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Scherer, W. F., & Dickerman, R. W. (1972). Ecologic studies of Venezuelan encephalitis virus in southeastern Mexico. 8. Correlations and conclusions. Am J Trop Med Hyg, 21(2), 86–89.
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Scherer, W. F., Dickerman, R. W., & Ordonez, J. V. (1970). Discovery and geographic distribution of Venezuelan encephalitis virus in Guatemala, Honduras, and British Honduras during 1965-68, and its possible movement to Central America and Mexico. Am J Trop Med Hyg, 19(4), 703–711.
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Guttridge, T. L., Dijk, S., Stamhuis, E. J., Krause, J., Gruber, S. H., & Brown, C. (2013). Social learning in juvenile lemon sharks, Negaprion brevirostris. Animal Cognition, 16(1), 55–64.
Abstract: Social learning is taxonomically widespread and can provide distinct behavioural advantages, such as in finding food or avoiding predators more efficiently. Although extensively studied in bony fishes, no such empirical evidence exists for cartilaginous fishes. Our aim in this study was to experimentally investigate the social learning capabilities of juvenile lemon sharks, Negaprion brevirostris. We designed a novel food task, where sharks were required to enter a start zone and subsequently make physical contact with a target in order to receive a food reward. Naive sharks were then able to interact with and observe (a) pre-trained sharks, that is, ‘demonstrators’, or (b) sharks with no previous experience, that is, ‘sham demonstrators’. On completion, observer sharks were then isolated and tested individually in a similar task. During the exposure phase observers paired with ‘demonstrator’ sharks performed a greater number of task-related behaviours and made significantly more transitions from the start zone to the target, than observers paired with ‘sham demonstrators’. When tested in isolation, observers previously paired with ‘demonstrator’ sharks completed a greater number of trials and made contact with the target significantly more often than observers previously paired with ‘sham demonstrators’. Such experience also tended to result in faster overall task performance. These results indicate that juvenile lemon sharks, like numerous other animals, are capable of using socially derived information to learn about novel features in their environment. The results likely have important implications for behavioural processes, ecotourism and fisheries.
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Yamada, T., Rojanasuphot, S., Takagi, M., Wungkobkiat, S., & Hirota, T. (1971). Studies on an epidemic of Japanese encephalitis in the northern region of Thailand in 1969 and 1970. Biken J, 14(3), 267–296.
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Krueger, K., Trager, L., Farmer, K., & Byrne, R. (2022). Tool Use in Horses. Animals, 12(15), 1876.
Abstract: Tool use has not yet been confirmed in horses, mules or donkeys. As this subject is difficult to research with conventional methods, we used a crowdsourcing approach to gather data. We contacted equid owners and carers and asked them to report and video examples of �unusual� behaviour via a dedicated website. We also searched YouTube and Facebook for videos of equids showing tool use. From 635 reports, including 1014 behaviours, we found 20 cases of tool use, 13 of which were unambiguous in that it was clear that the behaviour was not trained, caused by reduced welfare, incidental or accidental. We then assessed (a) the effect of management conditions on tool use and (b) whether the animals used tools alone, or socially, involving other equids or humans. We found that management restrictions were associated with corresponding tool use in 12 of the 13 cases (p = 0.01), e.g., equids using sticks to scrape hay within reach when feed was restricted. Furthermore, 8 of the 13 cases involved other equids or humans, such as horses using brushes to groom others. The most frequent tool use was for foraging, with seven examples, tool use for social purposes was seen in four cases, and there was just one case of tool use for escape. There was just one case of tool use for comfort, and in this instance, there were no management restrictions. Equids therefore can develop tool use, especially when management conditions are restricted, but it is a rare occurrence.
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Beck, B. B. (1982). Chimpocentrism: Bias in cognitive ethology. Journal of Human Evolution, 11(1), 3–17.
Abstract: Herring gulls drop hard-shelled mollusks and hermit crab-inhabited molluskan prey in order to break the shells and gain access to the edible interior. A field study of predatory shell dropping on Cape Cod, Massachusetts, U.S.A. showed that the gulls usually drop the same shell repeatedly, orient directly to dropping sites that are invisible from the point at which the mollusks are captured, drop preferentially on hard surfaces, adjust dropping heights to suit the area and elasticity of the substrate, orient directly into the wind while dropping, sever the large defensive cheliped of hermit crabs before consumption, and rinse prey that is difficult to swallow. Proficiency in prey dropping is acquired through dropping objects in play, trial-and-error learning, and perhaps, observation learning.
Observable attributes of predatory shell-dropping support inferences that the gulls are capable of extended concentration, purposefulness, mental representation of spatially and temporally displaced environmental features, cognitive mapping, cognitive modeling, selectivity, and strategy formation. Identical cognitive processes have been inferred to underlie the most sophisticated forms of chimpanzee tool-use.
Advanced cognitive capacities are not restricted to chimpanzees and other pongids, and are not associated uniquely with tool use. The chimpocentric bias should be abandoned, and reconstructions of the evolution of intelligence should be modified accordingly.
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Baumgartner, M., Boisson, T., Erhard, M. H., & Zeitler-Feicht, M. H. (2020). Common Feeding Practices Pose A Risk to the Welfare of Horses When Kept on Non-Edible Bedding. Animals, 10, 441.
