Abstract: Group living can confer advantages to individuals, but it can also impose severe costs through resource competition. Kleptoparasitism is one example in which some individuals (joiners) can exploit the food discovered by other animals (finders). This type of social foraging has been modelled either as an information-sharing model or as a producer-scrounger game. An important variable in these models is the finder's advantage: the number of items obtained by the finder before the arrival of other individuals. In this study we describe how the spatial position and rank of individuals in a group of wild tufted capuchin monkeys affect their ability to discover and exploit new food sources. We also analyse the factors that affect the finder's share and the total amount of food obtained by the finder from a newly discovered resource. By placing platforms filled with bananas at novel locations in their home range, we show that animals in the leading edge of a foraging group have a higher probability of discovering new food sources than animals occupying other spatial positions. The alpha male and the alpha female, which tended to occupy central-forward positions, were able to monopolize newly discovered food sources and thus obtain a major share of them. The finder's share at the feeding platforms was smaller when there was more food on a platform, but increased with longer delays before the arrival of other individuals. The total amount of food obtained by the finder from the feeding platforms was larger when there was more food on the platform, when the finder was of higher social status, and when it took longer for other individuals to arrive. Animals can increase their finder's share and total amount consumed from a newly discovered resource by keeping large interindividual distances and by avoiding giving cues about the presence of food (such as food-associated vocalizations) to other animals.

Abstract: OBJECTIVE: To compare financial returns between pinhooked yearling horses (ie, bought and trained for approximately 5 months with the goal of selling the horse at “2-year-olds in training” sales) that had mild or severe training failure and horses that had planned versus nonplanned training failure. ANIMALS: 40 Thoroughbred pinhooked yearling horses. PROCEDURE: During the period from September 1998 through and April 1999, 20 horses had mild training failure (1 to 11 days lost), and 20 horses had severe training failure (13 to 108 days lost). Horses were assigned to these 2 groups on the basis of frequency distribution (median) of days lost during training. Horses were also categorized on the basis of type of training failure (planned vs nonplanned training failure). The outcome of primary interest was financial return. Median financial returns were compared among groups by use of the Mann-Whitney U test. RESULTS: Median financial returns for horses that had severe training failure ($1,000) were significantly different, compared with horses that had mild training failure ($24,000). Analysis of results also indicated that median returns were significantly different among horses that had planned training failure (-$2,000; eg, horses with radiographic abnormalities detected during routine prepurchase examinations that required surgical treatment, resulting in days lost during training), compared with horses that did not ($10,000). CONCLUSIONS AND CLINICAL RELEVANCE: Training failure has an economic impact on revenues in pinhooked yearling horses. Lameness, planned training failure, respiratory disease, and ringworm were common and important causes of training failure.

Abstract: We studied influences of dental care, food and storage on the reproducibility of salivary steroid levels. Cortisol (F), 17OH-progesterone (17OHP) and Progesterone (P) were measured using adapted commercial radioimmunoassays. Saliva samples of healthy adults (n = 15; m:8; f:7) were collected directly before and after dental care, and directly before and after breakfast with various foodstuffs. A second experiment investigated stability of steroids under different storage conditions. Four series of identical saliva portions (I: Native saliva; II: Centrifuged saliva; III: Saliva with trifluor acetate (TFA); IV: Saliva with 0.5% NaN3) were stored at room temperature and at 4°C for up to three weeks. To demonstrate influences of repeated thawing and re-freezing of saliva on steroid values, saliva samples (n = 15) were divided into identical portions. These portions were frozen and re-thawed up to 5 times before measurement. Neither dental care nor intake of bread or milk effected the reproducibility of F, 170HP, and P. Steroid levels decreased significantly in the course of three weeks under different storage conditions (P < 0.001). This decrease was clinically relevant from the second week onward, with exception of NaN3 treated samples. After repeated freezing and re-thawing 17OHP and P decreased slightly (about 5%). Only F decreased significantly after the third thawing (P < 0.001). The results show the usefulness of standardized handling of saliva samples for improving reproducibility and reliability of salivary steroid measurements.

Abstract: Locating and capturing food are suggested as significant selection pressures for the evolution of various cognitive abilities in mammals and birds. The hypothesis is proposed that aspects of food procuring behaviour should be strongly indicative of particular cognitive abilities. Experimental data concerning higher mental abilities in mammals and birds are reviewed. These data deal with self-recognition studies, rule-learning experiments, number concept, deceptive abilities, tool-use and observational learning. A Darwinian approach reveals: (1) the adaptiveness of particular abilities for particular niches, (2) that in complex foraging environments, increases in foraging efficiencies in animals should result from the evolution of particular cognitive abilities, (3) that phenomena such as convergent mental evolution should be expected to have taken place across taxonomic groups for species exploiting similar niches, (4) that divergence in mental ability should also have taken place where related species have exploited dissimilar niches. Experimental data of higher mental abilities in animals concur with a Darwinian explanation for the distribution of these cognitive abilities and no anomalies have been found. There are, as a consequence, significant implications for the welfare of animals subject to training when training methodology gives little or no consideration to the various mental abilities of species.

Abstract: Seven experiments were conducted on four miniature pigs to determine: (1) whether the pigs can discriminate between people wearing the same coloured clothing; (2) what cues they rely on if they could discriminate. For 2 weeks before the experiments began, the pigs were conditioned in a Y-maze to receive raisins from the rewarder wearing dark blue coveralls. They were then given the opportunity to choose the rewarder or non-rewarder in these experiments. Each session consisted of 20 trials. Successful discrimination was that the pig chose the rewarder at least 15 times in 20 trials (P<0.05: by χ2-test). In Experiment 1, both rewarder and non-rewarder wore dark blue coveralls. By 20 sessions, all pigs successfully identified the rewarder. In Experiment 2: (1) both wore coveralls of the same new colours or (2) one of them wore coveralls of new colours. They significantly preferred the rewarder even though the rewarder and/or non-rewarder wore coveralls of new colours. In Experiment 3, both wore dark blue coveralls but olfactory cues were obscured and auditory cues were not given. The pigs were able to identify the rewarder successfully irrespective of changing auditory and olfactory cues. In Experiment 4, both wore dark blue coveralls but covered part of their face and body in different ways. The correct response rate decreased when a part of the face and the whole body of the rewarder and non-rewarder were covered. In Experiment 5, both wore dark blue coveralls and changed their apparent body size by shifting sitting position. The correct response rate increased as the difference in body size between the experimenters increased. In Experiment 6, the distance between the experimenters and the pig was increased by 30 cm increments. The correct response rate of each pig decreased as the experimenters receded from the pig, but performance varied among the pigs. In Experiment 7, the light intensity of the experimental room was reduced from 550 to 80 lx and then to 20 lx. The correct response rate of each pig decreased with the reduction in light intensity, but all the pigs discriminated the rewarder from the non-rewarder significantly even at 20 lx. In conclusion, the pigs were able to discriminate between people wearing coveralls of the same colour after sufficient reinforcement. These results indicate that pigs are capable of using visual cues to discriminate between people.