title: An investigation of quantity discrimination in Clark's nutcrackers (Nucifraga columbiana).
abstract: We examined quantity discrimination in the Clark's nutcracker (Nucifraga columbiana), a corvid bird with a strong dependence upon caching and recovering nuts. We presented 2 sets of nuts simultaneously, in 21 different conditions, to see if the nutcrackers could choose the larger of the 2 quantities. The nutcrackers displayed a strong ability to discriminate quantities of nuts. Like other animals tested previously, the nutcrackers' performance decreased as the ratio of the 2 quantities approached 1. Interestingly, at constant distances, the nutcrackers did not have more difficulty with contrasts containing larger quantities. Thus, nutcrackers have a fine sensitivity for discriminating between 2 quantities. We review the relevant literature and explore the possibility that nutcrackers, like some other birds, may have developed a keen ability to discriminate quantities. This ability may have developed as an adaptive specialization to cope with their scatter-hoarding ecology, though the evidence for such a conclusion is mixed.
authors.affiliation: Department of Psychology, University of New Hampshire.
authors.forename: Jan K
authors.initials: JK
authors.lastname: Tornick
authors.affiliation: Department of Psychology, University of New Hampshire.
authors.forename: Emily S
authors.initials: ES
authors.lastname: Callahan
authors.affiliation: Department of Psychology, University of New Hampshire.
authors.forename: Brett M
authors.initials: BM
authors.lastname: Gibson
mesh_terms: D000818:Animals; D000835:Animals, Wild / Q000502:physiology; D001522:Behavior, Animal / Q000502:physiology*; D004192:Discrimination, Psychological / Q000502:physiology*; D055641:Mathematical Concepts; D046109:Passeriformes