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Monarch Butterfly Populations In the West Are Down an Order of Magnitude (qz.com)
An anonymous reader quotes a report from Quartz: Far fewer [monarch butterflies] were heading south this year, and those that have arrived did so a month late, according to Xeres, a non-profit conservation group for invertebrates. One researcher said it was the fewest monarch butterflies in central California in 46 years. Surveyors at 97 sites found only 20,456 monarchs compared to 148,000 at the same sites last year, an 86% decline. It's possible more insects will make the journey late this year, says Xeres, but that now seems unlikely. The minimum population size before the species experiences "migration collapse" is unknown, but a 2017 modeling paper in Biological Conservation (pdf) found that 30,000 butterflies adult butterflies are probably the smallest viable population. Without this critical mass, there aren't enough insects in the western monarch population to continue one of the world's most remarkable lifecycles.
To me, this is also the best approach, to make sense of "chaotic" behavior. (As in: chaos theory)
Killing off the butterflies might reduce the number of hurricanes!
Strangely, there seemed to be an unusual number of monarchs here in SW BC. Usually just see the odd one, this year they seemed to be everywhere in late spring, never saw so many. I don't know if ours migrate or not.
Those are the ones that usually summer in Pismo Beach. This year, they have gone to Canada in protest of Trump's policy on refugees.