"Bicycling with Butterflies"

This book will be of interest to butterfly enthusiasts and to bicycle enthusiasts.  The author describes her adventure of bicycle camping alone while riding from the Mexican winter monarch reserve north during the spring/summer to Minnesota, then east to Boston/NYC, then back down to Mexico again in the autumn - a journey of over 10,000 miles.  

The narration is split about evenly between monarch and milkweed biology and the pragmatics of an extended bike trip (camping in churchyards, staying with friends to present lectures to local students, coping with errant drivers).

Herewith a few interesting tidbits and things I learned:

[in the mountains of Mexico] A winter storm on January 11-16, 2002 started with 48 hours of rain followed by a prolonged freeze.  

"An estimated 200 to 275 million monarchs, or 75 percent of the population at El Rosario and Sierra Chincua, were killed.  On the ground, dead butterflies formed a mass grave.  At some places the monarchs measured thirteen inches thick, and survivors insulated by the dead, were unable to crawl out."

Female monarchs taste milkweed leaves with their feet.  

Their "... brushfeet (the first pair of legs which, unlike the other two pairs, are typically tucked beneath the body and are difficult to see) cut the milkweed and trigger the release of more plant chemicals..."

The average female lays 300-500 eggs in her lifetime, typically one per plant.  

"By the time fifth instars finish eating and form their chrysalis, the full-grown caterpillar could be as much as 2000 times bigger than when it emerged from its egg."  (Ponder a human growing from 150# to 300,000# in two weeks and how much food intake that would require.)

The U.S. has a National Wildlife Refuge System.  

The butterfly weed (Asclepias tuberosa) is especially hairy.  Monarchs prefer laying their eggs on the flowers instead of the leaves.  

The timing of monarch migration is linked to the elevation of the sun above the horizon.  Because the height changes during the day, the monarchs calibrate its position using circadian clocks in their antennae.  Navigation is even more interesting.  On cloudy days monarchs can monitor the sun's polarized UV light.

"They can detect the pattern of UV light scattered across the sky... It seems that monarchs have a backup magnetic compass.  Light sensitive cryptochrome proteins in their antennae react with even a limited amount of light in such a way as to trigger signals that allow monarchs to sense the magnetic field... The angle of the field, in relation to the surface of the earth, changes predictably from the equator to the poles; the monarchs can sense this angle and navigate accordingly."

I believe there are other organisms capable of detecting and navigating by magnetic fields (?whales), but how they do that is totally a mystery to me.