Monarchs Need Sunlight

Monarchs cannot fly unless their flight muscles are warm enough, about 55°F (13°C). Basking in the sun is one way monarchs can warm their muscles. As a monarch basks in the sun, its wings and thorax absorb solar energy.

Paralyzed by Cold

• Cold temperatures paralyze monarchs. Their flight muscles must be at least 55°F (13°C) in order to fly.

Warming Up

• Monarchs can warm up by basking in the sun. Basking helps a monarch raise its muscle temperatures to flight threshold.

Catching Rays

• When monarchs bask they open their wings and tilt them toward the sun. Like solar panels, monarchs capture the sun's energy by exposing the surface area of their wings directly to the sun.

Color of Wings

• Dark colors absorb more of the sun's energy than light colors do. The absorbed solar energy is changed to heat energy. The monarch's dark-colored wings are an important adaptation for survival. They help a monarch warm up on a cold day.

Basking Observations

Observers have described the basking behavior they've witnessed as follows:

"It was cold, rainy, and windy for several days. Today, the sun came out and the monarchs were all sunning themselves on the trees around 7:30 a.m. When I went back outside around 1 p.m. it was a ghost town! They were all gone except one!" Journey North observer, Jane Marshall

"You can tell it was a cool morning. The monarchs were all holding their wings at the same angle, catching the rays of the sun. The overnight temperature was only 47°F. The monarchs needed to warm their muscles..." Journey North observer, Tom Nagel