Scientific Report of Tufted Capuchin Monkeys San Diego Zoo

Scientific Report of Tufted Capuchin Monkeys in SanDiego Zoo

Behavioral Differences Between Male and Female Capuchin Monkeys in an Artificial Habitat

Studies have shown that the activity and energy of an animal can be determined through the collection of data and presentation as an activity budget (Altmann 1974, Tacha 1985). An activity budget collects specific behavior data over a predetermined time for an animal or population for analysis in the evaluation of a hypothesis. This study reports the differences in activity between males and females for a population of tufted capuchin primates living in an outdoor artificial habitat within a North American zoo. The hypothesis that there are differences in activity levels between male and females for this population is confirmed for the duration of observation in this study. More study would be required to determine the effects of weather, seasonal variation, and daytime verses nocturnal behavior.

Introduction

The tufted capuchin (Sapajus paella) is a brown or black furred primate from South America with a natural range that includes the Amazon basin (Groves, Wilson, Reeder 2005). The behavior differences between male and female capuchins in captivity are not well understood. The purpose of this study is to determine if there are average differences between male and female groups within a captive population of capuchins. The hypothesis is that the male capuchin monkeys will be more active in feeding and at rest due to differences in body size between the sexes. Studying behavior of the two sexes in a population observing specific time intervals in different activities will be used to create an activity budget. The data will then be analyzed to determine if there are notable differences between the two sexes. The theory behind an activity budget is based on the amount of energy that an animal must expend to do different activities. Metabolism in animals place limits on how long an animal can spend engaged in a given activity such as foraging, sleeping, traveling or interacting with other animals (Bobick, 2004). Factors that influence this metabolism can include sex and relative physical size.

Tufted capuchins are small, brow to black primates with a head-body length of 30-60 cm and weights between 1.7 and 5 kg. Figure 1 shows a pair of tufted capuchins in the habitat at the San Diego Zoo. The males are generally larger than the females.

Figure 1: Pair of tufted capuchin monkeys at the San Diego Zoo (Bohn 2012)

The association between food and males vs. females in capuchin monkeys has been studied with regard to foraging and the share taken by the finder of food (di Bitetti 2001). In addition, the relationship between cooperation and pay-off vs. A task for capuchin monkeys has been studied to determine energy and activity for monkeys alone and in groups (de Waal 2002). The relationship between differences in activity for male verses female monkeys has not been studied in an artificial zoo habitat. The assessment of tufted capuchin monkeys in mapping an activity budget for behavior in different activities is used to test the hypothesis for this population.

Methods

Time activity budgets were collected for a static, captive population of Tufted Capuchin Monkeys. The population is housed within an outdoor habitat at the San Diego Zoo located in San Diego, California. The habitat is an outdoor open facility with open visibility through netting and windows for zoo visitors. The capuchin population is a single group within the habitat dedicated to them with no other species of primates or other mammals present. The capuchin habitat is approximately 10 meters long and 5-10 meters deep and is roughly oval in shape. The capuchin group is provided with multiple areas for play and interaction including ropes, real and simulated trees, platforms and hammock structures. The group is fed on feeding platforms and has multiple locations for water. The habitat receives both sun and shade and the group does have access to an indoor facility. The entire site is visible from multiple viewing locations and the animals are desensitized to observers through near-continuous observation by zoo attendees.

The tufted capuchin typically lives in a social group between two and twenty animals. The groups contain one dominant male and can have multiple subordinate males and a group of females (Groves 2005). The capuchin diet is omnivorous and feeding is often dictated by a social hierarchy presented by the dominant male and the closeness of a select group of preferred females (di Bitetti 2001).

The group was observed for 2 hours and 15 minutes in a single observation period. Animals were counted and the following classifications were made:

Total Number

Alpha Male(s)

Females

Subordinate Male(s)

Juvenile Males

Juvenile Females

The following parameters were established for behavior observations and the relative times for the individuals:

Resting

Moving

Feeding

Foraging

Grooming

Playing

Not visible to the observer

The data was collected by visual observation and recorded. Averages were determined and differences between the male and female animals are presented.

Results

A total of 15 animals were observed for 2 hours, 15 minutes. The group consisted of the following set of animals broken down by sex and superiority within the group:

3 adult males. 9 adult females. 1 subordinate male. 2 juvenile males

The adult males were the largest of the animals and the subordinate male was similar in size. The two juvenile males were similar in size to the females. The table below shows the percentage of time spent in each activity by the males and females.

Activity

Male (%)

Female (%)

Resting

44

67

Moving

18

17

Feeding

15

5

Foraging

10

0

Grooming

3

6

Playing

5

2

Out of Sight

2

0

The plots below show the differences in percentage of time overall for the two groups male vs. female in the population studied: