Development of snake‐directed antipredator behavior by wild white‐faced capuchin monkeys: III. the signaling properties of alarm‐call tonality

Abstract

In many primates, the acoustic properties of alarm calls can provide information on the level of perceived predatory threat as well as influence the antipredator behavior of nearby conspecifics. The present study examined the harmonics-to-noise ratio (tonality of spectral structure) of alarm calls emitted by white-faced capuchin monkeys (Cebus capucinus) in trees directed at photographic models of a boa constrictor, neotropical rattlesnake, scorpion eater snake, and white snake-shaped control presented on the ground. The average and peak harmonics-to-noise ratios of initial alarm calls by infants, juveniles, and adults and those of nearby second callers were analyzed using PRAAT software. Averaged for age class, the peak harmonics-to-noise ratio of alarm calls directed at the boa constrictor model, characterizing a primary capuchin predator, was reliably higher than the peak harmonics-to-noise ratio of alarm calls directed at the harmless scorpion eater model. This effect was influenced by the higher harmonics-to-noise ratio of infant alarm calls and it disconfirmed our prediction, based on primate vocalization research, that snake perception would increase arousal and alarm-call noisiness. Levels of call tonality did not distinguish the boa and rattlesnake or rattlesnake and scorpion eater models for any age class. Higher alarmcall tonality appeared contagious to nearby perceivers, with focal alarm calling influencing the level of tonality of the first calls of second callers. Together, these findings suggest that the higher peak harmonics-to-noise ratio of capuchin alarm calling directed at snakes is contagious and possibly conveys information about the level of perceived predatory threat.

Evolution of human language: duetting as part of prosociality and cognition

“…As recent research has shown, however, some primate and avian vocal abilities are far more complex and varied than once thought (Kaplan, 2014), starting, in primates, with the discovery of referential signals in vervet monkeys, Chlorocebus pygerythrus (Seyfarth et al, 1980;Seyfarth and Cheney, 1986), continuing with the discovery of referential food grunts in chimpanzees, Pan troglodytes (Watson et al, 2015), food calls in common marmosets, Callithrix jacchus (Rogers et al, 2018), and the vocal modifications found in pygmy marmosets, Cebuella pygmaea (Snowdon, 2018). Great apes and even new world monkeys (such as black-fronted titi monkeys, Callicebus nigrifrons: Caesar and Zuberbuehler, 2012; and white-faced capuchin monkey, Cebus imitator: Coss et al, 2019) have been shown to use referential gesturing and vocalizations. Indeed, the detailed linguistically based studies of the 1980s and 1990s confirmed that apes were able to learn American Sign Language (Gardner et al, 1989;Miles, 1994).…”

Knowledge and interactions of the local community with the herpetofauna in the forest reserve of Quininí (Tibacuy-Cundinamarca, Colombia)

“…The local community recognizes the existence of venomous snakes in the region, although it tends to ignore the existence of non-venomous species. This may be due to the association of the body morphology of these animals with risk factors, generally associating serpentiform animals as dangerous; given the evolutionary conditioning of human species [48], which has also been recorded in other primates [49].…”

Knowledge and interactions of the local community with the herpetofauna in the forest reserve of Quininí (Tibacuy, Cundinamarca)

“…The local community recognizes the existence of venomous snakes in the region, although it tends to ignore the existence of non-venomous species. This may be due to the association of the body morphology of these animals with risk factors, filing in a general way the serpentiform animals as dangerous; given the evolutionary conditioning of human species [49], which has also been recorded in other primates [50].…”