Each spring and fall, migrating birds take on journeys that put Olympic athletes in the shade. For example, a Western Tanager weighing-in at around one ounce may fly from Western Canada to Central America.
As well as covering immense distances, migration involves negotiating an assault course of hazards, including avoiding collisions with wind turbines and brightly lit city skyscrapers. Most birds migrate at night, so unnecessary lighting, even in small towns and rural areas, can direct birds off their routes to inhospitable places. Where they can become disoriented, waste their valuable energy reserves, and become more vulnerable to predators or injury.
In 2018 a project named BirdCast began publishing forecasts on how many birds will likely be aloft each night over the continental U.S. during migration season. The forecasts are based on 25 years of observations from weather surveillance radars, and the data show that over half of all birds move in pulses. They’re in the air on just 10% of potential travel nights, typically during optimal weather conditions.
In Arizona fall migration peaks in the first half of September. You can check BirdCast.info to see on which nights it is most critical to minimize lighting. For interior lights pull the shades – especially on higher stories of buildings. For exterior lights, add shields to prevent upward glare, install automatic motion sensor controls or best of all - turn them off completely to help birds safely finish their marathon fall flights.
Learn more from the Audubon Bird Friendly Buildings factsheet.
This Earth Note was written by Diane Hope and produced by KNAU and the Sustainable Communities Program at Northern Arizona University. I'm Melissa Sevigny.
