A Comparison of the Bacterial Microflora Found on the Surface of American Kestrel and House Wren Eggs

Beth A. Potte1, 2, *, Emily J. Hyde1, Holly N. Pier1, Michael A. Rutter1, Margaret A. Voss2
1 School of Science, The Behrend College, Pennsylvania State University, Erie, PA, 16563, USA
2 Department of Public Health, Food Studies, and Nutrition, Syracuse University, Syracuse, NY, 13244, USA

© 2014 Potter et al.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: ( This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the Penn State Erie, The Behrend College, 4205 College Drive, Erie, PA 16563, USA; Tel: 814-898-6510; Fax: 814-898-6213; E-mail:


It is generally accepted that avian eggs acquire a microflora during ovipositioning. The goal of this study was to identify and compare the eggshell microflora of two avian species, House Wrens and American Kestrels. Differences in the nesting habitats and incubation behavior of these species suggest that their eggshell microfloras also should differ. Culture-dependent techniques were combined with sequencing of the 16S rRNA gene to identify bacteria in samples taken from American Kestrel eggs during late incubation. These data were compared to previously collected data from House Wren eggs. In both studies, bacteria were isolated from three different phyla, Actinobacteria, Firmicutes and Proteobacteria. The eggshell microflora of Kestrels was dominated by bacteria in the Actinobacteria and Firmicutes phyla during late incubation, whereas the eggshell microflora of House Wrens was dominated by bacteria in the Gamma-Proteobacteria subphylum during pre- and late-incubation and bacteria within the Fimicutes phylum during early incubation. Actinobacteria genera on House Wren and American Kestrel eggshells differed, but the prominent genera in the Gamma- Proteobacteria and Firmicutes phyla, Pseudomonas and Staphylococcus, respectively, were similar between bird species. Thus, our results suggest that the microflora of avian eggshells have both variable (i.e., phyla) and conserved (i.e., specific genera) aspects of bacterial diversity.

Keywords: Actinobacteria, eggshell, firmicutes, microflora, proteobacteria, pseudomona, staphylococcus.