Laura Erickson's For the Birds

Robins Many people look forward to seeing their first robin of spring, but it’s hard to find any place in the lower 48 states, the southernmost areas of the Canadian provinces, or coastal Alaska where you can’t see at least a few robins every month of the year, though in winter they tend to concentrate in Washington, Texas, and coastal regions of the Southeast, especially Florida. As of February 21, almost two million had been reported for this year’s Great Backyard Bird Count, three quarters of them in Florida alone. I saw my first robins of 2010 in Duluth, Minnesota, on New Year’s Day. They’ve been common in my neighborhood this winter, concentrating in yards that have mountain ash and other berries, or crabapples. Winter flocks in Duluth often number 10 or 20, which seems like a lot when the temperature is double digits below zero. But these numbers would seem pathetically paltry in Florida. At the end of January, I headed to Florida for the Space Coast Birding Festival. Along a mile-long stretch of one road at the Merritt Island National Wildlife Refuge, all the trees lining both sides of the road were filled with robins. Even through closed car windows I could hear them calling, and they were flitting about everywhere—I had to drive 15 miles per hour to avoid hitting them. They ate berries in the trees, hopped on the ground in search of worms, bathed in puddles, preened in patches of sunshine, and in general acted like the robins I know, only more intensely.

In summer, as each batch of robin nestlings fledges, they hang out with their father, who brings them at nighttime to a roost with other dads and fledglings, while the moms stay back at their nests with new clutches of eggs. After those eggs hatch, the dads return to home base to care for the new nestlings. By then the fledglings are ready to be on their own, hanging out with other fledglings and some of their dads. None of these young robins are territorial. They pick up a lot of basic skills from watching each other, and they find security in numbers, thanks to the dads hanging out with each new batch of fledglings. When females stop producing eggs in July or August, they join these flocks, too. Shortening day length reduces robin hormonal levels, making them lose their territoriality and become more sociable—not just comfortable in the presence of other robins but actively seeking them out. This sociability holds steady throughout winter.

During winter, robins wander widely in search of fruit. The general trend of their movements is southward, but local numbers fluctuate wildly from one year to the next, along with fruit supplies. It’s the robin’s ability to wander irregularly that allows the species to capitalize so successfully on such a patchy winter food source.

By late January and early February, robins feel the effects of more daylight hours. They still find security in numbers, and they still eat mostly fruit, but they’re growing more restless than usual, the first hints of territoriality are starting to emerge, and they’re developing a craving for earthworms. By the end of the month just about all of them will be wandering north, concentrating where temperatures average about 37 degrees and worms are emerging. More and more males will get just too restless and territorial to feel comfortable in the flock. They’ll burst into occasional songs, making their flock mates more anxious, too. There will be more and more squabbles, and soon flocks will splinter apart. We’ll start seeing more and more robins in pairs, the males singing and sometimes fighting to maintain separate territories as far from other robins as possible.

During these weeks of transition, robins display their richest array of behaviors. Right when we are hungriest for signs of spring, robin watching is most rewarding and fun. Some robins may remain in the north all winter, but our first robins of spring are still the most thrilling of all.