The study of plumage is a foundational aspect of ornithology, and the features of even a single feather can provide valuable information on an individual’s health, sex, or age. Recent discoveries on the abilities of birds to see in the ultraviolet (UV) spectrum has led to study of the UV-reactive characteristics of bird plumage and the biological significance of such plumage. Long-eared owls (Asio otus) possess a demonstrative capability to see UV light, and their plumage contains deposits of UV-sensitive pigments that fluoresce bright red when exposed to UV light. Little is understood about the origin and function of these pigments, and few studies have attempted to describe their variation within a species. In this study, I describe phenotypic variation within the long-eared owl, with an emphasis on both visible and ultraviolet aspects of plumage coloration. I used a molecular genetic sexing assay to evaluate a published method of sexing long- eared owls in the field based on melanistic pigmentation. I found that although some long-eared owls exhibit distinct plumage dimorphism in the visible spectrum, there also is an intermediate polymorphism that greatly limits the number of individuals that can be classified. I also investigated variation in fluorescent pigmentation through the use of a fluorescence detector and found evidence that fluorescent pigment concentration varies both between the sexes and between juvenile and adult plumage.
","abstract_html":"<p>The study of plumage is a foundational aspect of ornithology, and the features of even a single feather can provide valuable information on an individual’s health, sex, or age. Recent discoveries on the abilities of birds to see in the ultraviolet (UV) spectrum has led to study of the UV-reactive characteristics of bird plumage and the biological significance of such plumage. Long-eared owls (Asio otus) possess a demonstrative capability to see UV light, and their plumage contains deposits of UV-sensitive pigments that fluoresce bright red when exposed to UV light. Little is understood about the origin and function of these pigments, and few studies have attempted to describe their variation within a species. In this study, I describe phenotypic variation within the long-eared owl, with an emphasis on both visible and ultraviolet aspects of plumage coloration. I used a molecular genetic sexing assay to evaluate a published method of sexing long- eared owls in the field based on melanistic pigmentation. I found that although some long-eared owls exhibit distinct plumage dimorphism in the visible spectrum, there also is an intermediate polymorphism that greatly limits the number of individuals that can be classified. I also investigated variation in fluorescent pigmentation through the use of a fluorescence detector and found evidence that fluorescent pigment concentration varies both between the sexes and between juvenile and adult plumage.</p>","abstract_has_math":false,"creators":["Griffith, Emily"],"institution":null,"degree_name":"Master of Science","degree_level":"Thesis","degree_discipline":"Biology","degree_department":null,"school":null,"contributors":["Dr. Alec R. Lindsay"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2021,"date_issued":"2021-08-01T07:00:00Z","date_published":"2021-08-01T07:00:00Z","updated_at":"2026-07-24T03:24:17Z","subjects":["Ornithology","Pigmentation","Plumage","Sexual Dimorphism","Porphyrin","Fluoresence","Owls","Strigiformes"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://commons.nmu.edu/theses/677","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Dr. Alec R. Lindsay"]},{"key":"dc:creator","label":"Author","values":["Griffith, Emily"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.available","label":"Dc Date Available","values":["2026-07-08T07:00:00Z"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Biology"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Thesis"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Ornithology","Pigmentation","Plumage","Sexual Dimorphism","Porphyrin","Fluoresence","Owls","Strigiformes"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://commons.nmu.edu/theses/677"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["The study of plumage is a foundational aspect of ornithology, and the features of even a single feather can provide valuable information on an individual’s health, sex, or age. Recent discoveries on the abilities of birds to see in the ultraviolet (UV) spectrum has led to study of the UV-reactive characteristics of bird plumage and the biological significance of such plumage. Long-eared owls (Asio otus) possess a demonstrative capability to see UV light, and their plumage contains deposits of UV-sensitive pigments that fluoresce bright red when exposed to UV light. Little is understood about the origin and function of these pigments, and few studies have attempted to describe their variation within a species. In this study, I describe phenotypic variation within the long-eared owl, with an emphasis on both visible and ultraviolet aspects of plumage coloration. I used a molecular genetic sexing assay to evaluate a published method of sexing long- eared owls in the field based on melanistic pigmentation. I found that although some long-eared owls exhibit distinct plumage dimorphism in the visible spectrum, there also is an intermediate polymorphism that greatly limits the number of individuals that can be classified. I also investigated variation in fluorescent pigmentation through the use of a fluorescence detector and found evidence that fluorescent pigment concentration varies both between the sexes and between juvenile and adult plumage.
"]},{"key":"dc:title","label":"Title","values":["PLUMAGE CHARACTERISTICS OF THE LONG-EARED OWL (Asio otus) IN THE VISIBLE AND ULTRAVIOLET SPECTRA OF LIGHT"]}]}],"canonical_facts":{"dc:contributor":["Dr. Alec R. Lindsay"],"dc:creator":["Griffith, Emily"],"dc:date.available":["2026-07-08T07:00:00Z"],"dc:description.abstract":["The study of plumage is a foundational aspect of ornithology, and the features of even a single feather can provide valuable information on an individual’s health, sex, or age. Recent discoveries on the abilities of birds to see in the ultraviolet (UV) spectrum has led to study of the UV-reactive characteristics of bird plumage and the biological significance of such plumage. Long-eared owls (Asio otus) possess a demonstrative capability to see UV light, and their plumage contains deposits of UV-sensitive pigments that fluoresce bright red when exposed to UV light. Little is understood about the origin and function of these pigments, and few studies have attempted to describe their variation within a species. In this study, I describe phenotypic variation within the long-eared owl, with an emphasis on both visible and ultraviolet aspects of plumage coloration. I used a molecular genetic sexing assay to evaluate a published method of sexing long- eared owls in the field based on melanistic pigmentation. I found that although some long-eared owls exhibit distinct plumage dimorphism in the visible spectrum, there also is an intermediate polymorphism that greatly limits the number of individuals that can be classified. I also investigated variation in fluorescent pigmentation through the use of a fluorescence detector and found evidence that fluorescent pigment concentration varies both between the sexes and between juvenile and adult plumage.
"],"dc:identifier":["https://commons.nmu.edu/theses/677"],"dc:subject":["Ornithology","Pigmentation","Plumage","Sexual Dimorphism","Porphyrin","Fluoresence","Owls","Strigiformes"],"dc:title":["PLUMAGE CHARACTERISTICS OF THE LONG-EARED OWL (Asio otus) IN THE VISIBLE AND ULTRAVIOLET SPECTRA OF LIGHT"],"thesis:degree_discipline":["Biology"],"thesis:degree_level":["Thesis"],"thesis:degree_name":["Master of Science"]},"updated_at":"2026-07-24T03:24:17Z"}