Just curious .. why goto a cold part of mexico

[crazymilkweedman]

Does anybody know or has is it even possible to know why the monarchs migrate to mexico? I mean the eastern monarchs bypass northern florida, southern alabama or louisiana where the temperatures in winter have to be on average warmer than way up at 10,000 feet in the mountains of mexico. Doesnt make sense to me!Leave the cool northern states fly thru the warm southern states and low altitude mexico to over winter in cold mountains?? Is there a specific plant they need there other than the pine trees to protect them from the cold?

[Monarch MaMa]

I heard that one theory of why the North American monarch migrates at all is POSSIBLY because during the last Ice Age, when ice covered most of the US, milkweed thrived in Mexico. As the glaciers receded, milkweed spread northward and possibly the monarchs followed suit. This would explain why they return to their 'original' area and why they would return when winter set in.

Again - its a theory.

[crazymilkweedman]

that's not a bad theory...however if you look at the glacial map..they(being the glaciers) didnt go that far south , just about right here in ohio and also during the pleistocene (time when the glaciers were here)the average daily temperatures in florida were only 12c less so more like spring than hot or freezing. and third they dont nectar much there do they? i mean if its freezing down/up there , cant be much to nectar on. sooo??? http://www.nationalatlas.gov/articles/g ... limit.html

[Mona Miller]

Some monarchs do winter over in South Florida, along the gulf coast states, Arizona, probably Baja, MX, too. Some years they don't make it because of severe freezes.

I think this species probably originated in Mexico and breeds in the US and Canada, just like the hummingbirds do.

Dr. Lincoln Brower thinks they go further north due to the competition from the Queen butterfly. Queen caterpillars will eat Monarch caterpillars. Monarch caterpillars will eat Monarch eggs if the eggs are laid too close. Large caterpillars eating through leaves will also eat smaller caterpillars.

I highly recommend reading, "Monarch Butterfly, International Traveler" by Dr. Fred Urquhart. He spent over 50 years studying Monarch behavior wherever they were found.

[crazymilkweedman]

interesting,,, are the ones that over winter in FLA and along the gulf recognized as a seperate species and if so is there a way to tell them apart from mex migrators or are they just the same species only the Fla ones did a darwin mini mute and dropped the migration aspect. I was reading an article the other night where 8th or 9th generation of Monarchs raised in a lab still migrated when set free.thats amazing. on one hand we have monarchs that dont migrate (very far)and on the other hand we have monarchs who for 9 generations never saw the light of day before and they head for Mex..crazy!

[Mona Miller]

Dr. Urquhart talks about the other species and whether they mix. He even did some breeding with the different species and there are pictures of his results.

http://www.amazon.com/gp/offer-listing/ ... ition=used
I just looked on Amazon. They are now selling "Monarch Butterfly, International Traveler" for around $22. That is cheap. I'd highly recommend getting a copy. Great information.

[Paul Cherubini]

Does anybody know or has is it even possible to know why the monarchs migrate to mexico? I mean the eastern monarchs bypass northern florida, southern alabama or louisiana where the temperatures in winter have to be on average warmer than way up at 10,000 feet in the mountains of mexico.

The majority of fall migrant monarchs MUST migrate up to the 10,500 foot level in order to have an excellent chance of surviving the winter. Northern florida, southern alabama and louisiana are all areas that experience lethally frigid temperatures (below 22-24 degrees F) very roughly every 5-7 years or so. The other problem with northern florida, southern alabama and louisiana is that they experience so many warm days during the late fall and winter that many of the butterflies would age too fast and break reproductive diapause before the native milkweeds are available (mid-late March).

Monarchs that emerge from their chrysalids too late in the season to have enough time to journey to central Mexico end up stopping in the coastal areas of northern florida, southern alabama and louisiana, etc. Some of them sometimes end up successfully passing the winter in those areas, some of them freeze to death and some end up laying eggs before the end of the winter.

[crazymilkweedman]

Thanks for the reply, temp aging is interesting, puzzling tho,to think , like you say they need to go dormant in a way, until the milkweeds are available and yet the further south you go INCLUDING florida you have a large number of Cynanchums and Mateleas which bloom continously unlike northern asclepias's such as common, swamp etc. being seasonal. so i would think food would be readily available year round in the south considering some of them are considered noxious ,out of control weeds gone wild.perhaps not enough.