Determining Wintering Areas and Migrations Routes of Red-throated Loons (Gavia stellata) in Atlantic Offshore Waters Using Satellite Tracking

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1 Determining Wintering Areas and Migrations Routes of Red-throated Loons (Gavia stellata) in Atlantic Offshore Waters Using Satellite Tracking Red-throated Loon (Gavia stellata) released with satellite transmitter. Photo by Rick Gray. Biodiversity Research Institute Portland, Maine, USA Carrie Gray - Wildlife Research Biologist Andrew Gilbert Data Management Director

2 Project Leads and Co-Authors USFWS Division of Migratory Birds, Hadley, MA Caleb Spiegel - Project Coordinator USGS Patuxent Wildlife Research Center, Laurel, MD Alicia Berlin, PhD Wintering Surf Scoter and Long-tailed Duck PTT tracking study & wintering Northern Gannet CTT tracking study. Glenn Olsen, PhD, DVM Project Veterinarian Memorial University, St. John s, Newfoundland, Canada Bill Montevecchi, PhD - Juvenile Northern Gannet tracking study on breeding grounds and wintering Northern Gannet CTT tracking study. Avian Specialty Veterinary Services, Menomonee Falls, WI Scott Ford, DVM Project Veterinarian Biodiversity Research Institute, Portland, ME Andrew Gilbert Satellite transmitter data management and analysis Carrie Gray - Red-throated Loon PTT tracking study Lucas Savoy Wintering Surf Scoter and Long-tailed Duck PTT tracking study Iain Stenhouse, PhD - Wintering Northern Gannet PTT tracking study

3 Project Funding Bailey Wildlife Foundation

4 Red-throated Loon (Gavia stellata) Photo credit: Dave Menke Source: USFWS National Digital Library Range map source: Birds of North America, online edition

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6 Background and objectives Current interest in offshore wind from MA to Carolinas Effects on birds unknown Expressed need to understand individual movement inform siting Primarily focused on wintering and migration Focus NC-NY Study species: Northern Gannet, Red-throated Loon, and Surf Scoter H. Hillewaert

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8 Wintering Loons on Eastern U.S. Coast 70, ,000 RTLOs estimated to winter off along the eastern U.S. coast ~500,000 Common Loons Largest concentrations reported off the coasts of Delaware and North Carolina 2,387 birds observed dead in gillnets, February - April 1998, 68% were Red-throated Loons and 21% were Common Loons (Forsell 1999). Another 825 dead Red-throated Loons were found washed ashore on beaches that winter. In total, Forsell (1999) estimated that this represented 1.2 to 2.4 % of the total number of fall migrating birds counted at Cape May, NJ earlier that season. Warden (2010) calculated that each year between 620 and 1,297 Red-throated Loons were taken as bycatch in commercial gillnet fisheries in the mid-atlantic region, totaling an estimated 10,758 birds between 1996 and 2007.

9 Capture Areas Delaware Bay Chesapeake Bay Pamlico Sound

10 Launch at dusk Run transects in search of birds

11 Adult NOGA and RTLO captured at sea in January, February and March using night-lighting techniques.

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13 Aged and weighed for PTT candidate assessment. ASY >1,500 g

14 Photo by Jonathan Fiely

15 Band and release all SY birds

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17 Weight of transmitter: 49 grams Telonics PTTs Argos

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20 SATELLITE TAG SAMPLE SIZE Year NOGA RTLO SUSC Total

21 Tracking Results LOONS 111 total RTLO captures and 66 NOGAs over four 6- week winter field seasons, Transmitters deployed: RTLO = 86, NOGA = 66

22 Data management and Analysis Automated download process from Argos Process to compile, remove duplicates, and filter poor quality data Culled first 14 days of data for each animal > 30 days of data Identified unique breeding, staging, molting, wintering, and migrating periods for each animal Used dynamic Brownian bridge movement model (dbbmm) to generate utilization distributions for each animal and period in R package, move (Kranstauber et al. 2012) Composite UD by calculating mean UD of all animals for each species

23 Kernel density estimation Autocorrelated kernel density estimation (AKDE)

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27 Spring staging areas Bay of Fundy Southwestern Gulf of St. Lawrence St. Lawrence River

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30 Breeding Grounds Nunavut, Northwest Territories, Quebec, Manitoba, and Greenland Farthest west: Banks Island, NWT Farthest north: 81 degrees N latitude

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35 Hudson Bay surface currents

36 Blood Hg (ppm, ww) Blood Hg (n = 44) Range: ppm, ww Mean: 0.50 ± 0.26 (SD) ppm, ww (SE = 0.04) Median: 0.44 ppm, ww RTLO (n = 44) Feather Hg (n = 55) Range: ppmm, dw Mean: ± 6.76 ppm, dw (SD) (SE = 0.92) Median = 8.79 ppm, dw

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38 Mean (± SD) latitude during annual cycle

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40 Captured in Chesapeake Bay on 02/28/12 6/11 8/17 9/2 11/16 4/12 6/6 11/19 4/9 start migration

41 ASY F Captured in Pamlico Sound, NC on 2/12/13 7/20 8/10 8/15 8/20 7/10 7/15 8/25 7/5 10/21 11/9 11/13 11/17 11/20 6/30 06/25 5/29 6/20 5/22 5/28 4/15 5/19 11/27 April 10, 2013 begin spring migration

42 Female captured near Bay Bridge, VA on 2/6/13 6/20 8/30 9/4 11/12 5/23 6/2 5/14 5/23 11/13 12/28 5/3 5/14 12/29 4/27 start migration

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49 Preliminary Conclusions Heavy use of large bays. Less use of offshore areas, focused on migration. More concerns in state waters. More work needs to be done to understand movements of juveniles.

50 Capture Crew Members: Carl Anderson, Allie Byrd, Mike Chickering, Jonathan Fiely, Carrie Gray, Rick Gray, Ian Johnson, Robby Lambert, Bill Montevecchi, Chris Persico, Vin Spagnuolo, Iain Stenhouse Vets: Scott Ford, Glenn Olsen, Michelle Kneeland, Ginger Stout, Darryl Heard

51 Photo by Rick Gray Any Questions?