Abstract: Abstract  Social foraging is suggested to increase foraging efficiency, as individuals might benefit from public information acquired by monitoring the foraging activities of other group members. We conducted a series experiments with captive common marmosets (Callithrix jacchus) to investigate to what extent marmosets utilize social information about food location when foraging simultaneously with conspecifics. Subjects were confronted with dominant and subordinate demonstrators in three experiments which differed in the amount of information about food location available to the demonstrators. In all three experiments, the focal subjects` performance in the social condition was not enhanced in comparison to a non-social control condition. Because we could rule out kleptoparasitism and aggressive displacements as explanations, we argue that the subjects tendency for scramble competition by avoiding others and dispersing over the foraging area seems to inhibit or mask the acquisition of social information about the location of rewarded patches.

Abstract: There are both benefits (e.g., social information) and costs (e.g., intraspecific competition) for individuals foraging in groups. To ascertain how group-foraging goats (Capra hircus) deal with these trade-offs, we asked 1) do goats use social information to make foraging decisions and 2) how do they adjust their intake rate in light of having attracted by other group members? To establish whether goats use social information, we recorded their initial choice of different quality food patches when they were ignorant of patch quality and when they could observe others foraging. After determining that goats use social information, we recorded intake rates while they fed alone and in the presence of potential competitors. Intake rate increased as the number of competitors increased. Interestingly, lone goats achieved an intake rate that was higher than when one competitor was present but similar to when two or more competitors were present. Faster intake rates may allow herbivores to ingest a larger portion of the available food before competing group members arrive at the patch. This however, does not explain the high intake rates achieved when the goats were alone. We provide 2 potential explanations: 1) faster intake rates are a response to greater risk incurred by lone individuals, the loss of social information, and the fear of being left behind by the group and 2) when foraging alone, intake rate is no longer a trade-off between reducing competition and acquiring social information. Thus, individuals are able to feed close to their maximum rate.

Abstract: The stabled (UK) or stalled (USA) horse is commonly fed a restricted-forage diet in contrast to the varied ad libitum high-fibre diet it evolved to consume. A low-forage diet has been linked to the performance of stereotypical behaviour and health problems including gastric ulceration and impaction colic (in cases where horses are bedded on straw). Provision of a diet closer to that which the horse is adapted to and which enables more natural feeding behaviour warrants investigation. This trial aimed to establish whether the behavioural effects observed in short-term trials when stabled horses were provided with a multiple forage diet persist over longer periods. It also aimed to develop a practical methodology for maintaining stabled horses under forage-enriched conditions. Nine horses (aged 5-20 years, various breeds), acting as their own controls, participated in an 18-day, cross-over, Latin Square designed trial, in which they received comparable weights of two dietary treatments: a Single Forage (SF, hay) diet and a Multiple Forage (MF) diet (three long-chop and three short-chop commercially available forages). Following a 2-day acclimatisation, horses were maintained on the forage treatments for 7 days. Horses were observed on alternate days, morning and afternoon, during the 25 min following forage presentation. Horses then crossed over onto their second treatment and, following a further 2 days' acclimatisation, the same protocol was followed for a further 7 days. Observations from video were made using The Observer 3.0(R) and SPPS (version 11). Horses on the MF treatment performed foraging behaviour significantly more frequently and for significantly longer periods than horses on the SF treatment. On the MF treatment horses sampled all forages during observations. However, there were significant differences in the frequency and duration of foraging on individual forages, indicating that horses demonstrated individual preferences for particular forages. Stereotypic weaving behaviour only occurred on the SF treatment. The results indicate that the potentially beneficial behavioural effects of short-term multiple forage provision do persist when horses are managed on a MF diet for a 7-day period. They suggest that a MF diet provides a means of enriching the stabled horse's environment, by offering variety and enabling patch foraging behaviour. The methodology proved practical for maintaining horses under forage-enriched conditions and could easily be adopted by horse owners to facilitate foraging behaviour.

Abstract: Active misleading of conspecifics has been described as a social strategy mainly for primates. Here we report a raven leading a competitor away from food in a social foraging task. Four individuals had to search and compete for hidden food at color-marked clusters of artificial food caches. At the beginning of the experiment, a subordinate male found and exploited the majority of the food. As a result, the dominant male displaced him from the already opened boxes. The subordinate male then developed a pattern, when the loss of reward to the dominant got high, of moving to unrewarded clusters and opening boxes there. This diversion often led the dominant to approach those unrewarded clusters and the subordinate then had a head start for exploiting the rewarded boxes. Subsequently, however, the dominant male learned not to follow the subordinate to unrewarded clusters and eventually started searching for the reward himself. These interactions between the two males illustrate the ravens' potential for deceptively manipulating conspecifics. We discuss under which circumstances ravens might use this capacity.