Convenience Stores: Repeated Use of Some Cache Sites by Clark's Nutcrackers (Nucifraga columbiana)

Abstract

AbstractField studies reveal that Clark's nutcrackers (Nucifraga columbiana) cache thousands of seeds in subterranean caches during the autumn in some years, and laboratory studies have shown that these caches can be recovered with high levels of accuracy. Over the life of a bird, numerous cache recovery cycles may be experienced and many of these may be in the same area. Birds may thus develop strong individual preferences for certain sites. These sites may become more memorable and used preferentially. These sites might also be more vulnerable to theft because of continual reuse. In this study, birds were allowed to cache and recover four times from the same set of potential cache sites in a large experimental room. Three of five birds used some cache sites more often than would be expected by chance. However, these birds did not place more seeds per cache, have higher recovery accuracy, or make more revisits to cache sites previously used. Birds did not create caches earlier in previously used holes until cycle 4, when birds actually cached in used sites significantly sooner than in previously unused ones. Birds neither recovered caches earlier from previously used sites nor made error probes earlier at them. Sites that were repeatedly used for caching were holes that were significantly closer to a centrally located feeder than less frequently used sites. Thus, some birds may develop slight preferences for some locations but these sites are not treated preferentially. Birds appear not to gain the advantages, nor suffer the consequences associated with repeated use of the same sites.