Use of heterospecific cues by the lizard Platysaurus broadleyi for food location

Flat lizards (Platysaurus broadleyi) at Augrabies Falls National Park, Sout h Africa, are restricted to rocky terrain where the predominant tree is the Namaqua fig (Ficus cordata cordata). P. broadleyi readily feeds on Namaqua figs when they are available, and the lizards sometimes form large (maximu m recorded = 134) congregations under fruiting fig trees. The distance liza rds travel to fruiting trees also exceed normal daily foraging distances. L ocation of fruiting fig trees by a lizard can have a high pay-off because f igs are energetically rich and trees fruit irregularly and asynchronously, resulting in a resource that is available, but unpredictable in time and sp ace. The prediction that bird activity in fig trees provides a cue to the p resence of ripe figs was tested experimentally. By placing cages containing birds and empty control cages in trees devoid of fruit, we demonstrated th at P. broadleyi are drawn to fig trees with high bird congregations. We als o tested if the presence of a fig tree was necessary to draw lizards to bir d congregations by placing cages containing birds and empty control cages i n a matched-pairs design on rock away from trees. Namaqua fig trees were no t necessary to draw lizards to bird congregations.