Effect of group size and experience on the ontogeny of sentinel calling behaviour in meerkats.

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Date: Jan. 2021
From: Animal Behaviour(Vol. 171)
Publisher: Elsevier B.V.
Document Type: Report
Length: 470 words

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Abstract :

Keywords acoustic communication; individual vocal signature; ontogeny; sentinel behaviour Highlights * Meerkats started acting as sentinels as subadults around 200 days of age. * They produced all six sentinel call types when they first acted as sentinel. * Call rate of the different sentinel call types changed with experience. * The acoustics of the common double note calls differed between individuals. * Meerkats showed individual distinctiveness when they first acted as sentinel. Increased vulnerability to predation results in young individuals of many species experiencing higher predation pressure than adults. Consequently, the production of antipredator-related calls by young can differ from that of the same vocalizations given by adults. Sentinel behaviour is a coordinated vigilance behaviour, where one individual climbs on an elevated position and scans the surroundings for predators, while the rest of the group is mainly foraging. Meerkat, Suricata suricatta, sentinels produce six distinct sentinel call types, which inform other group members about the perceived predation risk, resulting in the adjustment of personal vigilance behaviour in foraging group members. Here, we investigated the onset of sentinel behaviour and the ontogeny of the different sentinel call types as well as the development of individual vocal signatures in meerkats. We found that meerkats started acting as a sentinel around 200 days of age, but this was highly dependent on group size, with individuals from smaller groups exhibiting sentinel behaviour earlier than individuals from larger groups. All six sentinel call types were already present in the repertoire upon first emergence of the behaviour; however, call rates of 'all-clear' calls increased while 'warning' calls decreased with increasing experience as sentinel. Analysis of one of the most frequent sentinel calls, the double note calls, indicated that fundamental frequency, mean amplitude, duration and entropy differed consistently between individuals, but we found no effect of age. Rather, our results provide evidence that individual signatures in this call type were already developed when young meerkats first started to act as sentinel and changed little with age. To conclude, we showed little ontogenetic change in overall sentinel behaviour as well as in its vocal coordination, indicating potentially high selection pressures on antipredator behaviours, such as the sentinel system, resulting in consistent behavioural responses upon first emergence. Author Affiliation: (a) Animal Behaviour, Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland (b) Kalahari Meerkat Project, Kuruman River Reserve, Van Zylsrus, Northern Cape, South Africa (c) Mammal Research Institute, University of Pretoria, Pretoria, South Africa (d) Center for the Interdisciplinary Study of Language Evolution (ISLE), University of Zurich, Zurich * Correspondence: R. Rauber, Animal Behaviour, Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland. Article History: Received 2 May 2020; Revised 29 June 2020; Accepted 12 October 2020 (miscellaneous) MS. number: 20-00315R Byline: Ramona Rauber [ramona.rauber@ieu.uzh.ch] (a,b,*), Marta B. Manser (a,b,c,d)

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Gale Document Number: GALE|A648929891