US tab

Grooming Solicitation & Hierarchy
in Cercopithecus petaurista

By: Ryan Domitz | Mentor: Frank Logiudice

Methods

Lesser Spot-Nosed Guenon

Figure 1. Tumani grooming herself

C. petaurista live in polygynous social-mating groups called troops, consisting of 10 to 40 individuals (Central Florida Zoo). There is typically one dominant male; however, group compositions can fluctuate and it is hypothesized male numbers can increase due to the selective advantage gained from predator mobbing (Zuberbühler & Jenny, 2002; Nowak & Walker, 1999). Members of the genus Cercopithecus are territorial but predominantly avoid conflict (Nowak & Walker, 1999). Sexual dimorphism within the genus is notable, particularly in body and canine size (Fleagle, 1999). Average weights for females and males are 2.9 kg and 4.4 kg respectively (Fleagle, 1999). Distribution of the species averages 29.3 individuals per km2 (Zuberbühler & Jenny 2002). In the wild, C. petaurista occupies a vertical intermediate niche within the canopy of its habitat (McGraw, 2000). This species demonstrates relatively specialized niche partitioning amongst primate species such as C. campbelli and C. diana, both of which share the canopy, and such niching behavior lowers interspecific competition among species (Wachter et al., 1997). Individuals average between 0.91 and 1.22 meters in length and live approximately 20 years in captivity (Central Florida Zoo). The species uses cheek pouches to store small amounts of food while foraging, and this storage method has been shown to decrease the amount of interspecific competition between neighboring and overlapping niched species (Buzzard, 2006).

Enclosure and Individuals

My study took place at the Central Florida Zoo and Botanical Gardens in Sanford, Florida. The guenon enclosure (9.144 x 7.62 x 3.353 meters) has three individuals: two females and one male. Mama, subject A, the oldest, was born in 1999: 18 years old at the time of the study. Timbi, subject B, the only male, was born in 2003: 14 years old at the time of the study. Tumani, subject C, the newly introduced female was born in 2001: 16 years old at the time of the study. It should be noted that Tumani and Timbi are predominantly a mating pair and are half siblings on the father's side. The enclosure has two heating sources for colder days, as well as two exits for feeding.

Reintroduction Event

On March 26th, 2017, Mama was removed from the enclosure as a consequence of a fight with Tumani. Following the removal of Mama from the enclosure and her subsequent reintroduction into the captive troop, high levels of aggression were directed at her. The reintroduction event marked a change in behavior particularly from the females, Mama and Tumani.

Approach

The monkeys were observed at random times during the zoo's operating hours between 9:00am and 5:00pm. The observation took place over a period of 34 days for a total duration of 3376 minutes (mean: 99.3 min per day). Changes in each individual's location and behavior were recorded each minute using a grid and behaviors stereotyped in part from a previous study of the species (McGraw, 2000). Behavioral ratios include the proportion of time spent by a given individual engaged in one of the following behaviors, as reported in Figure 2. Specifically, I compiled and analyzed the behavioral ratios using averages of the time occupied by a given behavior, and divided by the average observation time. I then performed an analysis of covariance (ANCOVA) on the continuous behavioral independent variable, allogrooming, as a function of the dependent variables, grooming solicitation, monkey identification, and pre/ post reintroduction. I also used an ANCOVA test on the behavioral independent variable—grooming solicitation—as a function of the dependent variables— pre/post reintroduction, monkey identification, and time observed. In addition, I used a non-parametric Wilcoxon test to compare aggression ratios among individuals before and after the reintroduction event. Lastly, to elucidate behavioral consistency between individuals, I measured the variance of individual behaviors as a proportion of mean stereotyped behavior to calculate the coefficient of variation within each behavior profile.

Results >>