly frugivorous (fruit eaters) with 90% of their diet coming from fruits and nuts. They also eat leaves, flowers, and occasionally insects.

Spider Monkeys are highly intelligent, and have a brain that is twice the size of Howler Monkeys with an equivalent body size. Examples of their highly developed intelligence include their complex social system and their knowledge of over 150 species of plants that are used as food.

Black-handed Spider Monkeys are currently listed as Endangered on the IUCN Red List. Unfortunately, their numbers are currently declining. The major threat to these animals is habitat destruction, and they are also subject to pet trafficking in some areas.

-Gorog, A. 2002. "Ateles geoffroyi" (On-line), Animal Diversity Web. Accessed March 26, 2010 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Ateles_geoffroyi.html

-Cuarón, A.D., Morales, A., Shedden, A., Rodriguez-Luna, E. & de Grammont, P.C. 2008. Ateles geoffroyi. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.1. . Downloaded on 26 March 2010.

-Spider monkey. (2010, March 8). In Wikipedia, The Free Encyclopedia. Retrieved 19:35, March 26, 2010, from http://en.wikipedia.org/w/index.php?title=Spider_monkey&oldid=348506024

Rowe, Noel. 1996. The Pictorial Guide to the Living Primates / Noel Rowe; foreword by Jane Goodall; introduction by Russell A. Mittermeier, Pogonias Press, East Hampton, N.Y.



We hope you have enjoyed this issue of Pacific Primate Sanctuary’s E-Newsletter. Thank you for your support of our life saving work. Because of compassionate people, the Sanctuary can continue to provide a place of peace and happiness for 70 primates saved from research laboratories, animal dealers, and smugglers. Here they can heal, form families, and live free from exploitation.
You and I are the force for transformation in the world. We are the consciousness that will define the nature of the reality we are moving into. — Ram Dass


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