Date of Award
Campus Access Thesis
Master of Science (MS)
Luis De León
Anthropogenic disturbances alter the natural environment via shifts in habitat and resource availability, species richness and diversity, and the overall community and ecosystem dynamics of an area. More so, anthropogenic disturbances on the environment exist along a gradient, from natural, undisturbed areas, to intermediately disturbed environments, to highly urbanized places. While some species are unable to persist in human-disturbed environments, some species, called suburban adaptable and urban exploiters, are able to utilize the many novel resources made available in urban and suburban environments. Red-Winged Blackbirds (Agelaius phoeniceus) are a widespread, generalist species found across much of North America, and the Northern-most region of Central America. Red-Winged Blackbirds commonly breed in wetland and grassland habitats, but have in the last decade begun to utilize anthropogenic environments such as hay fields, old agricultural fields, and road side ditches. Previous studies have already found declines in Red-Winged Blackbird populations, specifically in the Great Plains region, where intensified agricultural practices and habitat modification have led to loss of breeding habitat for the species. One study found that urban noise influenced Red-Winged Blackbird song structure, while another found that supplemental feeding (a common occurrence in urban areas) was associated with increased offspring mortality. We therefore explored 1) the degree to which Red-Winged Blackbirds are inhabiting urban, suburban, and natural habitats using range-wide site occupancy modeling, and 2) the effect that urban habitats have on Red-Winged Blackbird body condition, using Scaled Mass Index (SMI). We found that Red-Winged Blackbirds occupy suburban habitats at a higher probability than they do urban habitats, and some natural habitats, with these results being consistent across the species’ range. We also found that body condition did not vary by site type, but mass did vary by site type, country, and season. Our study highlights the importance of suburban habitats in urban ecology studies, and provides important evidence for suburban habitat use in a widespread, suburban adaptable species.
Johnston, Mickayla M., "Exploring Urban Effects on Red-Winged Blackbirds (Agelaius Phoeniceus)" (2022). Graduate Masters Theses. 760.