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Keeling, L. J., Bøe, K. E., Christensen, J. W., Hyyppä, S., Jansson, H., Jørgensen, G. H. M., et al. Injury incidence, reactivity and ease of handling of horses kept in groups: a matched case control study in four Nordic countries. Appl Anim Behav Sci, .
Abstract: Abstract There is increasing interest in keeping horses in groups, but progress is hampered by a lack of knowledge about which horses can and should be kept together. Therefore, our objective was to investigate the effect of group composition on the occurrence of injuries among horses, the ease of removing horses from groups and horses’ reactivity to a fearful stimulus. Using a matched case control design, 61 groups of horses were studied in Denmark, Norway, Finland and Sweden. They were allocated into groups of similar or different age and sex or where membership changed regularly or remained stable. Injuries were recorded before mixing the horses into treatment groups, the day after mixing and four weeks later. Reactivity of horses to a moving novel object and the behaviour of a horse being removed from its group and the reactions of other group members towards this horse and the handler were evaluated. It was hypothesized that a more socially variable group composition has beneficial effects on behaviour, ease of handling and reducing reactivity whereas frequent changes in group composition has negative consequences, resulting in more injuries. We found that differences in treatment effects were mainly related to breed, rather than group composition. Icelandic horses reacted less to the movement of the novel object (P = 0.007) and approached it more afterwards (P = 0.04). They also had fewer new injuries than warmbloods following mixing (P < 0.001) and fewer than all other groups 4 weeks later (P < 0.01). Most new injuries after mixing were minor and recorded on the horse’s head, chest, hind legs and rump. In conclusion, variations in sex and age composition of the group had little effect on injury level, reactivity and ease of handling compared to the general effect of breed. Concerns about the risk of severe injuries associated with keeping horses in groups are probably overestimated. Thus, we propose that horses can be successfully kept in groups of different sex and age composition.
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Keiper, R., & Receveur, H. (1992). Social interactions of free-ranging Przewalski horses in semi-reserves in the Netherlands. Appl. Anim. Behav. Sci., 33(4), 303–318.
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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Keiper, R. R. (1988). Social interactions of the Przewalski horse (Equus przewalskii Poliakov, 1881) herd at the Munich Zoo. Appl. Anim. Behav. Sci., 21(1-2), 89–97.
Abstract: Data were collected on 972 aggressions and 233 acts of mutual grooming in a herd of 9 Przewalski horses in the Hellabrunn Tierpark in Munich, West Germany. The herd was composed of 1 adult stallion, 5 adult mares and 3 foals. A distinct linear dominance hierarchy was present in the herd, with the stallion being the top-ranking animal. Age was significantly correlated with rank. Almost 40% of all aggressions consisted of herding actions by the stallion. Threats to bite (20% of all aggressions) and threats to kick (11.4%) were next in frequency of occurrence. Most mutual grooms (71%) involved grooming the front part of the body. Although mutual grooming may be used to appease higher-ranked animals, most grooming bouts were between related horses. Foals initiate 47.6% of all allogrooming. Mutual grooming may reduce weaning conflict between a mare and her foal or may result in female coalitions that defend against predators or aggression by the herd stallion.
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Keiper, R. R., & Sambraus, H. H. (1986). The stability of equine dominance hierarchies and the effects of kinship, proximity and foaling status on hierarchy rank. Appl. Anim. Behav. Sci., 16(2), 121–130.
Abstract: Dominance hierarchies were determined in four bands of feral horses living on Assateague Island. The bands varied in size from 10 to 16 horses, and consisted of one stallion, several mares and their offspring. The animals ranged in age from less than 1 to over 18 years. Field observation of all social interactions during the summer of 1981 was used to determine dominance. 1981 hierarchies for three of the bands were compared with hierarchies determined for the same bands in 1978, and showed that hierarchies change over time. Age was significantly correlated with rank. Mares with foals did not rank any higher in the hierarchies than mares without foals. Kinship did not appear to have an effect on dominance rank either, since neither juvenile nor adult offspring ranks correlated with the ranks of their mothers. The band stallion was not the highest-ranking animal of any band, but the location of the stallion peripheral to the main body of the band, the nature of his interactions with band members, and his length of residence in the band may have contributed to his low rank.
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Kelly, C. D. (2006). Fighting for harems: assessment strategies during male-male contests in the sexually dimorphic Wellington tree weta. Anim. Behav., 72(3), 727–736.
Abstract: Females often aggregate at particular sites for feeding or shelter, thus giving adult males the opportunity to defend harems and increase male reproductive success. Rival males compete for control of harems via ritualized displays or direct combat using weaponry. Contests for harems or the resources required by females can be settled based on asymmetries in fighting ability or resource ownership. Males that accurately assess a rival's fighting ability prior to engaging in potentially costly combat should be favoured by selection. Game theory and optimality models provide three models to explain how individuals decide to persist in or flee from a fight. These models are the energetic war of attrition, the sequential assessment model and the cumulative assessment model. Using staged contests in the laboratory, I tested predictions of these models using the Wellington tree weta, Hemideina crassidens, a sexually dimorphic insect native to New Zealand. Male H. crassidens use their enlarged mandibles as weapons in fights for access to adult females that reside in cavities in trees. My results supported a prediction common to each assessment model: contest duration was negatively correlated with the asymmetry in opponent's weapon size. The sequential assessment model of contest settlement was partially supported but the strongest support was for the cumulative assessment model. Predictions of the latter model were supported because: (1) fights are apparently settled based on own-size assessment; (2) fights occur in a single phase and escalate; and (3) contests involve physical combat and injury. I suggest that, in nocturnal species, cumulative assessment will generally be most applicable.
