Experiment one

In the first experiment, a stuffed fox representing natural predators of mammalian carnivores was used. The fox, which were placed outside the mesh wall in front of the enclosure, was revealed by the keepers taking away the blanket hiding it. It was then presented still for five minutes before it was dragged on its wheels about one meter away. There it was left still for five minutes before it was covered with the blanket again and removed. As control, the same model but with an additional blanket of different color covering it was used in the same way.

Experiment two

The second experiment involved a larger snake model of grey color and 180 cm length, representing natural predators of tree-living boa snakes. It was placed on a shelf inside the enclosure before it was uncovered and left still for 5 minutes. A motion was then simulated by pulling a thin fishing line attached to the snake’s head, and it was then left still again for 5 minutes before it was removed by the keepers. The control was represented by a plastic plant placed at the same location to exclude the possibility of behaviors recorded only being a reaction to any novel object inside the enclosure.