IDENTIFYING PURPLE MARTIN DIET AND ITS EFFECT ON NESTLING DEVELOPMENT
Date
2024-05
Authors
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Publisher
University of Delaware
Abstract
Purple Martins (Progne subis) are entirely reliant on aerial insects to feed
themselves and their young. Like most other animals, a healthy diet is an integral
aspect for developing nestlings, which can be achieved through aquatic insects.
Aquatic insects contain a high density of omega-3 long chain polyunsaturated fatty
acids compared to any other prey item we see in aerial insectivores. These omega-3s
play a role all stages of life, but are especially crucial in early development in the form
of several functions like immune response and body growth, among a plethora of
others. This project aims to determine whether or not diet has an impact on Purple
Martin nestling growth within my sample colonies. I collected fecal samples and
measurement data (mass and tarsus length) from 147 Purple Martin chicks during their
entire nestling stage from hatching to fledging at three breeding colonies in the
Delaware Valley area during the summer of 2023. I identified prey items from fecal
samples through DNA metabarcoding and found that the martin colony with the
heaviest chicks had the highest proportion of aquatic flies in their diet. There was a
significant difference in nestling mass between two of the colonies, which may be a
result of a lack of proper nutrition or a lack of suitable prey items. The underlying
issues resulting in this stunted growth may play an important factor in aerial
insectivore conservation in the future