Seasonal Effects on Sleeping Site Ecology in a Nocturnal Pair-Living Lemur (Avahi occidentalis)

Abstract

Seasonal changes may have a strong effect on the safety of sleeping sites in arboreal primates. For example, changes in vegetation thickness may impact predation risk and energy expenditure related to thermoregulation. We investigated how seasonality influenced sleeping site characteristics and usage pattern in an arboreal primate living in a highly seasonal environment. The western woolly lemur (Avahi occidentalis) lives in the dry deciduous forest of northwestern Madagascar, where leaf coverage greatly varies across the year. We examined the hypothesis that these lemurs change their sleeping site behavior dependent on season. We collected data on sleeping site height and location, and characterized usage patterns in six radiotagged pairs between May and December 2008. During the late dry season, pairs preferentially slept in the middle part of a tree. In contrast, there was no height preference during the early rainy season. The lemurs used more sleeping sites during the early rainy than during the late dry season and stayed more days at the same sleeping tree in the late dry season. Our findings support the hypothesis that season affects sleeping site selection in an arboreal primate species living in a highly seasonal environment. During the late dry season, western woolly lemurs are particularly conspicuous to hunters and we therefore suggest a better monitoring of the forest in this season to guarantee their future survival.

Sleeping site ecology, but not sex, affect ecto- and hemoparasite risk, in sympatric, arboreal primates (Avahi occidentalis and Lepilemur edwardsi)

“…Apart from the morphological description, there is not much known about the Malagasy endemic genus Aetholaelaps , but it is possible that Aetholaelaps trilyssa behaves as a nidicolous temporary mite. In that case, this mite’s ecology would explain why it was found at high prevalence in L. edwardsi , a host that sleeps in regularly revisited tree holes, but not in A. occidentalis , a species that sleeps on open branches and rotates its sleeping site more frequently [ 35 , 36 ]. The fact that some host species adapt their sleeping behavior by changing their sleeping sites in order to avoid ectoparasite infestation supports this explanation [ 16 , 48 ].…”

“…Both species are nocturnal, exhibit a comparable body mass of approximately 1 kg with no sex dimorphism, share the same habitat and thereby same climate conditions and are pair-living and thus match in social pattern [ 33 , 34 ]. However, they differ prominently in their choice of sleeping sites as well as in their sleeping site related behavior: A. occidentalis sleeps on open branches or tree forks and changes its sleeping sites frequently, whereas L. edwardsi sleeps in tree holes with high sleeping site fidelity [ 35 , 36 ]. Thus, these two host species present unique models to assess the effect of host sleeping site ecology on parasite risk, while controlling for the factors climate condition, activity, host body size and sociality.…”

The role of acoustic signaling for spacing and group coordination in a nocturnal, pair‐living primate, the western woolly lemur (Avahi occidentalis)

“…Each animal was darted, weighed and morphometrically characterized and fitted with a radiotransmitter on a backpack (for more details on darting focal animals, Ramanankirahina et al, 2011;Ramanankirahina et al, 2012). The median body length was 20 cm for males and females, the mean body mass was 825 g for males and 999g for females with no significant difference between sexes (see Ramanankirahina et al, 2011).…”

“…Since both females were associated with the same male, data of both females were treated as one female pair partner for further analyses, as done in two previous papers (Ramanankirahina et al, 2011;Ramanankirahina et al, 2012). Focal animal sampling with continuous recording was conducted (Altmann, 1974;Martin and Bateson, 1993).…”

“…To collect first empirical data and embed them into the evolution of mechanisms governing primate group coordination in time and space, we studied the western woolly lemur (Avahi occidentalis), distributed in the dry deciduous forests of northwestern Madagascar. These weasel-sized lemurs that weigh approximately 1 kg (Ramanankirahina et al, 2011), form permanent pairs in which pair partners forage together during the night and sleep together at safe sleeping sites in trees with dense foliage during the day (Albignac, 1981;Warren and Crompton, 1997;Ramanankirahina et al, 2012). As do sportive lemurs, woolly lemurs belong to the so-called clingers and leapers (Warren, 1997;Warren and Crompton, 1997), and are able to move rapidly through dense forests.…”