Degree Name
Master of Science (MS)
Semester of Degree Completion
1992
Thesis Director
Eric K. Bollinger
Abstract
A foraging animal's choice of feeding location may represent a trade-off between maximizing its energy or nutrient intake and avoiding predation. In the present study, two hypotheses were investigated to test the influence of predation risk on feeding site preferences of birds: 1) there are differences among the preferences of feeding heights of birds, 2) the magnitude of preference increases with increasing predation risk found in different habitats. In my study site, three feeding stations (located in the woods, the woods/field edge, and an open field) each containing three feeders (0 m, 1.5 m, and 3 m from the ground) were established for attracting winter birds.
I found that birds apparently perceived different degrees of predation risk in the different habitats and responded accordingly. Birds visited the woods and edge stations significantly more than the open field station. In all three habitats, the birds preferred the higher feeders. As a probable consequence of the trade-off between foraging efficiency and predation risk, the preferences of feeder heights changed over the course of the experimental sessions in different patterns in the different habitats. At the woods station, the birds tended to maximize their foraging efficiency. They changed their feeding heights more according to the seed densities on the feeding tray, and shifted to the lower feeders earlier. In contrast, birds preferred the high feeder throughout the experimental period at the open field station. At the edge station, birds shifted to the lower feeders later than at the woods station. In addition, the frequency of aggressive encounters between birds decreased with increasing openness of the habitat. These results supported the following conclusions: 1) the preferences of feeding height increased with increasing distance from the ground; 2) the preferences of feeding habitat decreased with increasing openness of habitats; 3) the intensity of the preferences for the higher feeding sites increase with increasing openness of habitats; and 4) these feeding site preferences could be adaptive behaviors to reduce the predation risk perceived by birds in different habitats and different feeding heights.
Recommended Citation
Kuo, Yen-min, "Predation Risk and Feeding Site Preferences in Winter Foraging Birds" (1992). Masters Theses. 2199.
https://thekeep.eiu.edu/theses/2199
