An experimental analysis of cache recovery in Clark's nutcracker

Long-term spatial memory in clark's nutcracker, Nucifraga columbiana

Cache recovery and spatial memory in Clark's nutcrackers (Nucifraga columbiana).

Twenty of approximately 100 species of pines (Pinus spp.) have wingless seeds, and 19 of these are in the subgenusStrobus. Eight of the wingless-seedStrobus pines are known to be dispersed by seed-storing corvids, particularly the nutcrackers (Nucifraga spp.), and the other 11 are presumed to be. The principal consequences of these nearly obligate bird-pine mutualisms include tree clustering and a population structure that differs from that of wind-dispersed pines. The wingless-seedStrobus pines in general are typified by ranges that include xeric conditions and/or high elevations, and large seeds, which are considered to be adaptive under either xeric or competitive conditions. The proposed evolutionary scenario for bird dependency begins with the distribution of ancestralStrobus pines into high elevation or semi-desert environments, sympatric with one or more seed-storing corvid forms, and an increase in seed size. We propose that dependency on birds for seed dispersal has occurred primarily in subgenusStrobus, becauseStrobus pines tend more towards winglessness and increased seed size in stressful environments than doPinus pines. Seed winglessness and other bird-pine traits probably arose from a combination of genetic drift in small populations and selection by corvids.

The evolution of bird-dispersed pines.

Expose des recherches ecologiques et ethologiques sur les comportements de recherche de nourriture chez les animaux: description particuliere des mecanismes d'apprentissages et de memorisation

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Mervin Giuntoli

Papers

Stomach Contents of Clark's Nutcrackers Collected in Western Montana