Point Pelee National Park of Canada
Monarch Migration Fact Sheet (PDF, 1.7 Mb)
For a few special days each autumn, Point Pelee is a temporary home to thousands of migrating monarch butterflies. As soon as favourable conditions occur, they begin one of nature's greatest journeys by crossing Lake Erie. They cannot linger, for their destination is some 3000 km further south in the mountains of central Mexico! Why would this tiny insect make such a monumental journey? The answer lies in the monarch's food plant.
Monarchs and Milkweed
Monarchs© Parks Canada
Milkweed is the only plant that monarch caterpillars eat. It is believed that both milkweed and monarchs evolved in the tropical regions of Mexico. As the milkweed adapted and its range extended, the monarch followed. Milkweed is abundant and widespread in Ontario thus allowing monarch populations to greatly expand each summer. All milkweed plants contain poisons known as cardiac glycosides. Monarch larvae are not affected by the poisons, but store them in their bodies and pass them on to the adults. Most birds that attempt to eat adults or larvae vomit and learn to associate this unpleasant experience with the bright patterns of the adults and larvae and thus soon learn to avoid them.
During the autumn migration, the Visitor Centre provides special programs on monarch migration: family migration hike on Saturday and Sunday’s throughout September, and a summary chart for the migration period, theatre programs and special exhibits.
Why Point Pelee?
The Great Lakes are a significant barrier to the monarchs' migration. As they move south, they search for shorter ways across the lake and the Pelee peninsula provides an excellent start! Point Pelee's shape funnels the monarchs to the tip. If the weather is cold, they will roost in trees and wait for warmer temperatures and favourable winds to cross the lake. If the weather is warm, they will often go directly across the lake without stopping in the park.
Monarch migration at Point Pelee is dependent on weather conditions and is, therefore, highly unpredictable. It may take you half a dozen visits before you catch a sizeable concentration.
Here are a few tips:
Large movements often occur with cold fronts. Cold temperatures, southerly winds or rain often hold the monarchs here.
Viewing is best from late August until early October and generally peaks in September.
The Tip area is where most concentrations occur. Roosting is best observed very early in the morning.
Roosting monarchs are difficult to spot. Bring binoculars, look high in the trees in areas sheltered from wind and remember, the roosting monarchs resemble dead leaves.
While searching for monarchs, keep an eye out for other colourful butterflies!
*A butterfly checklist is available at the Nature Nook Book Store for a small fee.
Ancient Native legends have told of waves of monarch butterflies heading southward in the autumn. For thousands of years, their destination was unknown. In 1975, the monarchs' overwintering grounds were officially discovered by Dr. Fred Urquhart of the University of Toronto. Following reports of butterflies he and others had tagged in Canada, Dr. Urquhart was led to the evergreen forests high in the volcanic mountains of central Mexico. There he discovered the monarch.
The Mountain Hideaway
© Parks Canada
Tens of millions of monarchs arrive at their wintering grounds each autumn. Here, they hang on the trees in such numbers that they bend the boughs. The cold winter temperatures cause the monarchs to become almost dormant. This allows them to live off their previously stored energy. Monarchs do not become active again until February, when the drive to reproduce carries them northward.
© Parks Canada
The Migration Mystery
The monarch migration cycle is a mystery. Through the summer there are two, possibly three, generations raised in Ontario. The life cycle from egg to adult can take only a month, however, most large butterflies take about 45 days (see the life cycle). The generations that emerge in late summer and autumn are somehow triggered to become migratory.
These monarchs overwinter in Mexico and mate there in early spring. On their way north, eggs are laid on fresh milkweed and the adult dies some time thereafter. A few monarchs that have overwintered in Mexico return to Ontario (during May), an incredible journey of 3000 kilometres. However, it is the generation that is produced between Mexico and Canada that returns in numbers, mainly in June.
Monarch Migration Calendar
How can you help conserve the monarch?
Plant a butterfly garden to provide habitat for monarchs to feed and lay eggs.
Participate in a public program to learn more about monarchs.
Support environmental laws to protect the monarch in Canada, the United States, and Mexico.
Contribute to monarch research, conservation and education projects.
Support the monarch as the designated national insect of Canada.
Help to protect milkweed, the monarch caterpillars' only food source.