Advancing Methods of Diet Analysis: A Case Study Using Degraded Merlin (Falco columbarius) Prey Remains

Abstract

Prey remains have long been used as a mechanism to approach diet analyses. As understanding diet is key to comprehending ecosystem dynamics, prey remains identification requires a unique methodological approach to determine diversity within a sample. With the advancement of technology, molecular protocols designed for species-specific identification have improved to incredible accuracy and precision. Yet, the visual identification method has remained a predominant technique within diet studies. With entry-level observers, we matched visual identifications with molecular-based methods to quantify the accuracy of the visual identification method. This study determined what fraction of visually identified prey remains could be correctly identified to a high degree of certainty. Using the mitochondrial DNA of \u3e 40-year-old Merlin (Falco columbarius) feather samples, we found that the correct identification of visually identified “high” certainty samples was 41.7%. Furthermore, visually identified samples with a “medium to low” certainty plummeted to 19.0%. This study reveals that correct identification of visually identified samples is significantly lower than previously considered but that certainty level has a significant role in correct identification. Similarly, visual identification can provide rapid determination of separate taxa and the number of species in a sample. It is critical to assess prey remains using multiple techniques to procure definitive identification of individual prey items. Anecdotally, I found that the primers AWF2-R4 and AWF4-R6 targeting regions within the cytochrome c oxidase subunit-1 gene are effective for degraded (i.e. \u3e 40 years old) feather samples of Passeriformes and Charadriiformes

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