This Great Blue Heron is standing on one leg on a large driftwood on the river. It is believed that long-legged birds like the heron adopt the one-legged stance because they are cold and keeping one leg tucked up underneath their body helps prevent the loss of body heat.

But birds also stand on one leg in warmer climates, where conserving body heat isn't as vital as it is in cold weather. As such, some conclude that standing on one leg may simply be more comfortable for the long-legged birds.

Nikon. 500mm

crop Photoshop. clarity Affinity