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Linklater, W. L., Cameron, E. Z., Stafford, K. J., & Veltman, C. J. (2000). Social and spatial structure and range use by Kaimanawa wild horses (Equus caballus: Equidae). New Zealand J. Ecol., 24(2), 139–152.
Abstract: We measured horse density, social structure, habitat use, home ranges and altitudinal micro-climates in the south-western Kaimanawa ranges east of Waiouru, New Zealand. Horse density in the Auahitotara ecological sector averaged 3.6 horses.km-2 and ranged from 0.9 to 5.2 horses.km-2 within different zones. The population's social structure was like that of other feral horse populations with an even adult sex ratio, year round breeding groups (bands) with stable adult membership consisting of 1 to 11 mares, 1 to 4 stallions, and their predispersal offspring, and bachelor groups with unstable membership. Bands and bachelor males were loyal to undefended home ranges with central core use areas. Band home range sizes varied positively with adult band size. Home ranges overlapped entirely with other home ranges. Horses were more likely to occupy north facing aspects, short tussock vegetation and flush zones and avoid high altitudes, southern aspects, steeper slopes, bare ground and forest remnants. Horses were more likely to be on north facing aspects, steeper slopes, in exotic and red tussock grasslands and flush zones during winter and at lower altitudes and on gentler slopes in spring and summer. Seasonal shifts by bands to river basin and stream valley floors in spring and higher altitudes in autumn and winter are attributed to the beginning of foaling and mating in spring and formation of frost inversion layers in winter. Given horse habitat selectivity and the presence of other ungulate herbivores, results from present exclosures are likely to exaggerate the size of horse impacts on range vegetation. Proposals to manage the population by relocation and confinement are likely to modify current social structure and range use behaviour and may lead to the need for more intensive management in the longer term.
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Lampe, J. F., & Andre, J. (2012). Cross-modal recognition of human individuals in domestic horses (Equus caballus). Animal Cognition, 15(4), 623–630.
Abstract: This study has shown that domestic horses are capable of cross-modal recognition of familiar humans. It was demonstrated that horses are able to discriminate between the voices of a familiar and an unfamiliar human without seeing or smelling them at the same moment. Conversely, they were able to discriminate the same persons when only exposed to their visual and olfactory cues, without being stimulated by their voices. A cross-modal expectancy violation setup was employed; subjects were exposed both to trials with incongruent auditory and visual/olfactory identity cues and trials with congruent cues. It was found that subjects responded more quickly, longer and more often in incongruent trials, exhibiting heightened interest in unmatched cues of identity. This suggests that the equine brain is able to integrate multisensory identity cues from a familiar human into a person representation that allows the brain, when deprived of one or two senses, to maintain recognition of this person.
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Sankey, C., Richard-Yris, M. - A., Henry, S., Fureix, C., Nassur, F., & Hausberger, M. (2010). Reinforcement as a mediator of the perception of humans by horses (Equus caballus). Anim. Cogn., 13(5), 753-764.
Abstract: A central question in the interspecific human/animal relationship is how domestic animals perceive humans as a significant element of their environment. In this study, we tested the hypothesis that the use of positive or negative reinforcement in horse training may have consequences on the animals’ perception of humans, as a positive, negative or neutral element. Two groups of ponies were trained to walk backwards in response to a vocal order using either positive or negative reinforcement. Heart rate monitors and behavioural observations were used to assess the animals’ perception of humans on the short (just after training) and long (5 months later) terms. The results showed that the type of reinforcement had a major effect on the subsequent animals’ perception of familiar and unfamiliar humans. Negative reinforcement was rapidly associated with an increased emotional state, as revealed by heart rate measurements and behavioural observations (head movements and ears laid back position). Its use led the ponies to seek less contact with humans. On the contrary, ponies trained with positive reinforcement showed an increased interest in humans and sought contact after training. This is especially remarkable as it was reached in a maximum of 5 sessions of 1 to 3 min (i.e. 5 to 15 min) and had lasting effects (visible after 5 months). Even learning was positively influenced by positive reinforcement. Overall, horses seem capable of associating humans to particular experiences and display extended long-term memory abilities.
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Krueger, K. (2015). Social learning and innovative behaviour in horses. In Proceedings of the 3. International Equine Science Meeting. Wald: Xenophon Publishing.
