PARENT SESSION
Poster Session #2: Plant-Animal Interactions.
Monday, August 6, 2001. Presentation from 10:30 AM to 12:00 PM. Exhibition Hall

Effects of acorn size on the location of caches by Gray Squirrels (Sciurus carolinensis).

NGUMEZI, CHIOMA¹, CHASE, WILLIAM¹, VODZAK, JENNIFER¹, CONTRERAS, THOMAS¹, SMALLWOOD, PETER², STEELE, MICHAEL¹, ^{1 2}

ABSTRACT- Gray Squirrels (Sciurus carolinensis) pilfer each other's caches. Therefore, they may be more likely to cache larger, more valuable seeds further from potential competitors i.e., greater distances from canopy. We conducted an experiment in a park in Wilkes-Barre, PA in which 27 marked Gray Squirrels were presented with tagged acorns from 3 different acorn size classes: 1) large Quercus rubra, 2) small Quercus rubra, and 3) Quercus palustris (smallest acorns). The location of each cached acorn was determined using a differential GPS. Using an airphoto of the study site and a GIS, we were able to determine the shortest distance of each cache from tree canopy edge. An ANOVA, which controlled for individual differences in mean caching distance for each squirrel, shows a significant difference between mean caching distances based on acorn size (p < 0.05). Large Q. rubra acorns were cached greater distances from canopy edge than the smallest acorns (Q. palustris) (Scheffe's test, p < 0.05). The mean caching distance of small Q. rubra acorns was not significantly different than the other two size classes (p > 0.05). Our results suggest differences in the location of acorn caches relative to canopy edge based on acorn size. We suggest that by caching seeds beyond canopy edges, Gray Squirrels may be attempting to reduce cache pilfering by placing seeds in locations where caching can't be observed.

KEY WORDS: caching behavior, acorn size, squirrel, canopy edge