UC Davis

Over the years, government bodies have drafted and enforced numerous species protection acts to combat the issue of illegal wildlife trade. Nonetheless, protected species are still being poached, processed, and trafficked in illicit networks. To support law enforcement agencies, wildlife forensic practitioners aim to identify the species of origin for seized evidentiary items, including feathers. Current methods used in feather identification include morphological and/or DNA-based techniques. While useful, these methodologies have limitations. Feathers lacking distinctive morphological characteristics are difficult to resolve to the species level. Additionally, DNA in feather samples is often compromised or ambiguous as to whether genetic analysis yields any species-specific barcoding information. One way to overcome these limiting issues is by utilizing mass spectrometry (MS)-based proteomics to analyze peptide sequences. One category of abundant proteins that could be used in the proteomic analysis of feathers is keratin, an attractive substrate for analysis and species-identification. This protein class is ubiquitous and does not suffer from sample limitations. In this research, we demonstrate that a digestion protocol optimized for hair can successfully be applied to feathers, and peptides can be retrieved from every feather structure or site (the quill, rachis, vanes, tip, and plumulaceous portion). Additionally, proteomic analysis of the plumulaceous portion of the feather demonstrates that even the site with the lowest average peptide yield can successfully identify five taxonomically informative peptides for the Bald Eagle (Haliaeetus leucocephalus) and 12 taxonomically informative peptides for the Golden Eagle (Aquila chrysaetos; 9/12 being species-specific), with peptides coming from both keratin and non-keratin associated proteins. These species-specific peptides can serve as a basis for methods that identify and resolve species in a forensic context.