I've been planning now for over a year to investigate the hypothesis that
some of the Atlantic coast migrating Monarchs travel through western Cuba
to Mexico to their wintering grounds.
Banding records and visual sighting records-see map
<http://map.learner.org/cgi-bin/mapserv?mode=map&map=/var/www/content/jnorth/maps/monarch_peak_fall2015.map&mapext=-4134750.3345794394+-2383397+3223877.3345794394+4189000&mapsize=600+536&layers=This_Week>-suggest
that most of the Monarchs crossing at Cape May, New jersey, veer southwest
to Texas. It's less clear how many of the Monarchs migrating south along
the Carolina coasts, which peaks in October, veer southwest to Texas. There
are observations of Monarchs traveling west in southern Georgia and Alabama
and Mississippi. There is also a You Tube video showing
<https://www.youtube.com/watch?v=MvIw4EBeccs>Monarchs that crossed the Gulf
of Mexico to the Yucatan Peninsula, presumably from AL/MS/LA as they have
been seen flying from the north at the coastal town of Progresso, Yucatan,
and have also been reported at oil platforms in the Gulf.
My frequent trips to the Yucatan Peninsula suggest a small or negligible
population of non-migratory Monarchs. For instance, on Cozumel and
neighboring Quintana Roo, I do not see any in summer, but they are uncommon
on the mainland and fairly common on the Caribbean island Cozumel in fall
and winter. Without taking samples, it's probably not possible to determine
the wing morphology and whether they are the migratory or resident species,
but my seasonal observations suggest they are migrants and that the winter
ones, at least, don't make it to the mountain wintering grounds hundreds of
miles away where the mountain micro-climate provides the suitable
temperatures for overwintering.
I have only recently been successful in contacting someone in Cuba familiar
with the resident and migrating populations there.
He writes, "*Regarding migratory monarchs you are right, they usually fly
in western Cuba and coincidently Jorge Luis just saw several at
Guanahacabibes 2 weeks ago when took an ornithological course.*
*The resident Cuban monarchs are an entirely different issue since are very
difficult to find due their rarity. I only saw them at Topes de Collantes
in the Central Cuban Mountains, Santo Domingo (Bartolome Maso, Granma) at
the foothills of Sierra Maestra, and around La Melba, Moa, Holguin, in the
northeastern mountain. There are also some other literature records. *
*A colleague from Camaguey province also saw resident Monarchs on the north
limits of that city always in very low numbers. He can guide if you are
interested in watch other butterflies. Please let me know if need his
email."*
It is only 90 miles from Florida to Cuba and another 130 miles across the
Yucatan Channel from western Cuba to the Mexico, making such crossings many
fewer miles than the Gulf states' crossing to the Yucatan.
Another hypothesis worth investigating is that some migrating Monarchs may
fly to east Cuba and on to Hispaniola where 10,000' mountains might offer
a similar micro-climate to the Mexican wintering grounds.
The above letter offers support of my hypothesis that some Atlantic coast
migrating Monarchs fly to Cuba and probably on to the Yucatan Peninsula
from the western Cuba area of Guanahacabibes. I will be in the
Yucatan Peninsula in four weeks and hope to be in Cuba, too, before
Christmas, but am having difficulty in making travel and guide arrangements.
The Atlantic coast migration of Monarchs is possibly becoming a more
important and safer flyway compared to the mid-western flyway where both
milkweed (needed in spring) and other sources of nectar have been reduced
by the GMO/herbicide methods of agriculture.
I am interested in the Monarch observations of the regional butterfliers
and moth-ers and any references in the literature you can provide about the
coastal Atlantic migration.
Doug Allen
Inman, SC
https://sites.google.com/site/butterfliesofquintanaroo/