Behavioural Processes最新文献

Avoiding snake predation is essential for the survival of various animal species in the wild. Primates are occasionally predated by snakes, and their anti-predator strategies towards snakes can be better understood by field experiments that investigate behavioural responses to snakes. This study examined such behavioural responses of free-ranging Japanese macaques (Macaca fuscata) on Shodoshima Island. Three snake models (colored black, green, and yellow mottled) were presented to the subjects. Fleeing, alarm calls, looking, and latency of first response were recorded as behavioural responses. We analysed the effects of age and sex of the subject, as well as the effect of snake model on the frequency of each behaviour. Behavioural data were collected from 50 trials. Although the frequency of fleeing was higher in adult females than in adult males, such sex differences were not marked in juveniles. These results might be caused by sex role differences in primates, wherein males often display anti-predator behaviours for the protection of females and/or their offspring, whereas females prioritise protecting themselves and their offspring. Juveniles looked longer at the snake model than adults did, suggesting that juveniles acquire predator knowledge via observation. Age and sex differences were not observed in the frequency of alarm calls and latency of first response. None of the four behaviour measures was influenced by the snake model. This study highlights the age and sex differences in behavioural responses to snakes in non-human primates, contributing to a better understanding of anti-snake strategies in mammals and complex primate-snake relationships.

Sensory thresholds- the limits at which an organism can detect the presence of a given stimulus- can provide insight into the evolution of sensory abilities and the relative salience of different stimuli to a species. Understanding dog olfactory thresholds can further benefit the training of detection dogs by identifying odors that are salient and detectable. Current methods to measure olfactory thresholds vary widely and often lack controls or external validation. We aimed to (a) compare three commonly used procedures to measure olfactory thresholds in dogs, (b) evaluate how cognitive fatigue and/or sensory adaptation could be potential confounds, and (c) validate threshold methods by comparing them to a reference odor and empirical measurements of our odor delivery system. We first compared three differing threshold measurement methods using 1-bromooctane, a common training odorant for detection dogs: (1) random presentation of different concentrations; (2) a blocked descending procedure where an initial odor concentration is presented in a block of 10 trials with decreasing half-log concentrations presented in subsequent blocks until dogs reach chance performance; and (3) the descending staircase procedure. We found that a blocked procedure provided the lowest threshold values, with a mean dog threshold for 1-bromooctane equivalent to a ∼10^-5 dilution in mineral oil. Control tests indicated our findings were not driven by fatigue or sensory adaptation. We also found that the blocked procedure generated olfactory thresholds for amyl acetate- a volatile with multiple published olfactory thresholds for dogs- at 129 ppt, at the lower range of prior work, validating the descending block approach. Instrumental analysis found that our olfactometer delivered odor in decreasing concentrations as predicted. We identified a valid method for assessing dog olfactory thresholds that can guide future research on this topic.