How do birds know when it’s time to migrate?

Have you ever wondered how birds know when it’s time to fly south for the winter? It’s not like they count down the days on their mini bird calendars. There must be something else that tells them when it’s time to hit the road…er…sky. There is, and you’re about to find out!

Grumble…grumble…whoa, was that my stomach?

As the weather turns colder, it can get pretty hard to find food. You don’t exactly see many fruits growing or insects crawling when there’s snow on the ground. As food disappears, many birds know it’s time to say “see you later” and head down south. But when they leave depends on what they eat.

Birds that eat insects (insectivores) start their migration in late August or early September. That’s exactly when we start to see fewer insects around. Birds that eat fruit, seeds, and insects (omnivores) stick around longer. They might leave as late as November!

Is it getting dark out or is it just me?

Another way birds know that it’s time to leave is by paying attention to the length of the day. You know how it gets darker earlier in the winter? Birds notice it too. The darkness is a cue for birds that it’s time to head out.

Sometimes they just know

Migratory birds go through something called zugunruhe. No, that wasn’t a sneeze. Zugunruhe is a German word that scientists use to describe a restlessness birds get when it’s time to migrate. Even migratory birds kept as pets go through this. Bird owners might see their birds fluttering and being more active in the spring and fall.

There you have it! You can forget the calendar because birds don’t need it! They have lots of tools that tell them when it’s time to leave.

Many birds fly south but some stick around all winter long. It can be pretty hard for them to find food so you can be a big help by putting out a birdfeeder! Look for instructions to build your own in For the Birds in the Mission section of the Earth Rangers App.

Generously Supported By