The 2017 Monarch Migration Has Been a Difficult One

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Most monarch butterflies should be well on their way to Mexico by now, having stopped off here in Texas for a bit before continuing their journey across the border. But this season has proven a bit out of the norm for the monarch migration. Warmer weather in Canada has confused the butterflies and threatened their migration.

Unusually Warm Weather in the North Hampered the Monarchs

Monarch Migration

Photo: Flickr/Peter Miller

Tens of thousands of the butterflies are likely to be stranded far north of where they’d normally be this time of year because of the unusually warm weather and strong winds that have kept them from migrating south, said biologist Elizabeth Howard, director of the monarch tracking non-profit Journey North .

Many of these butterflies might not even be alive if not for the warm weather. They are thought to be a sort of bonus generation because they were able to develop and emerge late in the season because it’s been so unusually warm. But, now they may be stuck because temperatures are starting to fall. Howard said their muscles don’t work when temperatures dip into the 50s. And, if they don’t freeze, they are likely to starve to death because much of the plants they need to feed their long voyage south are already gone for the season, biologists said.

The Long Flight Isn’t the Only Threat to Monarchs


Photo: Flickr/Johanna Madjedi

Even during a normal migration year for monarchs, there are obstacles at every turn. It’s estimated that more than 15 percent of the overwintering population will fall victim to predators that pluck them like berries from trees. Monarchs are poisonous to some animals and taste horribly to others, which protects them a bit from predators. Unfortunately for the monarchs, the black-backed orioles don’t mind the taste of them at all. They kill and dislodge hundreds of thousands of monarchs each year during the migration period.

A Long, Difficult Journey

Monarch tagged

Photo: Flickr/Ohio Sea Grant

The distance that the monarchs travel during a migration is staggering. Monarchs travel some 3,000 miles between Canada and Mexico during a migration. Lucky for them, they’re expert flyers. They ride thermal waves all the way to Mexico and fly at speeds ranging between 15-25 mph. In fact, one tagged butterfly was recently reported on Journey North to have traveled 265 miles in one day. Recent flight study results also posted on Journey North revealed that a monarch with 140mg of fat to burn could fly for 44 hours when flapping, but 1,060 hours when soaring and gliding!

But, there’s good news coming out of Mexico! Journey North reported that on October 30, 2017, the monarchs arrived in El Cerrito, Angangueo, Michoacan, Mexico so researchers are hopeful that the migration (while difficult) will prove to be successful for these tenacious butterflies.