Monarch Butterflies

Perhaps like you, I have been seeing lots of monarch butterflies recently.

About a year ago wildlife officials in the United States, Canada, and Mexico signed off on an agreement to preserve and restore the breeding, migrating, and winter habitat for monarchs. That’s probably easier said than done.

As most elementary school kids learn, milkweeds are the only plants on which monarchs will lay their eggs and the only plants the caterpillars will eat. So the monarch’s breeding range is limited to the range of milkweeds, and their population size is a function of the milkweed populations.

But there’s a strange twist here. Although there are over one hundred milkweed species in North America, the common milkweed (Asclepias syriaca) is perhaps the most important and most abundant milkweed species for monarchs. That poses a problem, because the common milkweed is listed as a noxious week in many states and provinces.

Since the mid 1800′s it’s been known that monarchs migrate. One western population winters in the eucalyptus groves on the Monterey Peninsula of California. It was not known, however, where all the monarchs from east of the Rocky Mountains went for the winter. It wasn’t until 1976 that an article in National Geographic magazine reported to the world that all those monarchs wintered in an area above 10,000 feet in the Sierra Madre Mountains of Mexico. Millions of monarchs from the United States east of the Rockies and southern Canada wintered in a small area only about 20 by 30 miles. It has been suggested the wintering monarchs in Mexico is truly one of the “Seven Wonders of the World.” What a sight that must be!

Today, these wintering sites are threatened. Although the wintering grounds in Mexico are officially protected, illegal logging is destroying the monarch’s habitat. As you might suspect, the eucalyptus groves in California are falling (literally!) to development.

That gives us lots to think about when we see monarchs fluttering around in the North Dakota breezes. They’ll be leaving us around August; their primordial instincts telling them to head for Mexico. “Hasta la vista baby!” If they can dodge cars, predators, and a myriad of other threats, maybe they’ll complete the journey. If all goes well, their grandkids (or great grandkids) will make it back to North Dakota. How many future generations make it however, depends upon an international group of scientists, and whether they can get people to agree to the changes that will save the monarchs.

Chuck Lura

Natural North Dakota is supported by NDSU Central Grasslands Research Extension Center and Dakota College at Bottineau, and by the members of Prairie Public. Thanks to Sunny 101.9 in Bottineau for their recording services.