Mechanisms of truffle detection by northern flying squirrels

The objective of this study was to evaluate how northern flying squirrels ( Glaucomys sabrinus) locate truffles (Gautieria monticola), a subterranean a nd ephemeral but primary food source. Thus, we evaluated the importance of three factors to the foraging behavior of northern flying squirrels: (i) ol factory chemicals that emanate from truffles; (ii) the presence of coarse w oody debris (decaying logs), which are often associated with fungi; and (ii i) we explored the potential role animal memory could play in truffle detec tion as well. In a foraging arena, squirrels successfully retrieved buried truffles that lacked aboveground cues in 19 of 30 trials and failed to sear ch near treatments that lacked truffles altogether, confirming the importan ce of olfaction to squirrel foraging. However, squirrels also retrieved tru ffles that were associated most frequently with surface logs (27 of 30). In addition, the initial detection rate of the truffle + log treatment was si gnificantly greater than the truffle-only treatment. Thus, although squirre ls search for truffles primarily using olfaction, they may also benefit by searching near coarse woody debris on the forest floor as an aboveground cu e to truffle locations. In addition, because 82% of Sierra Nevada truffle-f ruiting locations that were marked in 1996 yielded truffles again the follo wing 2 years, mycophagous animals like northern flying squirrels may benefi t by memorizing fruiting locations and foraging at these same locations fro m year to year.