Abstract: During the evolution of the horse, an extended period of feed intake, spread over the entire 24-h period, determined the horses� behaviour and physiology. Horses will not interrupt their feed intake for more than 4 h, if they have a choice. The aim of the present study was to investigate in what way restrictive feeding practices (non ad libitum) affect the horses� natural feed intake behaviour. We observed the feed intake behaviour of 104 horses on edible (n = 30) and non-edible bedding (n = 74) on ten different farms. We assessed the duration of the forced nocturnal feed intake interruption of horses housed on shavings when no additional roughage was available. Furthermore, we comparatively examined the feed intake behaviour of horses housed on edible versus non-edible bedding. The daily restrictive feeding of roughage (2 times a day: n = 8; 3 times a day: n = 2), as it is common in individual housing systems, resulted in a nocturnal feed intake interruption of more than 4 hours for the majority (74.32%, 55/74) of the horses on shavings (8:50 ± 1:25 h, median: 8:45 h, minimum: 6:45 h, maximum: 13:23 h). In comparison to horses on straw, horses on shavings paused their feed intake less frequently and at a later latency. Furthermore, they spent less time on consuming the evening meal than horses on straw. Our results of the comparison of the feed-intake behaviour of horses on edible and non-edible bedding show that the horses� ethological feeding needs are not satisfied on non-edible bedding. If the horses accelerate their feed intake (also defined as �rebound effect�), this might indicate that the horses� welfare is compromised. We conclude that in addition to the body condition score, the longest duration of feed intake interruption (usually in the night) is an important welfare indicator of horses that have limited access to roughage.
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Huber, L., & Gajdon, G. K. (2006). Technical intelligence in animals: the kea model. Anim. Cogn., 9(4), 295–305.
Abstract: The ability to act on information flexibly is one of the cornerstones of intelligent behavior. As particularly informative example, tool-oriented behavior has been investigated to determine to which extent nonhuman animals understand means-end relations, object affordances, and have specific motor skills. Even planning with foresight, goal-directed problem solving and immediate causal inference have been a focus of research. However, these cognitive abilities may not be restricted to tool-using animals but may be found also in animals that show high levels of curiosity, object exploration and manipulation, and extractive foraging behavior. The kea, a New Zealand parrot, is a particularly good example. We here review findings from laboratory experiments and field observations of keas revealing surprising cognitive capacities in the physical domain. In an experiment with captive keas, the success rate of individuals that were allowed to observe a trained conspecific was significantly higher than that of naive control subjects due to their acquisition of some functional understanding of the task through observation. In a further experiment using the string-pulling task, a well-probed test for means-end comprehension, we found the keas finding an immediate solution that could not be improved upon in nine further trials. We interpreted their performance as insightful in the sense of being sensitive of the relevant functional properties of the task and thereby producing a new adaptive response without trial-and-error learning. Together, these findings contribute to the ongoing debate on the distribution of higher cognitive skills in the animal kingdom by showing high levels of sensorimotor intelligence in animals that do not use tools. In conclusion, we suggest that the 'Technical intelligence hypothesis' (Byrne, Machiavellian intelligence II: extensions and evaluations, pp 289-211, 1997), which has been proposed to explain the origin of the ape/monkey grade-shift in intelligence by a selection pressure upon an increased efficiency in foraging behavior, should be extended, that is, applied to some birds as well.
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Weir, A. A. S., & Kacelnik, A. (2006). A New Caledonian crow (Corvus moneduloides) creatively re-designs tools by bending or unbending aluminium strips. Anim. Cogn., 9(4), 317–334.
Abstract: Previous observations of a New Caledonian crow (Corvus moneduloides) spontaneously bending wire and using it as a hook [Weir et al. (2002) Science 297:981] have prompted questions about the extent to which these animals 'understand' the physical causality involved in how hooks work and how to make them. To approach this issue we examine how the same subject (“Betty”) performed in three experiments with novel material, which needed to be either bent or unbent in order to function to retrieve food. These tasks exclude the possibility of success by repetition of patterns of movement similar to those employed before. Betty quickly developed novel techniques to bend the material, and appropriately modified it on four of five trials when unbending was required. She did not mechanically apply a previously learned set of movements to the new situations, and instead sought new solutions to each problem. However, the details of her behaviour preclude concluding definitely that she understood and planned her actions: in some cases she probed with the unmodified tools before modifying them, or attempted to use the unmodified (unsuitable) end of the tool after modification. Gauging New Caledonian crows' level of understanding is not yet possible, but the observed behaviour is consistent with a partial understanding of physical tasks at a level that exceeds that previously attained by any other non-human subject, including apes.
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Watanabe, S., & Troje, N. F. (2006). Towards a “virtual pigeon”: a new technique for investigating avian social perception. Anim. Cogn., 9(4), 271–279.
Abstract: The purpose of the present study is to examine the applicability of a computer-generated, virtual animal to study animal cognition. Pigeons were trained to discriminate between movies of a real pigeon and a rat. Then, they were tested with movies of the computer-generated (CG) pigeon. Subjects showed generalization to the CG pigeon, however, they also responded to modified versions in which the CG pigeon was showing impossible movement, namely hopping and walking without its head bobbing. Hence, the pigeons did not attend to these particular details of the display. When they were trained to discriminate between the normal and the modified version of the CG pigeon, they were able to learn the discrimination. The results of an additional partial occlusion test suggest that the subjects used head movement as a cue for the usual vs. unusual CG pigeon discrimination.
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