Migration across oceans

[Basil Hallhead]

[This followup was posted to sci.bio.entomology.lepidoptera and a copy 
was sent to the cited author.]

Several months ago the Discovery channel (or ?) had a feature about 
just this -- but about monarchs in the UK.  Seems that they don't 
"migrate" but weather systems can carry them huge distances.  An 
interesting topic.

Basil


In article <3C5D7522.CA892D70 at csus.edu>, patfoley at csus.edu says...
> Dear lepidopterists, butterfliers and rugged individualists and big-brother
> Stalinists,
> 
>     For my present purposes, I am interested in the problem of whether some
> butterflies (such as Vanessa spp) can sometimes travel at night long distances
> over the oceans. I am not so interested in whether butterflies commonly fly at
> night or what night is. The answer to this question would help to clear up
> problems in the distributional biogeography of some butterflies.
> 
>     I have read that butterflies used to be observed by ships (under Cook and
> Bligh) off the coast of South America. If anyone knows more about these reports,
> it would be great to get more precise information.
> 
> Given the cosmopolitan distribution of Vanessa cardui and especially the Hawaiian
> Vanessa tammeamea (which is presumably close to Vanessa atalanta), the alternative
> means of dispersal would seem to be day and night flying, rafting or alighting on
> the water at night.
> 
> Patrick Foley
> patfoley at csus.edu
> 
> Woody Woods wrote:
> 
> > Stan and others, regarding the suggested experiment, perhaps another way would
> > be to work with marked butterflies in a walk-in cage, monitoring their
> > position 2-3 times through the night. If the butterflies are flying at night,
> > this would allow directionality of movement to be established. Colleagues have
> > done cage experiments with migrating butterflies in Costa Rica (crepuscular
> > behavior though, not nocturnal) and have found cage movements and activity
> > corresponding to outdoor observations.
> >
> > I have found Vanessa occasionally-- not often-- flying in an indoor walk-in
> > cage during the night portion of a 16L:8D light cycle, at a temperature of
> > around 21 decrees C. Those observations are at this point just anecdotal,
> > though.
> >
> > Monitoring activity of caged animals has contributed to understanding of bird
> > migration in a number of classic works.
> >
> > I guess I'd be concerned that in an outdoor experiment a butterfly could crawl
> > out and then be taken by spiders or something else-- a problem I had even with
> > some cage experiments when plants were in the cage. Often the remaining bits
> > were scattered. However, doing BOTH outdoor caged and cageless experiments
> > could be pretty strong.
> >
> > Also, it is certainly true that the eyes of nocturnally flying moths are have
> > the capacity to dark-adapt, with consistent physiological changes following a
> > circadian pattern (articles by Richard White and Ruth Bennett), and a logical
> > research step would be to ask whether the eyes of Vanessa and other suspected
> > nocturnal migrators have the same capacity.
> >
> > Woody Woods
> >
> > Stan Gorodenski wrote:
> > >
> > > Paul Cherubini wrote:
> > > >
> > > >
> > >
> > > Of course, the biology of the butterfly would have to be taken into
> > > consideration.  What I suggested is not a completely worked out
> > > experimental design, nor was it intended to be one.  If your observation
> > > regarding the Monarch translates to Vanessa, then the absence or
> > > presence of the butterfly would not be monitored throughout the night
> > > but just once, no later than one hour prior to sunrise.
> > >  (snip)
> > >
> > > > With regard to butterflies flying at night, here is a response
> > > > from Dr. Chip Taylor I found on the Web:
> > > >
> > > > http://www.monarchwatch.org/read/faq4.htm#29
> > > > 29. Why don't the Monarch butterflies fly at night?
> > > >
> > > > Dr. Chip Taylor replies:
> > > >
> > > > "Butterflies are diurnal insects which means they only fly
> > > > during the day. We are not aware of any butterflies
> > > > that fly at night. Why this is the case is not clear, but
> > > > butterflies are generally brightly colored and highly
> > > > visual and their eyes are not designed to function
> > > > under low light conditions. Moths are predominantly
> > > > nocturnal (night flying) and they have what are known
> > > > as "dark adapted" eyes which allow them to fly at night
> > > > when light levels are extremely low."
> > > >
> > >
> > >
> > >
> > --
> > *********************************************************
> > William A. Woods Jr.
> > Department of Biology
> > University of Massachusetts Boston
> > 100 Morrissey Blvd                      Lab: 617-287-6642
> > Boston, MA 02125                        Fax: 617-287-6650
> > *********************************************************
> >
> >
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-- 
= = = = =
Basil Hallhead  President & Principal Consultant
HEI Consulting     http://www.heiconsulting.com/
b_halhed at heiconsulting.com

 
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