Calls for concern: Matching alarm response levels to threat intensities in three Neotropical primates

Various species of animals maximise energy gained through foraging by minimising excessive energy spent on nonessential activities. Avoiding predation is key for maximising an individual's lifespan, as well as that of its kin; however, anti-predation behaviours can be energetically costly. We investigated the relationship between the potential threat levels by predators, pseudo-predators, and non-predators, and the subsequent energetic cost of behavioural reactions to these threats, in the white-bellied spider monkey (Ateles belzebuth), golden-backed uacari (Cacajao ouakary), and red-nosed cuxiú (Chiropotes albinasus). We analyzed a total of 270 interactions across three independent field studies of the three primate species. Our results revealed significant differences in the behavioural response to predators and non-predators for both C. ouakary and C. albinasus, but not for A. belzebuth. In terms of risk-categorized behaviours, response to predators differed from response to non-predators (being much more intense and energy intensive), while there was no difference in response to predators versus pseudo-predators. Thus, response to potential predators represents an integral part of the time-management and defence strategies of two of the three studied species, and should be integrated into future studies of primate responses to varying levels of predation threat.