Behavioural Brain Research 173 (2006) 315–319 Short communication Lateralized righting behavior in the tortoise (Testudo hermanni) Gionata Stancher a , Elena Clara a , Lucia Regolin a,∗ , Giorgio Vallortigara b a Department of General Psychology, University of Padova, Via Venezia 8, 35131 Padova, Italy b Department of Psychology, B.R.A.I.N. Centre for Neuroscience, University of Trieste, Trieste, Italy Received 28 April 2006; received in revised form 9 June 2006; accepted 13 June 2006 Available online 1 August 2006 Abstract Lateralization of brain and behaviour at the population level has been documented in all vertebrate classes. Research was mostly carried out on mammalian and avian species, the least investigated class with this regards being the Reptilia, with studies concentrating on lateralized aggressive behaviour in lizards. No research has been carried out on lateralization in the Chelonian order. We investigated the presence of motor asymmetries in the tortoise Testudo hermanni, using the righting response (i.e. the animal is positioned upside-down and the left/right side to which it uprights is observed), a procedure already employed to assess behavioural lateralization in amphibians. The ability of righting has a particularly high adaptive value in tortoises, as in case of overturning, and consequent exposure to sunrays, changes in body temperature and difficulties in respiration could occur leading to serious conditions. Thirty-four tortoises underwent a series of righting tests in a standardized apparatus, 15 tortoises were also retested 10 months later. A bias at the individual as well as at the population level was found for preferentially turning on the right side. Consistency of responses at retest was also observed. The results are discussed with reference to the implications for the evolution of brain lateralization in vertebrates. © 2006 Elsevier B.V. All rights reserved. Keywords: Righting response; Tortoise; Testudo hermanni; Motor asymmetry; Behavioural lateralization A shared general pattern of lateralization can be found for most vertebrate species [16,24,25]. Asymmetries in the central nervous system could manifest themselves as lateral biases in overt behaviour; motor lateralization is attested in all vertebrate classes and has been investigated in several amphibian and rep- tilian species [13,15,23]. Male lizards are more likely to attack conspecifics located on their left side [5,6,10,11]. In these studies a general tendency was found to respond (either to approach or to attack) to conspecifics when they appeared on the left side. Responses to the right side took longer than those to the left side and, for example, were used to select food objects and to respond to stimuli after allocating them to categories rather than on an individual basis [14]. Studies on newborn and adult amphibians have taken advan- tage of their spontaneous righting response when overturned [2,3,15]. According to these studies individual and population biases do exist with a consistent favourite righting preferred side in 70–80% of the cases. ∗ Corresponding author. Tel.: +39 049 8276650; fax: +39 049 8276600. E-mail address: lucia.regolin@unipd.it (L. Regolin). The righting response was also used in youngsters of Chely- dra serpentina as a measure of fitness [19], it correlates with temperature of incubation [7], but up to now it was never used as a measure of lateralized behaviour. We investigated the presence of lateralized bias in right- ing responses in two subspecies of the Mediterranean tor- toise Testudo hermanni [9]. T. h. ssp. hermanni and T. h. ssp. boettgeri were classified as subspecies on the base of morpho- logical, genetic, and biogeographical considerations. The two subspecies are currently distributed to the west (ssp. hermanni) and east (ssp. boettgeri) side of the Adriatic Sea, hence an allopatric speciation process is assumed [26]. Modern popula- tions are still reproductively isolated even though, during the last 10,000 years, with the end of the last glaciation, their habitats progressively extended to the North. Righting is a highly adaptive and efficiently performed response for tortoises, being it of vital importance as, when overturned, they might experience rather serious difficulties at breathing and at body temperature control. Overturning can occur in the natural environment during male fights [4], and, occasionally, when climbing/walking through the uneven grounds typical of Mediterranean habitat. The special adap- 0166-4328/$ – see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.bbr.2006.06.023