Portia's capacity to decide whether a detour is necessary

Proficiency at planning is known to be part of the exceptionally complex predatory repertoire of Portia, a genus of jumping spiders (Salticidae) that specialize in preying on other spiders. This includes proficiency at choosing between two detour routes, with only one leading to otherwise inaccessible prey. Less is known about Portia's proficiency at making strategic decisions pertaining to whether a detour is required or not. Using Portia africana, we investigated this by having lures (prey or leaf pieces) visible at the beginning of a trial but not later, and by using water to restrict P. africana's freedom of movement. A detour path was always present, but sometimes a causeway was also present, allowing direct access to lures. After seeing prey, P. africana more often took the causeway when present and, when absent, more often took the detour path. After seeing leaf pieces, P. africana never took the detour path.