Quantity discrimination in a lizard

While foraging or during social interactions, animals may benefit from judging relative quantity. Individuals may select larger prey or a patch with more food and likewise, it may pay to track the number and type of individuals and social interactions. We tested for spontaneous quantity discrimination in the gidgee skink (Egernia stokesii), a family-living lizard. Lizards were presented with food quantities differing in number or size and selected the larger quantity of food items when they differed in number, but not when items differed in size. We show, for the first time, superior spontaneous discrimination of items differing in number over size in a lizard species which contrasts with previous findings. Our simple method, however, did not include controls for the use of continuous quantities and further tests are required to determine the role of such information during quantity discrimination. Our results provide support for use of the parallel individuation system for the discrimi...