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Abstract Loud calls play an important function in regulating the use of space and structuring social groups and mating systems in a wide range of taxa. In pair‐living territorial animals, where encounters with neighbors and solitary conspecifics are common, these calls are mainly associated with resource defense or mate guarding behaviors. Owl monkeys (Aotus azarae) live in groups of one pair of reproducing adults and 1–4 younger, non‐reproducing individuals. Both sexes disperse when they are around 3 years of age; they become solitary floaters who compete to replace same‐sex adults from other groups. Here, we examined the behavioral responses of Azara's owl monkey pairs toward calls of unpaired and unfamiliar males and females to better understand if the competition between floaters and groups is in relationship to the defense of their territory, their mates, or both. We collected behavioral data from six groups, before, during, and after the playing back of unfamiliar male and female loud calls and of a control stimulus at the center and border of their home ranges. Overall, our results showed that the playback location did not elicit differential responses in the monkeys and that both sexes were more reactive to male than female unfamiliar calls, as evidenced by higher rates of sociosexual and vocal responses, movement toward the playback, and intergroup encounters during and after the experiments. Our study indicates that paired male and female owl monkeys mainly defend their partners toward intruders and emphasizes the need of including the role of sexual competition on both sexes in models about the evolution of pair‐living social organizations and sexual monogamy mating systems.
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Range utilization slopes as a measure of central tendency and intergroup overlap in primates
Animals that occupy stable home ranges tend to unevenly exploit different areas in their efforts to find fitness-limiting resources, while also reducing the risks of intergroup conflict. Most analyses of these extrinsic forces identify their effects on movement paths and home range geometry, but not on the interaction of these responses or how movements might be centrally constrained as a result of competition with neighbors. The range utilization slope is a measure of central tendency and consists of space use plotted against distance from the center of the range. Slopes tend to be linear, concave-up, or concave-down and are predicted to change as a function of feeding competition from neighbors. To test this prediction and determine the spatio-temporal scales over which the central tendency might vary, we calculated utilization slopes and an index of range overlap for grey-cheeked mangabeys (Lophocebus albigena), blue monkeys (Cercopithecus mitis), and red-tailed monkeys (C. ascanius) in Uganda, which consume similar diets but experience varying intensities of intergroup conflict. As predicted, we find variation in utilization slopes across and within species, which corresponds with the extent of range overlap among conspecific groups.
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- PAR ID:
- 10531365
- Publisher / Repository:
- Springer
- Date Published:
- Journal Name:
- Behavioral Ecology and Sociobiology
- Volume:
- 77
- Issue:
- 7
- ISSN:
- 0340-5443
- Subject(s) / Keyword(s):
- Movement Home range Utilization distribution Intergroup competition
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1007/s00265-023-03351-5
