Over all, transportation alone produced the longest durations of vocalisation, turning round, pawing and head tossing behaviour. In comparison, transportation with the mirror reduced the duration of these behaviours by 45%, but travelling with a live companion reduced the duration of these behaviours by a total of 91% when compared to travel alone. The duration of eating behaviour however, was at its highest when travelling with a companion and this only fell by 6% when horses travelled with the mirror, while transportation alone reduced eating behaviour by a total of 79% in comparison to travelling with a companion.
Horses emit a variety of vocalisations as well as other sounds that are likely to serve as communication within the herd and play an important role in maintaining cohesion, including greeting or separation calls such as whinnies and neighs, as well as snorts, squeals, and grunts (Houpt, 1998; McDonnell, 2003). In this study, vocalisation was the only activity to be displayed by all 12 horses during all three treatments; the highest values being recorded during transportation alone (total 1 hr 46.12 mins). The presence of this behaviour would suggest that the horse is not settled in the trailer, as it was often accompanied by turning round behaviour. The horse would unlikely to eat during vocalisation, and an elevation in heart rate could also occur.
Between treatments, the duration of this behaviour varied and statistical analysis revealed a very highly significant difference between the duration of vocalisation behaviour when travelling alone and with a conspecific (p<0.001), and between transportation alone and with the mirror (p<0.05) which meant the null hypothesis could be rejected. No significant difference was found between transportation with the mirror and a conspecific. This would suggest that although still vocalising, this behaviour was reduced when travelling with the mirror or conspecific, in comparison to travelling alone, and that the horses showed a similar reaction to travel with the mirror and conspecific.
Turning round while travelling in the trailer was often accompanied by vocalisation behaviour and the horses seemed to be turning to search for another horse, an activity previously observed in isolated horses by Jezierski and Gorecka (1999, 2000). This is unsurprising as horses usually maintain visual contact with others for social cohesion, and social isolation can have a profound effect on many aspects of behaviour (Kiley-Worthington and Wood-Gush, 1987; McDonnell, 2003).
Although initially this may not seem to cause any problems during travel, it does show that the horse is unsettled, and whilst turning round the head may (if tied too loosely) become trapped behind the central pole, causing the horse to panic. The horse may be unable to balance effectively against the motion of transport if the head is not positioned centrally, which could lead to bruising from restraints/partitions, and even scrambling or falling. It also means that whilst the head is turned the horse is likely to spend less time eating.
During transportation alone and with the mirror all 12 horses were recorded displaying turning round behaviour, the total duration while alone being 1 hr 11.32 mins, and with the mirror 28.55 mins.