For some reason the other day, I began thinking about an article I had read a while back on Kingsnake about a study done on v. albig's (white-throat monitor) counting ability. I thought it was very interesting and thought I'd look it up and post it here. Some of you may have seen/heard about it, but for those who haven't, it's an interesting read and an amazing example of varanid inteligence. Lizards may not be so dumb after all...
SAMUEL S. SWEET AND ERIC R. PIANKA REPLY: We based our statement about monitor counting on recent experiments on captive white-throated monitors (Varanus albigularis) by John Phillips, an investigator at the San Diego Zoo. A lizard was fed snails in groups of four. Each snail was placed in a separate compartment connected to three others within a chamber, and the compartments were opened one at a time to allow the monitor to eat the four snails. On finishing the fourth snail, the lizard was allowed into another chamber containing four more snails.
After such conditioning, one snail was removed from some snail quartets. The lizard reacted by searching extensively tier the missing fourth snail, even when it was free to move on to the next group. Similar experiments with yawing numbers of snails in the groups showed that the monitors can count up to six. With groups larger than six, however, the monitors seemed to stop counting: they merely classified them as "lots," eating them all before moving on to the next chamber. Such an ability to count probably evolved as a consequence of raiding nests of reptiles, birds, and mammals, because the average clutch or litter size is about six.
SAMUEL S. SWEET AND ERIC R. PIANKA REPLY: We based our statement about monitor counting on recent experiments on captive white-throated monitors (Varanus albigularis) by John Phillips, an investigator at the San Diego Zoo. A lizard was fed snails in groups of four. Each snail was placed in a separate compartment connected to three others within a chamber, and the compartments were opened one at a time to allow the monitor to eat the four snails. On finishing the fourth snail, the lizard was allowed into another chamber containing four more snails.
After such conditioning, one snail was removed from some snail quartets. The lizard reacted by searching extensively tier the missing fourth snail, even when it was free to move on to the next group. Similar experiments with yawing numbers of snails in the groups showed that the monitors can count up to six. With groups larger than six, however, the monitors seemed to stop counting: they merely classified them as "lots," eating them all before moving on to the next chamber. Such an ability to count probably evolved as a consequence of raiding nests of reptiles, birds, and mammals, because the average clutch or litter size is about six.
