Table 1.

Behaviours scored and their definitions. All four behaviours were scored in semi-naturalistic cages; lateral stretching was also scored in standard cages (the other three behaviours were not possible in the standard cage).

behaviour	definition
burrowing	rat is displacing soil using fore legs and/or kicking out with the hind legs
climbing	rat is suspended with all paws in contact with a vertical surface or the cage ceiling
upright standing	rat is upright; hind legs are extended and fore paws are either unsupported (rare) or resting on a vertical surface (common); back is either straight or slightly arched (concave)
lateral stretching	rat is parallel to the ground with the body elongated and back slightly arched; head and tail often angled upwards; hind legs and sometimes one fore leg are outstretched; rat is often yawning