Currently encompassing 16 sites from Shasta to San Diego County, the survey involves visually counting acorns of over 950 trees of 7 species of oaks. In order to address this issue, Jean Knops of the University of Nebraska and I initiated the California Acorn Survey in 1994. This brings us to the question of geographic synchrony in acorn production within and between species of California oaks. Whereas, if the acorn crop is not synchronous within and between species, they may only have to travel a few miles before coming to an area with lots of acorns where they could survive through the winter. If the acorn crop was poor and synchronous both among individuals of the same species and across species over a large geographic area, there would be few acorns anywhere nearby and the birds might have to travel a very long distance before finding an area where there were enough acorns to survive. How far they have to go presumably depends on how geographically synchronous the acorn crop is within and between species of oaks. However, in poor years, the birds are forced to abandon their territories and wander off in search of acorns elsewhere. In good acorn years, acorn woodpeckers not only reproduce extremely well the following spring but may even successfully breed in the fall, fledging young as late as early November. Indeed, such “storage trees” or “granaries” have been reported to contain up to 50,000 acorns or more! Holes are used over and over each year and accumulate with time. More dramatically, they harvest acorns in large numbers and store them in special trees in their territories in which the birds have drilled holes, each of which can hold an individual acorn. Acorn woodpeckers eat acorns directly off trees in the fall as acorns mature. No species is more intimately associated with oaks than the acorn woodpecker, a common resident of oak woodlands throughout California. Oaks ‘n Folks – Volume 15, Issue 1 – March 2000
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