Abstract: This experiment investigated whether domestic pigs can remember the locations of food sites of different relative value, and how a restricted retrieval choice affects their foraging behaviour. Nine juvenile female pigs were trained to relocate two food sites out of a possible eight in a spatial memory task. The two baited sites contained different amounts of food and an obstacle was added to the smaller amount to increase handling time. On each trial, a pig searched for the two baited sites (search visit). Once it had found and eaten the bait, it returned for a second (relocation) visit, in which the two same sites were baited. Baited sites were changed between trials. All subjects learnt the task. When allowed to retrieve both baits, the subjects showed no preference for retrieving a particular one first (experiment 1). When they were allowed to retrieve only one bait, a significant overall preference for retrieving the larger amount emerged across subjects (experiment 2). To test whether this preference reflected an avoidance of the obstacle with the smaller bait, 15 choice-restricted control trials were conducted. In control trials obstacles were present with both baits. Pigs continued to retrieve the larger bait, indicating they had discriminated between the two food sites on the basis of quantity or profitability and adjusted their behaviour accordingly when the relocation choice was restricted. This suggests for the first time that domestic pigs have the ability to discriminate between food sites of different relative value and to remember their respective locations.

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: In many cooperatively breeding species, group members form a dominance hierarchy or queue to inherit the position of breeder. Models aimed at understanding individual variation in helping behavior, however, rarely take into account the effect of dominance rank on expected future reproductive success and thus the potential direct fitness costs of helping. Here we develop a kin-selection model of helping behavior in multimember groups in which only the highest ranking individual breeds. Each group member can invest in the dominant's offspring at a cost to its own survivorship. The model predicts that lower ranked subordinates, who have a smaller probability of inheriting the group, should work harder than higher ranked subordinates. This prediction holds regardless of whether the intrinsic mortality rate of subordinates increases or decreases with rank. The prediction does not necessarily hold, however, where the costs of helping are higher for lower ranked individuals: a situation that may be common in vertebrates. The model makes two further testable predictions: that the helping effort of an individual of given rank should be lower in larger groups, and the reproductive success of dominants should be greater where group members are more closely related. Empirical evidence for these predictions is discussed. We argue that the effects of rank on stable helping effort may explain why attempts to correlate individual helping effort with relatedness in cooperatively breeding species have met with limited success.