Jay, Chadwick V. (ORCID: 0000-0002-9559-2189) Fischbach, Anthony S. (ORCID: 0000-0002-6555-865X) Kochnev, Anatoly A. 20121108 raster and vector digital data Anchorage, Alaska U.S. Geological Survey, Alaska Science Center Suggested Citation: Jay, C.V, Fischbach, A.S., Kochnev, A.A., 2012, Data supporting walrus areas of use in the Chukchi Sea during sparse sea ice cover: U.S. Geological Survey data release, https://doi.org/10.5066/F7X928C3 https://doi.org/10.5066/F7X928C3 The dataset consists of geospatial files depicting the estimated June-to-November distribution of walrus foraging and occupancy during a four year period of sparse sea ice cover above the Chukchi Sea continental shelf (2008-2011). The walrus distribution and utilization estimates are based on location data from satellite-linked radio-tracked walruses in the Chukchi Sea (2008-2011). Compared to previous years this period was marked by earlier and more extensive sea ice retreat (June - September) and delayed sea ice freeze-up (October - November). This allowed walruses to arrive earlier, occupy slightly more northern areas, and stay later in the Chukchi Sea than previously. Data are combined for all four years and structured by month (June [06] - November [11]). Within each month, we estimated walrus utilization distributions by using an unweighted movement based kernel density estimator. The kernel density was then weighted by the amount of time walruses spent foraging during each recorded track segment. We present contours of the kernel density ranging from the 10th to 95th percentile. These data were prepared to better understand the monthly distribution of walruses in the Chukchi Sea. 20080601 20111130 observed Complete None planned Chukchi Sea -179.85 -159.68 72.10 67.48 USGS Metadata Identifier USGS:ASC509 ISO 19115 Topic Category Biota Environment NASA GCMD Earth Science Keyword Thesaurus Animals/vertebrates Mammals Carnivores Seals/sea lions/walruses Species/Population interactions Use/Feeding habitats Marine habitat USGS CSA Biocomplexity Thesaurus Marine ecosystems Coastal ecosystems Wildlife food habits USGS Thesaurus Wildlife Geospatial datasets None Animal distribution USGS Geographic Names Information System (GNIS) Alaska Chukchi Sea None Walrus Pacific Walrus Odobenus rosmarus divergens ITIS Integrated Taxonomic Information System Unknown online database online ITIS-North America Taxonomic details retrieved December 8, 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. Taxonomy is complete for all samples. No vouchers were collected. Kingdom Animalia Subkingdom Bilateria Infrakingdom Deuterostomia Phylum Chordata Subphylum Vertebrata Infraphylum Gnathostomata Superclass Tetrapoda Class Mammalia Subclass Theria Infraclass Eutheria Order Carnivora Suborder Caniformia Family Odobenidae Genus Odobenus Species Odobenus rosmarus Walrus TSN: 180639 Subspecies Odobenus rosmarus divergens Pacific Walrus TSN: 622045 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 Jay, C.V. Fischbach, A.S. Kochnev, A.A. 2012 journal article Marine Ecology Progress Series (MEPS) 468:1-13 online Inter-Research Science Center Jay, C.V., Fischbach, A.S., Kochnev, A.A., 2012. Walrus areas of use in the Chukchi Sea during sparse sea ice cover. Marine Ecology Progress Series 468:1-13. https://doi.org/10.3354/meps10057 https://doi.org/10.3354/meps10057 All attributes have been checked for accuracy. 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. These monthly distribution polygons have been summarized from tracking location and hourly behavior records collected from numerous walruses tracked by Argos System satellite-linked radio tags. These summarized monthly distributions are subject to sampling variability as the authors infer the distribution of the Pacific walrus population as a whole within the study area and study month from the summarized distribution of sampled walruses. Please see the Discussion section of Jay et al. (2012) which discusses limitations of this sampling and suggests months during which the sampling may have resulted in a biased understanding of the distribution. In particular: "Tagging effort differed between the eastern and western sides of our study area. In U.S. waters, we feel we obtained good spatial coverage of walrus movements and areas of use throughout the Chukchi Sea from June through October (most walruses moved to the southwestern Chukchi Sea by November). In Russian waters, we feel the spatial coverage of walrus