Mountain
Geography Focuses the Migration
Field
Notes Contributed by Dr.
Bill Calvert
October
17, 2004
Cumbres de Monterrey, Nuevo Leon, Mexico
Apparently Cienegas de Gonzales is butterfly junction. It was very curious
traveling toward the mountains we weren’t seeing that many. We were
seeing an occasional monarch. There’s something about that mountainous
area there, where the mountains turn from an easterly direction to a southeasterly
or a south-south easterly direction that focuses the monarch migration.
This is a part of the Sierra Madre that is quite high. I believe some of the mountains go up to 9000 feet in this area. The ridges are very, very sharply defined, and they curve distinctively. They change direction. It’s just absolutely phenomenal to see from the air. They change directions from roughly an easterly direction, running from Saltillo to Monterrey. And at Monterrey they make this bend and they turn toward Linares. And the butterflies follow that bend. So if you go to Huasteca Canyon, for example, which is a cut in the range, you can find them flying due east. And when you get down to Linares, they’re flying south, southeast. Something about the mountains that’s guiding them.
| "At
Monterrey, the Sierra Madres Mountains make a southerly bend. The monarchs follow the bend." |
 Listen to Dr, Calvert |
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|
Image by NASA.
