Date of Award:
5-1-2001
Document Type:
Thesis
Degree Name:
Master of Science (MS)
Department:
Biology
Committee Chair(s)
James A. Gessaman
Committee
James A. Gessaman
Committee
William A. Brindley
Committee
Michael R. Conover
Abstract
When evaluating avian pesticide exposure, a number of factors must be considered to form an accurate risk assessment. In the past, such assessments have been conducted with substantial uncertainty about avian consumption of exposed food items. One such uncertain factor is whether or not the avian species would consume contaminated invertebrates that were killed by a chemical application, and which may present an increasing concentration of the chemical as they desiccate over time. Therefore I asked the question: do birds select dead and desiccated insects as food items? I addressed the research question in two steps. First, a laboratory study was conducted wherein wild-caught red-winged blackbirds were individually offered three food choices: live, fresh-dead, and desiccated insect larvae, under controlled laboratory conditions. Second, these same food choices plus live, fresh-dead, and desiccated crickets were presented in study plots in two agricultural crops: a cornfield and an orchard. The placed insects were monitored with videography equipment to determine the fate of the insects and to see if the same food preference shown by birds in the laboratory setting would be seen in the field. The laboratory results showed that red-winged blackbirds have a strong preference for live and fresh-dead prey over desiccated prey, with the live prey taken before the fresh-dead prey in most trials. The field study results indicated a similar preference for live prey over desiccated prey, with preference for fresh-dead prey intermediate to, but insignificantly different from, the two other types. Interesting behavioral parallels were noted between lab and field observations as well. Hypotheses explaining such food preference behaviors were developed based upon these data.
Recommended Citation
Stafford, Jennifer M., "Avian Food Selection With Application to Pesticide Risk Assessment: Are Dead and Dessicated Insects a Desirable Food Source?" (2001). Biology. 683.
https://digitalcommons.usu.edu/etd_biology/683
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