Earlier this month, Polly Willman of Gaithersburg, Md., spotted a single robin perched on the railing of her deck. Two days later, she looked out to see a veritable army of the red-breasted birds. They were alighting in the trees, marching across the grass, sunning themselves in her yard. She stopped counting at 40.
“This is February!” Polly wrote to me in an email. “With snow on the ground!”
Polly’s point: What is a bird commonly associated with spring doing strutting its stuff — en masse — in winter?
The American robin is such a common species that it doesn’t get the fawning press that, say, the painted bunting or rufous hummingbird does. That’s too bad, said Andrew Farnsworth, senior research associate at the Cornell Lab of Ornithology.
“American robin is a super cool species,” Farnsworth said.
I called Farnsworth because I was curious about whether this whole “first robin of spring” thing was a complete sham. Poets may employ the robin as a feathered metaphor for nature’s annual rebirth, but what do the birds actually do?
Do robins presage spring?
“It’s not wrong,” said Farnsworth. “There’s some validity to it. American robin is just a lot more complex than people give it credit for.”
The deal is this: Robins do all sorts of things. Some migrate. Some hang out in these parts year-round.
Said Farnsworth: “Some never left. Some that come back may actually be going someplace else.”
Compared with some other species, the robin is a mishmash. When you look at a map of the range of the ruby-throated hummingbird, you’ll see that it breeds in eastern North America and spends winters in Central America: two discrete areas joined by the path it follows during migration.
The American robin, on the other hand, blankets North America. Some breed in Canada and Alaska and winter in Mexico, but many are found year-round across the U.S.A.
“Even though you may see robins in the same place every year, throughout the year, whether that’s the same bird, or even the same population, is a big question mark,” Farnsworth said. “A lot of populations replace each other or leapfrog when they migrate.”
It all comes down to every animal’s favorite pastimes: food and sex.
“At some fundamental level, it’s very much about ‘Is there a sufficient resource available for a bird to subsist on year-round and produce more offspring?’ ” Farnsworth said.
Robins are especially well-suited to the landscapes humans create, such as the fruit- and berry-producing ornamental trees and bushes we plant around our houses. Birds that feel confident they can eat may decide to just stick around.
But migration also has its attractions.
“There’s the other side: Okay, you are spending time where there are a lot of other individuals like you. It would be ideal if you could escape the competitive pressure,” Farnsworth said.
Like flamingos and teenagers, robins gather in flocks. Sometimes the flocks are tremendous, numbering many thousands of birds.
“There’s a vigilance factor for predators,” Farnsworth said. “The more of you there are, the less likely you are to get picked off. And it’s more likely you or one of your cohort will see a problem if one exists.”
A flock is also helpful in finding food.
“The trade-off of being in a flock is you may be in direct competition with your neighbor just like you,” Farnsworth said. “There comes a point at which flocks are not so useful. During breeding season, males holding a territory don’t want to be competing with some other male to create a nest. At that time of year, flocks break down.”
That’s why Polly saw 40 robins together in her backyard on a February day but probably won’t see that in April, when it’s every bird for itself.
Robins are among the many species affected by climate change. “Birds that were not formerly resident are becoming resident and are able to take advantage of food all year round,” Farnsworth said.
(Another bird that has changed its behavior based on human activity is the turkey vulture, Farnsworth said. The birds once migrated in search of food, but the suburban deer explosion — and resulting deer-vehicle collisions — has provided them with ample carrion.)
Common the robin may be, but, said Farnsworth: “Common birds don’t always stay common. It’s really important we understand as much as we can about them. And even though they are common, that doesn’t mean we know everything there is to know about them. There’s an opportunity for more study.”
So look to the skies — and to the grass.
Walk this way
Bob Perrino of Arlington, Va., emailed after reading my column last week about what runs through my head while walking my dog. Bob and a friend used to take early morning walks in D.C.
“He loved building architecture and as a Master Gardener, I loved plants,” wrote Bob. “He was always gazing UP and I was gazing at the ground. We joked that a piano would never fall on our heads nor would we fall into a large pothole.”
For previous columns, visit washingtonpost.com/john-kelly.