Identifying the composition of avian diets is a critical step in characterizing the roles of birds within ecosystems. However, because birds are a diverse taxonomic group with equally diverse dietary habits, gaining an accurate and thorough understanding of avian diet can be difficult. In addition to overcoming the inherent difficulties of studying birds, the field is advancing rapidly, and researchers are challenged with a myriad of methods to study avian diet, a task that has only become more difficult with the introduction of laboratory techniques to dietary studies. Because methodology drives inference, it is important that researchers are aware of the capabilities and limitations of each method to ensure the results of their study are interpreted correctly. However, few reviews exist which detail each of the traditional and laboratory techniques used in dietary studies, with even fewer framing these methods through a bird-specific lens. Here, we discuss the strengths and limitations of morphological prey identification, DNA-based techniques, stable isotope analysis, and the tracing of dietary biomolecules throughout food webs. We identify areas of improvement for each method, provide instances in which the combination of techniques can yield the most comprehensive findings, introduce potential avenues for combining results from each technique within a unified framework, and present recommendations for the future focus of avian dietary research.
LAY SUMMARY
Providing accurate assessments of diet composition is an essential step in understanding the life history of birds as well as their roles within ecosystems.
A wide array of techniques exists to study the prey composition of birds, including recently developed laboratory-based methods, but each of these methods comes with their own strengths and weaknesses.
This review details the benefits and drawbacks of each technique, suggests pathways to overcoming methodological limitations, and demonstrates how these techniques can be leveraged to answer cutting-edge questions in avian dietary studies.
Finally, we discuss how the use of multiple techniques within a single study can yield a more comprehensive understanding of avian diet, present novel ways to combine data from each technique within a unified framework, and suggest areas of research to advance the field of avian dietary ecology.
