Abstract: Non-human animals vary in their ability to make and use tools. The goal of the present study was to further explore what, if anything, differs between tool-users and non-tool-users, and whether these differences lie in the conceptual or motor domain. We tested two species that typically do not use tools-cotton top tamarins (Saguinus oedipus) and vervet monkeys (Cercopithecus aethiops)-on problems that mirrored those designed for prolific tool users such as chimpanzees. We trained subjects on a task in which they could choose one of two canes to obtain an out-of-reach food reward. After training, subjects received several variations on the original task, each designed to examine a specific conceptual aspect of the pulling problem previously studied in other tool-using species. Both species recognized that effective pulling tools must be made of rigid materials. Subsequent conditions revealed significant species differences, with vervets outperforming tamarins across many conditions. Vervets, but not tamarins, had some recognition of the relationship between a tool's orientation and the position of the food reward, the relationship between a tool's trajectory and the substance that it moves on, and that tools must be connected in order to work properly. These results provide further evidence that tool-use may derive from domain-general, rather than domain-specific cognitive capacities that evolved for tool use per se.

Abstract: The ecology of virulent strains of Rhodococcus equi on horse farms is likely to influence the prevalence and severity of R. equi pneumonia in foals. This study examined the association between the ecology of virulent R. equi and the epidemiology of R. equi pneumonia by collecting air and soil samples over two breeding seasons (28 farm-year combinations) on Thoroughbred breeding farms with different reported prevalences of R. equi pneumonia. Colony blotting and DNA hybridization were used to detect and measure concentrations of virulent R. equi. The prevalence of R. equi pneumonia was associated with the airborne burden of virulent R. equi (both the concentration and the proportion of R. equi bacteria that were virulent) but was not associated with the burden of virulent R. equi in the soil. Univariable screening and multivariable model building were used to evaluate the effect of environmental and management factors on virulent R. equi burdens. Lower soil moisture concentrations and lower pasture heights were significantly associated with elevated airborne concentrations of virulent R. equi, as were the holding pens and lanes, which typically were sandy, dry, and devoid of pasture cover. Few variables appeared to influence concentrations of virulent R. equi in soil. Acidic soil conditions may have contributed to an elevated proportion of virulent strains within the R. equi population. Environmental management strategies that aim to reduce the level of exposure of susceptible foals to airborne virulent R. equi are most likely to reduce the impact of R. equi pneumonia on endemically affected farms.

Abstract: Locating food and refuge is essential for an animal's survival. However, little is known how mammals navigate under natural conditions and cope with given environmental constraints. In a series of six experiments, I investigated landmark-based navigation in free-ranging Columbian ground squirrels (Spermophilus columbianus). Squirrels were trained individually to find a baited platform within an array of nine identical platforms and artificial landmarks set up on their territories. After animals learned the location of the food platform in the array, the position of the latter with respect to local artificial, local natural, and global landmarks was manipulated, and the animal's ability to find the food platform was tested. When only positions of local artificial landmarks were changed, squirrels located food with high accuracy. When the location of the array relative to global landmarks was altered, food-finding accuracy decreased but remained significant. In the absence of known global landmarks, the presence of a familiar route and natural local landmarks resulted in significant but not highly accurate performance. Squirrels likely relied on multiple types of cues when orienting towards a food platform. Local landmarks were used only as a secondary mechanism of navigation, and were not attended to when a familiar route and known global landmarks were present. This study provided insights into landmark use by a wild mammal in a natural situation, and it demonstrated that an array of platforms can be employed to investigate landmark-based navigation under such conditions.

Abstract: This study explored the duration of cats' working memory for hidden objects. Twenty-four cats were equally divided into four groups, which differed according to the type of visual cues displayed on and/or around the hiding boxes. During eight sessions, the four groups of cats were trained to locate a desirable object hidden behind one of the four boxes placed in front of them. Then, the cats were tested with retention intervals of 0, 10, 30 and 60 s. Results revealed no significant differences between the groups during training or testing. In testing, the cats' accuracy to locate the hidden object rapidly declined between 0 and 30 s but remained higher than chance with delays of up to 60 s. The analysis of errors also indicated that the cats searched as a function of the proximity of the target box and were not subjected to intertrial proactive interference. This experiment reveals that the duration of cats' working memory for disappearing objects is limited and the visual cues displayed on and/or around the boxes do not help the cats to memorize a hiding position. In discussion, we explore why the duration of cats' working memory for disappearing objects rapidly declined and compare these finding with those from domestic dogs. The irrelevance of visual cues displayed on and around the hiding boxes on cats' retention capacity is also discussed.

Abstract: In several species, the ability to locate a disappearing object is an adaptive component of predatory and social behaviour. In domestic dogs, spatial memory for hidden objects is primarily based on an egocentric frame of reference. We investigated the geometric components of egocentric spatial information used by domestic dogs to locate an object they saw move and disappear. In experiment 1, the distance and the direction between the position of the animal and the hiding location were put in conflict. Results showed that the dogs primarily used the directional information between their own spatial coordinates and the target position. In experiment 2, the accuracy of the dogs in finding a hidden object by using directional information was estimated by manipulating the angular deviation between adjacent hiding locations and the position of the animal. Four angular deviations were tested: 5, 7.5, 10 and 15 degrees . Results showed that the performance of the dogs decreased as a function of the angular deviations but it clearly remained well above chance, revealing that the representation of the dogs for direction is precise. In the discussion, we examine how and why domestic dogs determine the direction in which they saw an object disappear.