We all know the answer to this one: birds migrate in the fall. That is when we see those iconic V’s of honking geese winging their way south. But why don’t we see other kinds of birds flying towards warmer climes? When do they migrate?
The answer is that other birds also migrate in the fall. But they do it at night.
Migrating under the cover of darkness is a smart strategy for many small birds. Flying predators, like hawks and eagles, tend to be active during the day. By making their long-haul flights after the sun goes down, small birds can avoid getting eaten along their journey.
Unfortunately, migrating at night comes with other dangers. Many birds use the stars to navigate on their long trips, and when they see lights closer to ground level, they can get confused and fly in circles until they exhaust themselves. Or they may simply crash into a lit window.
When we think about birds crashing into windows, we often think of glass-covered skyscrapers in big cities. In fact, most bird-window incidents occur around buildings that are less than four stories tall. In other words, migrating birds collide with ordinary houses more often than they collide with high-rises.
By dimming our lights on fall evenings – or by closing our curtains – we can help birds arrive safely at their destinations.