Date of Award

Summer 2024

Degree Type

Dissertation/Thesis

Degree Name

Masters of Science in Integrative Biology

Department

Ecology, Evolution, and Organismal Biology

Committee Chair/First Advisor

Dr. Nicholas S. Green

Second Advisor

Dr. Todd Pierson

Third Advisor

Dr. Jun Tu

Abstract

Urbanization, the phenomenon of increasing human population density and artificial structures, is known to decrease the richness, abundance, and diversity of native wildlife populations, fragment natural areas, and increase human and human-commensal animal interactions with wildlife. Dynamics of species persistence in habitat fragments is often understood in the framework of island biogeography theory (IBT), with habitat fragments being analogous to oceanic islands. Despite the conceptual similarities between oceanic islands in IBT and urbanized habitat fragments (fragment size, fragment age, and distance to immigration sources), there are important differences. In urban fragments, the matrix is not completely impassible, habitats within fragments are heavily modified, and fragment quality is much lower. Urban fragments also must cope with modified conditions from the surrounding matrix, such as urban heat islands, louder ambient noise, light pollution, and human socioeconomics like human populations and income. Considering the extreme variability between fragments, it can be difficult to predict the success of different species, especially small mammals. Small mammals are especially susceptible to urban fragmentation because they rarely cross impervious surfaces such as roads. I sampled small mammals at 23 sites along an urban to rural gradient northward from Atlanta GA, to assess small mammal richness, diversity, and functional group diversity. I collected numerous spatial, environmental, and socioeconomic variables from each site to determine what aspects of urbanization are driving small mammal populations. I found urbanization did not affect univariate measures of small mammal richness or diversity; however, urbanization impacted species composition. Although species composition densities were significantly different across the urban - rural gradient, functional group densities did not vary in the same way. Functional group densities were different only between rural and non-rural sites. Site-level correlations between small mammal densities and geospatial predictors suggest that some processes related to IBT may drive responses to urbanization, but much variation in community structure remains unexplained.

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