Migration across oceans

Patrick Foley patfoley at csus.edu
Sun Feb 3 12:36:34 EST 2002


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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