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Nocturnal Bird and Bat Migration in the Central Appalachians

Nocturnal Bird and Bat Migration in the Central Appalachians. Increase understanding of spatiotemporal distribution

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Nocturnal Bird and Bat Migration in the Central Appalachians

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    3. Nocturnal Bird and Bat Migration in the Central Appalachians Increase understanding of spatiotemporal distribution & flight characteristics of nocturnal migrants Specific objectives: Document broad-scale patterns Document site-specific passage rates, flight directions & altitudes

    4. Nocturnal Bird and Bat Migration in the Central Appalachians Specific objectives: Obtain information on identity & relative abundance of bird species that call while migrating Model effects of location, topography, weather, etc. on migrant abundance & flight characteristics

    5. Results will be used to: Identify where or when migrants might be at risk from wind power development Inform project review/permitting process Assess risk to migratory populations Siting & operational guidelines Identify important migration pathways for conservation actions

    6. Broad-scale Patterns ANALYSIS OF NEXRAD DATA Temporal and spatial distribution & density Direction of movement to assess migrant response to topography

    7. NEXRAD radial velocity images 4 Sept 2003, 2300 EDT Note the clean hourglass-like pattern typical for Raleigh, located in the Piedmont, indicating one primary traffic vector. In contrast, migration passage near Roanoke & Charleston often shows discontinuities in direction and larger areas of ambiguity, indicating birds moving in multiple directions, possibly in response to topography. Ragged edges to the sampled areas occur where topography blocks radar coverageNote the clean hourglass-like pattern typical for Raleigh, located in the Piedmont, indicating one primary traffic vector. In contrast, migration passage near Roanoke & Charleston often shows discontinuities in direction and larger areas of ambiguity, indicating birds moving in multiple directions, possibly in response to topography. Ragged edges to the sampled areas occur where topography blocks radar coverage

    8. Limitations of NEXRAD data Incomplete coverage Topographic blockages within areas of coverage Does not provide information on altitudinal zone of interest

    9. Site-specific Information on Migrant Abundance & Flight Acoustic Monitoring Index abundance of migrating birds that call while in flight Relative abundance of species or species groups Portable Radar Sampling Target density, altitude, direction & speed of movement

    11. Acoustic Monitoring of Migrant Passage

    12. Acoustic Monitoring Advantages Samples altitudinal zone that could be occupied by wind turbines ARUs relatively inexpensive (~$500) Suitable for forested or remote locations Can be established in small clearings Easily portable Limitations Not all migrating birds call in flight, or call at all times Technical problems with recording units

    13. Data Management Huge effort required to process & analyze sound files 60 – 90 gigabytes compressed audio per site per fall season 1.7 – 2.6 terabytes per fall season (compressed) Uncompressed ratio 11:1

    14. Sound File Analysis Scan recordings to detect calls Summarize calls for each location and night

    15. What Have We Found? Highly variable spatially & temporally Need to develop sub-sampling approach Large number of false positives (weather & spring peepers) If time allows will be able to identify some to species level

    17. Portable Radar Sampling Detects ‘all’ targets, including bats, out to 1850 m Altitudinal distribution to 1400 m AGL Complementary technique Radar sampling allows estimation of proportion of migrants detected acoustically Acoustic monitoring ‘informs’ radar of species composition of bird targets

    18. Vertical Radar

    20. Portable radar sampling Limitations Site requirements Relatively large open area (or need jack to raise radar above tree level) For vertical radar, clear view from E-W horizons Accessible by road Few topographic blockages Cannot reliably distinguish birds from bats Relatively expensive Few possible sites in Central Appalachians, at least on public lands. Few possible sites in Central Appalachians, at least on public lands.

    21. Preliminary Radar Results Approx 1/3 of biological targets occur below 300 meters AGL Limited to spring 2006 More results to be presented March 24 in conjunction with Wilson Meeting

    23. Acknowledgements Funding USGS FWS Science Support Program (R5) USFWS – Atlantic Coast Joint Venture Monongahela National Forest Maryland DNR (SWG) West Virginia DNR (SWG) Virginia DGIF (SWG) The Nature Conservancy of VA (matching funds for VA SWG)

    24. Acknowledgements Logistical Support Monongahela National Forest George Washington & Jefferson National Forests Virginia DGIF Canaan Valley NWR The Nature Conservancy Cornell Lab of Ornithology

    25. For additional information: Deanna Dawson ddawson@usgs.gov Tim Jones tim_jones@fws.gov http://www.pwrc.usgs.gov/resshow/windpower/

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