The migration of monarch butterfly along shore of Ontario Lake. In the fall of last year, we witnessed an amazing phenomenon that occurs every year, but possibly that not every year it is so intense. This phenomenon is the migration of monarch butterflies (Danaus plexippus) along the shores of Lake Ontario. In early September, we observed how individual butterflies and their small clusters easily rise above farm fields and flowering meadows and rush into the blue sky, driven by strange forces. Thus, the migration of monarch-butterflies starts.

In mid-September, I arrived to Toronto on business and keeping in memory of these soaring butterflies over fields and meadows, I suggested to visit the shore of Lake Ontario, where my friends observed congregations of butterflies many years ago. What if we are lucky this year with similar migration? Before that, we already knew that flying monarch butterflies gather during the autumn migration period in Point Pelee National Park in southern Ontario, where their migration clusters are monitored annually. But in Colonel Smith’s park in Toronto, where we planned to go, the monitoring of migratory butterflies is not carried out, since the clusters here are not so large and are not always observed …

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On the first day – September 14th – we arrived at the park after dawn at about 8 a.m. There were quite a few monarchs on the bushes along the path leading to the lake, but all of them were kept alone or in small groups on the bushes of the goldenrod (Solidago ssp.), Canadian horseweed and asters, and on the branches of various bushes.

Butterflies just woke up, they lazily spread their wings and reluctantly flew from bush to bush when we approached them. Along the path closer to the lake there were many thickets of goldenrod and asters. Some movement was already noticeable there. The awakened monarchs scattered and settled comfortably on the flowers for morning feeding. Noticeable assemblages were nowhere to be seen. However, butterflies were everywhere, and there were surprisingly abundant. They gathered in small groups, mainly on plants of the goldenrod, where solitary butterflies and small clusters constantly moved and interacted with each other, finding out the dominance relationship. Of course, there were many butterflies scattered, compared to what happens here in the summer, but not as many as expected… We did not find monarch roosting places.

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On the second day, we arrived at the park earlier – even before dawn and immediately went towards the bank, where on the eve we saw many butterflies dancing over the thickets and flowers. At first we did not notice anything – the sun had not yet risen and all the bushes and tree branches seemed equally gray. We walked slowly along the tree line, growing closely to the banks of Lake Ontario, carefully looking at the flower thickets, as well as bushes and trees. And finally – a miracle! Suddenly, the first rays fell on the still hanging branches of green maples and we saw that they were strewn with garlands of butterflies.

Butterflies merged with the surface of the foliage, they all sat with their wings closed and looked like a monotonous brownish-gray fringe, which at first we did not even distinguish from the surrounding foliage, because the butterflies were numb. First, we saw garlands of butterflies on one tree, then on another, then on a third, then more and more… Butterflies sat very tightly and it was impossible to estimate their number. But it was obvious that tens of thousands of monarchs gathered on the narrow strip of trees along Lake Ontario, and maybe more, because we stopped at a spot with a dozen trees to watch the butterflies.

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It was gradually getting light. The rays of the sun peeked, then hid behind the clouds that had rushed at dawn. When a bright beam pierced through the clouds and illuminated the trees, individual butterflies spread their wings and bushes came to life from bright “lightings”. But the beam was hiding and again the monarchs closed their wings and fell into a lethargy. Nevertheless, the morning gradually came into its own, and with its light the living bulk on tree branches came to life and began to swarm.

The monarchs opened their wings, catching the energy sent by the sun’s rays, and preparing for a new day. Those that were higher in the branches were better stricken by sun and they woke up earlier. When the butterflies woke up and warmed up, they slowly took off from the bushes, circled around in a slow dance and gradually descended down into the thickets of flowering fodder plants – the goldenrod, Canadian horseweed and asters. A little more than half an hour passed and the morning magic disappeared. All the butterflies left their roosting places and literally disappeared into the surrounding thickets of grass and shrubs or, probably, flew away to south. At about 9 a.m., butterflies could only be seen fluttering over colored plant patches and feeding on flowers. There was nothing left on the trees. However, there was a memorable happiness and the urge to touch one of the secrets of the wilderness…

Well, of course, our wonderful pictures and videos of this amazing natural phenomenon of the migration of monarch butterfly remained… After a few days, the accumulations of butterflies in the park disappeared. It is likely that they flew to their wintering sites in Mexico in the Mariposa Monarca Biosphere Reserve, located in the pine and oak forests of the Trans-Mexican Volcanic Belt.

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Whatever it is – the mass migration of monarch butterfly along shore of Ontario Lake is one of the wonders of the world, which keeps the secret of Universe that remains to be solved one day…