This chilly boy is in trouble. Though gregarious in winter, often forming large flocks and roosting communally in natural cavities and nest boxes at night, over 90 percent of their numbers have died in the 20th century. They are adversely affected by severe snowstorms that kill them in great numbers. If you have some peanut butter and cornmeal put it near a nest box and they will decorate your garden while singing the bluebird folk song, true-a-ly, true-a-ly, true-a-ly.