Radar Reveals Monarch Butterfly 'Cloud' Migrating to Mexico

Is it a plane? Is it a bird? No! It's a cloud of migrating Monarch butterflies.

St. Louis, Mo., meteorologists spotted the shape-shifting butterflies on their radars just this week as they were headed over from southern Illinois and into central Missouri.

Some people mistook them for clouds; others even thought they could be a UFO. Yet these meteorologists confirmed them as Monarchs who were headed toward Mexico, preparing for seasonal changes.

"High differential reflectivity values as well as low correlation coefficient values indicate these are most likely biological targets. High differential reflectivity indicates these are oblate targets, and low correlation coefficient means the targets are changing shape. We think these targets are Monarch butterflies," the National Weather Service noted, via Facebook.

The Monarch butterfly is one of the most common to the United States, with its black and orange colored wing pattern easy to spot in the country. These insects usually migrate during the winter months from the United States and Canada to Mexico in search of a warmer climate.

Though they are not endangered, their numbers have been in decline since the last few decades. The U.S. National Weather Service notes that this may have indeed revealed the secret behind their bulky flight.

Unfortunately, climate change across the globe could disturb their migratory patterns. Things like abnormal rain and drought patterns in the butterfly's breeding regions of the United States and Canada are also believed to be a determinant factor in less migration to Mexico during the winter.

As spring approaches, the Monarchs will return to the United States. For now, they'll continue on their journey to Mexico.