Procedural memory lets animals more efficiently solve previously encountered tasks over weeks to months to years. It has been thoroughly documented in vertebrate clades such as mammals and birds; however, studies of procedural memory in squamate reptiles are lacking. Filling this gap is important to understand the degree to which this ability is (or is not) unique to birds and mammals. We tested for memory of a problem-solving task in two species of monitor lizard (Varanus spp.) and a beaded lizard (Heloderma sp.) after a 20-month hiatus in exposure, representing approximately 25% of their ages at the time of testing. All the monitor lizards had lower initial latencies to solve the task upon re-exposure post-hiatus than they had as naïve individuals pre-hiatus, and reached minimum latencies in fewer trials than when previously tested. Our results indicate procedural memory of puzzle-solving behaviors on the time scale of years. These results add to an emerging literature suggesting that squamate and other non-avian reptiles share a number of cognitive traits with birds and mammals, suggesting that such traits are far more widespread across taxa than previously recognized. We also discuss a framework for studying cognition in squamates that would allow tests of cognition across a great diversity of body forms and ecologies.
Cooper• & Zabinski• [& 10 others] (in press) Long-term memory of a complex foraging task in monitor lizards (Reptilia: Squamata: Varanidae). J Herpetol.