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Smuts, M. M. S., & Penzhorn, B. L. (1988). Descriptions of antomical differences between skulls and mandibles of Equus zebra and E. burchelli from southern Africa. South African Journal of Zoology, 23((4)3), 328–336.
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VanDierendonck, M. C., de Vries, H., Schilder, M.B.H. (1995). An Analysis of Dominance, Its Behavioural Parameters and Possible Determinants in a Herd of Icelandic horses in captivity. Netherl. J. Zool., 45(3-4), 362–385.
Abstract: Feral horses are social animals, which have to rely on survival strategies centered on the formation of cohesive social bonds within their bands. Many problems in the husbandry of social animals such as horses, are due to the fact that the limits of their adaptive abilities are exceeded. Evidence suggests that the fundamental social characteristics of domestic horses have remained relatively unchanged. The social structure, social strategies and social interactions were investigated (3 non-consecutive years, 24 hr per day for several weeks) in long term established groups of domestic horses (mares and geldings of all ages) and a few small introduced groups, kept in (semi)natural environments. The general aim was to investigate the social needs of domestic horses. The social life of domestic horses was characterised by long lasting bonds with preferred partners which were established and maintained by allogrooming, play, proximity and dominance behaviours. Bonding partners were mainly found within the same sex-age group, but adult geldings also bonded with sub-adult mares and geldings. Adult mares were clustered in a group, while the other animals formed a second group. Among the adult mares, subgroups according to reproductive state were formed. Individuals regulated their social network by interfering with interactions between other members of the herd, which in itself is complex. An intervention is a behavioural action of one animal that actively interferes with an ongoing interaction between a dyad with the apparent aim of altering that interaction. This was verified by post-hoc analyses of disturbed and undisturbed interactions. Interventions in allogrooming or play were performed significantly more often when at least one member of the initial dyad was a preferred partner of, or familiar to (within the small introduced bands) the intervener. The stronger the preferred association in allogrooming between the intervener and member(s) of the initial dyad, the higher the probability the intervener would displace one initial member and continue allogrooming with the other. Just five behaviours were extracted which reliably reflected the dominance relations among horses. Aggression with the hind quarters was used both offensively and defensively and therefore not suitable as a reliable parameter. Individual dominance relationships were related to social experience. The implications of these findings for horse husbandry were assessed. It is argued that the execution of affiliative behaviours may be rewarding in itself, and therefore always will be a highly motivated behaviour. It is shown that social positive physical interactions (allogrooming, play) with other horses is an ethological need and therefore indispensable in modern husbandry systems. Ethological needs are so important for the animal that husbandry systems that lack the possibilities to execute such behaviours will cause chronic stress. It is concluded that all horses need physical social contact, and that horses, which lack appropriate social learning experiences during ontogeny, may be hampered in their social functioning later in life. Solutions for problems, including dominance problems, in individual social housing and group housing are presented.
Keywords: Dominance; rank order; horses; Icelandic horses.
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Hogan, J. (2005). Causation: the study of behavioural mechanisms. Animal Biology (formerly Netherlands Journal of Zoology), 55(4), 323–341.
Abstract: This paper describes current work on the causal analysis of behaviour systems. It is noted that while causal work investigating the neural, hormonal, and genetic bases of behaviour is flourishing, work being conducted at a strictly behavioural level of analysis has declined greatly over the past 40 years. Nonetheless, most recent research on animal cognition and applied ethology is still being carried out at a behavioural level of analysis and examples of both types of research are presented: memory mechanisms of food-storing birds and decisions of spider-eating jumping spiders, as well as feather pecking in fowl and animal welfare issues, are all briefly discussed. Finally, I discuss the similarities between neural network modelling and early ethological models of motivation, and then show how a modern version of Lorenz's model of motivation can account for current research findings on dustbathing in chickens and sleep in humans. I conclude that valuable information can still be obtained by research at a behavioural level of analysis.
