Siegfried Matull photographed a juvenile Western Scrub Jay all "puffed up." He caught the bird molting - growing in its new feathers. For instance, the gray feathers on its head are being replaced with blue ones.
Jays completely molt once a year, an activity that takes place in times of low stress - after nesting and before migration. Other birds that have a complete molt are Chickadees, Flycatchers, Hawks, Hummingbirds, Owls, Swallows, Thrushes, Vireos and Woodpeckers. It's an amazing phenomenon, don't you think? To completely replace each and every feather, that is a lot of energy expended.
To learn more about molting and much, much more about birds, here's a link to the Cornell Lab of Ornithology: cornell lab of ornithology
Thanks to Siegfried for allowing me to share his photo with you here.