Nocturnal activity in wild chimpanzees (Pan troglodytes): Evidence for flexible sleeping patterns and insights into human evolution

Nikki Tagg, Maureen McCarthy, Paula Dieguez, Gaëlle Bocksberger, Jacob Willie, Roger Mundry, Fiona Stewart, Mimi Arandjelovic, Jane Widness, Anja Landsmann, Anthony Agbor, Samuel Angedakin, Ayuk Emmanuel Ayimisin, Mattia Bessone, Gregory Brazzola, Katherine Corogenes, Tobias Deschner, Emmanuel Dilambaka, Manasseh Eno-Nku, Henk EshuisAnnemarie Goedmakers, Anne Céline Granjon, Josephine Head, Veerle Hermans, Sorrel Jones, Parag Kadam, Mohamed Kambi, Kevin Langergraber, Vincent Lapeyre, Juan Lapuente, Kevin Lee, Vera Leinert, Giovanna Maretti, Sergio Marrocoli, Amelia Meier, Sonia Nicholl, Emmanuelle Normand, Lucy Jayne Ormsby, Alex Piel, Orume Robinson, Volker Sommer, Martijn ter Heegde, Alexander Tickle, Els Ton, Joost van Schijndel, Hilde Vanleeuwe, Virginie Vergnes, Erin Wessling, Roman M. Wittig, Klaus Zuberbuehler, Hjalmar Kuehl, Christophe Boesch

Research output: Contribution to journalArticlepeer-review

28 Scopus citations


Objectives: We investigated occurrences and patterns of terrestrial nocturnal activity in wild chimpanzees (Pan troglodytes) and modelled the influence of various ecological predictors on nocturnal activity. Methods: Data were extracted from terrestrial camera-trap footage and ecological surveys from 22 chimpanzee study sites participating in the Pan African Programme: The Cultured Chimpanzee. We described videos demonstrating nocturnal activity, and we tested the effects of the percentage of forest, abundance of predators (lions, leopards and hyenas), abundance of large mammals (buffalos and elephants), average daily temperature, rainfall, human activity, and percent illumination on the probability of nocturnal activity. Results: We found terrestrial nocturnal activity to occur at 18 of the 22 study sites, at an overall average proportion of 1.80% of total chimpanzee activity, and to occur during all hours of the night, but more frequently during twilight hours. We found a higher probability of nocturnal activity with lower levels of human activity, higher average daily temperature, and at sites with a larger percentage of forest. We found no effect of the abundance of predators and large mammals, rainfall, or moon illumination. Discussion: Chimpanzee terrestrial nocturnal activity appears widespread yet infrequent, which suggests a consolidated sleeping pattern. Nocturnal activity may be driven by the stress of high daily temperatures and may be enabled at low levels of human activity. Human activity may exert a relatively greater influence on chimpanzee nocturnal behavior than predator presence. We suggest that chimpanzee nocturnal activity is flexible, enabling them to respond to changing environmental factors.

Original languageEnglish (US)
Pages (from-to)510-529
Number of pages20
JournalAmerican journal of physical anthropology
Issue number3
StatePublished - Jul 2018


  • PanAf
  • camera trap
  • chimpanzee
  • fragmentation
  • nocturnal awakening
  • sleeping patterns

ASJC Scopus subject areas

  • Anatomy
  • Anthropology


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