ABSTRACT
Monitoring the concentration of glucocorticoid metabolites (GCMs) in faecal samples is a non-invasive tool for physiological stress evaluation, particularly useful when studying wild species. However, both negative and positive stimuli (distress and eustress, respectively) can lead to a rise in glucocorticoids. Thus, besides validating whether GCM concentration in faeces reflects endogenous adrenal activity, we also need to identify behavioural indicators of distress to avoid misinterpretation. Therefore, we submitted four adult male spotted pacas (Cuniculus paca) to an exogenous adrenocorticotropic hormone (ACTH) challenge-test in a Latin square design (4 × 4) to monitor changes in the GCM concentration in faeces. We also aimed to describe behaviours potentially indicative of distress. We collected excreted faeces and video-recorded the animals' behaviours for five consecutive days, one day before and four days after application of the following four treatments: 1st control (no-handling); 2nd control (intra-muscular [IM] injection of saline solution); low-dose ACTH (IM injection of 0.18 ml ACTH); and high-dose ACTH (IM injection of 0.37 ml ACTH). There was a peak in the concentration of GCM in faeces collected 24 h after the injection of the high-dose ACTH treatment. Additionally, independent of the treatments, spotted pacas spent less time on exploration and feeding states, while spending more time in the inactive but awake (IBA) state following the treatment application (challenge day). The use of GCM concentration in faecal samples together with the behavioural changes (less exploration and feeding, and more IBA) showed to be efficient as a non-invasive tool for welfare assessment of farmed spotted paca.
ABSTRACT
Inter-individual differences in behavior, together with phenotypic plasticity, may play a key role in the reintroduction success of captive-born individuals. Therefore, we aimed to investigate whether and how personality traits affect the plasticity of defensive behavior in collared peccary (Dicotyles tajacu). Twenty-six adult captive-born collared peccaries (12 males and 14 females) were submitted to three short-term challenges for personality assessment. Thereafter, each individual was submitted to four sequential tests, with different degrees of risk, allowing us to assess temporal/context consistencies in personality traits as well as the plasticity of defensive behavior. We noted a pronounced variability among the individuals' boldness trait, while males and females did not differ in their behavioral responses in all tests. Additionally, collared peccaries show behavioral plasticity of defensive behavior across risk conditions. We also verified an association between boldness and defensive behavior in this species: the higher the boldness score, the less time collared peccaries spent on wariness behaviors in the higher risk condition. The link between personality traits and behavioral plasticity of collared peccaries across risk conditions warrants further investigation to understand the impact of this association on the post-release success of this and other species.
