Optimization Modeling in Foraging of the Goldenrod Ball Gall (E urosta solidaginis)
Eastman, Timothy J.
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The goldenrod ball gall larva, Eurosta solidaginis , is a common winter food source for the Downy Woodpecker, Picoides pubescens, and the Black-capped Chickadee, Parus atricapillus. Galls were examined in order to investigate aspects of recognition constraints within optimization models. Galls were collected from various sites at the Michigan State University Kellogg Biological Station, Calhoun County, Michigan. Predated and non-predated galls were collected and then measured for average diameter. Results indicate a difference in size between predated galls and those not predated. These results suggest that visual cues may have a role in determining profitability. The size selectivity shown may be related to either profitability or rate of encounter. The results can also provide a springboard for further study of the decision process.