. Patterns of participation and free riding in territorial conflicts among ringtailed lemurs

Looking into individual variation in territorial defense among female ringtailed lemurs, subjects at Duke University Primate Center in two groups were studied. To identify the location of individuals relative to aggressive territorial conflict, there were three zones identified progressively closer to the territorial boundary.


 Different acts were recorded, such as aggressive (bite, cuff, chase, lunge, and grab), submissive (spat, flee, jump away, and cower) and affiliative (touch, body/face greet, lick, play). There were also self directed behaviors. Group size may influence patterns of individual participation, with free riding thought to be more common in larger groups.



Also, there were potentials for increased risk of injury, increased risk of overheating, and behavioral indicators of stress. Individuals may also provide incentives, such as grooming, to encourage other animals to participate in territorial defense. However, individuals that participated in aggressive intergroup interactions were not more likely to receive affiliative acts from group mates during encounters.



Additional unexplained variation may be accounted for by patterns of policing, in which free riders are punished for failing to participate in territorial defense. During inter-group encounters, however, within-group aggression among females was uncommon, with only four aggressive acts observed among individuals of the same group. The rate of aggression appeared to increase slightly in the thirty minutes after encounters ended, but it was not significantly different from the rate of aggression in the thirty minutes before encounters started. On an individual basis, There was no statistical association between rates of aggressive acts to the other group during encounters and rates of aggressive acts toward group mates found or received from group mates following encounters.

  
    Nunn, C. and Deaner, R. Patterns of participation and free riding in territorial conflicts among ringtailed lemurs (Lemur catta). Behavioral Ecology and Social Biology. Vol 57, No. 1, 50-61.