Abstract: The evaluation of important parameters for measuring the horses’ cognitive capacities is one of the central topics of the equine behaviour team at Nürtingen-Geislingen University. Social complexity has been said to be one of the settings in which needs for cognitive capacities arise in animals. A variety of studies throughout the last two decades proved the horses’ social complexity to be far more elaborate than previously assumed. Horses form social bonds for the protection of offspring, intervene in encounters of others, identify group mates individually and easily orientate in a fission fusion society.
In such socially complex societies, animals will benefit from learning socially. In many bird and primate species the degree of social complexity correlates nicely with the species abilities for social learning. Social learning was, therefore, argued to be an indicator for elaborate mental capacities in animals. We were delighted to prove that horses actually copy social behaviour and techniques for operating a feeding apparatus from older and higher ranking group members. In a recent study we found young horses, at the age of 3 to 12, to copy the operation of a feeding apparatus from a human demonstrator. Social learning seems to work nicely in horses when the social background of the animals is considered. The degree to which individual animals adapt to changes in their social or physical environment by finding innovative solution appears to be the other side of the coin, of whether animals adjust to challenges by social learning. It is not very astonishing, that along with the animals’ social complexity and their ability to learn socially also the degree to which they show innovative behaviour was claimed to be one of the most important demonstrations of advanced cognitive capacities. In a recent approach, we started to ask horse owners and horse keepers in many countries to tell us about unusual behaviour of their horses via a web site (http://innovative-behaviour.org). To date, we received 204 cases of innovative behaviour descriptions from which six cases were clear examples of tool use or borderline tool use. We categorized the innovative behaviours into the classes, a) innovations to gain food, b) innovations to gain freedom, c) social innovations, d) innovations to increase maintenance, and e) innovations that could not be clearly assigned to a category. About 20% of the innovative horses showed more than one innovation. These animals could be termed “true innovators”. Again, young horses were more innovative than older ones with the age group 5 – 9 showing the highest number of innovative behaviour descriptions. In a nutshell, the horses’ cognitive capacities appear to be underestimated throughout the last decades. The horses’ social complexity is far more elaborate than previously assumed, horses learn socially from conspecific and humans, some of them demonstrate innovative behaviour adaptations to their environment and even simple forms of tool use. |
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Péron, F., Ward, R., & Burman, O. (2013). Horses (Equus caballus) discriminate body odour cues from conspecifics. Animal Cognition, , 1–5.
Abstract: Knowledge about social recognition and memory in animals can help us to determine appropriate management and husbandry techniques. In this study, we used a habituation–discrimination procedure to investigate the ability of horses (Equus caballus) to distinguish between the body odour samples of unfamiliar conspecifics. To pick up body odour, we rubbed material on the coat of horses and presented these unknown body odours to 16 different conspecifics of the same sex and similar age. The test consisted of two successive two-min presentations of a sample from one individual (e.g. individual ‘A’) and a simultaneous presentation of samples from individual ‘A’ and a novel individual (e.g. individual ‘B’) during a final third presentation. The results showed that horses, regardless of sex, decreased the time they spent investigating conspecific body odour across the initial two presentations—demonstrating habituation. In the final presentation, the results demonstrated successful discrimination of the previously experienced odour because horses investigated the novel olfactory sample (‘B’) significantly more than the pre-exposed sample (‘A’). Taken together, these findings suggest, for the first time, that horses are able to discriminate two stimuli derived from body odours of unfamiliar conspecifics over short period of time.
Keywords: Body odour; Discrimination; Equus caballus; Habituation; Social memory
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Ransom, J. I., & Cade, B. S. (2008). Influences of immunocontraception on intraband social behavior in free-ranging feral horses, Equus caballus. In IESM 2008.
