Locomotor ecology ofLepilemur edwardsi andAvahi occidentalis

Abstract

A well-known principle holds that where food supply is limited, two sympatric species with the same diet, morphology, and behavior will compete, leading to exclusion of one species or differentiation of their ecological niches. Avahi occidentalis and Lepilemur edwardsi are two saltatory, nocturnal folivorous lemurs of similar body size which live sympatrically over much of their range and may often be seen feeding in the same trees. We report a study of their locomotor behavior, carried out in order to determine to what extent locomotion might contribute to niche separation. Avahi lives at a higher level in the forest and is the more committed leaper, with a much larger home range and nightly travel distance, while Lepilemur climbs more and has a very small nightly travel distance. Avahi uses small, low-angled supports more often, while Lepilemur makes more use of large, high-angled supports (however, neither species uses vertical supports at a frequency greater than the availability of such supports in the forest stratum in which they live). Both species tend to land on larger-diameter supports on longer leaps, but Avahi also takes off from larger-diameter supports in longer leaps, reducing loss of energy to the substrate during takeoff. We suggest that the differences in locomotion and ranging behavior between them are consistent with niche differentiation on the basis of food quality, Avahi investing more energy in harvesting better quality but more patchy food, Lepilemur minimizing expenditure in harvesting a less selective, quantitatively poorer diet.

Effects of support diameter and compliance on common marmoset (Callithrix jacchus) gait kinematics

“…Specifically, compliant substrates absorb some of the mechanical work that would be otherwise employed to redirect and accelerate the CoM during steady locomotion, and compromise stability by undermining the animal's ability to estimate body orientation (MacLellan and Patla, 2006). Previous research has shown that increasing branch compliance significantly compromises the locomotor performance of leaping primates (Crompton et al, 1993;Demes et al, 1995;Warren and Crompton, 1997;Walker, 2005;Channon et al, 2011) and lizards (Gilman et al, 2012;Gilman and Irschick, 2013), and necessitates numerous postural and locomotor adjustments in orangutans (Thorpe et al, 2009;Myatt and Thorpe, 2011). However, relative to the breadth of research on the effects of substrate diameter, studies of how perch compliance affects quadrupedal gait mechanics are sparse (but see Stevens et al, 2001;GosselinIldari, 2010).…”

Feeding Patterns and Dietary Profile of Nocturnal Southern Woolly Lemurs (Avahi meridionalis) in Southeast Madagascar

“…Avahis are particularly intriguing in this context because their body mass is at the lower limits for primate folivores (750-1400 g: Kay 1984;Lehman 2007), they are nocturnal (Norscia and Borgognini-Tarli 2008) and thus active at a time when low ambient temperature possibly increases metabolic requirements to remain normothermal (Willmer et al 2000), and their locomotion is energetically expensive (vertical leaping; Warren and Crompton 1997). Like all indriids, Avahi spp.…”

Habitat Utilization of Blue-Eyed Black Lemurs,Eulemur Macaco Flavifrons(Gray, 1867), in Primary and Altered Forest Fragments

“…Energy saving might also explain the relatively small home ranges of sportive lemurs-about 1 ha for L. edwardsi (see Albignac 1981;Warren and Crompton 1997) and L. ruficaudatus (Zinner et al 2003), and 0.18 ha for female and 0.33 ha for male L. leucopus (see Dröscher and Kappeler 2013). The much smaller grey mouse lemur (Microcebus murinus), with its broad diet, has similar home ranges of 0.7-1.6 ha for females and 2.8-4.8 ha for males in dry deciduous forest (Eberle and Kappeler 2004;Lahann 2008;Radespiel 2000).…”