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Reader, S. M. (2003). Innovation and social learning: individual variation and brain evolution. Anim. Biol. Leiden., 53(2), 147–158.
Abstract: This paper reviews behavioural, neurological and cognitive correlates of innovation at the individual, population and species level, focusing on birds and primates. Innovation, new or modified learned behaviour not previously found in the population, is the first stage in many instances of cultural transmission and may play an important role in the lives of animals with generalist or opportunistic lifestyles. Within-species, innovation is associated with low neophobia, high neophilia, and with high social learning propensities. Indices of innovatory propensities can be calculated for taxonomic groups by counting the frequency of reports of innovation in published literature. These innovation rate data provide a useful comparative measure for studies of behavioural flexibility and cognition. Innovation rate is positively correlated with the relative size of association areas in the brain, namely the hyperstriatum ventrale and neostriatum in birds, and the neocortex and striatum in primates. Innovation rate is also positively correlated with the reported variety of tool use, as well as interspecific differences in learning. Current evidence thus suggests similar patterns of cognitive evolution in primates and birds.
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Bolhuis, J. (2005). Function and mechanism in neuroecology: looking for clues. Animal Biology (formerly Netherlands Journal of Zoology), 55(4), 457–490.
Abstract: The four questions that Niko Tinbergen identified for behavioural biology ? evolution, function, development and causation ? are all important and should be studied in their own right. Recently, there has been a debate as to whether these four questions should be investigated separately or whether they should be integrated. Integration of the four questions has been attempted in novel research disciplines such as cognitive ecology, evolutionary psychology and neuroecology. Euan Macphail and I have criticised these integrative approaches, suggesting that they are fundamentally flawed as they confound function and mechanism. Investigating the function or evolutionary history of a behaviour or cognitive system is important and entirely legitimate. However, such investigations cannot provide us with answers to questions about the mechanisms underlying behaviour or cognition. At most, functional or evolutionary considerations can provide clues that may be useful for a causal analysis of the underlying mechanisms. However, these clues can be misleading and are often wrong, as is illustrated with examples from song learning and food storing in birds. After summarising the main issues in the neuroecology debate, I discuss some misunderstandings that were apparent in the responses to our critique, as well as some recent relevant data. Recent results do not support the neuroecological approach. Finally, I suggest that the way forward is a cautious and critical use of functional and evolutionary clues in the study of the mechanisms of behaviour.
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Geisbauer, G., Griebel, U., Schmid, A., & Timney, B. (2004). Brightness discrimination and neutral point. Can. J. Zool, 82(4), 660–670.
Abstract: Abstract: Equine brightness discrimination ability and color discrimination were measured using a two-choice discrimination
task. Two Haflinger horses (Equus caballus L., 1758) were trained to discriminate 30 different shades of grey varying from low to high relative brightness. Their ability to distinguish shades of grey was poor, with calculated Weber fractions of 0.42 and 0.45. In addition, a “neutral point” test to determine the dimensionality of color vision was carried out. Three hues of blue-green were tested versus a range of grey targets with brightnesses similar to those of the blue-green targets. A neutral point was found at about 480 nm. Thus, we can conclude that horses possess dichromatic color vision. |
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Weckerly, F. W. (1999). Social bonding and aggression in female Roosevelt elk. Can J Zool, 77(9), 1379–1384.
