Birders that visit southeastern Arizona in the spring are treated to the dazzling displays of brilliant color and iridescence by the smallest of the many avian migrants from Central and South America — the hummingbirds.
The flash of color seen on their throats and heads is a product of specially constructed feathers that contain layers of elliptical plates that reflect certain wavelengths of light. In the absence of direct sunlight on these feathers, they look black, but in direct light, they shimmer with brilliant color. (Read more about iridescence in bird feathers here.)
More than 15 species of these glittering gems pass through the cooler canyons of the southwestern deserts, attracted to seasonal blooms of flowers, and all the sugar water feeders in residents’ backyards. Eventually, they will migrate to higher latitudes and altitudes, such as the flower- and insect-rich meadows of the Rocky Mountains to breed. But for a few weeks, hundreds of birders come to southeastern Arizona to enjoy their displays.