An odd summer for monarchs
It began as an unusual summer for monarchs when the world’s most famous monarch apparently jumped out of a helicopter.
And around here our monarchs seem to be having their own odd summer.
Nearing the end of their time in Minnesota, the small numbers of monarch butterflies we are seeing now should soon be heading south with hopes of making it to Mexico for the winter. Oddly enough, their endpoint destination is not some tropical paradise like Cozumel or Baja, but instead higher mountain elevations northwest of Mexico City.
For the millions who make it to Mexico, probably after another couple months of flying, they will ‘hang around’ mostly in large oyamel fir trees. They often endure bitter cold, wind and snow that may even drive them off the trees by the millions, only to usually climb right back up when the sun warms them.
Some monarchs will survive the winter and begin mating and preparing for a northward migration in late February.
However, these are not the ones that will show up here next spring, as most will exhaust their energies well before reaching the United States. It is their offspring, perhaps two or three generations later, that will arrive around here next April or May ready to start the cycle all over.
Those offspring, any hatched out before mid-August, we call the breeders. They have lifespans of only a few weeks, quickly spending their energies mating and repopulating the species.
Based upon mine and others observations, the odd part of this year was the apparent lack of normally high monarch numbers through the summer. While they seemed to arrive in fairly good numbers in May, come June and July I saw very little signs of eggs and feeding caterpillars.
Normally in mid-July one can find abundant numbers of eggs and caterpillars on local milkweed plants, but that was not the case this year.
With lower egg-laying numbers, the numbers of monarchs preparing for migration in late August also seemed considerably down. At a recent program I did at the Northern Hills Prairie Park I was only able to catch and tag about a dozen monarchs compared with a couple hundred in previous years.
I have previously called this park the best monarch migration site in all of southeast Minnesota, something I am not sure of now.
The small disc-shaped tags that thousands of volunteers like me have put on the monarchs over the past 50years helped researchers locate the wintering grounds of the monarchs in 1976.
In years when I tagged hundreds of monarchs, as high as 2,000 one year, about one percent of the tagged monarchs would be later found by Mexican children who sold the tags to researchers doing work in the Mexico sanctuaries.
It is hard telling why numbers are down, although we know the climate is changing and we are impacting habitat used by monarchs and other critters.
At Northern Hills alone the numbers of the monarch’s favorite plant, the Meadow Blazing Star, is probably now per cent of the thousands at that site just a decade ago.
I’d like to think the monarch dip this summer was just a blip, but unfortunately it seems to be part of a larger pattern which should be cause for concern.