Lewis, Tyler L. (ORCID: 0000-0002-4998-3031) Esler, Daniel (ORCID: 0000-0001-5501-4555) 20200921 tabular digital data, document Anchorage, Alaska U.S. Geological Survey, Alaska Science Center Suggested Citation: Lewis, T.L., Esler, D., 2020, Data for determining age of Barrow's Goldeneye (Bucephala islandica) from external characteristics, Alaska and Canada, 2007-2015, U.S. Geological Survey data release, https://doi.org/10.5066/P92GRT3C https://doi.org/10.5066/P92GRT3C These data describe an exercise in which known age and sex class of 100 Barrow’s goldeneyes (Bucephala islandica), determined by expert examination bursa and plumage, was contrasted with age and sex classes estimated from photos by trained observers. These data were collected to evaluate whether observer-based surveys could accurately estimate age and sex classes in the field. Data fields include the number identifying the individual duck, the known age and sex class of that individual, and the estimated age and sex class for each of 20 independent observers. 20070206 20150411 observed Complete None planned North Pacific coast of Alaska and British Columbia. -149.25 -122.08 61.65 47.87 USGS Metadata Identifier USGS:ASC312 ISO 19115 Topic Category Biota Environment NASA GCMD Earth Science Keyword Thesaurus Terrestrial ecosystems Animals/vertebrates Birds Ducks/geese/swans USGS CSA Biocomplexity Thesaurus Waterfowl Migratory birds Age composition Plumage USGS Thesaurus Field sampling Sexing (plants and animals) Wildlife biology Population dynamics None Barrow's Goldeneye Bucephala islandica USGS Geographic Names Information System (GNIS) Alaska Prince William Sound Stephens Passage NGA GEOnet Names Server Canada British Columbia Indian Arm None Barrow's Goldeneye ITIS Integrated Taxonomic Information System Unknown online database online ITIS-North America Taxonomic details retrieved October 26, 2022, from the Integrated Taxonomic Information System online database https://www.itis.gov https://doi.org/10.5066/F7KH0KBK Species were identified by skilled observers in the field based on general appearance of feathers and plumage, behavior, and vocalization. Taxonomy is complete for all samples. No voucher specimens were collected. Kingdom Animalia Subkingdom Bilateria Infrakingdom Deuterostomia Phylum Chordata Subphylum Vertebrata Infraphylum Gnathostomata Superclass Tetrapoda Class Aves Order Anseriformes Family Anatidae Subfamily Anatinae Genus Bucephala Species Bucephala islandica Barrow's Goldeneye TSN: 175144 No access constraints. No use constraints. These data are marked with a Creative Common CC0 1.0 Universal License and are in the public domain. It is requested that this USGS data release be cited for any subsequent publications that reference or utilize these data. Users are advised to read the dataset's metadata thoroughly to understand appropriate use and data limitations. U.S. Geological Survey, Alaska Science Center Mailing and Physical

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Anchorage Alaska 99508 USA 907-786-7000 gs-ak_asc_datamanagers@usgs.gov Lewis, T.L. Esler, D. Hogan, D.H. Boyd, W.S. Bowman, T.D. Thompson, J. 2020 journal article Wildlife Society Bulletin 44(4):654-661 online The Wildlife Society Lewis, T.L., Esler, D., Hogan, D.H., Boyd, W.S., Bowman, T.D., Thompson, J. 2020. Reliability of External Characteristics to Age Barrow’s Goldeneye. Wildlife Society Bulletin 44(4):654-661. https://doi.org/10.1002/wsb.1123 https://doi.org/10.1002/wsb.1123 Individual ID's, age and sex, and observer responses were cross-checked and verified with original worksheets. Attribute values fall within expected ranges and data were proofed for the presence of duplication and omission. No data were omitted and there are no missing data or blank entries. FIELD: We captured Barrow’s goldeneyes in flight with floating mist nets, placed captured birds in small kennels, transported them to shore for processing, and marked each bird with a uniquely numbered metal tarsal band. We determined the sex of each captured bird based on plumage and cloacal characteristics. Because we did not know the ages of captured birds, we measured the bursa of Fabricius (hereafter bursa) of each individual, using these measurements as estimates of age class. For sea ducks, the degree of bursal involution provides an accurate measure of age, especially when used to separate first-year birds (0–1 yr of age) from adults (>1 yr of age). We measured bursal depth (± 1 mm) by inserting a blunt metal probe into the bursal sac and categorized all Barrow’s goldeneyes with bursal depths >10 mm as first-year birds and <10 mm as adults. Additionally, we documented presence or absence of notched tail feathers for each captured bird as a secondary benchmark of age class. Unknown FIELD: We photographed the head, wing, and belly of each captured bird. From these photographs, as well as previous descriptions of Barrow’s goldeneye plumage, we focused on 5 external characteristics, for both males and females, with binary states that