Scatter hoarding by kangaroo rats (Dipodomys merriami) and pilferage from their caches

We observed radio-implanted Merriam's kangaroo rats disposingof 10-g bonanzas of rolled oats in 48 trials in the field. Theprincipal determinant of the initial disposition of discoveredfood was apparently its distance from the day burrow: food foundwithin about 10m was mainly larder hoarded, whereas food encounteredfarther afield was usually dispersed immediately in shallowcaches. Cache sites were newly dug for the purpose and not reused;most caches were nearer the current day burrow than was thefood source, but a few were placed far from both the cacher'sday burrow and its habitual nocturnal range. An experiment withartificial caches indicated that security from discovery increaseswith spacing and with proximity to perennial shrubs. Nine kangaroorats cached dyed food, and fecal dye traces revealed extensivepilferage from five of them, by both conspecifics and otherrodent species. Limited evidence indicates that food encounterednearer home and initially larder hoarded was more secure frompilferage than food initially scattered, and yet kangaroo ratswere observed to scatter caches soon after initial larder hoarding.A kangaroo rat whose dyed stores escaped pilferage fed fromthem at intervals for at least 12 days. Even cachers who incurredpilferage made as much, or more, use of their caches as anythief, suggesting that scattering caches may be a defense againstcatastrophic losses.