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Author |
Keiper, R.; Receveur, H. |
Title |
Social interactions of free-ranging Przewalski horses in semi-reserves in the Netherlands |
Type |
Journal Article |
Year |
1992 |
Publication |
Applied Animal Behaviour Science |
Abbreviated Journal |
Appl. Anim. Behav. Sci. |
Volume |
33 |
Issue |
4 |
Pages |
303-318 |
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Abstract |
Social interactions were recorded in two bands of free-ranging Przewalski horses living on large (greater than 30 ha) pastures in the Netherlands. The average number of aggressive interactions per hour was 8.86 at Lelystad and 10.36 at Noorderheide. The most common aggressive interactions were lower intensity, lower cost displacements (17.2% of all aggressive acts at Lelystad, 13.2% at Noorderheide), threats to bite (42.3% and 40.7%, respectively) and threats to kick (15.4% and 23.9%, respectively). Analysis of aggression revealed that a clear, linear dominance hierarchy was present in each band. For each band there was a positive and highly significant correlation between the age of a horse and its rank in the hierarchy. In each band, the stallion was not the highest ranked horse. Non-agonistic behaviors exceeded the number of agonistic interactions (1253 vs. 558 for Lelystad; 1257 vs. 995 at Noorderheide). There was a negative correlation between the rank of a horse in the dominance hierarchy and the number of non-agonistic behaviors displayed. The group displaying the highest number of non-agonistic interactions were foals (48.9% of total non-agonistic behaviors at Lelystad; 51.1% at Noorderheide). The non-agonistic/agonistic ratio was greater than 1 for yearlings and the band stallion, as was also the case for foals, but was less than 1 for males. |
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refbase @ user @ |
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778 |
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Author |
Timney, B.; Keil, K. |
Title |
Visual acuity in the horse |
Type |
Journal Article |
Year |
1992 |
Publication |
Vision Research |
Abbreviated Journal |
Vis. Res. |
Volume |
32 |
Issue |
12 |
Pages |
2289-2293 |
Keywords |
Horse Visual acuity Visual discrimination |
Abstract |
We assessed the ease with which horses could learn visual discriminations and measured their resolution acuity. We trained three horses to press their noses against one of two large wooden panels to receive a small food reward. Following training on a series of two-choice discrimination tasks, resolution acuity was measured. Although there was some variability between animals, the best acuity obtained was 23.3 c deg-1. Within the margin of error imposed by limited anatomical data, the obtained values are consistent with predictions based on retinal ganglion cell density estimates and posterior nodal distance/axial length ratios. They suggest that the resolution acuity of the horse is limited by ganglion cell density in the temporal portion of the narrow visual streak. |
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refbase @ user @ |
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851 |
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Author |
Duncan P, |
Title |
Zebras, asses, and horses |
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Book Whole |
Year |
1992 |
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Kelvyn Press USA |
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Provides summaries of the conservation status, biology, and ecology of wild zebras, asses, and horses. The Action Plan presents chapters on taxonomy, genetics, reproductive biology, population dynamics, management, disease and epidemiology, and the importance of developing an assessment methodology that considers the role of equids in ecosystems. |
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Kelvyn Press |
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Broadview, Illinois |
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978-2831700564 |
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from Professor Hans Klingels Equine Reference List JA - |
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yes |
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1032 |
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Elzenga, J. W, |
Title |
Why zebras are striped |
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Journal Article |
Year |
1992 |
Publication |
Swara |
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Swara |
Volume |
15 |
Issue |
4 |
Pages |
28-30 |
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from Professor Hans Klingels Equine Reference List |
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yes |
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1068 |
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Winkler A, |
Title |
The feeding ecology of the Cape Mountain zebra in the Mountain Zebra National Park |
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1992 |
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Doctoral thesis |
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from Professor Hans Klingels Equine Reference List |
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yes |
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1713 |
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Author |
Kabuga, J.D. |
Title |
Social relationships in N'dama cattle during supplementary feeding |
Type |
Journal Article |
Year |
1992 |
Publication |
Applied Animal Behaviour Science |
Abbreviated Journal |
Appl. Anim. Behav. Sci. |
Volume |
34 |
Issue |
4 |
Pages |
285-290 |
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Social relationships of 30 N'dama cows during supplementary feeding, post-grazing, were studied over a period of 1.5 years. Dominance ranks determined during idling and feeding periods were strongly correlated (Spearman's rank correlation (rs = 0.964, P < 0.01). The number of animals dominated by a cow during feeding was strongly (P < 0.01) related to liveweight (r = 0.822) and age (r = 0.755). Low status cows ate less frequently than medium and high status animals, while middle ranking cows were ejected more frequently from the feed trough than other dominance groups. Animals had preferences in the use of feed troughs, with social rank being the dominant factor determining the location of feed trough space used. Cows of similar status were generally preferred feeding and movement neighbours and antagonists. However, the dominance rank of an animal and its preferred neighbour during idling were not significantly correlated (rs = 0.220, P > 0.05). Voluntary leadership ranks into and out of the pen were, respectively, related closely (P < 0.01) to feeding dominance ranks (rs = 0.661, 0.640) and idling dominance ranks (rs = 0.621, 0.669). |
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Equine Behaviour @ team @ room B 3.029 |
Serial |
2033 |
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Author |
Brunner, D.; Kacelnik, A.; Gibbon, J. |
Title |
Optimal foraging and timing processes in the starling, Sturnus vulgaris: effect of inter-capture interval |