putatively corresponded to age class. For males, we used the following 5 characteristics: (1) Belly color – all white or edged with gray; (2) Head color – Purplish-black or brown; (3) Eye color – yellow or brown; (4) Facial crescent – full or partial; (5) Median secondary coverts – white or black. For females, we used the following 5 characteristics: (1) Belly color – all white or edged with gray; (2) Bill radiance – bright or dull; (3) Bill blackness – <50% black or >50% black; (4) Eye color – yellow or brown; and (5) Median secondary coverts – white or black. Unknown LAB: We assessed the ability of 20 novice observers, after receiving training on external markers of age, to estimate age classes of Barrow’s goldeneyes. For our training, we provided observers a manual that highlighted the various external characteristics for each age and sex combination, and observers were given unlimited time to review the manual. We restricted our training to external markers of the head because these markers are most useful for field-based age surveys of Barrow’s goldeneyes, in which observers view birds from a distance through magnifying optics. After completing training, observers viewed a slideshow of 100 photographs of Barrow’s goldeneyes, having 10 seconds per photo to estimate sex and age class. We randomly selected 25 photographs per age-sex cohort for inclusion in the slideshow, and we used only photographs from our capture efforts. Lastly, to assess accuracy of observers’ age classification, we compared their results to bursal-derived age classes. Unknown Results were transcribed into digital data tables. Unknown barrowsGoldeneye_ageDetermination_alaskaBC_esler_2007_2015.csv Table with the inventory of photos used for the exercise. Each record includes: the actual sex and age of each individual goldeneye and the visual assessments of age and sex of those individuals by the 20 observers. Presented in a Comma Separated Value (CSV) formatted table. Author defined Photo Consecutive numbering indicating the order in which photos were displayed to observers. Corresponds to the slide number in the upper left corner in each photo in the PDF file included with this data package. Author defined 1 100 Photo ID number Band_ID Unique identification code used to mark individual birds. Composed of the final 5 digits stamped on a metal leg band issued by the U.S. Geological Survey, Bird Banding Lab, Patuxent Wildlife Research Center, Patuxent, Maryland. The initial capture and banding event and associated band number are reported to the USGS Bird Banding Laboratory in the year of banding and all banding and encounter data can be obtained from the Bird Banding Laboratory. USGS Bird Banding Laboratory https://www.pwrc.usgs.gov/bbl/ 1152 36498 integer Real_Sex Indicates the known sex of the individual bird, based on cloacal and plumage examination in the field, with F = female and M = male. Author defined F Female Author defined M Male Author defined Real_Age Indicates the known age class of the individual bird, based on measurement of bursal involution in the field. Author defined Y Young (first year of life) Author defined A Adult (in second year or later) Author defined Real_Sex_Age Combines the sex and age categories into a single category. Author defined FY Female young Author defined FA Female adult Author defined MA Male adult Author defined MY Male young Author defined Obs 1 Column representing results from a single observer. The code representing the estimated sex and age classification by observer 1, formatted per the Real_Sex_Age column. Author defined FY Female young Author defined FA Female adult Author defined MA Male adult Author defined MY Male young Author defined Obs 2 The code representing the estimated sex and age classification by observer 2, formatted per the Real_Sex_Age column. Author defined FY Female young Author defined FA Female adult Author defined MA Male adult Author defined MY Male young Author defined Obs 3 The code representing the estimated sex and age classification by observer 3, formatted per the Real_Sex_Age column. Author defined FY Female young Author defined FA Female adult Author defined MA Male adult Author defined MY Male young Author defined Obs 4 The code representing the estimated sex and age classification by observer 4, formatted per the Real_Sex_Age column. Author defined FY Female young Author defined FA Female adult Author defined MA Male adult Author defined MY Male young Author defined Obs 5 The code representing the estimated sex and age classification by observer 5, formatted per the Real_Sex_Age column. Author defined FY Female young Author defined FA Female adult Author defined MA Male adult Author defined MY Male young Author defined Obs 6 The code representing the estimated sex and age classification by observer 6, formatted per the Real_Sex_Age column. Author defined FY Female young Author defined FA Female adult Author defined MA Male adult Author defined MY Male young Author defined Obs 7 The code representing the estimated