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Ogbourne, C. P. (1971). Variations in the fecundity of strongylid worms of the horse. Parasitology, 63(2), 289–298.
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Polyanskaya, A. I., & Ovchinnikov, V. V. (1974). Rate of growth and size of the brain of the horse mackerel. Sov J Ecol, 4(3), 256–257.
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Punzo, F., & Ludwig, L. (2002). Contact with maternal parent and siblings affects hunting behavior, learning, and central nervous system development in spiderlings of Hogna carolinensis (Araeneae: Lycosidae). Anim. Cogn., 5(2), 63–70.
Abstract: The purpose of this study was to determine the effects of early experience (rearing conditions) on the central nervous system (CNS) and behavior of spiderlings of Hogna carolinensis (Lycosidae). We were interested in whether or not spiderlings that were allowed to remain in contact with their maternal parent and siblings (enriched condition, EC) would exhibit differences in CNS development or subsequent behavior when compared with those reared in isolation (improverished condition, IC). Spiderlings emerged from their egg sacs and climbed onto the dorsal surface of their mother's abdomen where they remained until their yolk supply was depleted (5 days). They dispersed on day 6 after emergence. We compared the ability of 16-day-old EC and IC spiderlings to capture prey in a linear runway and to learn a complex maze (spatial learning). We also compared certain aspects of CNS development (brain weight, total number of brain cells, volume of central body and protocerebral neuropil) in EC and IC spiderlings. Results indicated that EC subjects are more efficient at capturing moving prey (crickets) and exhibited improved performance (significantly fewer blind alley errors) in the maze. The volume of the protocerebral neuropil in 6-day-old EC animals increased 30% over a 5-day period after emergence as compared to IC animals of the same age. The volume of the central body of EC animals increased 34.8% over the same time period. On day 6 after emergence, the weight of the protocerebrum was significantly greater in EC versus IC subjects. There were no significant effects of rearing condition (EC vs IC) or age (1- and 6-day-old spiderlings) on the total number of nerve cells in the protocerebrum, suggesting that the difference in protocerebral weight was due primarily to differences in supporting glial tissues and neuropil matrix. In conclusion, the data suggest that early contact with the maternal parent and siblings is of vital importance to CNS development in lycosid spiderlings and can influence the capacity for spatial learning as well as the ability to capture prey.
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Reinhardt, I., Kluth, G., Nowak, C., Szentiks, C. A., Krone, O., Ansorge, H., et al. (2019). Military training areas facilitate the recolonization of wolves in Germany. Conservation Letters, 12(3), e12635.
Abstract: Abstract Wolves (Canis lupus) are currently showing a remarkable comeback in the highly fragmented cultural landscapes of Germany. We here show that wolf numbers increased exponentially between 2000 and 2015 with an annual increase of about 36%. We demonstrate that the first territories in each newly colonized region were established over long distances from the nearest known reproducing pack on active military training areas (MTAs). We show that MTAs, rather than protected areas, served as stepping-stones for the recolonization of Germany facilitating subsequent spreading of wolf territories in the surrounding landscape. We did not find any significant difference between MTAs and protected areas with regard to habitat. One possible reason for the importance of MTAs may be their lower anthropogenic mortality rates compared to protected and other areas. To our knowledge, this is the first documented case where MTAs facilitate the recolonization of an endangered species across large areas.
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Riebli, T., Avgan, B., Bottini, A. - M., Duc, C., Taborsky, M., & Heg, D. (2011). Behavioural type affects dominance and growth in staged encounters of cooperatively breeding cichlids. Anim. Behav., 81(1), 313–323.
Abstract: In animals, behavioural properties such as aggressive propensity are often consistent over a life span, and they may form part of a behavioural syndrome. We studied how aggressive propensity influences dominance, contest behaviour and growth in the cooperatively breeding cichlid fish Neolamprologus pulcher. We tested whether intrinsic aggressive propensity (1) influences dominance in paired contests, (2) causes different aggression levels in contests with partners matched for aggressive propensity compared to unmatched partners, and how it (3) affects growth rate in groups that were either matched or unmatched for aggressive propensity. Intrinsic aggressive propensity was first scored with a mirror test and classified as high, medium or low. Thereafter we tested fish with either high or low aggressive propensity with partners matched for size and either matched or unmatched for aggressive type in a paired contest for a shelter. We scored dominance, aggression and submission. As predicted, (1) dominance was more clearly established in unmatched than in matched contests and (2) individuals with high aggressive propensity launched more attacks overall than fish with low intrinsic aggressiveness, suggesting a higher propensity to escalate independently of winning or losing the paired contest. However, contrary to expectation, (3) individuals with low aggressiveness grew faster than aggressive ones in unmatched groups, whereas the opposite occurred in matched groups. This suggests that individuals with low aggressive propensity may benefit from conflict evasion, which might allow them to gain dominance in the future owing to larger body size.
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Santamaria, S., Bobbert, M. F., Back, W., Barneveld, A., & van Weeren, P. R. (2005). Effect of early training on the jumping technique of horses. Am J Vet Res, 66(3), 418–424.
