SUMMARYFrogs are characterized by a unique morphology associated with their saltatory lifestyle. Yet, arboreal species show morphological specializations relative to other ecological specialists allowing them to hold on to narrow substrates. However, almost nothing is known about the effects of substrate characteristics on locomotion in frogs. Here, we quantified the 3D kinematics of forelimb movement for frogs moving across branches of different diameters (1 and 40mm) and two different inclines (horizontal and 45deg uphill). Our results show that grip types differ while moving across substrates of different diameters and inclines. The kinematics of the wrist, elbow and shoulder as well as the body position relative to the substrate also showed significant effects of individual, diameter and incline. Kinematic differences involved duration, velocity of movement and angular excursions. Differences were most pronounced for the proximal joints of the forelimb and effects for substrate diameter were greater than for incline. Interestingly, the effects of diameter and incline on both grip type and kinematics are similar to what has been observed for lizards and primates, suggesting that the mechanics of narrow substrate locomotion drive the kinematics of movement independent of morphology and phylogeny.

The senses involved in food detection in primates in general, and lemurs in particular, remain poorly investigated. However, as lemurs include diurnal, nocturnal, and cathemeral species they represent a good model to test whether prey detection is dependent on activity pattern. As both diurnal and nocturnal species have been investigated previously we here aim to quantify the relative importance of different sensory modalities during prey detection in a cathemeral species, the red-bellied lemur (Eulemeur rubriventer). A series of experiments was performed using a group of four Eulemur rubriventer (Zoo de La Londe les Maures, France) to test the role of visual, olfactory and acoustic cues in prey detection. Both unimodal and multimodal cues were tested. The responses obtained in the different experiments show that visual cues are essential for prey detection in this species, at least in captivity. However, the use of multiple sensory modalities improves the success of detection suggesting that cathemeral species may benefit from the use of multiple sensory modalities.