sex and age classification by observer 7, formatted per the Real_Sex_Age column. Author defined FY Female young Author defined FA Female adult Author defined MA Male adult Author defined MY Male young Author defined Obs 8 The code representing the estimated sex and age classification by observer 8, formatted per the Real_Sex_Age column. Author defined FY Female young Author defined FA Female adult Author defined MA Male adult Author defined MY Male young Author defined Obs 9 The code representing the estimated sex and age classification by observer 9, formatted per the Real_Sex_Age column. Author defined FY Female young Author defined FA Female adult Author defined MA Male adult Author defined MY Male young Author defined Obs 10 The code representing the estimated sex and age classification by observer 10, formatted per the Real_Sex_Age column. Author defined FY Female young Author defined FA Female adult Author defined MA Male adult Author defined MY Male young Author defined Obs 11 The code representing the estimated sex and age classification by observer 11, formatted per the Real_Sex_Age column. Author defined FY Female young Author defined FA Female adult Author defined MA Male adult Author defined MY Male young Author defined Obs 12 The code representing the estimated sex and age classification by observer 12, formatted per the Real_Sex_Age column. Author defined FY Female young Author defined FA Female adult Author defined MA Male adult Author defined MY Male young Author defined Obs 13 The code representing the estimated sex and age classification by observer 13, formatted per the Real_Sex_Age column. Author defined FY Female young Author defined FA Female adult Author defined MA Male adult Author defined MY Male young Author defined Obs 14 The code representing the estimated sex and age classification by observer 14, formatted per the Real_Sex_Age column. Author defined FY Female young Author defined FA Female adult Author defined MA Male adult Author defined MY Male young Author defined Obs 15 The code representing the estimated sex and age classification by observer 15, formatted per the Real_Sex_Age column. Author defined FY Female young Author defined FA Female adult Author defined MA Male adult Author defined MY Male young Author defined Obs 16 The code representing the estimated sex and age classification by observer 16, formatted per the Real_Sex_Age column. Author defined FY Female young Author defined FA Female adult Author defined MA Male adult Author defined MY Male young Author defined Obs 17 The code representing the estimated sex and age classification by observer 17, formatted per the Real_Sex_Age column. Author defined FY Female young Author defined FA Female adult Author defined MA Male adult Author defined MY Male young Author defined Obs 18 The code representing the estimated sex and age classification by observer 18, formatted per the Real_Sex_Age column. Author defined FY Female young Author defined FA Female adult Author defined MA Male adult Author defined MY Male young Author defined Obs 19 The code representing the estimated sex and age classification by observer 19, formatted per the Real_Sex_Age column. Author defined FY Female young Author defined FA Female adult Author defined MA Male adult Author defined MY Male young Author defined Obs 20 The code representing the estimated sex and age classification by observer 20, formatted per the Real_Sex_Age column. Author defined FY Female young Author defined FA Female adult Author defined MA Male adult Author defined MY Male young Author defined barrowsGoldeneye_ageDetermination_alaskaBC_esler_2007_2015.pdf PDF document containing all of the 100 photos of Barrow's Goldeneyes shown to the observers in this exercise. The number in the upper left corner of each photo corresponds to the "Photo" attribute in the table included with this data package. Presented in single PDF formatted document. Author defined U.S. Geological Survey USGS ScienceBase Team Mailing and Physical

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Denver Colorado 80225 USA 1-888-275-8747 sciencebase@usgs.gov The U.S. Geological Survey, Alaska Science Center is the authoritative source of these data, distributed by ScienceBase (a USGS Trusted Digital Repository). Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey, no warranty expressed or implied is made regarding the display or utility of the data for other purposes or on all computer systems, nor shall the act of distribution constitute any such warranty. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. CSV, PDF Tabular data in CSV format; Images in PDF format; FGDC metadata in XML and HTML formats. https://doi.org/10.5066/P92GRT3C None 20250428 U.S. Geological Survey, Alaska Science Center Mailing and Physical

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Anchorage Alaska 99508 USA 907-786-7000 gs-ak_asc_datamanagers@usgs.gov FGDC Biological Data Profile of the Content Standard for Digital Geospatial Metadata (CSDGM) FGDC-STD-001.1-1999