Term of Award

Fall 2021

Degree Name

Master of Science in Biology (M.S.)

Document Type and Release Option

Thesis (open access)

Copyright Statement / License for Reuse

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.


Department of Biology

Committee Chair

Ray Chandler

Committee Member 1

Alan Harvey

Committee Member 2

Steve Vives


Habitat fragmentation has negative effects on bird species diversity, as well as reproductive success of some species. However, there is little comparative information on the effect it may have on bird behavior. For example, small forest fragments are likely to have fewer bird species and individuals. This may limit the success of mobbing as an antipredator behavior because mobbing success depends on recruiting other birds to the group. This possibility has never been tested. The objective of my study is to quantify the effects of forest size on mobbing behavior in forest-dwelling birds. Mobbing behavior was elicited in 100 randomly selected forest patches ranging in size using a model owl as a focal point. The results show that the probability of birds participating in a mobbing event increases as forest size increase (p = 0.002). The latency as which birds respond to a predator vocalization decreases as the forest size increases (p = 0.007). However, forest size had no effect on the intensity of the mobbing event, the probability of birds making alarm calls, the number of individuals participating, or the number of species participating in the mobbing event (p = 0.097, p = 0.952, p =0.1987, p =0.1983). Additionally, no mobbing events were observed in forests fragments below 0.97 hectares, suggesting that this may near a threshold forest size at which mobbing behaviors can no longer be supported.

OCLC Number


Research Data and Supplementary Material