The role of visual cues in learning escape behaviour in the little brown skink (Scincella lateralis)

Abstract

Many small animals escape predators by running under an escape retreat such as a rock, log, or pile of leaves. Rapid escape to a retreat would be facilitated if the animal already learned the location of the retreat before it ever had to flee from a predator. One way a small animal might do this is to attend to a prominent ‘local cue’, that is, a visual cue that is part of, or contiguous with, the retreat. I tested the hypothesis that a small lizard commonly known as the little brown skink, Scincella lateralis, can use a local visual cue to learn an escape behaviour. Little brown skinks were presented with two retreats side-by side in an observation chamber. One retreat was backed with a vertical striped cue and the other backed with a horizontal striped cue. Each lizard was induced to run from one end of the observation tank to the opposite end with the two retreats; the retreat that each lizard chose for escape was recorded through a series of 15 trials conducted over three days. Half of the lizards were trained to escape to the vertical cue retreat; half were trained to escape to the horizontal cue retreat. About one-third of little brown skinks met the learning criterion of escaping to the correct retreat in five consecutive trials. However, significantly more of the vertical cue lizards met the learning criterion than did horizontal cue lizards. Also, the vertical cue lizards escaped to the correct retreat significantly more often than expected by chance. Furthermore, even the horizontal cue lizards showed a preference for escaping to the vertical cue retreat. This suggests little brown skinks can use a local visual cue to learn an escape behaviour, but only if it a vertical cue. This may be related to the use of a vertical cue to obtain positional information to locate a retreat or perhaps to the tendency of this forest species to attend to abundant vertical cues in its habitat.