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Mori, A.; Iwamoto, T.; Bekele, A. |
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Title |
A case of infanticide in a recently found gelada population in Arsi, Ethiopia |
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1997 |
Publication |
Primates |
Abbreviated Journal |
Primates |
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38 |
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1 |
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79-88 |
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Keywords  |
heropithecus gelada – Infanticide – Male takeover – Leadership change |
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Abstract There have been no reports of infanticide in wild gelada baboons and it has been argued that infanticide is not necessary in geladas, since the birth interval of female gelada can be shortened after takeover of a unit by a new leader male without infanticide. However, we observed an instance of infanticide in a newly-found wild gelada population in the Arsi Region of Ethiopia. After a leader male of the unit was severely wounded by a leopard attack, he was quite weakened. The second male of the unit, a young adult male, became the leader of the unit three weeks later, but the former leader continued to stay in the unit as a second male. After a week, two other adult males joined the unit which, therefore, came to include four adult males. The infanticide took place nine days later. The perpetrator was one of the immigrant males and he showed great interest in the mother of the unweaned victim infant. Although the perpetrator copulated with her after the infanticide, the usurper was found to own all three adult females after two weeks following the infanticide; i.e. the perpetrator could not own any female. The wounded former leader showed conspicuous protective behavior towards the victim's mother and the dead infant. One possible explanation for the occurrence of infanticide in this population of geladas is as follows. Gelada males in this area may be able to join units more easily to form multi-male units but then have shorter tenure in the units. Facing the unstable condition of units, they may sometimes engage in infanticide to increase their breeding opportunities, even before becoming a leader. |
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2061 |
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Author |
Flannery, B. |
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Title |
Relational discrimination learning in horses |
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1997 |
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Applied Animal Behaviour Science |
Abbreviated Journal |
Appl. Anim. Behav. Sci. |
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54 |
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4 |
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267-280 |
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Keywords |
Horses; Shaping; Complex discrimination; Concept formation; Generalization ability; Training |
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Abstract |
This series of studies investigated horses' ability to learn the concept of sameness under several different conditions. Before experimentation began, three horses were shaped to touch individually presented stimuli with their muzzles, and then to make two responses to two matching cards from an array of three. A modified version of the identity matching-to-sample (IMTS) procedure was used to present stimuli in a variety of configural arrangements on a barn wall (Experiment 1 and Experiment 2), and on a flat panel mounted to a barn door (Experiment 3). The task in each experiment was to select the two stimulus cards that were the same (either circles or Xs) and to avoid the nonmatching stimulus card (either a star or a square). In Experiment 1, the mean accuracy rate for selecting the matching alternatives was 74%. The horses' accuracy levels reached a mean level of 83% during Experiment 2, in which they received additional trials and an intermittent secondary reinforcement schedule. In Experiment 3, when the stimuli were moved further apart from each other within arrangements and were presented on a novel background, the mean accuracy rate was 73%. These data demonstrate that horses can learn complex discrimination problems involving the concept of sameness, and that they are able to generalize this learning to a novel stimulus presentation situation. These results also suggest that a relational discrimination test may be useful for assessing horses' learning ability and the level of training appropriate for individual horses. |
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Equine Behaviour @ team @ |
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3557 |
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Foster, T.M.; Matthews, L.R.; Temple, W.; Poling, A. |
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Concurrent schedule performance in domestic goats: persistent undermatching |
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1997 |
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Behavioural Processes |
Abbreviated Journal |
Behav. Process. |
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40 |
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3 |
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231-237 |
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Matching equation; Undermatching; Variable-interval schedule; Nose-press response; Goats |
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Performance of nine domestic goats responding under concurrent variable-interval variable-interval schedules of food delivery was examined, with results analyzed in terms of the generalized matching equation. Substantial undermatching of response and time allocation ratios to obtained reinforcement ratios was evident. Post-reinforcement pause time ratios approximately matched obtained reinforcement ratios. Subtracting these times from total time allocation values yielded net time allocation ratios, which undermatched obtained reinforcement ratios to a greater degree than whole-session time allocation ratios. Slopes of regression lines relating behavioral outputs to environmental inputs characteristically were below 0.6, which is similar to previous findings in dairy cows tested under comparable conditions. |
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Equine Behaviour @ team @ |
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3602 |
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Khalil, A.M.; Kaseda, Y. |
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Title |
Behavioral patterns and proximate reason of young male separation in Misaki feral horses |
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Journal Article |
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1997 |
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Applied Animal Behaviour Science |
Abbreviated Journal |
Appl. Anim. Behav. Sci. |
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54 |
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4 |
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281-289 |
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Misaki feral horse; Horse maternal-filial bond; Social behavior; Separation season; Separation reason |
