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Author |
Lucas, Z.; Raeside, J.I.; Betteridge, K.J. |
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Title |
Non-invasive assessment of the incidences of pregnancy and pregnancy loss in the feral horses of Sable Island |
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Journal Article |
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Year |
1991 |
Publication |
Journal of Reproduction and Fertility. Supplement |
Abbreviated Journal |
J Reprod Fertil Suppl |
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44 |
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479-488 |
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Abortion, Veterinary/*epidemiology; Animals; Animals, Wild/*physiology; Atlantic Islands; Estrogens/analysis; Feces/chemistry; Female; Fertilization; Gestational Age; Horse Diseases/*epidemiology; Horses; Incidence; Pregnancy; *Pregnancy, Animal |
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Field observations of 400 totally unmanaged feral horses on Sable Island, Nova Scotia, were complemented by oestrogen determinations in faecal samples from 154 identified females over a 4-year period (454 mare-years). Of mares that were sampled throughout the year and subsequently produced foals, 92.1% exhibited elevated faecal oestrogens between 15 October and 30 March. The results confirm that faecal oestrogens are a useful indicator of pregnancy after approximately 120 days gestation. Distribution of foaling resembled that seen in other feral populations, with 95% of births occurring from April through July. The foaling rate for mares aged 3 years or older was 62.0%, with 50.7% of mares foaling in 3 or 4 years. Foaling rates were low (4.1%) in mares bred as yearlings and rose with age to 70.8% in those bred as 4-year-olds. Fetal loss after Day 120 was deduced from faecal oestrogens to be 26.0% overall, with marked variation from year to year (9.6-37.3%) and with age (70.0% in those bred as yearlings, decreasing to 5.6% in those bred as 4-year-olds). Of 58 mares aged 2 years or older that were sampled every year, about half (49.6%) the barren years were attributable to fetal loss after 120 days gestation. All mares conceived in at least 2 of the 4 years, suggesting that pregnancy loss, even after Day 120, is as important as failure to conceive in causing barren years. |
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Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Canada |
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0449-3087 |
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PMID:1795292 |
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Equine Behaviour @ team @ |
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2247 |
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Author |
Garott, R.A. |
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Title |
Sex Ratios and Differential Survival of Feral Hors |
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Journal Article |
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Year |
1991 |
Publication |
Journal of Animal Ecology |
Abbreviated Journal |
J Anim Ecol |
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Volume |
60 |
Issue |
3 |
Pages |
929-936 |
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(1) Sex and age data were collected on 60 111 feral horses (Equus caballus L.) removed from eighty-nine areas in Nevada, Wyoming, and Oregon between 1976 and 1987. (2) Sex ratios of young seldom differed from parity; however, sex ratios of adults were commonly skewed toward females. No evidence of differential capture probability between adult males and females could be detected; therefore, skewed adult sex ratios were attributed to differential survival. (3) Age-specific trends in sex ratios indicated that the proportion of males steadily decreased from near parity in foals, to lows of 0.61-0.77 in the 4-5-year age-classes. The trend then reversed with males becoming predominant (1.08-1.36) in the > 10 years age-class. (4) Population simulations suggest that survival diffentials of 0.05-0.07, favouring females to 4 years of age, and 0.02-0.04 favouring males in older age-classes were required to mimic observed age-specific sex ratio changes. To obtain the high proportion of males in the > 10-years age-class, onset of senescence also had to be earlier for females. (5) Causes for differential survival in the immature age-classes are uncertain, but may relate to behavioural or metabolic differences between the sexes. Differential survival between adult males and females is attributed to differences in the energetic costs of reproduction and disparity in their reproductive life spans. |
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Equine Behaviour @ team @ |
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2294 |
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Kirkpatrick, J.F.; Turner, J.W. |
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Title |
Changes in herd stallions among feral horse bands and the absence of forced copulation and induced abortion |
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Journal Article |
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Year |
1991 |
Publication |
Behavioral Ecology and Sociobiology |
Abbreviated Journal |
Behav. Ecol. Sociobiol. |
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29 |
Issue |
3 |
Pages |
217-219 |
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Forced copulation and induced abortion were investigated in a herd of feral horses inhabiting a coastal barrier island. Eight mares were diagnosed pregnant in August and October 1989 by means of urinary and fecal steroid metabolites, prior to documented changes in herd stallions. These mares were observed for harassment and forced copulation by the new stallions and for the presence of foals during the spring and summer of 1990. No incidents of harassment or attempts at forced copulation were witnessed and seven of the eight mares produced foals in 1990. These data indicate that forced copulation and induced abortion are not common events among all feral horse herds and suggest reinvestigation of this hypothesized phenomenon. |
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Equine Behaviour @ team @ |
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2327 |
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Author |
Marean, C.W.; Gifford-Gonzalez, D. |
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Title |
Late Quaternary extinct ungulates of East Africa and palaeoenvironmental implications |
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Journal Article |
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Year |
1991 |
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Nature |
Abbreviated Journal |
Nature |
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350 |
Issue |
6317 |
Pages |
418-420 |
