A bird's eye view on human disturbance
Katie Egan, Danielle Langley
Habitat loss, urbanization, and the introduction of non-native species often decrease species diversity. However, the relative impacts of different types of disturbances are not equal. Longer lasting disturbances include deforestation and constructing infrastructure, while activities such as hiking and dog-walking are more temporary. Previous research in our lab demonstrated that habitat type, human infrastructure, and human presence alter mammal activity patterns and other behaviors but do not significantly alter mammal species diversity. We are interested in determining how these same categories of human disturbance affect species diversity in birds. We predicted that species diversity would be higher at sites with higher habitat heterogeneity and lower at sites with high human presence and infrastructure. To test our hypotheses, we collected data using camera traps placed at six sites with 3-4 stations each. Each camera station was marked as an open, edge, or forest habitat type. An infrastructure score was determined by calculating the density of roads and buildings around each camera using GIS. Human presence was quantified using the frequency of images containing human activity at each station. For each bird observation, we recorded the species present and used the Chao estimator to determine Smax for each site and each station. We found a positive correlation between habitat heterogeneity (as measured by the number of habitat types per site) and bird diversity (Smax). Human infrastructure did not affect avian species diversity, but stations with higher human presence had lower avian diversity. Overall, we found that birds respond differently to different types of disturbance. Human presence decreases avian species diversity, likely because some species of birds spatially avoid sites where humans are common. However, humans also cut down forests and maintain open fields, which can increase bird diversity by creating niches for a wide range of species.
Katie Egan is a sophomore biology major from Columbia, SC. She has given a presentation at a conference meeting of the Association of Southeastern Biologists and will be inducted into TriBeta Honor Society this semester. Katie enjoys spending time with family and with her rabbit, Jack.
Danielle Langley is a sophomore biology major from Lexington, SC and is a member of the Honors College. She enjoys birdwatching, reading, and painting in her free time and has given a presentation at the conference of the Association of Southeastern Biologists. Danielle hopes to attend graduate school and obtain a career in ornithology.