Associative learning in hatchlings of the lizard Calotes versicolor: taste and colour discrimination

Abstract

The study examined whether newly born hatchlings of Calotes versicolor discriminate between tastes and exhibit associative learning. The one-day-old hatchlings ate 2nd instar silk-moth larvae (prey) placed in non-painted, orange or green dishes without any bias for the background colour. They ate sucrose coated sweetened prey, but given a choice preferred natural larvae. But they spat bitter tasting chloroquine phosphate (CP)-coated prey and exhibited aversion behaviour. Hatchlings fed on natural larvae from non-painted or orange dishes for 10 days preferred food from the dish to which they were accustomed when choice of both colour backgrounds was given suggesting they also remember different tastes in association with background colour cues. Upon swapping sucrose and CP-coated prey/dish colours the hatchlings were misled and they attempted to eat from the dishes to which they were accustomed prior to the trials regardless of whether food/prey was coated with sucrose or CP. However, bitter prey was immediately spat and aversion behaviour followed. The study shows for the first time, taste discrimination and associative learning behaviour in new-born lizard hatchlings.