movements we obtained was good in June, fair in July, weak in August and September, good in October (except perhaps in the northwestern areas), and good in November. Therefore, the relative concentration of walrus foraging and occupancy within our study area are biased towards the eastern side of our study area, particularly in July to September." (Jay et al 2012) METHODS - FIELD: We attached 251 satellite radio-tags (Telonics Inc., Mesa, Arizona) to walruses (Odobenus rosmarus divergens) resting on sea ice and beaches in the northern Bering Strait region and the Chukchi Sea in summer and fall (2008-2011). The tags were similar to the tags described in Fischbach and Jay (2016) and were deployed by using a crossbow or jab stick. We attached the tags on adult walruses (primarily females, n = 222). Unknown METHODS - LAB: We received data and geographic location estimates from the Argos location and data collection system. Argos location estimates were filtered through the Douglas Argos-filter algorithm (Douglas et al 2012), which uses spatial redundancy, movement rates, and angles to select between primary and alternate Argos locations and rejects unreasonable location estimates. We estimated utilization distributions (UDs) using kernel methods (Kie et al. 2010). We used a grid cell size of 5 km2 to partially account for spatial errors associated with Argos location estimates while allowing for relatively fine resolution of spatial structure on the scale of our study area. To minimize linear distortion of walrus movements, all data were projected into an azimuthal equidistant projection centered on the study area (70°N, 170° W). We used the Benhamou and Cornelis 2010 movement-based kernel density estimator to estimate a UD of walrus foraging and, separately, a UD of walrus occupancy across the Chukchi Sea during each of the study months using the spatial analysis package adehabitatHR written in Program R. To estimate a UD of foraging in a month, we estimated, for each walrus, a UD for each track segment, then summed the UD volume within each grid cell across all track segments with the volume from each track segment multiplied by the proportion of hours spent foraging during the track segment, and then re-scaled each cell volume so that the total volume within the study area summed to 1. In addition to estimating monthly UDs of walrus foraging, we estimated monthly UDs of walrus occupancy by following the above procedure, but without weighting each track segment by number of hours spent foraging. Additional data processing details are available in Jay et al 2012. Unknown LITERATURE CITED: Benhamou S., Cornélis D., 2010. Incorporating movement behavior and barriers to improve kernel home range space use estimates. Journal of Wildlife Management 74(6):1353−1360. https://doi.org/10.1111/j.1937-2817.2010.tb01257.x Douglas, D.C., Weinzierl, R., Davidson, S.C., Kays, R., Wikelski, M., Bohrer, G., 2012. Moderating Argos location errors in animal tracking data. Methods in Ecology and Evolution 3(6):999-1007. https://doi.org/10.1111/j.2041-210X.2012.00245.x Jay, C.V., Heide-JØrgensen, M.P., Fischbach, A.S., Jensen, M.V., Tessler, D.F., Jensen, A.V., 2006. Comparison of remotely deployed satellite radio transmitters on walruses. Marine Mammal Science 22(1):226-236. https://doi.org/10.1111/j.1748-7692.2006.00018.x Jay, C.V., Fischbach, A.S., Kochnev, A.A., 2012. Walrus areas of use in the Chukchi Sea during sparse sea ice cover. Marine Ecology Progress Series 468:1-13. https://doi.org/10.3354/meps10057 Kie, J.G., Matthiopoulos, J., Fieberg, J., Powell, R.A., Cagnacci, F., Mitchell, M.S., Gaillard J.-M., Moorcroft, P.R., 2010. The home-range concept: are traditional estimators still relevant with modern telemetry technology? Philosophical Transactions of the Royal Society B: Biological Science 365(1550):2221−2231. https://doi.org/10.1098/rstb.2010.0093 Unknown Raster Pixel 3046 2208 Azimuthal Equidistant -170 70 0 0 coordinate pair 5000 5000 meters World Geodetic System of 1984 (WGS84) World Geodetic System of 1984 (WGS84) 6378137 298.257223563 [FOLDER] walrus_utilizationDistribution_forage_PNG.zip Zip folder with georeferenced raster files showing estimated Walrus foraging utilization distributions by month. Files are projected into an Azimuthal Equidistant Rrojection centered on the study area (70°N, 170° W). Presented as georeferenced Portable Network Graphic (Geo PNG) files. Additionally, a non-georeferenced 'browse