Type |
Journal Article |
Year |
1992 |
Publication |
Animal Behaviour. |
Abbreviated Journal |
Anim. Behav. |
Volume |
44 |
Issue |
4 |
Pages |
597-613 |
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Laboratory experiments with starlings, Sturnus vulgaris, were conducted to investigate the interaction between timing and cost-benefit considerations. The design simulated an environment in which food was distributed in patches. Patches contained a random number of food items (N=0-4) separated by a fixed inter-capture interval or fixed interval. All patches ended with sudden depletion. The time elapsed since the last prey capture was the only way to detect the depletion of the patch. Once the patch was depleted a new patch could be reached by travelling between two perches. Three measures of timing were taken: (1) rate of working for food as function of `waiting' time in a patch, (2) the time of the last response in a patch or `giving-in' time, and (3) the time at which travel was initiated or `moving-on' time. The fixed interval that characterized patches was varied between conditions. The mean time of the peak in working rate was consistently centred around the fixed interval, while the other two measures of timing kept a roughly linear relation to the fixed interval, with slope greater than one. In accordance with Scalar Expectancy Theory, variability in the three forms of timing was proportional to the magnitude of the fixed interval. The birds seemed to take account of this increase in variability as shown by the mean value of their giving-up criterion. These results imply that information-processing constraints are important for modelling behavioural optimality. |
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2112 |
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Author |
Caraco, T.; Kacelnik, A.; Mesnick, N.; Smulewitz, M. |
Title |
Short-term rate maximization when rewards and delays covary |
Type |
Journal Article |
Year |
1992 |
Publication |
Animal Behaviour. |
Abbreviated Journal |
Anim. Behav. |
Volume |
44 |
Issue |
Part 3 |
Pages |
441-447 |
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Abstract |
In nature foragers must exploit resources that vary randomly in both the energy acquired per item (reward) and the time required to pursue, capture and process an item (delay). Furthermore, rewards and delays associated with particular resources may often covary significantly. An analytical model asks how variance-covariance levels for rewards and delays could influence choice of resources when lack of information or cognitive limitation implies that a consumer attempts to maximize its short-term rate of energy gain. Both greater expected reward and reduced expected delay clearly should enhance preference for a resource. The model predicts that increased delay variance and reduced reward-delay covariance should increase a forager's preference for a resource. A forager should be risk-averse towards reward variance when the reward-delay covariance is positive, but should become risk-prone towards reward variance when the reward-delay covariance is negative. |
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2113 |
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Author |
Kacelnik, A.; Todd, I.A. |
Title |
Psychological mechanisms and the Marginal Value Theorem: effect of variability in travel time on patch exploitation |
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Journal Article |
Year |
1992 |
Publication |
Animal Behaviour. |
Abbreviated Journal |
Anim. Behav. |
Volume |
43 |
Issue |
2 |
Pages |
313-322 |
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The Marginal Value Theorem (MVT) describes the behaviour that maximizes the ratio of expected gain over expected foraging time in a patchy environment. When travel time is variable, the MVT rationale and its predictions are sensitive only to the mean travel time and not to the spread or skew of the distribution. Two mechanistic arguments contradict these predictions. First, tests of the MVT have previously shown that there is a disproportionate influence of the last travel time, and second, psychological models of information processing suggest that memory for time intervals is strongly dependent on the scatter of the distribution experienced. These mechanistic concepts, combined with Jensen's inequality, suggest that patch exploitation should decrease as the scatter of the travel distribution increases. In a Skinner box experiment with pigeons, Columba livia, the problem was examined by simulating three environments with identical patches and the same mean travel time, but different travel time variability. Patch exploitation decreased with increasing variance in travel time. The results are used to argue in favour of the inclusion of realistic psychological properties as constraints in functional models of behaviour. Although both the MVT and the mechanistic models account for some features of the results, none of them can explain all the findings. |
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2114 |
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Author |
Dugatkin, L.A.; Godin, G.J. |
Title |
Predator inspection, shoaling and foraging under predation hazard in the Trinidadian guppy,Poecilia reticulata |
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Journal Article |
Year |
1992 |
Publication |
Environmental Biology of Fishes |
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34 |
Issue |
3 |
Pages |
265-276 |
Keywords |
Antipredation – Social group – Feeding – Predation risk – Trade-off – Fish |
Abstract |
Guppies,Poecilia reticulata, living in stream pools in Trinidad, West Indies, approached a potential fish predator (a cichlid fish model) in a tentative, saltatory manner, mainly as singletons or in pairs. Such behavior is referred to as predator inspection behavior. Inspectors approached the trunk and tail of the predator model more frequently, more closely and in larger groups than they approached the predator's head, which is presumably the most dangerous area around the predator. However, guppies were not observed in significantly larger shoals in the stream when the predator model was present. In a stream enclosure, guppies inspected the predator model more frequently when it was stationary compared to when it was moving, and made closer inspections to the posterior regions of the predator than to its head. Therefore, the guppies apparently regarded the predator model as a potential threat and modified their behavior accordingly when inspecting it. Guppies exhibited a lower feeding rate in the presence of the predator, suggesting a trade-off between foraging gains and safety against predation. Our results further suggest that predator inspection behavior may account for some of this reduction in foraging. These findings are discussed in the context of the benefits and costs of predator inspection behavior. |
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Equine Behaviour @ team @ |
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2176 |
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