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UNGULATE communities of two East African savannas, the Serengeti and Athi-Kapiti Plains, are dominated by wildebeest (Connochaetes taurinus) supplemented by zebra (Equus burchelli), topi (Damaliscus lunatus), hartebeest (Alcelaphus buselaphus), buffalo (Syncerus caffer) eland (Taurotragus oryx) and gazelles (Gazella grand and G. thomsoni)1-3. Before this research, little was known of East African large mammal communities in the Late Pleistocene and early to middle Holocene. We document an extinct impala-sized alcelaphine antelope that is numerically dominant in Late Pleistocene archaeofaunal assemblages from the Athi-Kapiti Plains. The extinct giant buffalo Pelorovis antiquus is present, and a number of arid-adapted regionally extinct species are common. The small alcelaphine is rare in northern Tanzania, but regionally extinct arid-adapted species are present in Late Pleistocene deposits. These data indicate that as recently as 12,000 years ago, the large mammal community structure of East African savannas was very different and dry grasslands and arid-adapted ungulates expanded at least as far south as northern Tanzania during the Last Glacial Maximum. |
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10.1038/350418a0 |
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no |
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Equine Behaviour @ team @ |
Serial |
2345 |
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Author |
Duncan, I.J.; Petherick, J.C. |
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Title |
The implications of cognitive processes for animal welfare |
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Journal Article |
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Year |
1991 |
Publication |
Journal of Animal Science |
Abbreviated Journal |
J. Anim Sci. |
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Volume |
69 |
Issue |
12 |
Pages |
5017-5022 |
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Keywords |
*Animal Welfare; Animals; Animals, Domestic/*psychology; *Cognition |
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Abstract |
In general, codes that have been designed to safeguard the welfare of animals emphasize the importance of providing an environment that will ensure good health and a normal physiological and physical state, that is, they emphasize the animals' physical needs. If mental needs are mentioned, they are always relegated to secondary importance. The argument is put forward here that animal welfare is dependent solely on the cognitive needs of the animals concerned. In general, if these cognitive needs are met, they will protect the animals' physical needs. It is contended that in the few cases in which they do not safeguard the physical needs, it does not matter from a welfare point of view. The human example is given of being ill. It is argued that welfare is only adversely affected when a person feels ill, knows that he or she is ill, or even thinks that he or she is ill, all of which processes are cognitive ones. The implications for welfare of animals possessing certain cognitive abilities are discussed. For example, the extent to which animals are aware of their internal state while performing behavior known to be indicative of so-called states of suffering, such as fear, frustration, and pain, will determine how much they are actually suffering. With careful experimentation it may be possible to determine how negative they feel these states to be. Similarly, the extent to which animals think about items or events absent from their immediate environment will determine how frustrated they are in the absence of the real item or event but in the presence of the cognitive representation. |
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University of Guelph, Canada |
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0021-8812 |
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PMID:1808195 |
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Call Number |
Equine Behaviour @ team @ |
Serial |
2753 |
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Author |
Curtis, S.E.; Stricklin, W.R. |
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Title |
The importance of animal cognition in agricultural animal production systems: an overview |
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Journal Article |
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Year |
1991 |
Publication |
Journal of Animal Science |
Abbreviated Journal |
J. Anim Sci. |
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Volume |
69 |
Issue |
12 |
Pages |
5001-5007 |
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*Agriculture; Animal Population Groups/*psychology; *Animal Welfare; Animals; *Behavior, Animal; *Cognition; Heat; Helplessness, Learned; Housing, Animal/standards; Immobilization; Nesting Behavior; Pain/psychology/veterinary |
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To describe and then fulfill agricultural animals' needs, we must learn more about their fundamental psychological and behavioral processes. How does this animal feel? Is that animal suffering? Will we ever be able to know these things? Scientists specializing in animal cognition say that there are numerous problems but that they can be overcome. Recognition by scientists of the notion of animal awareness has been increasing in recent years, because of the work of Griffin and others. Feeling, thinking, remembering, and imagining are cognitive processes that are factors in the economic and humane production of agricultural animals. It has been observed that the animal welfare debate depends on two controversial questions: Do animals have subjective feelings? If they do, can we find indicators that reveal them? Here, indirect behavioral analysis approaches must be taken. Moreover, the linear additivity of several stressor effects on a variety of animal traits suggests that some single phenomenon is acting as a “clearinghouse” for many or all of the stresses acting on an animal at any given time, and this phenomenon might be psychological stress. Specific situations animals may encounter in agricultural production settings are discussed with respect to the animals' subjective feelings. |
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University of Illinois, Urbana 61801 |
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0021-8812 |
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PMID:1808193 |
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Equine Behaviour @ team @ |
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2754 |
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Author |
Rilling, M.E.; Neiworth, J.J. |
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Title |
How animals use images |
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Journal Article |
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Year |
1991 |
Publication |
Science Progress |
Abbreviated Journal |
Sci Prog |
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75 |
Issue |
298 Pt 3-4 |
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439-452 |
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Animals; Association Learning; Columbidae; *Concept Formation; *Imagination; *Mental Recall; Motion Perception; Problem Solving; *Thinking; *Visual Perception |
