On calm days, watch the trees come alive with the fluttering of a few million monarchs here in Michoacán, Mexico http://on.natgeo.com/2Dhp1hW pic.twitter.com/ETnKGbIMtG

On calm days, watch the trees come alive with the fluttering of a few million monarchs here in Michoacán, Mexico http://on.natgeo.com/2Dhp1hW  pic.twitter.com/ETnKGbIMtG

https://twitter.com/NatGeoTravel/status/972555250866499584