@article{ref1,
title="Variation in aggression rates and urinary cortisol levels indicates intergroup competition in wild bonobos",
journal="Hormones and behavior",
year="2020",
author="Cheng, Leveda and Lucchesi, Stefano and Mundry, Roger and Samuni, Liran and Deschner, Tobias and Surbeck, Martin",
volume="ePub",
number="ePub",
pages="ePub-ePub",
abstract="Intergroup competition is a widespread phenomenon across taxa and groups typically compete over access to limited resources, such as food and mates. Such intergroup  competition may be quantified by changes in individuals' behavioral and  physiological status in response to intergroup encounters (IGEs). Bonobos, one of  our closest living relatives, are often regarded as xenophilic and exhibit high  tolerance towards out-group individuals. This tolerance between groups may still be  accompanied by intergroup competition over resources. We hereby compared variation  in aggression rates and urinary cortisol levels of bonobos during and outside  contexts of IGEs in the Kokolopori Bonobo Reserve and investigated whether food and  mate availability influenced males' and females' aggression and cortisol levels,  when controlling for dominance rank and the number of individuals present. We found  that although females had higher aggression rates and urinary cortisol levels during  than outside contexts of IGEs, these increases were not related to food availability  or changes in between-group dynamics when maximally tumescent females were present,  rather than absent. Furthermore, males showed higher aggression rates and urinary  cortisol levels during than outside contexts of IGEs. However, males' responses  during IGEs were not related to the presence of maximally tumescent females and food  availability. Taken together, while competition intensified during seemingly  tolerant IGEs in bonobos, such competition was unrelated to short-term changes in  food and mate availability. Despite physical and physiological costs of aggression,  bonobos associate with out-group individuals frequently and for extended periods. This suggests potential benefits of bonobo intergroup associations.<p /> <p>Language: en</p>",
language="en",
issn="0018-506X",
doi="10.1016/j.yhbeh.2020.104914",
url="http://dx.doi.org/10.1016/j.yhbeh.2020.104914"
}