Abstract: Dominance hierarchies are widely described in nature. Commonly, an individual's ordinal rank is used as a measure of its position in the hierarchy, and, therefore its priority of access to resources. This use of ordinal ranks has several related drawbacks: (1) it is difficult to assess the magnitude or the significance of the difference in degree of dominance between two individuals; (2) it is difficult to evaluate the significance of differences between dominance matrices based on different behaviours or on the same behaviour at different times, and (3) it is difficult to use parametric statistical techniques to relate dominance rank to other quantities of interest. In this paper we describe a method for assigning cardinal dominance indices that does not suffer from these drawbacks. This technique is based on the Bradley-Terry model from the method of paired comparisons. We show how this model can be reinterpreted in terms of dominance interactions. and we describe a simple iterative technique for computing cardinal ranks. We then describe how to evaluate (1) whether the rank differences between individuals are significant, and (2) whether differences in the cardinal hierarchies based on different behaviours or the same behaviour at different times are significant. We then show how to generalize the method to deal with behaviours that sometimes have ambiguous outcomes, or behaviours for which the rank difference between a pair of individuals affects the rate of interaction between them.

Abstract: Tail-biting and other harmful social behaviours are a common problem on pig farms. The aims of the current experiment were (1) to investigate the genetic component of harmful social behaviours such as tail-biting by assessing breed differences, and (2) to further investigate the reliability and predictability of a test, [`]the tail-chew test', previously identified as potentially being capable of predicting a pig's predisposition for tail- and ear-biting. The behaviour of three pig breeds (Large White (LW), Landrace (LR), Duroc (DR)), with 100 pigs per breed, was observed in a [`]tail-chew test', and by observing the performance of harmful social behaviour directed to pen mates in flat deck pens after weaning. The tail-chew test, carried out on two consecutive days pre-weaning, involved observing the behaviour of individual pigs towards two suspended ropes. Pigs were weaned at 28 days and the occurrence of harmful social behaviour was recorded 4 weeks later over 2 consecutive days (1 h per day) using a group [`]period occurrence' scanning method. Breed had a significant effect on rope-directed behaviour in the tail-chew test and on harmful social behaviour. DR pigs interacted with the ropes in the tail-chew test more often (median 23.0 vs 19.0 and 17.5 times in 20 min, P<0.001) and for longer (31.0 vs 20.0 and 23.2 s, P<0.001) than LR and LW pigs, respectively. Although not significantly different from LW, DR pigs tended to direct more total harmful social behaviour towards pen mates than the other breeds. In particular, DR were observed in more total pig-directed biting of pen mates (median 9.0 vs 6.0 and 7.0, P<0.01) than LR and LW, and tended to nose pen mates more often than the other breeds (13.0 vs 11.0 and 10.0, P=0.06). LR pigs bit the ears of pen mates less often than LW and DR (4.0 vs 5.0 and 6.0, P<0.001). Belly-nosing activity was low, with a median of 0 for all breeds, but LR belly-nosed pen mates more often than Durocs (interquartile ranges 0-2.0 vs 0-1.0 and 0-1.0, P<0.01). The behaviour observed in the tail-chew test on day 1 correlated significantly with that observed on day 2 of the test (e.g. frequency of rope-directed behaviour rs=0.380,P<0.01). There were significant but weak correlations between rope-directed behaviour and the performance of some harmful social behaviours. The significant breed differences indicate some genetic contribution to expression of harmful social behaviours. However, the tail-chew test was found to be of limited ability to predict tail- and ear-biting under commercial conditions.

Abstract: Observation of behaviour, especially social behaviour, and experimental studies of learning and brain function give us information about the complexity of concepts that animals have. In order to learn to obtain a resource or carry out an action, domestic animals may: relate stimuli such as human words to the reward, perform sequences of actions including navigation or detours, discriminate amongst other individuals, copy the actions of other individuals, distinguish between individuals who do or do not have information, or communicate so as to cause humans or other animals to carry out actions. Some parrots, that are accustomed to humans but not domesticated, can use words to have specific meanings. In some cases, stimuli, individuals or actions are remembered for days, weeks or years. Events likely to occur in the future may be predicted and changes over time taken into account. Scientific evidence for the needs of animals depends, in part, on studies assessing motivational strength whose methodology depends on the cognitive ability of the animals. Recognition and learning may be associated with changes in physiology, behaviour and positive or negative feelings. Learning and other complex behaviour can result in affect and affect can alter cognition. The demonstration of cognitive bias gives indications about affect and welfare but should be interpreted in the light of other information. All of the information mentioned so far helps to provide evidence about sentience and the level of awareness. The term sentience implies a range of abilities, not just the capacity to have some feelings. The reluctance of scientists to attribute complex abilities and feelings to non-humans has slowed the development of this area of science. Most people consider that they have obligations to some animals. However, they might protect animals because they consider that an animal has an intrinsic value, or because of their concern for its welfare. In social species, there has been selection promoting moral systems that might result in behaviours such as attempts to avoid harm to others, collaboration and other altruistic behaviour. An evaluation of such behaviour may provide one of the criteria for decisions about whether or not to protect animals of a particular species. Other criteria may be: whether or not the animal is known as an individual, similarity to humans, level of awareness, extent of feelings, being large, being rare, being useful or having aesthetic quality for humans. Cognitive ability should also be considered when designing methods of enriching the environments of captive animals.

Abstract: An experiment with starlings was conducted to investigate the effect of variability in inter-reinforcement intervals on foraging decisions. The experimental design simulated an environment in which food was distributed in patches. Patches contained zero to four food items which could be collected by pecking at a key. All patches ended with sudden depletion. The time elapsed since the last reinforcement was the only way to detect the depletion of the patch. Once a patch was depleted, a new patch could be reached by completion of a travel requirement of 20 flights between two perches. Key pecks within a patch and the time of the last response in a patch (giving-in time) were recorded. The level of variability in the inter-reinforcement intervals was varied between different conditions. An increase in inter-reinforcement interval variability resulted in a flattening of response rate functions and giving-in time distributions, and in more asymmetry of the response functions, but not of the giving-in time distributions. Two theoretical models of decision making are presented, which differ in the assumptions about memory constraints. In one case, all inter-reinforcement intervals are remembered but in the other, only the intervals with extreme values are remembered. Both models accommodate response rates as a function of trial time, but only the second is compatible with the observed departure decision. Our results are compatible with net rate maximization.

Abstract: Previous studies have shown that dogs have developed a special sensitivity to the communicative signals and attentional states of humans. The aim of the current study was to further investigate what dogs know about the visual perception of humans and themselves. In the first two experiments we investigated whether dogs were sensitive to the properties of barriers as blocking the visual access of humans. We presented dogs with a situation in which a human forbade them to take a piece of food, but the type and orientation of the barrier allowed the dog to take the food undetected in some conditions. Dogs differentiated between effective and ineffective barriers, based on their orientation or the particular features of the barriers such as size or the presence of window. In the third study we investigated whether dogs know about what they themselves have seen. We presented subjects with two boxes and placed food in one of them. In the Seen condition the location of the food was shown to the dogs while in the Unseen condition dogs were prevented from seeing the destination of the food. Before selecting one of the boxes by pressing a lever, dogs had the opportunity to seek extra information regarding the contents of the boxes, which would be particularly useful in the condition in which they had not seen where the food was hidden. Dogs rarely used the opportunity to seek information about the contents of the box before making their choice in any condition. Therefore, we found no evidence suggesting that dogs have access to what they themselves have seen, which contrasts with the positive evidence about visual perspective taking in others from the first two experiments and previous studies.