Baby, it's hot outside!
These 4 Western Bluebird nestlings must have been a second brood for the parents. The tree they were nesting in was cut down, leaving no shade on the property to re-nest them in. If at all possible we put nestlings up in a makeshift nest, (or box in the case of cavity nesting birds), in the same area for their parents to raise, but this heat would have been lethal to them with no shade.