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Kendrick, K. M. (1998). Intelligent perception. Appl. Anim. Behav. Sci., 57(3-4), 213–231.
Abstract: For an animal from any species to exhibit intelligent perception it must be capable of being consciously aware of what it perceives and capable of learning from this experience. Although many organisms, and for that matter machines, are capable of rapid adaptive learning in response to perception of environmental changes, such adaptations can occur without them being consciously aware either of external stimuli or their response to them. While behavioural and neurophysiological evidence suggests that, apart from ourselves, other higher primates must also be capable of such awareness, an important central question is whether such awareness is a characteristic of primate evolution or if it also occurs in sub-primate mammals as well. In this review I will examine our behavioural and neurophysiological evidence from visual and olfactory recognition studies in the sheep to support the argument that they are likely to be aware of and learn about both social and non-social objects and that they are therefore capable of intelligent perception. However, the impact of motivational changes on these perceptual processes suggests that they may be limited in terms of both prospection and retrospection and dealing with symbolic associations.
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Kenward, B., Rutz, C., Weir, A. A. S., & Kacelnik, A. (2006). Development of tool use in New Caledonian crows: inherited action patterns and social influences. Anim. Behav., 72(6), 1329–1343.
Abstract: New Caledonian crows, Corvus moneduloides, are the most advanced avian tool makers and tool users. We previously reported that captive-bred isolated New Caledonian crows spontaneously use twig tools and cut tools out of Pandanus spp. tree leaves, an activity possibly under cultural influence in the wild. However, what aspects of these behaviours are inherited and how they interact with individual and social experience remained unknown. To examine the interaction between inherited traits, individual learning and social transmission, we observed the ontogeny of twig tool use in hand-reared juveniles. Successful food retrieval was preceded by stereotyped object manipulation action patterns that resembled components of the mature behaviour, demonstrating that tool-oriented behaviours in this species are an evolved specialization. However, there was also an effect of social learning: juveniles that had received demonstrations of twig tool use by their human foster parent showed higher levels of handling and insertion of twigs than did their naive counterparts; a choice experiment showed that they preferred to handle objects that they had seen being manipulated by their human foster parent. Our observations are consistent with the hypothesis that individual learning, cultural transmission and creative problem solving all contribute to the acquisition of the tool-oriented behaviours in the wild, but inherited species-typical action patterns have a greater role than has been recognized.
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Kerth, G. (2010). Group decision-making in animal societies. In P. Kappeler (Ed.), Animal Behaviour: Evolution and Mechanisms (pp. 241–265). Springer Berlin Heidelberg.
Abstract: Individuals need to coordinate their activities to benefit from group living. Thus group decisions are essential for societies, especially if group members cooperate with each other. Models show that shared (democratic) decisions outperform unshared (despotic) decisions, even if individuals disagree about actions. This is surprising as in most other contexts, differences in individual preferences lead to sex-, age-, or kin-specific behaviour. Empirical studies testing the predictions of the theoretical models have only recently begun to emerge. This applies particularly to group decisions in fission-fusion societies, where individuals can avoid decisions that are not in their interest. After outlining the basic ideas and theoretical models on group decision-making I focus on the available empirical studies. Originally most of the relevant studies have been on social insects and fish but recently an increasing number of studies on mammals and birds have been published, including some that deal with wild long-lived animals living in complex societies. This includes societies where group members have different interests, as in most mammals, and which have been less studied compared to eusocial insects that normally have no conflict among their colony members about what to do. I investigate whether the same decision rules apply in societies with conflict and without conflict, and outline open questions that remain to be studied. The chapter concludes with a synthesis on what is known about group decision-making in animals and an outlook on what I think should be done to answer the open questions.
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Khalil, A. M., & Kaseda, Y. (1998). Early experience affects developmental behaviour and timing of harem formation in Misaki horses. Appl. Anim. Behav. Sci., 59(4), 253–263.
Abstract: A study was made of the behavior of young male Misaki feral horses in the developmental stage, by observing nine of them once a week from January 1988 to December 1996. The relationship between behavior before separation and in the developmental stage was also investigated. This stage begins just after young males separate from their natal band or mothers, and it continues until they start to form harems. The duration of the developmental stage in the study ranged from 0.6 to 3.9 years, depending on the age of the young males at the time of separation. Young males associated with three types of social groups at the beginning of the developmental stage, according to their social groups before separation. These were bachelor groups, harem groups and wandering female groups. During this period, males joined the three groups, mixed sex groups and sometimes were solitary. It was considered that these associations provided a good opportunity for males to acquire different behavioral patterns and experiences before they entered the next stage. Depending on the groups with which they associated, young males that spent more time with bachelor groups had the longest average developmental stage. They associated with harem groups more often during the breeding season and more frequently with other groups or were solitary during the non-breeding season. This may be a transition period because by the end of this stage all males had spent time in solitude before forming their own harem bands.
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Khalil, A. M., & Kaseda, Y. (1997). Behavioral patterns and proximate reason of young male separation in Misaki feral horses. Appl. Anim. Behav. Sci., 54(4), 281–289.
Abstract: 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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