Huddling is more important than rest site selection for thermoregulation in southern bamboo lemurs. (May 2017)

• Record Type: Journal Article
• Authors: Eppley, Timothy M.; Watzek, Julia; Dausmann, Kathrin H.; Ganzhorn, Jörg U.; Donati, Giuseppe
• Is Part Of: Animal behaviour. Volume 127(2017)
• Page Start: 153
• Page End: 161
• Publication Date: 2017-05
• Subjects: energy conservation -- Hapalemur meridionalis -- huddling -- Madagascar -- skin temperature -- southern bamboo lemur -- strepsirrhines -- thermal ecology; Animal behavior -- Periodicals; 591.5
• DOI: 10.1016/j.anbehav.2017.03.019
• Languages: English
• ISSNs: 0003-3472

Abstract

Abstract : Resting site selection can have important effects on the behaviour and fitness of organisms. The maintenance of optimal body temperatures ( T b ) when faced with environmental variables has often been attributed to either specific microhabitat rest site characteristics or to behavioural strategies. Among many small group-living endotherms, social thermoregulation (i.e. huddling) is utilized as an energy conservation mechanism at low ambient temperatures ( T a ), thus decreasing the metabolic cost of maintaining T b . Although unusual among primates, lemurs maintain a low metabolic rate and exhibit a diversity of thermoregulatory strategies; however, objective T b measurements have thus far been limited to small-bodied lemurs (e.g. Cheirogaleids). As such, we sought to determine whether a medium-sized lemur model, the southern bamboo lemur, Hapalemur meridionalis, would maintain thermoregulation through microhabitat rest site selection, huddling behaviour, or potentially both strategies. Within a degraded littoral forest fragment in southeast Madagascar, we conducted full-day focal observations on three groups of H . meridionalis between January and December 2013. Adult individuals were collared with data-loggers that collected instantaneous skin temperature T sk (°C). We calculated the mean T sk of the focal individual during each resting bout, and the proportional rate of huddling between the focal individual and conspecifics. In addition, we recorded all resting sites utilized for at least 15 min and collected standard tree characteristics. We fitted linear mixed-effects models to determine the thermoregulatory combined effect of specific resting site characteristics, huddling behaviour and environmental variables on T sk . Our results showed that lemurs selected tree sites with larger diameter at breast height; however, huddling was most predictive of increasing T sk whereas resting site characteristics were not included in the best-fit model. It is possible that microhabitat rest site selection is not significant in a degraded forest as the potential environmental buffering is limited; thus, thermoregulatory mechanisms are probably best served by behavioural strategies, i.e. social huddling. Highlights: First systematic study of lemurid thermoregulation using skin temperature data. Huddling with conspecifics on cold days increases lemurid body temperature. Microhabitat selection is not as influential as huddling for thermoregulation.