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Nicol, C. J. (2000). Equine Stereotypies. In: Houpt K.A. (Ed.),. In Recent Advances in Companion Animal Behavior Problems. International Veterinary Information Service.
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Allen, C. (2006). Transitive inference in animals: Reasoning or conditioned associations? In S. Hurley, & M. Nudds (Eds.), Rational Animals? (pp. 175–186). Oxford: Oxford University Press.
Abstract: It is widely accepted that many species of nonhuman animals appear to engage in transitive inference,
producing appropriate responses to novel pairings of non-adjacent members of an ordered series
without previous experience of these pairings. Some researchers have taken this capability as
providing direct evidence that these animals reason. Others resist such declarations, favouring instead
explanations in terms of associative conditioning. Associative accounts of transitive inference have
been refined in application to a simple 5-element learning task that is the main paradigm for
laboratory investigations of the phenomenon, but it remains unclear how well those accounts
generalise to more information-rich environments such as social hierarchies which may contain scores
of individuals, and where rapid learning is important. The case of transitive inference is an example of
a more general dispute between proponents of associative accounts and advocates of more cognitive
accounts of animal behaviour. Examination of the specific details of transitive inference suggests
some lessons for the wider debate.
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Packer, C., & Pusey, A. E. (1985). Asymmetric contests in social mammals: respect, manipulation and age-specific aspects. In P. J. Greenwood, M. Slatkin, & (Ed.), Evolution: Essays in Honour of John Maynard Smith (pp. 173–86). Camebridge: Camebridge University Press.
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Ruffner Ga, C. S. (1979). Age structure, condition, and reproduction of two burro (Equus asinus) populations from Grand Canyon National Park, Arizona.
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Heyes, C., & Galef, B. G. (Eds.). (1996). Social learning in animals: the roots of culture. San Diego, CA: Academic Press, Inc.
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Berger, J., & Cunningham, C. (1988). Size-Related Effects on Search Times in North American Grassland Female Ungulates. Ecology, 69(1), 177–183.
Abstract: Feeding and searching (= vigilance) rates arise as a result of many interrelated factors including trophic level, diet, reproductive condition, sex, habitat, body mass, and potential predation pressure. Because of unique ecological conditions in which the confounding influences of all but two of these variables could be minimized, we examined the hypothesis that body mass alone accounts for interspecific differences in search times, and tested it with females of four sympatric native North American ungulates (Bison bison, Antilocapra americana, Ovis canadensis, and Odocoileus hemionus). When the effects of group size were controlled, smaller bodied species were more vigilant (per unit body mass) than larger ones. However, search times (ST) also scaled to body mass, and between 81 and 97% of the ST variance was explained by either exponential or power functions. To remove the potential bias that predators exert different influences on species of varying size, search times of bison in areas with and without their major predator, wolves (Canis lupus), were contrasted; search times did not differ between sites. Our results highlight the importance of designing field research that controls for confounding variables prior to attempting to scale behavioral processes to ecological events. See full-text article at JSTOR
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Nuñez, C. M. V., Adelman, J. S., Smith, J., Gesquiere, L. R., & Rubenstein, D. I. (2014). Linking social environment and stress physiology in feral mares (Equus caballus): Group transfers elevate fecal cortisol levels. General and Comparative Endocrinology, 196, 26–33.
Abstract: Abstract Feral horses (Equus caballus) have a complex social structure, the stability of which is important to their overall health. Behavioral and demographic research has shown that decreases in group (or band) stability reduce female fitness, but the potential effects on the physiological stress response have not been demonstrated. To fully understand how band stability affects group-member fitness, we need to understand not only behavioral and demographic, but also physiological consequences of decreases to that stability. We studied group changes in feral mares (an activity that induces instability, including both male and female aggression) on Shackleford Banks, NC. We found that mares in the midst of changing groups exhibit increased fecal cortisol levels. In addition, mares making more group transfers show higher levels of cortisol two weeks post-behavior. These results offer insights into how social instability is integrated into an animal’s physiological phenotype. In addition, our results have important implications for feral horse management. On Shackleford Banks, mares contracepted with porcine zona pellucida (PZP) make approximately 10 times as many group changes as do untreated mares. Such animals may therefore be at higher risk of chronic stress. These results support the growing consensus that links between behavior and physiological stress must be taken into account when managing for healthy, functional populations.
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Cunningham, C., & Berger, J. (1986). Wild horses of the Granite Range. Natural History, , 32–39.
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Kolter, L., Schach, C., & Weber, T. (1999). Habitat use of feral and Przewalski's horses. Natur- und Kulturlandschaft, 3(332-342).
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Kruger, K., Gaillard, C., Stranzinger, G., & Rieder, S. (2005). Phylogenetic analysis and species allocation of individual equids using microsatellite data. Journal of Animal Breeding and Genetics, 122(s1), 78–86.
Abstract: Summary The taxonomic status of all equid species is not completely unravelled. This is of practical relevance for conservation initiatives of endangered, fragmented equid populations, such as the Asiatic wild asses (in particular Equus hemionus onager and E. hemionus kulan). In this study, a marker panel consisting of 31 microsatellite loci was used to assess species demarcation and phylogeny, as well as allocation of individuals (n = 120) to specific populations of origin (n = 11). Phylogenetic analysis revealed coalescence times comparable with those previously published from fossil records and mtDNA data. Using Bayesian approaches, it was possible to distinguish between the studied equids, although individual assignment levels varied. The observed results support the maintenance of separate captive conservation herds for E. hemionus onager and E. hemionus kulan. The first molecular genetic results for E. hemionus luteus remained contradictory, as they unexpectedly indicated a closer genetic relationship between E. hemionus luteus and E. kiang holderi compared with the other hemiones.
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