Simple and integrated detours: field tests with Columbian ground squirrels.

An internal representation of space offers flexibility to animals during orientation and allows execution of short cuts and detours. We tested the ability of 19 free-ranging Columbian ground squirrels (Spermophilus columbianus) to perform integrated detours that required travelling under- and aboveground. Squirrels were individually tested on their territories (2 tests) and in an arena (7 tests). During tests, animals could reach food by running aboveground and then through tunnels. For the territory tests, natural tunnels were available. For the arena tests, animals used artificial tunnels within a fenced-in part of the meadow. For the last arena test, tubes were placed aboveground replicating the underground structure. In this test animals were asked to make a simple detour, when the full path to the goal was visible. On their territories, 41% of squirrels performed detours. All animals reached the food in the arena. When choosing an arena detour, squirrels based their decision on the proximity of the burrow as well as on whether it led to food. On the last arena test, more squirrels performed correct detours on the first attempt compared to other tests. The results suggest that ground squirrels can perform simple and integrated detours, but animals perform better if the full path is visible.