Thousands of monarch butterflies migrate to Mexico for the winter each year, to find refuge from the cold weather in the country’s pine forests. But last week a rare snowstorm interrupted their sleep as freezing winds blew the butterflies out of their safe colonies, grouped together in the trees, and deposited many of them across the forest floor where they are at risk of freezing to death while still in hibernation. The species itself is not at risk but, as this film project by Univision Planeta shows, there is still no accurate number for how many of the butterflies have died