DOI
https://doi.org/10.25772/55NJ-P703
Author ORCID Identifier
https://orcid.org/0000-0002-2842-2163
Defense Date
2023
Document Type
Dissertation
Degree Name
Doctor of Philosophy
Department
Integrative Life Sciences
First Advisor
Lesley Bulluck
Second Advisor
Paul Bukaveckas
Third Advisor
Brian Verrelli
Fourth Advisor
Jennifer Olson
Fifth Advisor
Christopher Tonra
Abstract
Insectivorous birds and their arthropod prey are experiencing widespread population declines, driven largely by anthropogenic disturbance and climate change. For wetland-dependent insectivores that consume a mixture of terrestrial and aquatic insects, understanding the availability, consumption, and nutritional qualities of aquatic diet subsidies is important for conservation. I use prothonotary warblers (Protonotaria citrea) as a model species throughout this work, because their breeding season aligns with aquatic insect emergence and they include aquatic insects when provisioning nestlings. In the first chapter, I estimate aquatic insect emergence from tidal freshwaters, which are understudied compared to nontidal systems. Using continuous field sampling with emergence traps, I found that aquatic insect biomass emerging from tidal freshwater habitats along the James River Estuary are among the highest published to date. These emergence estimates help to assess the overlap of pulsed aquatic resources with critical life history periods of riparian consumers. In the second chapter, I quantify prothonotary warbler nestling diet across two years and nine populations throughout their breeding range. Using DNA metabarcoding, I found that nestlings in all populations were provisioned with emergent aquatic insects and aquatic mollusks. However, aquatic diet components in each population differed taxonomically and throughout the breeding season. Diet determinations confirm widespread consumption of aquatic prey, but do not speak to how nestlings are impacted by presence or absence of aquatic diet items during development. In the third chapter, I analyze the variation in nestling condition for the James River Estuary populations with estimated aquatic insect emergence and quantified diets. Using a combination of mass-based and physiological indicators for condition, I found that early-season nestlings tended to be heavier than average, with greater circulating concentrations of essential polyunsaturated fatty acids and lower concentrations of pro-inflammatory lipid metabolites. Better nestling condition at times when nestlings are provisioned with more aquatic prey provides evidence that aquatic prey subsidies are important for developing nestlings.
Rights
© The Author
Is Part Of
VCU University Archives
Is Part Of
VCU Theses and Dissertations
Date of Submission
5-11-2023