Preferential limb use in relation to epicoracoid overlap in the shoulder girdle of toads.

We studied left-right asymmetry in forelimb and hindlimb use in green toads (Bufo viridis) and fire-bellied toads (Bombina bombina) and investigated its possible relationship to the asymmetric structure of the shoulder girdle (epicoracoid overlap) in the latter species. To estimate forelimb use preference we used a modified ''snout-wiping test'' (Bisazza et al., 1997) and to estimate hindlimb use preference we used the ''righting response test'' (Robins et al., 1998). The position of epicoracoids in living animals was determined as proposed earlier (Borkhvardt & Malashichev, 1997). We also examined behavioural laterality in B. viridis to check whether B. viridis is a left-handed species, as it was not clear from the previous study. Our results showed that B. viridis predominantly used the left forelimb and left hindlimb in experimental situations at both the population and individual levels. The same tests were applied to fire-bellied toads, B. bombina, with right or left epicoracoids in the top (dorsal) position. We found that (1) B. bombina is mostly a symmetric species, sometimes using both hands or feet simultaneously; (2) it is ambidextrous in hand and foot use with non-significant left side preference at the population level; (3) there is a positive and significant concordance between the position of epicoracoids and the forelimb preference in B. bombina. Animals with the right epicoracoid in the dorsal position (R. top = L. superficial) prefer to use the right forelimb in the ''snout-wiping test'' and L. top animals predominantly use their left forelimb.