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  • Kathy &/or Dave Biggs
    Hello All; The prevailing winds during the flight season (May to Sept. in Acadia) would certainly assist A. junius in reaching Europe from the northeast
    Message 1 of 1 , Jan 27, 2011
      Hello All;
      The prevailing winds during the flight season (May to Sept. in Acadia)
      would certainly assist A. junius in reaching Europe from the northeast
      Atlantic coast (which seems a likely point of departure).
      Major weather events might speed the insects on their way, and often go
      in more or less the right direction for this, but they could probably
      reach the eastern side of the Atlantic without such events.
      A. junius consistently reaches Sable Island every year, which is 160km
      offshore towards Europe from the closest land in Nova Scotia. That
      species' travel west to east is easier then from south to north is
      suggested by its absence from the island of Newfoundland, which is only
      110km away from the closest point of Nova Scotia.
      I have speculated that there may be weather features, perhaps associated
      with the Gulf Stream, which lead them to the island. Not an easy
      land-fall as it is a sickle-shaped feature about 37km long east to west,
      but only about 6km wide north to south (taking the arc into account) -
      approaching from the west it is therefore narrow relative to the
      distance travelled, from the south considerably easier to find. I would
      expect many individual insects to miss this land-fall and continue on
      down-wind to the east.
      It is not necessary to imagine the individuals spending all their time
      in crossing in the air - there are abundant perches on the ocean
      surface; patches of floating seaweed, flotsam and jetsam, vessels, and
      an apparently extraordinary number of plastic bottles. Although the air
      temperature at the water surface would be low, sunlight could warm the
      individuals sufficiently for them to take off again after a rest (even
      on days when you see your breath the ground can be quite hot in the sun,
      I expect it to be similar for floating objects, and at any rate the
      insects would catch the direct sunlight themselves).
      And 'aeolian plankton' might serve A. junius as well as it apparently
      does for the Pantala species - they need not even fast during the trip.
      Quite an interesting subject - I wish our birders up here would put
      attention towards the odonates during their coastal watches, as is done
      further south.
      Regards,
      Paul
      -----------------------------------------------------------------------------------
      *Paul M. Brunelle, BDes, CGD, FGDC*
      64 Buccaneer Road, East Chester
      Nova Scotia, Canada, B0J 1J0
      902-277-0101
      About 44.58°N, -64.0°W.
      /Fellow of the Society of Graphic Designers of Canada/
      /Research Associate, New Brunswick Museum/
      /Regional Coordinator, Atlantic Dragonfly Inventory Program/
      /Coordinator, Maine Damselfly and Dragonfly Survey/

      --
      California Dragonflies http://www.sonic.net/dragonfly
      Southwest Dragonflies http://southwestdragonflies.net/
      Bigsnest Wildlife Pond http://www.bigsnestpond.net/
      ----------------------------------------------------------------
      Kathy and Dave Biggs bigsnest@... 707-823-2911
      308 Bloomfield Rd. Sebastopol, CA 95472

      dba Azalea Creek Publishing azalea@... fax:707-823-2911
      http://www.sonic.net/~bigsnest/azaleacreekpublishing/








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