Humans have been observing animals for millennia and using their behaviors to predict what is to come. Some of these sayings hold truth. Others are more folklore.

One forecast that has been met with some confusion is about the recent sightings of American Robins. They are widely thought to be an early sign of spring. So why are they showing up, sometimes in large flocks in our yards and forests, in February?

According to the range maps, American Robins can be seen in any month of the year throughout most of the United States. But the maps also show they move north into Canada and Alaska during the spring and summer breeding season and travel into Florida, Mexico, and Central America for the nonbreeding or winter season. That sounds and looks like migration.

Confused? The seasonal movements of American Robins are a little complicated. But it makes sense when you look at what they eat. Robins are omnivores and their diet changes with the season. In the warmer months, when the adults and young need high protein food, robins eat mostly insects and other small critters. They are one of the few birds that actually eat worms; despite what children’s books and cartoons might show, most birds do not eat worms. But they only pull up these soft-bodied creatures from the ground in the warmer months.

American Robins eat worms, insects, and other small invertebrates in spring and summer. Photo by Dave Cooney Jr.

When the leaves change, so does their diet. A robin can’t pull a worm from frozen, snow-covered ground. In winter, they eat mostly berries. But the abundance of berries from plants such as crabapple, hawthorn, wild grape, and holly, is spotty and vary from year to year. Rainfall, temperatures, and pollination can affect fruit production. One year there may be a bumper crop of wild grapes in a patch of forest, while another year is a bust.

Winter robins tend to be more nomadic – going where the eating is good. These traveling flocks are nonterritorial. They are more concerned with survival than competing for space and food. And for a good food source, like a loaded crabapple tree, robins may show up in force. Flocks may range in size from a dozen birds to hundreds. They devour the available food and then leave in search of more.

The robins that built a nest and raised young on your porch in June are probably not the same robins that are eating the sumac berries in your backyard in February, and there’s science that supports that. Bird banding is a technique in which an individual bird is fitted with a metal band with a unique number. That bird can then be tracked if it is observed by other bird banders. Banding data shows that, on average, robins move about 60 miles between summer and winter. But they can travel farther or not at all. It just depends on the availability of food.

This seasonal movement of robins and other birds can be better understood using new range maps, developed, in part, from reports on eBird, an online reporting tool of Cornell Lab of Ornithology. These animated maps show where robins typically reside, week by week through the year. The map can be viewed by visiting https://science.ebird.org/en/status-and-trends.

So, are robins a sign of spring? Yes and no. Bird watchers may see robins any month of the year, and sometimes in large groups, but winter flocks of robins break up and they start scouting territories and moving north to spread out for spring mating and nesting. And when they return to your yard to feed, or to forest and field to nest and raise their young, you can be sure it is spring.

In winter, American Robins flock to berries, such as Staghorn Sumac. Photo by Putneypics

Audubon Community Nature Center builds and nurtures connections between people and nature. ACNC is located just east of Route 62 between Warren and Jamestown. The trails are open from dawn to dusk and birds of prey can be viewed anytime the trails are open. The Nature Center is open from 10 a.m. until 4:30 p.m. daily except Sunday when it opens at 1 p.m. More information can be found online at auduboncnc.org or by calling (716) 569-2345.