ARTICLE Detour behaviour in horses (Equus caballus) Paolo Baragli • Valentina Vitale • Elisa Paoletti • Claudio Sighieri • Adam R. Reddon Received: 22 July 2010 / Accepted: 27 October 2010 / Published online: 30 November 2010 Ó Japan Ethological Society and Springer 2010 Abstract The objective of this study was to investigate the ability of horses (Equus caballus) to detour around symmetric and asymmetric obstacles. Ten female Italian saddle horses were each used in three detour tasks. In the first task, the ability to detour around a symmetrical obstacle was evaluated; in the second and third tasks sub- jects were required to perform a detour around an asym- metrical obstacle with two different degrees of asymmetry. The direction chosen to move around the obstacle and time required to make the detour were recorded. The results suggest that horses have the spatial abilities required to perform detour tasks with both symmetric and asymmetric obstacles. The strategy used to perform the task varied between subjects. For five horses, lateralized behaviour was observed when detouring the obstacle; this was con- sistently in one direction (three on the left and two on the right). For these horses, no evidence of spatial learning or reasoning was found. The other five horses did not solve this task in a lateralized manner, and a trend towards decreasing lateralization was observed as asymmetry, and hence task difficulty, increased. These non-lateralized horses may have higher spatial reasoning abilities. Keywords Detour behaviour Á Equus caballus Á Horses Á Lateralization Á Spatial reasoning Introduction Spatial orientation (i.e. the ability to orient in the envi- ronment and to find the shortest path to an objective) is among the most fundamental of cognitive processes and is essential for survival (Kimchi and Terkel 2003). Without the ability to orient accurately and efficiently, animals may be unable to locate food and mates (Kimchi and Terkel 2003). The ability of an animal to detour around an obstacle to reach a desired objective has been investigated by placing a barrier between the animal and a target object. This ‘‘detour task’’ requires the animal to distance itself from the desired object as it goes around the obstacle to reach it (Zucca et al. 2005). Detour studies originated in apes with the work of Ko ¨ hler (1925) and have been extended to many other animal species (Poucet et al. 1983; Pongra ´cz et al. 2001; Kimchi and Terkel 2003; Regolin et al. 1995a, b; Bisazza et al. 1997a, b; Tarsitano 2006; Smith and Litchfield 2010). When per- forming a detour, an animal demonstrates spatial reasoning ability by choosing the shortest route at the outset on the basis of visual inspection alone (Wynne and Laguet 2004). If, instead, the animal tends to choose the shortest route more often as the task proceeds, it may be using spatial learning rather than reasoning (Wynne and Laguet 2004). It is pos- sible to infer whether an animal is using spatial learning or reasoning strategies by examining behaviour while detour- ing around an asymmetrical barrier (Wynne and Laguet 2004). When the animal can maintain visual contact with the object, the task of going around the obstacle seems to be more difficult to perform, as noted by Ko ¨hler (1925) and confirmed for chicks (Regolin et al. 1994), cats (Poucet et al. 1983), and dogs (Chapuis et al. 1983). Feral equids are adaptable, ranging from high to low altitudes and inhabiting northern boreal plains, and P. Baragli (&) Á V. Vitale Á E. Paoletti Á C. Sighieri EtoVet Research Group, Department of Physiological Sciences, University of Pisa, Viale delle Piagge 2, 56124 Pisa, Italy e-mail: pbaragli@vet.unipi.it A. R. Reddon Animal Behaviour Group, Department of Psychology, Neuroscience and Behaviour, McMaster University, 1280 Main St West, Hamilton, ON L8S 4L8, Canada 123 J Ethol (2011) 29:227–234 DOI 10.1007/s10164-010-0246-9