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Abstract |
Animal cognition is a field within experimental psychology in which cognitive processes formerly studied exclusively with people have been demonstrated in animals. Evidence for imagery in the pigeon emerges from the experiments described here. The pigeon's task was to discriminate, by pecking the appropriate choice key, between a clock hand presented on a video screen that rotated clockwise with constant velocity from a clock hand that violated constant velocity. Imagery was defined by trials on which the line rotated from 12.00 o'clock to 3.00 o'clock, then disappeared during a delay, and reappeared at a final stop location beyond 3.00 o'clock. After acquisition of a discrimination with final stop locations at 3.00 o'clock and 6.00 o'clock, the evidence for imagery was the accurate responding of the pigeons to novel locations at 4.00 o'clock and 7.00 o'clock. Pigeons display evidence of imagery by transforming a representation of movement that includes a series of intermediate steps which accurately represent the location of a moving stimulus after it disappears. |
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Department of Psychology, Michigan State University, East Lansing 48824 |
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0036-8504 |
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PMID:1842858 |
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Equine Behaviour @ team @ |
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2831 |
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Author |
Real, L.A. |
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Title |
Animal choice behavior and the evolution of cognitive architecture |
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Journal Article |
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Year |
1991 |
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Science (New York, N.Y.) |
Abbreviated Journal |
Science |
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253 |
Issue |
5023 |
Pages |
980-986 |
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Animals; Bees/genetics/*physiology; Biomechanics; *Choice Behavior; *Cognition; *Evolution; Mathematics; Models, Genetic; Probability |
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Abstract |
Animals process sensory information according to specific computational rules and, subsequently, form representations of their environments that form the basis for decisions and choices. The specific computational rules used by organisms will often be evolutionarily adaptive by generating higher probabilities of survival, reproduction, and resource acquisition. Experiments with enclosed colonies of bumblebees constrained to foraging on artificial flowers suggest that the bumblebee's cognitive architecture is designed to efficiently exploit floral resources from spatially structured environments given limits on memory and the neuronal processing of information. A non-linear relationship between the biomechanics of nectar extraction and rates of net energetic gain by individual bees may account for sensitivities to both the arithmetic mean and variance in reward distributions in flowers. Heuristic rules that lead to efficient resource exploitation may also lead to subjective misperception of likelihoods. Subjective probability formation may then be viewed as a problem in pattern recognition subject to specific sampling schemes and memory constraints. |
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Department of Biology, University of North Carolina, Chapel Hill 27599-3280 |
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0036-8075 |
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PMID:1887231 |
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Equine Behaviour @ team @ |
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2846 |
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Author |
Chapais, B.; Girard, M.; Primi, G. |
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Title |
Non-kin alliances, and the stability of matrilineal dominance relations in Japanese macaques |
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Journal Article |
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1991 |
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Animal Behaviour. |
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Anim. Behav. |
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41 |
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3 |
Pages |
481-491 |
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Alliances among kin play a major role in a female's acquisition of her mother's dominance rank in many species of cercopithecines. It is noteworthy, however, that kin rarely form coalitions to challenge females from higher-ranking matrilines, and that matrilineal hierarchies are remarkably stable. One possible reason for the rarity of destabilizing coalitions is that members of high-ranking matrilines form alliances against lower ranking ones. In this paper the patterning of aggressive support among non-kin, and its effect on the stability of rank relations are analysed in a captive group of Japanese macaques, Macaca fuscata, composed of three unrelated matrilines. Analysis of the distribution of non-kin interventions in conflicts between matrilines over a 52-month period revealed a clear pattern of preferential support between the two dominant matrilines against the third-ranking one. This pattern was confirmed experimentally. Any member of the two dominant matrilines was unable, individually, to maintain its rank above the third-ranking matriline, but was able to do so in the presence of the other dominant matriline. Non-kin alliances appear to prevent subordinate females from challenging higher ranking females through revolutionary coalitions (formed among subordinates) or through bridging coalitions (formed among individuals ranking above and below the target). Non-kin support is interpreted in terms of cooperation versus reciprocal altruism. |
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refbase @ user @ |
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2863 |
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Kendrick, K.M. |
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How the sheep's brain controls the visual recognition of animals and humans |
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Journal Article |
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1991 |
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Journal of Animal Science |
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J. Anim Sci. |
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69 |
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12 |
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5008-5016 |
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Equine Behaviour @ team @ |
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2940 |
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