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The
Effect of Social Environment on the Development Introduction Free-ranging horses exist in cohesive social groups that usually consist of one to six mares, their offspring and a stallion. Foals normally have several conspecifics to engage with in social play. Object play is described as “manipulation of an inanimate object with out obvious purpose or reward” (Hughes, 2002). It has been suggested that providing foals with objects at weaning may improve their welfare as a substitute for social play (Mills and Nankervis, 1999). Object play has been reported to substitute for social play in free-roaming dogs (Bekoff, 1974) and marmosets (Jolly, 1985). In the preceding two studies (Hughes, 2002) the authors studied 24 foals. In the first study the foals were from different breeds and kept either socially, or isolated from other foals. The breed of the foals was thought to be an important factor in the large differences in object play behaviour observed between the foals. Therefore, the second study included only Arabian foals. These foals were all kept with at least one other foal. However, individual differences were again observed. The aim of the study reported here was to determine whether social environment affects the display of object play in domestic horse foals within a single breed group. Methods Three solitary and three socially kept Arabian foals were observed for 30 minutes, once a week from one week to three months of age. All the foals were handled daily by staff at the stud farms. They were maintained at pasture during the day and stabled with their dam at night. Two of the foals were located in the South of England, three were located in South Wales and one was located in the West Midlands of England. The size of the sample was small due to a foot and mouth disease outbreak in the UK, which restricted the type of land that could be visited. During these observations a Jolly Ball (Horseman’s Pride, Ravenna, OH, USA), a large ball (25cm in diameter) with a handle, was placed in the field to ensure that all the foals had the opportunity to manipulate an object. An observer using a hand held video camera filmed the observations. During observations the observer was located in the same field as the foals, but did not interact with them. The videotapes were then viewed and the duration of object play behaviour was timed using a stopwatch and recorded using check sheets. As in previous studies a “boldness” score was devised based on the foals’ interaction with the observer (observer score). Boldness was defined as the willingness of the foals to take risks. The observer score was then compared to an object score, based on the foals’ interaction with objects in the presence of the observer. These scores were as follows: 0 = Foal displays no interest in the object/observer; 1 = Foal orients toward the object/observer; 2 = Foal approaches object/observer; 3 = Foal sniffs object/observer; 4 = Foal makes physical contact with the object/observer. Results Total duration of object manipulation was greater for solitary than social foals. The mean duration during observations for solitary foals was 1.65% versus 1.19% for social foals (Z=-2.04, P<0.05). Total duration of observer interaction was also greater for solitary than social foals. The mean duration during observations for solitary foals was 7.64% versus 2.33% for social foals (Z=-2.70, p<0.01). The solitary kept foals also had significantly higher object and observer scores than the socially kept foals (Object score: Z=-2.51, p<0.05; Observer score: Z=-2.79, p<0.01). Discussion Solitary kept foals appear to be bolder with objects and people than socially kept foals. This could be because their owners have more time to spend with them and so they receive more handling. However, solitary kept foals also appear to manipulate objects more than socially kept foals. It is possible that the isolated foals are re-directing frustrated social play behaviour toward the object. The lower duration of object manipulation displayed by the socially kept foals may be due to competition between the foals for objects. It could also be that the socially kept foals play with objects less because they are able to engage in social play. In this case the composition of the social group could affect the levels of object manipulation observed. Social environment does appear to have an effect on the levels of object play displayed by foals. Isolated foals appear to manipulate objects for longer than socially kept foals. The initial results of this study indicate that object manipulation and play could be useful as a substitute for social play in socially isolated foals. However, the sample size for this study was small and further studies will be required to increase sample size and therefore reliability. References Bekoff M (1974) Social play and play-soliciting by infant canids. Am Zool 14: 323-340. Hughes CF (2002) Object Play in the Domestic Horse. PhD Thesis. University of Southampton, Southhampton, UK. Jolly A (1985) The Evolution of Primate Behavior 2nd ed. Macmillan, New York, p 410. Mill DS and Nankervis KJ (1999) Equine Behaviour: Principles and Practice. Blackwell Science, London, p 64. |
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