Journey south (Vanessa atalanta)

[bill and Dale]

To all those who marvel at migration,
       When we were flooded with an irruption of Red Admirals from the
south here in southern New England this June and July it was a first for
many of us and a spectacle to behold.  I wondered about the possibility
of witnessing the return trip (of the progeny) and today at the beach in
Hammonassett State Park I was not disappointed.  A continuous stream of
perfect, crisp, fresh V. atalanta flowed from east to west from 9:30 AM
until I left at 2:00 PM.  I did several one point 15 minute fixed counts
which averaged just under 40 per time unit for a rate of at least 160
per hour. Keep in mind that they were also moving out of my narrow field
of view and you can imagine a very large movement. When I left at two
they were going stronger than ever.   Frontal conditions were perfect
for this type of movement in that a line of T-storms went through the
state yesterday and the weather cleared out last night and produced
steady, brisk winds out of the northwest all day.  No other butterflies
(besides a modest Monarch movement) were observed in sustained
directional movement. There were also thousands of dragonflies but
that's another matter.
      One of the most fascinating sidelights of this migration was my
discovery of a pit-stop a large number of the migrators were making. I
was watching two immature Little Blue Heron in the marsh at the east end
of the park and Admirals kept flying through my field of view. I forgot
about the birds and started watching the butterflies. They were flying
across open marsh away from the beach directly INTO THE WIND. I
wondered? Why were they leaving the main migratory route on the beach?
It was strange because they were flying over open ground yet in a very
narrow corridor. Against the wind? It stuck me: They were on a scent
trail!  I followed them for a quarter mile from the point where they
entered the marsh and there it was; a pear tree!  Rotten fruit on the
ground, Admirals spread out re-fueling. Somehow they were able to pick
up molecules of pear scent a quarter mile away in a twenty knot wind and
navigate directly to the rotten fruit. I watched this stream of
re-fuelers for an hour and counted over a 100 individuals. No other
butterflies were observed on the pears although both V. cardui and V.
virginiensis were in the park flower feeding.
      I hope some of you'all were out there today too, if not there's
always tomorrow.
                                                                   Bill
Yule