Abstract: Contraception is often considered for population control of wildlife that is otherwise protected from more traditional management strategies, though little is known about the behavioral consequences of contraception in wild populations of socially complex animals. Feral horses, Equus caballus, in the western United States are ideal candidates for contraceptive management due to broad scale federal protection, reported herd growth rates of 15-25% per year, and finite public land allocated for them. We investigated influences of the immunocontraceptive porcine zona pellucida (PZP) on social behavior within bands of feral horses in three discrete populations for 4 years. Each band consisted of a single stallion and a harem of adult females (>1 years old) and their foals, as well as associated yearling males and females. Four mutually exclusive behaviors (herding, reproductive, harem tending, and agonism) were analyzed to investigate the difference between behaviors initiated by band stallions toward control mares and contracepted mares within the bands. Additionally, spatial relationships between each stallion and each harem female were analyzed to assess possible passive interactions. A candidate set of 22 hierarchical mixed effects models, using the discrete populations as a random effect on various fixed effects, was analyzed by restricted maximum likelihood estimation. The most supported models were selected by corrected Akaike"s Information Criteria (AICc). Analyses were done on 3 female age cohorts based on distinct fecundity rates: 2 to 5 year olds, 6 to 14 year olds, and > 14 year olds. Stallions herded control mares in the 6 to 14 year cohort more than contracepted mares (n=128, P=0.037) with treatment being the most supported effect, but foal presence (dependent foal) also contributed significantly to the model. Contracepted mares received more reproductive behaviors than control mares in the 6 to 14 year cohort (n = 151, P=0.020). No differences were detected in herding or reproductive behaviors in
the least fecund groups, the 2 to 5 year olds and ≥ 15 year olds. The only independent variable in the most supported model for reproductive behavior was treatment, and the covariates of foal presence, band residence (resident or transient female), band size, and body condition did not contribute. There were no differences in any age cohort for harem tending or agonism. Spatially, stallions maintained closer relationships with 2 to 5 year old contracepted females than with the same age control females (n=136, P < 0.001) while the group was feeding (at its most dispersed structure), but there were no differences while the band was resting or in locomotion. There were no spatial differences detected in the other age cohorts. Given the polyestrous nature and high fecundity of feral horses, the observed difference in reproductive behaviors between treatment groups was not surprising; however, the difference detected in herding rates was an unexpected behavioral modification. This change in herding behavior suggests that further investigation is needed to determine if PZP immunocontraception has an underlying influence on mare social rank, band structure, and band stability, as well as the scope and long-term importance of these behavioral dynamics. |
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Bartosova, J., Komarkova, M., Dubcova, J., Bartos, L., & Pluhacek J. (2012). Nursing behaviour in pregnant domestic mares (Equus caballus): Can they cope with dual maternal investment? In K. Krueger (Ed.), Proceedings of the 2. International Equine Science Meeting (Vol. in press). Wald: Xenophon Publishing.
Abstract: Among mammals, lactation is the most energy demanding part of parental care and so parentoffspring conflict should arise over milk provided by the mother. Mother and offspring should disagree over the length and amount of the milk provision. We focused on effect of pregnancy on suckling behaviour variables as indicators of mother-offspring conflict in domestic horses. We presumed shorter suckling bouts and higher rates of rejected and/or terminated suckling in pregnant mares compared to non-pregnant ones. Increasing conflict over amount of maternal investment between mother and her young are to be expected because of her parallel investment into a nursed foal and a foetus. Eight groups of loose housed lactating mares with foals of Kladruby horse were studied at the National Stud Kladruby nad Labem (Czech Republic) from deliveries to abrupt weaning (at the age of 127 to 210 days). We recorded 10 848 suckling solicitations of 79 mare-foal pairs, from which 10 607 resulted in a suckling bout. In 41 cases a nursing mare became pregnant during lactation. We found no significant effect of pregnancy either on probability of the mother rejecting suckling solicitation of her foal or probability that she terminated a suckling bout. However the overall effect of mother’s pregnancy on suckling bout duration was not significant, there were considerable differences in pregnant and non-pregnant mares according to who terminated a suckling bout, whether the mother or the foal (F(1, 9776) = 12.1, P < 0.001). In case it was the mother then the suckling bout was longer if she was pregnant (65.36 ± 1.25 s) than barren (60.55 ± 1.36 s). We found no impact of pregnancy on duration of suckling bouts terminated by the foal. Further, nursing a foal during the first two trimesters of pregnancy had no negative impact on birth weight of the foetus. In conclusion, we found not higher, but a lower mother-offspring conflict in pregnant than in non-pregnant lactating mares while expecting just the opposite. We suggest that pregnant mares compensate their nursed foals during intensive stages of lactation through a relaxed mother-offspring conflict for later decrease in investment due to increasing demands of the foetus and/or for the shorter period of milk supply. Our results (partly published in Bartosova et al. 2011, PLoS ONE 6(8): e22068) are of high importance in horse breeding. One of the main arguments for early weaning of the foals is regeneration of their pregnant mothers before upcoming delivery. Here we present evidence that a pregnant mare “counts” with her dual maternal investment and “employs” evolutionary mechanisms enabling her to rear a vital foetus. From this point of view there is no objective reason for stressful weaning of her nursed offspring practised in conventional breeding. Supported by AWIN, EU FP7 project No. 266213.
