The size, shape, color, length and thickness of crests in birds can vary greatly. Some birds have just a very small and subtle crest, such as the ruby-crowned kinglet, while others have longer, thicker, more prominent crests like the northern cardinal or blue jay, who are the bird types featured (respectively) in the images posted directly above, which were taken from the vantage point of my rooftop garden.
According to The Spruce, "birds are often able to control their crests, and crest position can be an indication of a bird's emotions or stress... Birds may raise or lower a crest for a courtship display or to show aggression, dominance or submission. The stronger the movements of the crest, the stronger the emotions that cause the action."







