EFFECTS OF STORAGE ON TANNIN AND PROTEIN-CONTENT OF CACHED ACORNS

We tested the hypothesis that burying acorns in the ground as done by Western scrub-jays (Aphelocoma californica) and storing acorns in hole s drilled in the bark or other dead tissue of trees as practiced by ac orn woodpeckers (Melanerpes formicivorus) alter the relative tannin an d protein content of three different species of acorns common in centr al coastal California Simulated caching by either procedure had no inf luence on the relative tannin concentrations of either Quercus douglas ii or Q. agrifolia acorns compared to controls, and the effects detect ed in Q. lobata are unlikely to have a positive influence on the nutri tional value of acorns to the birds caching them. Relative protein con tent increased with time in cached Q douglasii and, to a lesser extent , Q. lobata acorns, two closely-related, low-protein species in the wh ite oak subgenus, and decreased with time in cached compared to contro l Q. agrifolia acorns, a relatively high-protein species in the black oak subgenus. These results indicate that caching does not reduce tann in levels compared to controls, but may increase or decrease protein l evels of stored acorns depending on the species.