Urbanization affects environmental conditions for developing songbirds

Urbanization introduces a set of novel stressors for animals in these modified habitats. Developing young, in particular, can be at risk due to increased predation, exposure, and high food intake requirements. Song sparrows (Melospiza melodia) are a model wild songbird system that persist in both urban and rural habitats, and have young that develop very quickly. I investigated how urbanization changes the arthropod community, how that in turn affects nestling diet, and ultimately if there were any differences in nestling amino acid profiles or body condition between habitat types. Prior work found that urban habitats also have far higher rates of brood parasitism, which can additionally restrict food intake for urban nestlings. However, this prior work has also found that urban song sparrow adults avoid consequences for living in urban habitats, so I wanted to see if nestlings were also able to avoid the consequences of urban living. In chapter one, I found our urban arthropod communities had lower average arthropod abundance, biomass, and diversity when compared to rural arthropod communities. Song sparrow nestling diets differed somewhat in composition of arthropod prey items by habitat, but urban and rural nestlings had the same average biomass of stomach contents. In chapter two, I investigated whether different habitat types or brood parasitism altered body size and amino acid concentration of song sparrow nestlings. Only gamma-aminobutyric acid differed, being significantly lower in urban, parasitized nestlings. No groups differed in metrics of body condition. In chapter three, I performed a meta-analysis to investigate how brood-parasitic brown-headed cowbirds (Molothrus ater) affect host clutch size and nest success. Host clutch sizes were lower when parasitized, but surprisingly non-parasitized nests were more likely to fail. Despite lower arthropod food availability and high levels of brood parasitism, urban song sparrow nestlings are not compromised, supporting the conclusion that urbanization does not necessarily have negative consequences for individuals of this species.

Name thesis:degree_name

Doctor of Philosophy

Level thesis:degree_level

doctoral

Discipline thesis:degree_discipline

Biological Sciences

Department dc:contributor.department

Biological Sciences

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

2024

Author dc:creator

• VanDiest, Isaac

Chair dc:contributor.committeechair

• Sewall, Kendra

Committee members dc:contributor.committeemember

• Hopkins, William A.
• Gilbert, Elizabeth Ruth
• Belden, Lisa Kay

• urbanization
• arthropod community
• diet
• songbird
• amino acids
• brood parasitism

Statement dc:rights

• Creative Commons Attribution 4.0 International

Licence dc:rights.uri

• http://creativecommons.org/licenses/by/4.0/

Language dc:language.iso

en

Dc Identifier Other

vt_gsexam:41194

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/120991