Spotlight: Migratory Birds

Five months before the passage of the Migratory Bird Treaty Act in 1918, an article was published in the NY Times proclaiming that our Nation’s gamebirds were under threat of extinction.  Interestingly enough the article contained a quote by Dr. E.W. Nelson, Chief of the U.S. Bureau of Biological Survey, that has transcended North American borders and become worldly relevant 90 years later.

“If you slaughter hundreds of thousands of these birds in Louisiana in winter for food, why wouldn’t it be just as fair for Canada to put hundreds of thousands of their eggs in cold storage for food in nesting time?  At that rate, how long would it be before every other state in the Union would be without these gamebirds?”

Times and the cause of migratory bird threats and declines may have changed, but the task of their preservation remains an international responsibility. Unlike the commercial trade in birds, feathers, and eggs in the early 1900’s that led to decimated bird populations, current declines are attributed to the increasing loss of habitats and environmental contaminants and pesticides. With Latin America boasting the highest rate of deforestation in the world, losing about 2 million acres of forest per year, and North America facing forests marred by fragmentation, development, clear cutting and roads, and wetlands drained for developers and farmland, it should not be a surprise that migratory birds are disappearing from our skies.  Because migratory birds require multiple areas for wintering, breeding, and stopover points, their decline is not the responsibility of one nation, but a global issue that needs to be addressed.

When it comes to current threats, we typically find the usual suspects, and for good reason, occupying the environmental headlines.  Loss of open spaces and habitat due to encroaching human population, growth and urbanization is principally responsible for bird declines.  An overabundance of pollution that includes more than 4 million tons of pesticides applied annually in the U.S. expose some 670 million birds to toxins, of which approximately 67 million birds are estimated to die right away. Oil and wastewater pits in the Western states kill up to 2 million birds each year according to the USFWS, and tens to hundreds of thousands of seabirds die as bycatch in U.S. fisheries each year.

But a lesser known pollution culprit is putting a spotlight on the plight of migratory birds too.  Those bright cityscapes might look great on a horizon, but are wreaking havoc on nighttime navigating birds. Sending birds off course or crashing into buildings is not something we intend, but is a consequence of an ever increasing amount of light pollution. In the January 2009 Frontiers in Ecology and the Environment, the publication Polarized light pollution: a new kind of ecological photopollution has linked smooth dark surfaces with highly polarized reflected lights, which are believed to be mistaken for bodies of water.  “The alteration of natural cycles of light and dark by artificial light sources has deleterious impacts on animals and ecosystems.”

With more than 900 million birds estimated to die as a result of collisions each year, maybe it is time to dim our lights (at least in part realistically) and leave lighting the night to celestial bodies.