Monarch mapping

[Ron Gatrelle]

>From Ron,
    I must be turning into a disciple of Paul (not the apostle). This is
because when I read this post. My thoughts went like this. Hum, here we go
with the portables again. And, these are pretty smart monarchs. They must
have topo and road maps to help them CHOOSE the best route home. Now don't
go getting defensive. I didn't say that Fred's hypothesis is not exactly
what happened -- I just said these are the stupid thoughts that went through
my head.
Its almost 2 am. here in SC so you guys on the west coast can figure this
out by yourselves. Ta Ta

----- Original Message -----
From: "Heath, Fred" <Fred.Heath at power-one.com>
To: <leps-l at lists.yale.edu>
Sent: Monday, October 16, 2000 1:15 AM
Subject: RE: Subspecies and protection


> Paul,
> I might be able to accept the hypothesis that some of the Monarchs
> hung around the Saline Valley because the conditions were to their liking,
> but your suggestion that the Bishop butterflies have a tougher time
getting
> to coastal southern California is certainly not true. These Monarchs
> probably moved south along the eastern flank of the Sierras (which run
> basically north and south) and then SW along the Tehachapi Mts until they
> hit the Transverse Range (east-west tending mountains) and worked their
way
> through the passes (such as where I-5 goes). At that time of year, there
is
> abundant Rabbitbrush to nectar on along the entire route. Once they work
> through the Transverse Mts. they are in the LA Basin and can easily move
to
> the coast. Interestingly, I found and reported one (after reading its
letter
> and numbers with binoculars) of these bright orange-tagged butterflies
that
> year in my backyard in Simi Valley (southeast Ventura Co.) within two
weeks
> of the release.
> However Monarchs which find themselves in the Saline Valley are
> really trapped and can't as Paul points out, go west or south or even east
> for that matter. Although there are some passes to the south, the habitat
is
> less hospitable and if they managed to get through to the Panamint Valley,
> they would end up at the south end in the middle of the Mojave Desert.
Thus
> it would be a lot less likely that a Monarch released from Saline Valley
> could get to the coast even if it really had a strong instinct to do so.
>
> On a related note, Paul mentioned that Mark Walker found a winter
> roost in Anza-Borrego. Could Paul or Mark enlighten me as to exactly where
> that was? Thanks.
>
> ---Fred
>
> > -----Original Message-----
> > From: Paul Cherubini [SMTP:cherubini at mindspring.com]
> > Sent: Saturday, October 14, 2000 11:35 AM
> > To: leps-l at lists.yale.edu
> > Subject: Re: Subspecies and protection
> >
> Paul wrote:
>
>
> > The authors of that paper assumed the butterflies were
> > "trapped" by the 10,000-11,000 foot mountains surrounding
> > the Saline Valley. To test this hypothesis, I released about
> > 300 tagged monarchs (caught at the roosts along the California
> > coast) in the Saline Valley during the first week of November
> > 1991 and a "control" group of 300 outside the valley at
> > Bishop, CA.
> >
> > The Inyo mountains south and west of the Saline Valley are
> > 10,000-11,000 feet tall, but the Sierra Nevada mountains
> > south and west of Bishop are 13,000 - 14,000 feet tall.
> > Thus, the butterflies released at Bishop had a more
> > formidable barrier to cross to get back to the California coast.
> >
> > Within 10 days of release, some of the Bishop butterflies
> > were recaptured along the California coast just north of
> > Los Angeles and in the Santa Barbara area. Around half
> > a dozen total were sighted back at the Calif. coast. So this
> > group did not appear to have much difficult crossing
> > the 13,000-14,000 foot Sierra Nevada Mountains. None
> > apparently stayed in the Bishop area according to
> > a local naturalist (Derham Giuliani) who was monitoring
> > the situation.
> >
> > But no butterflies from the Saline Valley group were
> > recaptured back at the California coast or anywhere outside
> > the valley. When Derham checked the Saline
> > Valley monarch roosts in late November, lots of the
> > tagged monarchs were still there and they were still there
> > in mid December.
> >
> > So it appears the reason the tagged monarchs released
> > in the Saline Valley stayed there is because the butterflies
> > detected proximate environmental cues that "overrode"
> > the southward migratory urge. In other words, the mountains
> > were no barrier to movement, the butterflies simply had
> > no "desire" to leave the place (balmy winter climate,
> > blooming Mule Fat bushes, and a permanent creek running
> > through this desert area).
> >
> > > In other words, there does not appear to be any innate
> > > requirement that they _complete_ the migration to the Pacific
> > > coast. The migratory urge may be far less focused than many
> > > people have assumed. This raises an interesting possibility:
> > > that Monarchs from any part of the continent would, when
> > > introduced into another part of North America, would migrate
> > > along with the other individuals from that region.
> >
> > Exactly. In fact back in the late 70's when I was an undergrad
> > at UC Davis, Prof. Art Shapiro urged me to get ahold of
> > some tropical monarchs from a lepidopterist he knew in Samoa
> > and raise them outdoors in late summer here in California to see
> > if they would become diapausers in September and have a
> > migratory urge to fly to the California coast.  I never got around
> > to doing that most important experiment. Of course in today's
> > political climate an international transfer experiment could never
> > be considered.
> >
> > Paul Cherubini, Placerville, Calif.
>