But approximately 80% of them all have one thing in common: they travel nocturnally. This flies in the face of normal behavior for most of the year. That’s because the overwhelming majority of songbirds are, in fact, diurnal – active by day and resting at night. So, what makes them flip the script come fall (and spring) migration?

Nature, in its infinite wisdom, has a reason. Actually, several.

1. Temperature. At rest, birds have an average body temperature of 105F. But during the exertions of migration, it surges far higher. The cooler evening air keeps them from overheating.

2. Turbulence. Largely devoid of thermal disruption, weather is a lot calmer at night. The result: far fewer headwinds, storms and other events that could endanger travel or even result in death.

3. Safety. Apart from Owls, the night-time skies are relatively free from raptors – and the chance of becoming dinner.

4. Food. Migrating birds need to eat – a lot! Daylight hours are far more fruitful for fueling up to continue the journey ahead.

5. Navigation. Like old-time mariners, many songbirds use the stars to successfully navigate staggering distances. (Unlike ours, birds eyes can detect the motion of stars and planets in real time!)

Ironically, one of the greatest dangers birds experience during night-time migration is from humans: light. Excessive light disorients birds. Even worse, it attracts them, contributing to the approximately 365 million to 1 billion birds that die from window strikes in the U.S. each year. Most of those strikes happen at residential, not commercial, structures.

So please turn off all non-essential lights at night. Helping out is that simple. And it just may be the reason one more bird makes it through the gauntlet of this fall’s migration.