Collection methods of wild barn owl pellets at low environmental contamination and proposals of microbiological and ecological investigations

The barn owl Tyto alba is a medium-sized nocturnal raptor, predator of small mammals, birds, reptiles, and insects, distributed all over the world. Environmentally uncontaminated wild barn owl pellets are hard and rare to find and provide a natural matrix for biological investigations. Different solutions for collecting wild barn owl pellets at low environmental contamination are proposed. These solutions are based on a daily sanitized surface for sample retrieval, followed by rapid analysis. As an example of the possible investigations that can be carried out on these matrices, with the aim to highlight the relevance of the obtained results also from a biotechnological perspective. Two rare pellet samples from wild barn owl T. alba, appropriately collected in a rural area of central Italy, were analyzed using culture-dependent, molecular (Next-Generation Sequencing), and enzyme profile analysis techniques. The osteological observations of the bone remains provided useful information for identifying the prey, mainly rodents (Apodemus sp.). Under our experimental conditions, the results revealed both a wide heterogeneity between the pellet microbiota and a great percentage of uncultured bacteria not classified at the species level. Furthermore, microbial cultures of Malbranchea albolutea, Debaryomyces hansenii, and Lactobacillus sp. were isolated and studied. Finally, we quantified the environmental impact of our experimental work in terms of CO2 equivalent release. To compensate for the release of 300 kg/CO2 eq., three Taxus. baccata L. were planted. This work provides a starting point for developing an effective strategy to study and characterize wild barn owl pellets at low environmental contamination. It presents a simple and easy technique/protocol for collecting the pellets. The microbiota heterogeneity found in the two analyzed samples suggests that barn owl pellets can represent a potential natural reservoir for the discovery of new microorganisms to be used in various biotechnological applications. This could open the way for further large-scale studies on a greater number of samples and populations.