Some Robins do not Migrate

Maynard, MA no longer has a newspaper. This is a re-posting of an old column.

Robins don’t leave anymore. American robins are omnivores, consuming fruit, berries, earthworms, and insects. They used to leave – their Latinate name Turdus migratorius says exactly that – and then come back in the spring. The “Turdus” part refers to being of the thrush family.  Emily Dickinson’s poem “I dreaded that first robin so” started with robins and went on to list other Spring-signs she dreaded such as daffodils and bees. And actually, they still do leave, mostly, but enough stay to make robin sightings year-round not particularly newsworthy. The reasons for seeing robins year-round is probably a combination of in part global warming and part a better winter food supply. A good resource for shifting bird territories is The Great Backyard Bird Count (www.birdsource.org). 

Robin in a winterberry bush

Robins that leave New England spend the winter months in the southern states along the Gulf of Mexico or in central Mexico. Coming back, the male show up first. They travel 50 to 200 miles a day, staying behind the northward advancing line of temperatures above 37° degrees. That temperature is when earthworms will start appearing on the surface and also when the ground softens enough for female robins to collect mud with their beaks for nest building.

Spring sightings here in New England will be a combination of flocks stopping off temporarily but heading further north, and those that have stopped here, declared territories (the males) and started nest building (the females). If you hear a robin singing it is a local male declaring his territory.

In passing, “robin egg blue” as a color is defined as a shade of cyan (greenish-blue color) approximating the shade of the eggs laid by the American robin. Tiffany Blue is a trademarked name and trademark-protected version of robin egg blue uniquely associated with Tiffany & Co., a New York City based jewelry company. The company began using the color in 1845, not many years after its founding in 1837.

The robins that don’t leave, more males than females, gather in flocks of 20-50, sometimes co-mingling with wintering flocks of starlings. These are not the plump and gentle birds of summer with the hop-hop-hop-stop method of working a lawn for worms and grubs. In winter, robins are noisy and combative, working their way though berry bushes with the remembered aggressiveness of Bostonians at a Filene’s bargain basement sale.

Robins like winterberry berries (as do Cedar waxwings), but will eat just about any type of berry or fruit. One reason they may find New England more winter-friendly now compared to years ago is the prevalence of two invasive plant species: Oriental bittersweet and multiflora rose. Both the tree-topping vines and the arching ground brambles are lush with red berries by late-November. Many bird species will eat the multiflora rose berries, but the bittersweet crop is left for robins and waxwings

And why the name “robin?” When the English colonists started arriving in the 1630’s they named the local bird “robin” because its appearance reminded them of the European Robin. The species are not related. The European bird is smaller and has a red/orange face and bib, but a whitish belly. It is the national bird of the United Kingdom. When the English got to Australia the local red-breasted birds also became named robins. These “Flame robins” look a bit like our birds, only brighter. Unlike our species, the females lack the red breast color.

“Little Robin Redbreast” is an English language nursery rhyme. It goes, “Little Robin Redbreast, Sat upon a rail; Niddle noble went his head, Widdle waggle went his tail.” Earlier versions, dating to the 1700s, revealed a more coarse humor, to wit: “Little Robin Red breast, Sitting on a pole, Nidde, Noddle, went his head, And poop went his hole.”

There was an Atlantic Ocean crossing important to American robins. The common earthworms we see robins tugging from the earth and feeding to their chicks came over with the colonists. Although there were many species of worms native to the Americas, these immigrants are more adept at managing the colder climate of the northeast. Back across the ocean, earthworms are being threatened by another invasive species: the New Zealand flatworm. In parts of Scotland and Ireland native earthworms are now scarce – and the fertility of the soil is declining. Here in the US, earthworms are threatened by another invasive species: "jumping worms." from Asia. These (actually three species) live in the leaf litter on the surface, consume dead organic materials, and leave behind nutrient-poor worm poop. Unlike earthworms, they do not burrow, and thus do not contribute to soil aeration and water absorption. Robins will eat jumping worms.