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Dubcová, J., Bartošová, J., & Komárková, M. (2012). Impact of weaning method on weanlings’ weight gain in domestic horses. In K. Krueger (Ed.), Proceedings of the 2. International Equine Science Meeting (Vol. in press). Wald: Xenophon Publishing.
Abstract: Artificial weaning is associated with various stresses for the foal, such as loss of the mother, feeding changes, new and unfamiliar environment, etc. We investigated the impact of two different methods of abrupt weaning on weight gain in group housed Kladruby horses born 2009 (National Stud Kladruby nad Labem, CZ). Two groups of the foals were weaned abruptly at age from 5,5 to 8 months and transported to the other facility but the first group (G1, N=14) spent one week in their home environment after their mothers were led away. The other foals (G2, N=15) were moved away immediately after separation from the mothers (i.e. they lost the mother and known environment at one time). Foals were weighed: at the weaning day, weekly within the first month and then monthly up to 6 months after weaning. Neither birth nor weaning weight differed significantly between the two groups kept under similar nutrition. We hypothesised that a week spent in the home environment should reduce foal’s weight loss usually following the loss of the mother and moving to the unknown environment. The weaning type significantly influenced weight gain the foals reached one week after weaning (p < 0.001, GLM, PROC GLM, SAS). Contrary to our expectations, G1 foals lost their weight whereas G2 ones gained weight during the same period (-4.9 vs. +3.2 kg). G1 foals reached back their weaning weight within 3 weeks after weaning. The weight of the foals at 6 months after weaning was still marginally higher in G2 than G1foals (388.2 vs. 365.7 kg, p < 0.07). We found lower detrimental effect on weight gain in G2 foals (i.e. weaned and immediately moved) compared to G1 foals (weaned and stayed before moved). Thus, our results indicate lower stress induced to the foals in more radical type of weaning. Supported by AWIN, EU FP7 project No. 266213.
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Hollenhorst, H., Weil, S., & Krueger, K. (2015). Innovative behavour in horses (Equus caballus). In , & K. Krueger (Ed.), Proceedings of the 3. International Equine Science Meeting. Proc. 3. Int. Equine. Sci. Mtg. Wald: Xenophon Publishing.
Abstract: Contrary to the widely-spread assumption that horses just have restricted cognitive capacities and are not very flexible in their behaviors, we showed that horses display innovative behavior and even make use of tools (Krueger 2015, Krueger et al. 2015). These findings derive from a database (http://innovative-behaviour.org/) the Equine behavior team managed in the past two years. Some horses did not only show single innovations, but several different innovations. The number of innovations per individual varied from 1 to 10. 20 % of all innovative horses in the database showed more than one innovation. These individuals can be called the ‘true innovators’. Moreover innovations were dependent on age. Young horses were more innovative than older ones, whereby horses at the age of five to nine years were the most innovative. When considering the housing system innovative horses in a single housing (inside box, outside box, paddock box) had a slight majority towards horses in group housing (open stable, active stable, pasture day and night). But given the fact that ratings on housing system frequencies state 95% of the horses to be kept in individual housing, innovations in individual housing are rare. Nevertheless, horses kept in inside boxes without a window, opened doors more often than all other horses. Aside from this effect, housing systems did not trigger the frequency of innovative behavior. Innovations for gaining freedom and innovations in general were widespread among horses with daily access to pasture and daily contact with conspecifics. Innovations for gaining food were not more likely to occur in horses that were fed little amounts of roughage. In conclusion, the housing of horses does not seem to be the primary catalyst for developing innovative behavior in horses. What makes a “true innovator” in horses, in addition to age, remains to be seen.
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