Many people consider the sight of a robin a sign of spring, a promise of warmer days ahead. But robins are also sometimes spotted in the dead of winter. What is with these robins? Did they lose their way on their migration? Is there something wrong with their internal clock and GPS system?
The answer is no. Robins are always here in the winter, but not in as high of numbers as at other times of the year. In fact, robins are nearly as widespread in the winter as they are during fair weather. They've been reported in every U.S. state with the exception of Hawaii and every southern province of Canada in the winter.
This isn't to say robins don't migrate. Robins from the far northern parts of Canada mostly all migrate. In fact, the majority of robins do travel south in the winter, but not all do. And not all robins migrate all the way south to warmer parts of the country.
Researchers don't fully understand why some robins choose to migrate and others do not. Females are more likely to journey south in winter than males, so it is possible more males stay to give them an advantage when establishing a breeding territory in the spring.
When robins migrate, it's all about food, not temperature. They can withstand cold winter temperatures, but in the winter, they mainly eat fruit. If fruit isn't available, they will move on in search of a good food supply. In cold winter weather, they need more food, and food becomes increasingly scarce as robins and other birds eat the remaining fruit supply, so they tend to congregate in areas where a lot of fruit is present.
These winter flocks of birds can include hundreds or even thousands of robins, but they may remain mostly out of sight, unless you happen to be close to a steady supply of fruit like crabapples and berries.
Robins are also much quieter in winter, making very little noise at all. This helps explain how even large flocks of robins can go unnoticed.
We often think robins have returned to the area in the spring because the large flocks of robins disperse and start appearing where we are used to seeing them: feasting on earthworms in our yards. And while some of these robins may have returned from points south, others were here all along, just not where we are used to seeing them.
And there's one more reason we often think of robins as a first sign of spring. It's not just that they suddenly seem to pop up around our homes, but we also hear them more in early spring. The song of a male robin is identifiable to many people, and early spring is when they start to sing their familiar song.
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