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The present investigation was undertaken to study the proximate reasons why and the behavioral patterns of young male Misaki feral horses when they left their natal band or mothers. We observed a total of ten young males twice a month from January 1988 to December 1995. Almost all young males left their natal band or mothers at between 1 and 4 years of age. We found that, during the separation process, all the young males from first parity dams returned several times after the initial separation, indicating a strong attachment between primiparous mares and their male offspring. The other five separated only once without rejoining. Our observations showed five variable behavior patterns of young males at separation time, depending on the consort relation between their mothers and harem stallion and the reason for separation at that time. Eight young males separated in the non-breeding season at average 2.1 years and the other two separated in the breeding season at average 3 years and the average difference was not significant. These results revealed that 80% of the young males separated voluntarily when the natural resources become poor whereas 20% separated when their siblings were born. |
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Equine Behaviour @ team @ |
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2209 |
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Foster, T.M.; Temple, W.; Cameron, B.; Poling, A. |
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Title |
Demand curves for food in hens: Similarity under fixed-ratio and progressive-ratio schedules |
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Journal Article |
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Year |
1997 |
Publication |
Behavioural Processes |
Abbreviated Journal |
Behav. Process. |
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39 |
Issue |
2 |
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177-185 |
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Progressive-ratio schedule; Fixed-ratio schedule; Demand curves; Behavioral economics; Animal welfare; Keypecking; Chickens |
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Demand curves were generated for five domestic hens under progressive-ratio 5 schedules of food delivery and under fixed-ratio schedules of food delivery that began at fixed-ratio 5 and were incremented by 5 each session. All sessions ended after 10 consecutive minutes without a response. Although response rates at a given ratio were higher under the progressive-ratio schedule, all hens completed higher ratios under the fixed-ratio schedule. Similar, but not identical, demand curves were generated under progressive-ratio and fixed-ratio schedules. Under both schedules, consumption (reinforcers earned) decreased as cost (ratio size) increased. Data generally were well described by an equation in which elasticity of demand is constant, although an equation in which elasticity could vary accounted for slightly more of the variance. |
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Equine Behaviour @ team @ |
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3603 |
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Bergstrom,C. T.; Lachmann, M. |
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Title |
Signalling among relatives. I. Is costly signalling too costly? |
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Journal Article |
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1997 |
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Proceedings of the National Academy of Sciences of the United States of America |
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Proc. Natl. Acad. Sci. U.S.A. |
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352(1353) |
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609-617 |
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Signalling |
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Abstract |
ahavi's handicap principle,originally proposed as an explanation for sexual selection ofelaborate male traits, suggests that a sufficient cost to dishonest signals can outweigh the rewards of deception and allow individuals to communicate honestly. Maynard Smith (1991) and Johnstone and Grafen (1992) introduce the Sir Philip Sidney game in order to extend the handicap principle to interactions among related individuals, and to demonstrate that stable costly signalling systems can exist among relatives.
In this paper we demonstrate that despite the benefits associated with honest information transfer, the costs incurred in a stable costly signalling system may leave all participants worse off than they would be in a system with no signalling at all. In both the discrete and continuous forms of the Sir Philip Sidney game, there exist conditions under which costly signalling among relatives, while stable, is so costly that it is disadvantageous compared with no signalling at all. We determine the factors which dictate signal cost and signal benefit in a generalized version of this game, and explain how signal cost can exceed signal value. Such results raise concerns about theevolutionary pathways which could have led to the existence of signalling equilibria in nature. The paper stresses the importance of comparing signalling equilibria with other possible strategies, beforedrawing conclusions regarding the optimality of signalling. |
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refbase @ user @ |
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559 |
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Author |
Reeve, H. Kern |
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Evolutionarily stable communication between kin: a general model |
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1997 |
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Proceedings of the Royal Society B: Biological Sciences |
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Proc. Roy. Soc. Lond. B Biol. Sci. |
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264 |
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(1384) |
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1037-1040. |
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Signalling Systems |
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At present, the most general evolutionary theory of honest communication is Grafen's model of Zahavi's 'handicap' signalling system, in which honesty of signals about the signaller's quality (e.g. mate suitability or fighting ability) is maintained by the differentially high cost of signals to signallers having lower quality. The latter model is here further generalized to include any communication between signallers and receivers that are genetically related (e.g. parents and begging offspring, cooperative or competing siblings). Signalling systems involving relatives are shown to be evolutionarily stable, despite a potential pay-off for false signalling, if the Zahavian assumption of differential signal costs holds and there are diminishing reproductive returns to the signaller as the receiver's assessed value of its attribute increases, or if, regardless of whether the Zahavian assumption holds, signallers with high values of the attribute benefit more from a given receiver assessment than signallers with low values (e.g. begging chicks that are hungrier benefit more from being fed). In stable systems of signalling among kin, it is also shown to be generally true that (i) levels of signalling and thus observed signal costs will decline as relatedness increases or as the receiver's reproductive penalty for erroneous assessment increases, and (ii) receivers will consistently, altruistically overestimate the true value of the signalled attribute. |
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