How Clark's nutcrackers (Nucifraga columbiana) weigh geometric cues depends on their previous experience

Following passive disorientation, Clark's nutcrackers (Nucifraga columbiana) learned to search for a hidden food reward located in one corner of a rectangular-shaped enclosure that contained either identical or distinct features in each corner. Identical features allowed for explicit learning of geometric cues, whereas distinct features allowed for both explicit learning of featural cues and incidental learning of geometric cues. Birds that only learned about geometry incidentally (group Distinct) weighed features greater than geometry when the two cues were placed in conflict. However, birds that received explicit training with geometry, in addition to feature training (groups Distinct-Identical and Identical-Distinct), weighed geometry heavier relative to features. Cue preference by the birds also depended on the order in which learning was experienced; if explicit training with geometry followed that of features (group Distinct-Identical), then both geometry and features were weighed equally, but if explicit training with geometry training preceded that of features (group Identical-Distinct), the birds weighed geometry greater than features. Results suggest both a heightened sensitivity to geometric cues by Clark's nutcrackers relative to other species of birds and an increased sensitivity to any spatial cue (either features or geometry) that has proven both stable and reliable.