Subspecies and protection
MWalker at gensym.com
Mon Oct 16 16:00:11 EDT 2000
Fred wrote some stuff and:
> 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.
First, I must add that I'm fairly certain that Monarchs do use the San
Andreas Fault and Grapevine Hill as a corridor for movement into the L.A.
basin. While they can be found throughout the Tehachapi's and the Los
Padres NF and Mt. Pinos areas, the roadside areas along highway 138 and
through Tejon Pass can often boast high concentrations of Monarchs during
As for the Anza Borrego overwintering site - the spot that I found a few
years back is just below Sentenac Mt., off of Highway 78 about 3 miles west
of the turnoff to Plum Canyon (the canyon is named something-Quartz?). On
December 31, 1997 I found Monarchs roosting in the trees along this canyon -
side by side with Danaus gilippus (which I found more surprising). Later
trips to AB during November and January also resulted in high Monarch
> > -----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.
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