March 31st, 2016

Monarch Migration northwards from the wintering grounds in the mountains of central Mexico has begun.  We were heartened by the increase this year in the number of wintering butterflies…

Good News from Mexico (From the Website Journey North)
The number of monarchs overwintering in Mexico has increased dramatically from the record lows of the past 3 years, though the population remains 32% below the historic average. The clustering butterflies cover 4.01 hectares of forest compared to a peak of 18 hectares in 1996 and an average of 6 acres. This year’s population contains 200 million monarchs compared to a long-term average of 300 million and a peak of 1 billion. Favorable breeding conditions in summer 2015 are credited for the substantial increase.

The Bad news…

Dr. Lincoln Brower reports mortality estimates as high as 50% of the population from a late winter storm  just prior to typical departure dates.

Surviving butterflies must find milkweed growing in the southern States such as Texas and Oklahoma  in order to lay eggs and rear a new generation that, several weeks later, will continue the journey north.  It is these butterflies, or even a second generation, that will ultimately reach southern Ontario.  Their reproductive success also depends on the availability of milkweed and our summer weather conditions.