|A mourning dove puffs up to keep warm on a chilly spring morning. Photo by J.J. Meyer|
The calendar might say it's spring, but it's been chilly during the night and early morning in Southern California recently.
When it's chilly outside, birds fluff their feathers to trap a layer of warm air against their body. The concept is similar to how humans keep warm under a pile of blankets. It may be cold when we first snuggle in, but soon the air underneath the blankets warms up from our body heat.
Mourning doves have the ability to look like a round ball. Some birds also tuck their legs and feet into their breast feathers to keep heat from escaping.