Sexual dimorphism in the performance of chemosensory investigatory behaviours by African elephants (Loxodonta africana)

Sexual dimorphism in morphology can be accompanied by behavioural differences between the sexes. We examined if investigatory behaviour involving the trunk of African elephants showed sexual dimorphism. Males compete and search for females, but they have a lengthy period of development before they are socially viable mates. Receptive females are relatively rare. We hypothesized that males would display higher rates of chemosensory behaviour following puberty than females. Because males disperse, they were hypothesized to be more likely to contact elephants outside their kinship group. We observed the trunk tip, chemosensory behaviours of African elephants at Addo Elephant National Park, South Africa. For 208 elephants, we found no significant differences in state behaviours around waterholes by age or sex. Yet, older elephants were more likely to investigate the environment and elephant excrement than younger animals. Males were more likely to investigate urine and faeces than females. Only post-puberty animals contacted non-family with males investigating both sexes, while investigations by and to females only involved post-puberty males. Overall, the probability of performing chemosensory behaviours depended on age and sex. Male elephants appear more reliant than females on signals in urine and faeces with ensuing inspections of individuals through trunk tip contacts.

SOCIAL STATUS AND INVESTIGATORY BEHAVIOUR IN THE ANGELFISH (PTEROPHYLLUM SCALARE)

The response of juvenile angelfish (Pterophyllum scalare) with different dominance ranks towards a potential predator and a nonthreatening novel stimulus was studied when in a group, to assess the influence of the social status on investigatory behaviour. Dominant fish showed a cautious predator inspection behaviour, often approaching the predator model from a relatively safe distance. In contrast, middle ranking fish inspected the predator model closely and the number and duration of the inspection visits to the area closest to the predator were greater than those of the other group members. Subordinate fish tended to avoid the potential predator, but showed the greatest interest in the novel harmless stimulus, investigating it more readily and for more time from the shortest distance than their companions. Dominant fish displayed a rather weak response towards the nonthreatening stimulus, exhibiting the shortest duration of investigation and the longest latency of approach. The response of intermediate ranking fish was more variable, existing little differences with that showed by any of the other fish categories in the parameters considered. The results indicate that dominance relationships within a group may affect behavioural decisions during investigatory behaviour, and suggest that individuals with different social status use different behavioural strategies dependent on the focal stimulus, possibly reflecting adaptive changes and physiological condition.

A comparison of the early behaviour of intensively and extensively reared calves

ABSTRACTThis study involved two groups of calves, one group consisted of eight Angus × (Friesian × Hereford) calves born in the late summer and kept with their dams in the field. The other group consisted of 20 autumn-born Friesian calves kept indoors in individual stalls. Similar ethograms and techniques were used to study their behaviour up to 8 weeks of age, thus allowing comparisons to be made of the proportion of time spent in various activities, as well as changes in the sequences of behaviour with age. In general, the activity of the calves of both groups showed a similar trend in development. However, the field calves spent significantly more time in investigatory behaviour while the confined calves showed a significantly higher frequency of investigatory behaviour and indulged in more self grooming. The analysis of behavioural sequences showed few differences in focal points or direction of transitions from one behavioural pattern to another, suggesting that the integration of activities into developing motor patterns in the calf is determined ontogenetically with little modification by the environmental factors encountered in this study. However, the confined calves showed a greater mean number of transitions per hour. The findings are discussed in relation to the welfare of the confined calf.

Investigatory behaviour of plains garter snakes, Thamnophis radix (Reptilia: Colubridae), in tests of repellant chemicals

Nineteen adult and 24 young Thamnophis radix, collected at two sites in southern Saskatchewan, were tested for avoidance to 10 common chemicals and commercial repellants. Avoidance was noted only to a repelling fumigant containing pyrethrum. Analysis of tongue flick rate showed that the adults used this part of searching behaviour significantly more than the young.