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Moving With the Sun: Monarch butterflies' long trip south and back again 

click to enlarge Snow Geese & Monarchs
  • Snow Geese & Monarchs
Snow Geese & Monarchs
This is it, Good People, the time when Mother Nature's Children must obey the Sun. Whether it be Monarch butterflies, Snow Geese, hummingbirds, night hawks, plovers, whales or Flammulated Owls, they can not stop themselves from obeying the Call of the Sun. Even human Snowbirds traveling south in their gas-guzzling Mini-Winnies must obey the call of our Sun.

Way back, when most of you were just a gleam in your daddy's eye - and for some, even before that - I was a duck-hunter. Yes, I do love to eat mallards and geese. Every Thanksgiving I would head off for Summer Lake to shoot snow geese, and Crane Prairie Reservoir for Canada Geese and mallards. (When I discovered I was killing families of Canada Geese and leaving orphans, I realized the error of my ways and quit.)

It was the discovery of Russian bands on snow geese harvested at Summer Lake, however, that also gave me further insight on the migration of birds. At the same time, some of the pin-tail ducks I killed were also wearing bands


Pintails nest in the sub arctic in Alaska and Canada. Banding revealed that some of them, almost upon taking wing, head south. The angle of the Sun and the duration of daylight triggers a signal in their tiny brain that says, "Hey, time to help out with rice harvest in California." And off they go, almost non-stop from Alaska to Central California. After fattening up on rice, they head back north to places like Malheur and Klamath National Wildlife Refuges and Summer Lake Management Area.

However, nothing can surpass the amazing migration of the bar-tailed godwit, a shorebird that nests in Alaska and winters in New Zealand. It flies non-stop for nine days over the Pacific Ocean without food or water. A feat accomplished without sleeping, or eating. Why? Perhaps flying nonstop across the Pacific Ocean is the safest thing to do.

It is also the annual migration of Monarch butterflies that amazes me. My wife, Sue and our family have tagged Monarch butterflies at Lava Beds National Monument for over 20 years.

Sue carefully removes the colored scales from the butterfly's wing and places a sticky-back vinyl numbered tag on the forewing. Monarchs are strong fliers, they must make that long flight to and from their wintering habitat, so the tiny tag is hardly noticeable. One of the tagged Monarchs from Lava Beds was found in Half Moon Bay near San Francisco, but other Monarchs keep going south to Santa Cruz and Monterey Bay.

Monarchs go through the summer laying eggs on a variety of milkweed species on which the larvae eat, grow and are protected from being eaten by birds and mammals. Chemicals in milkweed make Monarch caterpillars and adults poisonous, and most birds and mammals recognize the color of the insects and stay away from them.

Then one summer morning the Sun comes up over the horizon at a little different angle and a new message comes to the Monarchs. "No more sex!" What a pity; now all they can do is eat and build up layers of fat in their bodies to fuel them for the long flight south and keep them alive until nectar is available and head north.

Rabbitbrush that turns the desert a bright yellow in late summer and early Fall is an important fueling stop for Monarchs heading for California.

On the East Coast, Monarchs from Canada start out on a much longer trek to wintering grounds in Mexico. On my recent trip to the East Coast I had the pleasure of seeing hundreds of them working their way south.

Hundreds of thousands of hummingbirds, songbirds and Monarchs stop all along the Florida, Louisiana and Texas coastlines waiting for just the right weather system that will give them a tail-wind as they depart over the open water for Mexico and points south.

As the angle of our great and all powerful Sun slowly shifts in Spring, and the duration of daylight changes, survivors of that multitude of birds and Monarchs that trekked south begin to stir. Sex begins to become important again. Birds put on their best and showiest clothing that will knock the socks off the opposite sex, an annual event that guarantees survival of their kind.

For Monarchs, the Sun changes their chemistry, new and alluring pheromones begin to waft from special glands on the male's hind wings. The females are aware of this chemical change and probably shout, Yahoo! and head north. That same Sun-driven urge to go "home" and procreate is just as strong as the one that sent them south to survive in the warm climes of Mexico.

The ones that make it non-stop over-water back to the US are only given one opportunity to mate and lay eggs - and as soon as that's done, they will die. The new generation is the insurance policy that Monarchs will make it back to Maine, New Hampshire and eventually to Canada. It's the same with the western Monarchs. The survivors that leave Monterey Bay, Santa Cruz and other wintering refuges will only go as far as the first milkweed patch where they will also lay eggs and die.

Four to five generations later the Monarchs arrive back in their "home" for the summer, and I have no inkling how they "know" that's home. All I do know is the Great Migration will begin again when the Sun tells them it's time to go.

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