The effect of distance on foraging strategies of the Eastern Chipmunk, Tamias striatus.

Abstract

Foraging strategies among animals can help maximize the net rate of energy gain which results in an increase in fitness. The optimal foraging theory states this searching behavior is based on a goal to maximize fitness. The foraging strategies of the Eastern Chipmunk as a function of distance from the burrow were studied. Ninety chipmunks were marked at UMBS in Cheboygan County, Michigan. The foraging efficiency (number of seeds/minute) and number of seeds captured by fifteen of these individuals were computed. Trays of 150 sunflower seeds were set at 3 m and 12 m from the chipmunk burrow and the number of seeds and rate of foraging (foraging efficiency) were calculated for three feeding trips at each distance. The foraging efficiency was computed and the data were analyzed using Student's t-tests (alpha=0.05). We found that there was no significant difference at either distance for the average number of seeds collected and average foraging efficiency. There was a significant difference in the mean amount of time spent on the trays; the chipmunks spent more time feeding at 3 m than at 12 m. This suggests that the foraging behavior of Tamias striatus changes with distance to minimize the costs of foraging. Additionally, a large variance in the time spent traveling to and from the feeding tray was found, possibly the cause of an insignificant difference in the time spent traveling at either distance. Even though there was no difference in the rate of foraging or the number of seeds collected per trial, the amount of time spent feeding at each distance was different, suggesting a change in foraging behavior with changing distances of food from the burrow.