Evaluating the nutritional content of insect diets fed to Florida grasshopper sparrows (Ammodramus savannarum floridanus) at White Oak Conservation

Citation

Schumann AG, Garlinger RD, Parrot RE, Greiser RA, Talavera-Arroyo GA, and Ritter CL. 2021. Evaluating the nutritional content of insect diets fed to Florida grasshopper sparrows (Ammodramus savannarum floridanus) at White Oak Conservation. In Brooks M, Koutsos E, and Henry B Eds. Proceedings of the Fourteenth Conference on Zoo and Wildlife Nutrition, Zoo and Wildlife Nutrition Foundation and AZA Nutrition Advisory Group, Virtual.

Abstract

Avian insectivores obtain many essential nutrients that they cannot synthesize on their own through a diet of seeds and diverse wild insects. At White Oak Conservation, Florida grasshopper sparrows (Ammodramus savannarum floridanus) are fed a diet of feeder insects that aims to replicate the nutritional profile consumed by wild birds; however, plumage abnormalities in recent years may indicate nutrient deficiencies in the managed sparrows’ diets. Specifically, duller adult plumage compared to wild counterparts and consistent fault-barring in young hatch-year birds were apparent beginning in 2019. In spring 2020, feeder insects and wild insect samples consistent with those fed to grasshopper sparrows were analyzed for nutrient content, specifically vitamin A, protein, and amino acid content. The goal was to determine if wild insects contained superior nutrient levels compared to feeder insects provided to the breeding population of sparrows at White Oak. These nutrients were selected due to their roles in plumage development, structure, and coloration. Results indicated that wild insects had higher levels of total vitamin A and beta-carotene compared to all feeder insects, while amino acids and proteins were comparable in feeder crickets and wild insects. Feeder mealworms and waxworms were insufficient in most nutrients, and vitamin A was completely undetectable in waxworm samples. This study suggests that wild insects should be prioritized to a greater extent in grasshopper sparrow diets to supplement feeder insect nutrients. Further solutions may involve dusting insects with supplements higher in total vitamin content than those currently provided to sparrows at White Oak to increase birds’ intake of vitamin A.

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