Abstract: OBJECTIVE: To investigate the effects of early training for jumping by comparing the jumping technique of horses that had received early training with that of horses raised conventionally. ANIMALS: 40 Dutch Warmblood horses. PROCEDURE: The horses were analyzed kinematically during free jumping at 6 months of age. Subsequently, they were allocated into a control group that was raised conventionally and an experimental group that received 30 months of early training starting at 6 months of age. At 4 years of age, after a period of rest in pasture and a short period of training with a rider, both groups were analyzed kinematically during free jumping. Subsequently, both groups started a 1-year intensive training for jumping, and at 5 years of age, they were again analyzed kinematically during free jumping. In addition, the horses competed in a puissance competition to test maximal performance. RESULTS: Whereas there were no differences in jumping technique between experimental and control horses at 6 months of age, at 4 years, the experimental horses jumped in a more effective manner than the control horses; they raised their center of gravity less yet cleared more fences successfully than the control horses. However, at 5 years of age, these differences were not detected. Furthermore, the experimental horses did not perform better than the control horses in the puissance competition. CONCLUSIONS AND CLINICAL RELEVANCE: Specific training for jumping of horses at an early age is unnecessary because the effects on jumping technique and jumping capacity are not permanent.
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Santos, L. R., Miller, C. T., & Hauser, M. D. (2003). Representing tools: how two non-human primate species distinguish between the functionally relevant and irrelevant features of a tool. Anim. Cogn., 6(4), 269–281.
Abstract: Few studies have examined whether non-human tool-users understand the properties that are relevant for a tool's function. We tested cotton-top tamarins (Saguinus oedipus) and rhesus macaques (Macaca mulatta) on an expectancy violation procedure designed to assess whether these species make distinctions between the functionally relevant and irrelevant features of a tool. Subjects watched an experimenter use a tool to push a grape down a ramp, and then were presented with different displays in which the features of the original tool (shape, color, orientation) were selectively varied. Results indicated that both species looked longer when a newly shaped stick acted on the grape than when a newly colored stick performed the same action, suggesting that both species perceive shape as a more salient transformation than color. In contrast, tamarins, but not rhesus, attended to changes in the tool's orientation. We propose that some non-human primates begin with a predisposition to attend to a tool's shape and, with sufficient experience, develop a more sophisticated understanding of the features that are functionally relevant to tools.
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Smith, D. G., & Pearson, R. A. (2005). A review of the factors affecting the survival of donkeys in semi-arid regions of sub-Saharan Africa. Trop Anim Health Prod, 37 Suppl 1, 1–19.
Abstract: The large fluctuations seen in cattle populations during periods of drought in sub-Saharan Africa are not evident in the donkey population. Donkeys appear to have a survival advantage over cattle that is increasingly recognized by smallholder farmers in their selection of working animals. The donkey's survival advantages arise from both socioeconomic and biological factors. Socioeconomic factors include the maintenance of a low sustainable population of donkeys owing to their single-purpose role and their low social status. Also, because donkeys are not usually used as a meat animal and can provide a regular income as a working animal, they are not slaughtered in response to drought, as are cattle. Donkeys have a range of physiological and behavioural adaptations that individually provide small survival advantages over cattle but collectively may make a large difference to whether or not they survive drought. Donkeys have lower maintenance costs as a result of their size and spend less energy while foraging for food; lower energy costs result in a lower dry matter intake (DMI) requirement. In donkeys, low-quality diets are digested almost as efficiently as in ruminants and, because of a highly selective feeding strategy, the quality of diet obtained by donkeys in a given pasture is higher than that obtained by cattle. Lower energy costs of walking, longer foraging times per day and ability to tolerate thirst may allow donkeys to access more remote, under-utilized sources of forage that are inaccessible to cattle on rangeland. As donkeys become a more popular choice of working animal for farmers, specific management practices need to be devised that allow donkeys to fully maximize their natural survival advantages.
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Sousa, C., Okamoto, S., & Matsuzawa, T. (2003). Behavioural development in a matching-to-sample task and token use by an infant chimpanzee reared by his mother. Anim. Cogn., 6(4), 259–267.
Abstract: We investigated the behavioural and cognitive development of a captive male infant chimpanzee, Ayumu, raised by his mother, Ai. Here we report Ayumu's achievements up to the age of 2 years and 3 months, in the context of complex computer-controlled tasks. From soon after birth, Ayumu had been present during an experiment performed by his mother. The task consisted of two phases, a matching-to-sample task in which she received token rewards, and the insertion of these tokens into a vending machine to obtain food rewards. Ayumu himself received no reward or encouragement from humans for any of the actions he exhibited during the experiment. At the age of 9 months and 3 weeks, Ayumu performed his first matching-to-sample trial. At around 1 year and 3 months, he began to perform them consistently. Also during this period, he frequently stole food rewards from his mother. At 2 years and 3 months, Ayumu succeeded for the first time in inserting a token into the vending machine. Once he had succeeded in using a token, he performed both phases of the task in sequence 20 times consecutively. The infant's behaviour was not shaped by food rewards but by a strong motivation to copy his mother's behaviour. Our observations of Ayumu thus mirror the learning processes shown by wild chimpanzees.
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Stamps, J. A. (2007). Growth-mortality tradeoffs and 'personality traits' in animals. Ecol Lett, 10(5), 355–363.
Abstract: Consistent individual differences in boldness, reactivity, aggressiveness, and other 'personality traits' in animals are stable within individuals but vary across individuals, for reasons which are currently obscure. Here, I suggest that consistent individual differences in growth rates encourage consistent individual differences in behavior patterns that contribute to growth-mortality tradeoffs. This hypothesis predicts that behavior patterns that increase both growth and mortality rates (e.g. foraging under predation risk, aggressive defense of feeding territories) will be positively correlated with one another across individuals, that selection for high growth rates will increase mean levels of potentially risky behavior across populations, and that within populations, faster-growing individuals will take more risks in foraging contexts than slower-growing individuals. Tentative empirical support for these predictions suggests that a growth-mortality perspective may help explain some of the consistent individual differences in behavioral traits that have been reported in fish, amphibians, reptiles, and other animals with indeterminate growth.
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