Behavioral Ecology and Sociobiology

, Volume 68, Issue 6, pp 957–970

Dominance rank differences in the energy intake and expenditure of female Bwindi mountain gorillas

  • Edward Wright
  • Andrew M. Robbins
  • Martha M. Robbins
Original Paper

DOI: 10.1007/s00265-014-1708-9

Cite this article as:
Wright, E., Robbins, A.M. & Robbins, M.M. Behav Ecol Sociobiol (2014) 68: 957. doi:10.1007/s00265-014-1708-9

Abstract

Socioecological models predict that contest competition for clumped foods can lead to higher energy intake and lower energy expenditure for higher-ranking individuals. Here, we examine the relationships between dominance rank and energy intake and expenditure of female mountain gorillas in Bwindi Impenetrable National Park, Uganda (Gorilla beringei beringei). Bwindi gorillas have weak dominance relationships, feed on nonreproductive plant parts throughout the year, and consume fruit when it is seasonally available. We used behavioral observations on one group of gorillas and nutritional analysis of their major food items to calculate energy intake rates and estimated energy expenditure. Using linear mixed models, we found a significant positive relationship between dominance rank and energy intake rates, due to higher-ranking females having faster ingestion rates, rather than consuming foods with higher energy concentrations. Lower-ranking females did not spend significantly more time feeding to compensate for their lower energy intake rates. Lower-ranking females spent significantly more time traveling than higher-ranking females, leading to a negative relationship between dominance rank and energy expenditure. The combined results revealed a significant positive relationship between dominance rank and energy balance. Higher-ranking females did not spend longer feeding on fruit than lower-ranking ones, and the relationship between dominance rank and energy intake rates was not stronger when fruit was available. According to socioecological models, these results suggest that contest competition may be occurring with both fruit and nonreproductive plant parts, which would be consistent with growing evidence that nonreproductive plant parts can be contestable.

Keywords

Dominance rank Energy balance Energy intake Energy expenditure Mountain gorillas 

Copyright information

© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  • Edward Wright
    • 1
  • Andrew M. Robbins
    • 1
  • Martha M. Robbins
    • 1
  1. 1.Max Planck Institute for Evolutionary AnthropologyLeipzigGermany

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