Behavioural variability among captive African elephants in the use of the trunk while feeding

The Proboscideans, an order of mammals including elephants, are the largest of the Earth lands animals. One probable consequence of the rapid increase of their body size is the development of the trunk, a multitask highly sensitive organ used in a large repertoire of behaviours. The absence of bones in the trunk allows a substantial degree of freedom for movement in all directions, and this ability could underlie individual-level strategies. We hypothesised a stronger behavioural variability in simple tasks, and a correlation between the employed behaviours and the shape and size of the food. The observations of a captive group of African elephants allowed us to create a complete catalogue of trunk movements in feeding activities. We noted manipulative strategies and impact of food item properties on the performed behaviours. The results show that a given item is manipulated with a small panel of behaviours, and some behaviours are specific to a single shape of items. The study of the five main feeding behaviours emphasises a significant variability between the elephants. Each individual differed from every other individual in the proportion of at least one behaviour, and every behaviour was performed in different proportions by the elephants. Our findings suggest that during their lives elephants develop individual strategies adapted to the manipulated items, which increases their feeding efficiency.

Effect of prolonged captivity on the hemolymph profile of Tachypleus gigas

ABSTRACTHorseshoe crabs amebocyte cells degranulate to form a gel clot when in contact with endotoxins. This phenomenon is the basis of both Horseshoe crab immune system and detection of endotoxin in biologicals. The present study investigates the amebocyte cells quality in Tachypleus gigas pre and post bleeding under captivity. Wild and captive horseshoe crabs (5 months captivity) were bled in 6 anticoagulant formulations (A, B, C, D, E and F). No profound difference in cell density between captive and wild groups with the mean value of 0.883×107 a cells/mL and 0.917×107 cells/mL, respectively. while, the cell viability of the captive group was significantly lower than the wild crabs (F=808.075, p<0.001). Anticoagulant formulation significantly affected cell viability and cell morphology in both captive and wild groups (p<0.001). Amebocyte cells collected from the wild T. gigas using optimum anticoagulant (formula C) showed 0.6 ×107 cells/mL cell density and 86.9% cell viability, while morphology analysis revealed the percentage of contracted, granular flattened and degranulated flattened cells were 14.62%, 71.39% and 14%, respectively. The anticoagulant formulations showed varying capabilities in maintaining cell viability due to its buffering and chelating capacity. We conclude that captivity has a negative effect on the amebocyte cell quality.HIGHLIGHTSCaptivity has a negative impact on amebocyte quality in horseshoe crab (Tachypleus gigas).No significant difference in cell density between captive and wild crabs.Anticoagulant formulations have significant impact on the cell density, viability and morphologyCaptive crabs were immunocompromised due to single specific feed intake.

Sulawesi Crested Macaque (Macaca nigra) Grooming Networks Are Robust to Perturbation While Individual Associations Are More Labile

Social and environmental disturbance occurs naturally, and species in bonded social groups should be resilient to it. Empirical evidence of social responses to disturbance in primates, however, remains limited. We constructed social networks using group-level scan samples (N = 299) to test the robustness of grooming networks in a captive group of 20 Sulawesi crested macaques (Macaca nigra) to two management interventions involving environmental and social disturbance. During the first, the institution removed six castrated males and one female, contracepted six of the nine remaining females, and moved the group to a new enclosure. The second involved the introduction of a novel, reproductive male five weeks later. Networks remained stable following the first intervention. However, after introduction of the male, the number of grooming partners and the frequency of grooming with non-maternal kin increased in female-only networks. We observed less marked increases in the grooming frequency and number of grooming partners in whole group networks. Ten weeks later, network structure was more similar to that of pre-intervention networks than post-intervention networks. Our results suggest that reproductive males play a more important role in structuring Sulawesi crested macaque social networks than castrated males, as networks expanded and relationships between non-maternal kin occurred more frequently after introduction of the reproductive male. However, network responses to interventions appeared to be temporary as networks following a period of acclimation more closely resembled pre-intervention networks than post-intervention networks. Our study demonstrates the utility of social network analysis for understanding the impact of disturbance on stable social groups.

Spontaneous Yawning and its Potential Functions in South American Sea Lions (Otaria flavescens)

Spontaneous yawning is a widespread behaviour in vertebrates. However, data on marine mammals are scarce. In this study, we tested some hypotheses on the functions of yawning in a captive group of South American sea lions (Otaria flavescens). According to the Dimorphism Hypothesis, species showing low levels of sexual dimorphism in canine size do not show sex differences in yawning distribution; this was supported by our findings, since yawning did not differ between the sexes. Yawning was more frequently performed during resting/sleeping contexts, thus supporting the Drowsiness Hypothesis. Yawning and self-scratching are considered reliable indicators of short-term anxiety in sea lions, since they immediately increased after conflicts both in aggressors and victims (Social Distress Hypothesis supported). In the long-term, yawning was not correlated with individuals’ dominance status, thus showing that anxiety is similarly experienced by dominants and subordinates. The last two findings can be explained by the social competition of this species, that involves individuals independently from their sex, age or ranking status. Therefore, the exposure to frequent stressful events can induce similar levels of anxiety in all the subjects (Resource Inequity Hypothesis supported). In conclusion, spontaneous yawning in sea lions seems to share similar functions with other social mammals, suggesting that this behaviour is a possible plesiomorphic trait.

Understanding behavior in a captive Lion-tailed macaques (Macaca silenus) group

A captive lion-tailed macaque group, consisting of two adult males and one adult female, was observed over a period of three months. We collected the data from 8.30hrs to 17.30hrs, using both focal and scan animal sampling methods. In the study, we divided the behaviors into abnormal and normal behavioral traits which were further divided into self-directed and social interchange behaviors. When compared with the past records on the wild and captive group, most of the behaviors were similar which included behaviors like forage, grooming, aggressive display and reproductive behavior. Animals who were born in a zoo or confiscated from another zoo showed higher levels of abnormal behaviors. The results of this study discuss the range of behavioral patterns displayed by the captive animals, discuss the causal factors for the behavioral pathogens, and further suggests feasible solutions to increase the welfare of these macaques. In the study, the early life history of the animal and the lack of social and environmental stimulus could be very critical for the development of behavioral pathogens. However, to establish this would require more research.