The Free-Range Rock Cavy (Kerodon rupestris) Communicates the Urgency of a Threat Using Different Alarm Calls

Abstract

This study examines whether rock cavies (Kerodon rupestris), which are social rodents, modulate their alarm calls in response to various threat contexts. Conducted across four sample areas within two study sites in the Brazilian Caatinga region, alarm calls were collected using the ad libitum method. The acoustic responses of free-ranging rock cavies were then analyzed using discriminant function analysis and generalized mixed linear models to classify vocal types and assess differences in vocalization rates and acoustic parameters. The findings reveal that rock cavies produce both slow and fast alarm whistles in response to threats. Fast alarm whistles, emitted exclusively in response to nearby ocelots (Leopardus pardalis), exhibited a lower pitch (F_1,16.20 = 11.41, p = 0.004), shorter duration (F_1,22.59 = 14.93, p = 0.001), and shorter pulse intervals (F_1,21.29 = 6.08, p = 0.022) compared to the slow alarm whistles. Slow alarm whistles were produced when rock cavies were threatened by distant ocelots, as well as by both distant and closer humans, dogs (Canis familiaris), marmosets (Callithrix spp.), tayras (Eira barbara), and birds of prey (Caracara plancus). The type of threat influenced the pulse intervals (F_6,23.26 = 12.69, p < 0.001) and the high frequency (F_6,18.15 = 12.08, p < 0.001) of slow alarm whistles. Rock cavies produced shorter pulse intervals when threatened by ocelots, birds of prey, or tayras compared to humans and dogs (p < 0.05) and higher-pitched slow alarm whistles when threatened by dogs, ocelots, humans, or birds of prey compared to capuchin monkeys and tayras (p < 0.05). Additionally, shorter pulse intervals (F_1,25.73 = 28.87, p < 0.001) were emitted when threats were nearby compared to more distant threats. This study highlights the influence of various threats and their proximity on the modulation of rock cavy alarm calls, showcasing their behavioral adaptability. This crucial survival strategy not only enhances our understanding of rock cavies' behavior but also has the potential to inspire research in other species and ecological contexts.