title: Characterizing sleep behavior of the wild black rhinoceros (Diceros bicornis bicornis).
abstract: OBJECTIVE
  The objectives of this study were to characterize sleep patterns and determine factors, including sex, age, season, and environmental pressures, that influence sleep in the endangered black rhinoceros (rhino; Diceros bicornis bicornis).
  
  
  METHODS
  To noninvasively observe sleep behavior of wild rhinos, digital infrared cameras were erected on poles at two bedding sites from September 2009 to March 2010.
  
  
  METHODS
  The study site was located in South Africa's Addo Elephant National Park (AENP) in the Main Camp (Addo) and Nyathi sections.
  
  
  METHODS
  A total of 2,417 photos captured rhino sleep behavior on eight individual rhinos during 40 separate sleeping bouts (Addo, n = 15; Nyathi, n = 25).
  N/A.
  
  
  RESULTS
  Results demonstrated that age and season did not affect rhino sleep behavior (P > 0.05); however, sex did influence the length of sleep bouts with males (n = 27; mean, 105.6 ± 11.3 min; range, 14.0-202.0 min) sleeping longer (F(1,48) = 6.93, P = 0.01) than females (n = 13; mean, 58.6 ± 10.4 min; range, 11.0-132.0 min). Park section did not influence the length of sleep episodes, but did affect (rw(40) = 0.88; P < 0.025) the time at which rhinos slept (Addo, 20:00-24:00; Nyathi, 20:00-04:00).
  
  
  CONCLUSIONS
  This is the first study to characterize sleep behavior in wild black rhinos. This study resulted in a greater understanding of the biologic factors that affect sleep in wild rhinos and can provide information to assist their management and conservation.
authors.affiliation: Department of Conservation and Science, Lincoln Park Zoo, Chicago, IL, USA. rsantymire@lpzoo.org
authors.forename: Rachel
authors.initials: R
authors.lastname: Santymire
authors.forename: Jordana
authors.initials: J
authors.lastname: Meyer
authors.forename: Elizabeth W
authors.initials: EW
authors.lastname: Freeman
mesh_terms: D000367:Age Factors; D000704:Analysis of Variance; D000818:Animals; D001522:Behavior, Animal; D005260:Female; D008297:Male; D010527:Perissodactyla; D012621:Seasons; D012737:Sex Factors; D012890:Sleep; D013019:South Africa; D013997:Time Factors
keywords: Black rhinoceros; in situ population; predation risks; sex; sleep characterization