Time for Nature

Incredible Journey Over Lake Erie

September Edition (September 18, 2002)

Did You Know?

The Milkweed Connection

Milkweed is the only food Monarch caterpillars are able to eat. During the breeding season, Monarch caterpillars depend on various species of milkweed for food. In Canada, there are 14 known milkweed species. One particular species, Common Milkweed or Asclepias syriaca, is by far the most important food source for the Monarch.

Unfortunately, Common Milkweed is aggressive and persistent on agricultural land. It was also believed to be toxic to livestock, but recent studies have proven otherwise. These undesirable characteristics have earned Common Milkweed a place on the "noxious weed lists" of 5 Canadian provinces, making it a target for herbicide use.

Danger Here!

Warning! That's what the Monarch's bright orange colouring tells birds who consider it a potential meal.

Monarch caterpillars eat milkweed which contains poisons known as cardiac glycosides. The poisons don't affect the caterpillars, who store the toxic substances in their bodies and pass them on to the adult butterflies. But the poisons do affect birds who try to eat the butterflies or the caterpillars. The birds vomit as a result and learn to associate the unpleasant experience with the Monarch's bright patterns.

Yet some birds have developed a resistance to the Monarch's toxic properties. Both the Black-headed Grosbeak and the Black-backed Oriole feed on Monarch butterflies at the wintering sites in Mexico. The openings and thinned areas resulting from logging and grazing in the forest are making it easier for the birds to access the dormant butterflies.

A Canadian Found the Answer

Canadian Monarch researcher, Dr. Fred Urquhart of the University of Toronto, had spent 40 years searching for the answer to where the Monarch butterflies were travelling to every fall. He had tagged thousands of butterflies with stickers that read "Return to the Museum of Zoology, Toronto, Ont."

With each butterfly that came back to him, he learned a little more about where they travelled. Finally, in 1976, he was led to the oyamel fir forests high in the volcanic mountains of central Mexico. There, among millions, he found a butterfly wearing one of his tags.

International Network of Monarch Butterfly Reserves

In 1995, Canada and Mexico signed a declaration to create an International Network of Monarch Butterfly Reserves. The two nations pledged to jointly expand this network to include other nations which play host to Monarch butterflies.

Three areas in Southern Ontario were designated as Monarch Butterfly Reserves under the declaration:

• Point Pelee National Park of Canada
• Long Point National Wildlife Area
• Prince Edward Point National Wildlife Area.

Presqu'ile Provincial Park is being considered as an additional Canadian International Monarch Butterfly Reserve, to be established under a separate agreement.

Monarch Butterfly Model Forest

Canada and Mexico have established a cooperative program, called the International Model Forest Network, to manage specific forests in Mexico in a sustainable manner.

The Monarch Butterfly Model Forest, partnered with the Manitoba Model Forest Network, covers an area of 795,000 hectares, encompassing 22 municipalities in the states of Michoacán and Mexico. Its activities involve local communities and institutions and revolve around three main themes:

• integrated resources management
• ecotourism
• community development.

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