image' map (showing all months together) is provided as a separate image file in this data package: "USGS_Walrus_UD_Forage_Jun_Nov_BrowseImage.png". *NOTE - a legend indicating the color representation for each UD contour is provided as a separate image file in this data package: "USGS_Walrus_UD_Forage_Legend.png". Filenaming convention: USGS_Walrus_UD_Forage_aed170_70_[MM]; where [MM] = two-digit month Author defined [FOLDER} walrus_utilizationDistribution_forage_Jun-Nov_KMZ.zip Zip folder with vector polygon files showing estimated Walrus foraging utilization distribution by month, using unprojected geographic coordinates (WGS84). Presented as a Keyhole Markup Language Zipped (KMZ) file. Filenaming convention: WalrusUD[MM]_fromGM_transparent; where [MM] = two-digit month Author defined id Unique ID for each record. A concatenation of the method, month, contour. Author defined Unique ID for each record Area_sq_Km Area of the Chukchi Sea encompassed by the contour (Method, month, percentile). Author defined 38 233346 Square Kilometers Method Whether the contour represents walrus occupancy or foraging distribution Author defined Foraging Foraging distribution Author defined Month Month represented by the contour Author defined 06 11 Month (MM) Contour The percentile of the walrus population estimated to be utilizing the area within contour. Author defined 10 95 Percentile [FOLDER] walrus_utilizationDistribution_occupancy_KMZ.zip Zip folder with vector polygon files showing estimated Walrus occupancy distribution by month, using unprojected geographic coordinates (WGS84). Presented as a Keyhole Markup Language Zipped (KMZ) file. File naming convention: USGS_Walrus_UD_Occupancy_[MM]; where [MM] = two-digit month Author defined id Unique ID for each record. A concatenation of the method, month, contour. Author defined Unique ID for each record Area_sq_Km Area of the Chukchi Sea encompassed by the contour (Method, month, percentile). Author defined 422 23614 Square Kilometers Method Whether the contour represents walrus occupancy or foraging distribution Author defined Occupancy Occupancy distribution Author defined Month Month represented by the contour Author defined 06 11 Month (MM) Contour The percentile of the walrus population estimated to be utilizing the area within contour. Author defined 10 95 Percentile [FOLDER] walrus_utilizationDistribution_occupancy_aed_SHP.zip Zip folder with vector polygon file showing utilization distribution contours for walruses in the Chukchi Sea June-November (2008-2011), projected into an Azimuthal Equidistant Rrojection centered on the study area (70°N, 170° W). Geospatial data presented as an ESRI Shapefile (SHP). Author defined id Unique ID for each record. A concatenation of the method, month, contour. Author defined Unique ID for each record Area_sq_Km Area of the Chukchi Sea encompassed by the contour (Method, month, percentile). Author defined 38 23614 Square Kilometers Method Whether the contour represents walrus occupancy or foraging distribution Author defined Occupancy Occupancy distribution Author defined Foraging Foraging distribution Author defined Month Month represented by the contour Author defined 06 11 Month (MM) Contour The percentile of the walrus population estimated to be utilizing the area within contour. Author defined 10 95 Percentile [FOLDER] walrus_utilizationDistribution_occupancy_geo_SHP.zip Zip folder with vector polygon file showing occupancy distribution contours for walruses in the Chukchi Sea June-November (2008-2011), using unprojected geographic coordinates (WGS84). Geospatial data presented as an ESRI Shapefile (SHP). Author defined id Unique ID for each record. A concatenation of the method, month, contour. Author defined Unique ID for each record Area_sq_Km Area of the Chukchi Sea encompassed by the contour (Method, month, percentile). Author defined 422 23614 Square Kilometers Method Whether the contour represents walrus occupancy or foraging distribution Author defined Occupancy Occupancy distribution Author defined Month Month represented by the contour Author defined 06 11 Month (MM) Contour The percentile of the walrus population estimated to be utilizing the area within contour. Author defined 50 95 Percentile 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 Tabular data in CSV format; FGDC metadata in XML and HTML formats. https://doi.org/10.5066/F7X928C3 None 20250327 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