A Microscopic Analysis of the Plumulaceous Feather Characteristics of Accipitriformes with Exploration of Spectrophotometry to Supplement Feather Identification
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Coddington, Charles
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Abstract
Microscopic feather structures can reveal conserved traits that may be used to identify taxonomic groups of birds based on mere fragments of feathers. Analyzing microscopic feather structure has many practical applications including: criminal investigations, food contamination cases, anthropological artifact analysis, prey remains analysis, and identification of bird species involved in aircraft collisions. This thesis research investigates specialized microscopic feather identification techniques by surveying pigmentation patterns and intensity, basic morphology, spinal distribution, and by using statistical analysis and spectrophotometry to examine the variation within feather characters of Accipitriformes representing 16 species from 3 different taxonomic families (Cathartidae, Accipitridae, Pandionidae) that occur in the United States. Further, feather micro-structure of some Falconiformes (Falconidae) were compared with Psittacidae (parrots) to test recent hypotheses of the evolutionary relationships of these groups. Significant differences were found among some microscopic characters of the avian families Cathartidae, Accipitridae and, Pandionidae. Falconidae and Psittacidae are visually more similar to each other than to any Accipitriformes based on pigmentation patterns and plumulaceous feather structure. Differences were discovered between family, and genera in pigmentation pattern and spine distribution along the downy barbules of vultures, eagles, kites, Accipiter hawks and Buteo hawks. Significant differences in quantitative and qualitative feather characters between species within the same genera were seldom observed. Spectrophotometry was investigated as a potential new method of identifying fragmentary feathers of species by generating quantitative measurements of the color of the primary and secondary feathers of select species. Significant differences in spectrophotometry reflectance peaks were found between species pairs that had visually distinguishable coloration, but species that had similar coloration showed no significant differences suggesting that spectrophotometry may not be an effective method for melanin-based feather fragment analysis in the species studied here. The results of this study indicate that microscopic plumulaceous feather characters of Accipitriformes contain quantifiable, and basic morphological differences that may aid in separation of distinct groups based on micromorphology if similar feather types and feather barbs are compared. Additionally, feather characters studied here support recent taxonomic organization of previously unrelated taxa such as falcons and parrots. This study of plumulaceous microstructure of Accipitriformes and Falconiformes enhances our knowledge of these biological structures and provides additional justification that feather microstructure is indeed useful for the practical applications of forensic feather identification and for taxonomic studies.
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Keywords
Feathers, Microstructure, Accipitriformes, Plumulaceous, Microcharacters