It’s a part of the passing of wintertime and moving into spring: you open up the windows or you step outside, and you hear them - birds singing.

And perhaps you hear the sounds of the male western tanager, a songbird that migrates thousands of miles once the seasons begin to change, heading to the Mountain West for springtime.

But maybe you’ve noticed, over the past few years, that spring seems to be arriving earlier than normal - flowers blooming, insects coming to life, sometimes months ahead of time.

Birds are noticing these changes and researchers are, too.

A recent study has looked at the effects of climate change on the seasons and found that by the time many migrating birds reach their destination, the food sources they search for have already bloomed or flown away.

And so the consequences of spring starting sooner - for the western tanager and for many other migrating birds - could be drastic.

To help us take a closer look at what we’re seeing in the world of migrating birds and how climate change is altering their world, I’m joined by Morgan Tingley, associate professor of ecology and evolutionary biology at UCLA.