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- Title
Arrived in the light: diel and seasonal activity patterns in wild Verreaux’s sifakas (Propithecus v. verreauxi; Primates: Indriidae).
- Authors
Erkert, Hans; Kappeler, Peter M.
- Abstract
Madagascar is characterised by pronounced annual climatic and ecological seasonality and harbours a radiation of closely related sympatric primates (Lemuriformes) that exhibit diurnal, nocturnal and cathemeral activity patterns. We collected continuous activity data over a complete annual cycle from wild diurnal Verreaux’s sifakas (Propithecus v. verreauxi) to contribute detailed and comparative data: (1) to characterise their diel and seasonal activity rhythms, (2) to identify factors shaping variation in activity rhythms, and (3) to help reconstruct the evolutionary transition from nocturnal to diurnal activity. We fitted eight adult sifakas from seven different groups living in Kirindy forest with an accelerometer/data logger device and recorded their activity in 5-min bins for a total of 12 months. We characteriseP. verreauxias a strictly diurnal species with a pronounced bimodal activity pattern that briefly changed to a more unimodal pattern during their annual mating season (January to March). We documented significant annual variation in total daily activity, activity time, and activity level, as well as in most parameters characterising their bimodal activity pattern. Despite a significant positive correlation of the animals’ activity time with day length, pronounced annual variation in the phase position of onset and end of activity in relation to sunrise and sunset times could also be discerned. Minor enhancing effects of moonlight on nocturnal activity were only found for the first 3 h of the inactivity period. Bimodality of the activity pattern and the additional reduction of activity time during the cold and dry winter months associated with reduced food availability can be interpreted as flexible behavioural adaptations to reduce energy expenditure. We therefore propose that energetic and thermoregulatory benefits are important factors shaping these primates’ activity pattern.
- Subjects
MADAGASCAR; VERREAUX'S sifaka; CIRCADIAN rhythms; ECOLOGY; CLIMATOLOGY; BODY temperature regulation; BEHAVIOR
- Publication
Behavioral Ecology & Sociobiology, 2004, Vol 57, Issue 2, p174
- ISSN
0340-5443
- Publication type
Article
- DOI
10.1007/s00265-004-0845-y