Lemur kinematic and substrate morphology data

An accident during arboreal locomotion can lead to risky falls, but little is known how primates, as adept arborealists, might change their locomotion to accommodate increased substrate height. By using more stable forms of locomotion on higher substrates, primates might avoid potentially fatal consequences. Using high-speed cameras, we recorded the quadrupedal locomotion of four wild lemur species – Eulemur rubriventer, Eulemur rufifrons, Lemur catta, and Hapalemur aureus. We quantified the diameter, orientation, and height of locomotor supports using remote sensors and tested the influence of these parameters on gait kinematics (N=112). Lemurs did not adjust stride speed, length, or frequency on substrates of varying height. However, E. rubriventer increased the mean number of supporting limbs on higher substrates, and lemurs overall decreased the use of unstable limb support patterns and increase the use of stable ones on higher substrates. Results suggest walking is a relatively safe form of locomotion for lemurs, resulting in only subtle changes in gait to increase stability on higher – i.e., riskier – substrates. Continued investigation of the impact of height on locomotion will be important to determine how animals assess risk in their environment and how they choose to use this information to move more safely.