When the sun sets and evening stars shine bright, the night sky quickly becomes a busy place as millions of southbound songbirds take to the flyways. And of all the feathery families cruising the moonlit flyways, few are more intriguing than the grouping of birds collectively known as wood warblers. Listed among the smallest of birds, warblers annually travel unfathomable distances – winging their way from remote far-northern forests to the tepid neotropical wintering areas of Central and South America.
Most migrate at night. Descending to earth at dawn, warblers spend their daylight hours resting and replenishing spent fuel reserves. Long distance migration is a perilous activity for all bird species.
But for those as tiny as the warblers, the flights are especially grueling. Mortality due to natural causes such as wind, heavy storm activity, and predators runs high – a sobering and natural part of life for migratory birds. Other mortalities are strictly the product of human development.
Nighttime collisions with unnatural structures such as power lines and communication towers can exact an alarming toll. But the worst artificial hazard of all is the glass window. Up to one billion birds die in the U.
S. each year from collisions with glass windows, according to the Cornell Lab of Ornithology. Like a moth to flame, many birds are drawn to the lights of big city skyscrapers.
Many birds use the natural light of the moon and stars to successfully navigate the dark skies. But.