Robins migrate northward in the spring — or do they? Some migrate “upward” instead! What does that mean? And what did some curious scientists in Colorado discover about the timing of those migrations? Read on to find out!

Robins in parts of Colorado spend the winter at low elevations where the temperatures are mild. In the spring, it gets even warmer. This cue tells robins it’s time to head up to the mountains where they'll find plenty of nesting sites and food. After all, they can handle the temperatures!

Usually, the higher you go, the lower the temperature. It takes a while for spring to "climb" a mountain! A group of scientists in a mountain lab wondered about robins that came there to breed. They knew that in the early 1980s, the birds arrived around April 4th. But they thought the robins were showing up earlier. So they gathered some data. What do you think they discovered? It takes time for spring to climb up mountains. For each 1,000 feet of elevation, the temperature is about 3.5 degrees F. lower.

Robins were arriving in their Rocky Mountain breeding grounds two weeks earlier than they did in 1981! Isn't that good news? After all, they say that the early bird gets the worm!

Not so fast! When the robins got to their higher-altitude breeding grounds, it was snowy and wintry. In fact, the migrants arrived about 18 days before the bare ground showed.

Scientists think that a warming climate in the lower-altitude wintering grounds gives robins an early signal to migrate. But up in the Colorado Rockies, climate change seems to lead to heavier snows, NOT warmer temperatures! What does that mean for our feathered friends?

The early-arriving robins might find no food! Here's why: It’s so cold and snowy when they get to the mountains that earthworms haven’t yet come up to the soil surface. Wild berries and fruits have already been eaten by other winter birds. And the wildflowers aren’t yet blooming. This is a sign that other food sources will be late to bloom and bear fruit. Can the robins survive? Temperature affects when wildflowers bloom.

Fortunately, robins are adaptable to changing conditions. They can easily fly a half mile or mile back to lower elevations. There they can find food while waiting for the snow to melt . . . for now. But what will the future bring?

Scientists predict that continued climate change will cause even heavier winter precipitation in Colorado and warming at low elevations. If this happens, spring robins could have trouble finding food in high and low elevations. But climate change in other places could lead to a different (and better) story for robins. How? Earthworms might be hard to find! In the mountains, they'd be under heavy snow. In lower elevations, heat could dry out soils so worms would burrow very deep.


Robins are also arriving earlier than ever in the Northern United States and in Canada. Those early birds might get the worm! Why? They don't travel very far away in the winter. As weather improves, they wander back north. So in a warming climate, early spring robins could find food and nesting spots before birds that have to migrate back from much farther south. This warbler is a 'long distance migrant." It uses day length as a cue to migrate. Such birds usually arrive on breeding grounds later than robins do.

It's not easy to tell how changing climates will affect different living things. Many birds in North America are migrating an average of 9 days earlier and breeding sooner than they did 30 years ago. To shed new light, scientists keep looking, gathering data, and thinking. Your Journey North observations and records are part of this detective work. Are your robins arriving earlier, later, or at about the same time as usual? Help scientists watch and track:
Share your sightings.
Track your own sightings from year to year.