Abstract: Abstract: The relationship between degree of social bonding (extent of association among individuals) and level of aggression in ruminants is unclear. I examined social bonding and aggression in three groups of female Roosevelt elk (Cervus elaphus roosevelti) over 2 years. I hypothesized that when animals are socially bonded, bouts of aggression will be won by the individual initiating the aggression, occur quickly, and involve little physical contact, and the level of aggression does not correlate with group size. The degree of social bonding was high among individuals in all groups. Dyads of known individuals were together >80% of the time. A permutation analysis indicated that groups with the observed sizes had <0.001 chance of random association, except on one occasion when the probability was 0.72 for one group. Using focal-animal sampling, aggressive interactions were won 72% of the time by the initiator, occurred quickly (<5 s), and involved little physical contact, and the level of aggression was not correlated with group size. The level of aggression was, however, significantly lower in one of the groups. This group may have had access to more abundant food resources than the other groups. Socially bonded elk conducted aggressive interactions in a fashion that did not disrupt social stability. Résumé : La relation entre le degré de liaison sociale (importance des associations entre individus) et l`agressivité n`est pas claire chez les ruminants. J`ai étudié les liaisons sociales et l`agressivité chez trois groupes de femelles du Cerf de Roosevelt (Cervus elaphus roosevelti) pendant 2 ans. J`ai posé en hypothèse que, chez les animaux liés socialement, la victoire devrait être emportée par l`individu qui entreprend l`agression, l`agression devrait être de courte durée, se faire avec peu de contacts physiques et la fréquence des agressions ne devrait pas être liée à la taille du groupe. Des paires d`individus passaient plus de 80% de leur temps ensemble. Une analyse des permutations a démontré que, chez les groupes des tailles observées, la probabilité d`une association aléatoire était de moins de 0,001, sauf en un cas où cette probabilité a été évaluée à 0,72 chez un groupe. Par échantillonnage directionnel, j`ai observé que les interactions agressives étaient gagnées par l`individu attaquant 72% du temps, étaient de courte durée (<5 s), se faisaient avec peu de contacts physiques et leur fréquence n`était pas reliée à la taille du groupe. Il y avait cependant moins d`agressivité chez l`un des groupes. Il se peut que ce groupe ait eu accès à plus de ressources alimentaires que les autres. Chez les cerfs liés par des liens sociaux, l`agressivité ne se manifeste pas de façon à déséquilibrer la stabilité sociale.
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Peterson R.O., Jacobs A.K., Drummer T.D., Mech L.D., & Smith D.W. (2002). Leadership behavior in relation to dominance and reproductive status in gray wolves, Canis lupus. Canadian Journal of Zoology, 80, 1405–1412.
Abstract: We analyzed the leadership behavior of breeding and nonbreeding gray wolves (Canis lupus) in three packs during winter in 1997-1999. Scent-marking, frontal leadership (time and frequency in the lead while traveling), initiation of activity, and nonfrontal leadership were recorded during 499 h of ground-based observations in Yellowstone National Park. All observed scent-marking (N = 158) was done by breeding wolves, primarily dominant individuals. Dominant breeding pairs provided most leadership, consistent with a trend in social mammals for leadership to correlate with dominance. Dominant breeding wolves led traveling packs during 64% of recorded behavior bouts (N = 591) and 71% of observed travel time (N = 64 h). During travel, breeding males and females led packs approximately equally, which probably reflects high parental investment by both breeding male and female wolves. Newly initiated behaviors (N = 104) were prompted almost 3 times more often by dominant breeders (70%) than by nonbreeders (25%). Dominant breeding females initiated pack activities almost 4 times more often than subordinate breeding females (30 vs. 8 times). Although one subordinate breeding female led more often than individual nonbreeders in one pack in one season, more commonly this was not the case. In 12 cases breeding wolves exhibited nonfrontal leadership. Among subordinate wolves, leadership behavior was observed in subordinate breeding females and other individuals just prior to their dispersal from natal packs. Subordinate wolves were more often found leading packs that were large and contained many subordinate adults.
