Inactivity/sleep in two wild free-roaming African elephant matriarchs – Does large body size make elephants the shortest mammalian sleepers?

• DOI: 10.1371/journal.pone.0171903
• Publication Date: 2017-03-01T18:31:00Z
• Authors: Nadine Gravett; Adhil Bhagwandin; Robert Sutcliffe; Kelly Landen; Michael J. Chase; Oleg I. Lyamin; Jerome M. Siegel; Paul R. Manger
• Keywords: Sleep; Poaching

The current study provides details of sleep (or inactivity) in two wild, free-roaming African elephant matriarchs studied their natural habitat with remote monitoring using an actiwatch subcutaneously implanted the trunk, a standard collar equipped GPS system and gyroscope, portable weather station. We found that these elephants were polyphasic sleepers, had average daily total time 2 h, mostly between 02:00 06:00, displayed shortest any mammal recorded to date. Moreover, exhibited both standing recumbent sleep, but only every third or fourth day, potentially limiting ability enter REM on basis. In addition, we observed five occasions went without for up 46 h traversed around 30 km 10 possibly due disturbances such as potential predation poaching events, bull musth. They no form rebound following night sleep. Environmental conditions, especially ambient air temperature relative humidity, analysed wet-bulb globe temperature, reliably predict onset offset times. selected novel sites each amount activity periods did not affect A number similarities differences studies captivity are noted, specific factors shaping architecture elephants, various temporal scales, discussed.