Nous avons analysé le comportement de commandement chez des loups gris (Canis lupus) reproducteurs et non reproducteurs appartenant à trois meutes durant les hivers de 1997-1999. Le marquage d'odeurs, la position en tête de meute (la durée et la fréquence au cours des déplacements), l'initiation des activités et la prise de décisions ailleurs qu'en tête du groupe ont été notés pendant 499 h d'observations au sol dans le Parc national de Yellowstone. Tous les marquages (N = 158) ont été faits par des loups reproducteurs, surtout des individus dominants. Ce sont surtout les couples dominants qui assurent le commandement, en accord avec une tendance chez les mammifères sociaux chez lesquels la fonction de chef est en corrélation avec la dominance. Les loups reproducteurs dominants ont conduit les meutes en déplacement pendant 64 % (N = 591) des épisodes de comportement et pendant 71 % des épisodes de déplacement (N = 64 h). Les mâles et les femelles reproducteurs ont dirigé les meutes en déplacement à peu près également, ce qui reflète probablement l'investissement parental important aussi bien de la part des reproducteurs mâles que des femelles. Les comportements nouveaux (N = 104) ont été adoptés presque trois fois plus souvent par des reproducteurs dominants (70 %) que par des individus non reproducteurs (25 %). Des femelles reproductrices dominantes ont été instigatrices des activités de leur meute environ quatre fois plus souvent que les femelles reproductrices subordonnées (30 vs. 8 fois). Bien qu'une femelle reproductrice subordonnée ait pris la direction de sa meute plus souvent que les individus non reproducteurs au cours d'une saison, cela n'est pas habituel. Dans 12 cas, des loups reproducteurs ont pris la direction de leur meute sans être en tête. Chez les individus subordonnés, le comportement de commandement a été observé chez des femelles reproductrices et chez d'autres individus juste avant qu'ils ne quittent leur meute d'origine au moment de la dispersion. Les loups subordonnés mènent surtout de grands troupeaux qui comptent beaucoup d'individus subordonnés.[Traduit par la Rédaction] |
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de Villiers, M. S., Richardson, P. R. K., & van Jaarsveld, A. S. (2003). Patterns of coalition formation and spatial association in a social carnivore, the African wild dog (Lycaon pictus). J Zool, 260(4), 377–389.
Abstract: In many social species, relationships within groups seem to be non-random but related to variables such as rank, kinship or sexual attractiveness. The endangered African wild dog Lycaon pictus is a social carnivore that lives in large, stable packs, and intra-pack associations might be expected to display similar patterns. We investigated patterns of coalition formation (support during dominance interactions, and partnership interactions) and resting associations between members of a captive pack of 19 wild dogs. The social organization of the captive pack was similar to that of free-ranging packs in many respects. Polyadic (group) incidents of coalition support were also observed in a free-ranging pack. Patterns of coalition formation in the captive pack were related to rank. Most aggressive interactions involved high-ranking individuals (particularly the alpha, beta and third-ranking males) and coalitionary support tended to reinforce the existing hierarchy. However, there was at least one example of support influencing a successful rank challenge. Support was affected by potential risks and benefits, the latter including dominance through association and revolutionary alliances. An even stronger pattern overlaid associations between pack members: coalitions and resting associations were strongest between members of the same age–sex cohort, and may have enabled the eventual dominance of younger pack members over adults. Among adults, coalitionary associations were sometimes overridden by intersexual relationships. The results from this captive pack suggest that wild dogs are sensitive to differences in competitive ability. This information, in conjunction with strong affiliative bonds between littermates, is used to manoeuvre for position in the social hierarchy. It may also be important during dispersal, in encounters with other dispersing groups of the same sex. Although most features of the social structure of the captive pack were comparable to those of free-ranging packs, aspects such as the influence of relatedness on coalition formation still need to be explored.
Keywords: coalitions; social systems; Carnivora; Lycaon pictus
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Clutton-Brock, T. H., & Harvey, P. H. (1980). Primates, brains and ecology. J. Zool. Lond., 190(3), 309–323.
Abstract: The paper examines systematic relationships among primates between brain size (relative to body size) and differences in ecology and social system. Marked differences in relative brain size exist between families. These are correlated with inter-family differences in body size and home range size. Variation in comparative brain size within families is related to diet (folivores have comparatively smaller brains than frugivores), home range size and possibly also to breeding system. The adaptive significance of these relationships is discussed.
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