The Robin in Winter…or why Robins don’t migrate

Their scientific name (Turdus migratorius) suggests that Robins are only temporary inhabitants of this harsh northland, and indeed, it would seem to be a bad idea for a fruit and insect specialist to stick around here during the coldest weather when plants and insects are inactive.

We are used to thinking of Robins as harbingers of spring, migrating back only when the ground thaws and the earthworms become active, but some Robins are hearty and savvy enough to remain here all winter, even during the coldest, and snowiest weather.

The overwintering Robin -- see my earlier post in December 2013.

The overwintering, non-migratory Robin — see my earlier post in December 2013.

So, how do they manage to stay warm, find enough food they like, and tolerate these harsh conditions?  (On a day like today, with 40 mph winds chilling the already subzero air, I have to wonder how anything tolerates living here.)

Maybe eating fruit isn’t such a bad strategy for a bird that overwinters in northern latitudes.  Consider the advantages:

1) fruit is full of sugar, and some fruits have a waxy coating that is digestible, providing extra calories;

2) when you find a tree or bush with fruit, there is usually a lot of it, and a bird can “stuff its gut”, literally, in one sitting;

Frozen crabapple -- what could be better on a cold day?!

Frozen crabapple — what could be better on a cold day?!

3) fruit passes through the gut rather quickly, compared to the protein and fat content of seeds or insect bodies, so the bird can go back and fill its gut again and again, until its fat stores are replenished;

4) plucking enough fruits to meet the daily energy quota is much less expensive than foraging for seeds or insects, and lastly

5) fruit-eaters that harvest dense patches of food (berry bushes or crabapple trees) have a lot of down-time, when they can economize on their daily expenditures by resting in sheltered areas, away from predators and bad weather.

So the next question might be:  is there enough fruit here to sustain Robins all winter?  What is their diet in the winter?

A high proportion of a Robin's winter diet is buckthorn berries.

A high proportion of a Robin’s winter diet is buckthorn berries, along with fruits of the dogwood, honeysuckle, holly, Viriginia creeper, and waxy fruits of bayberry, juniper, red cedar, and poison ivy. 

The increasing infestation of northern forests by invasive Buckthorn seems ideal for overwintering Robins, who can feast on its fruits and return the favor by dispersing buckthorn seeds in their excreta.

As much as 85% of the buckthorn berries may fall directly beneath the shrub, so Robins which like to forage at ground level anyway, have a high density food resource there as well.

As much as 85% of the buckthorn berry crop may fall directly beneath the shrub, so Robins, which like to forage at ground level anyway, have a high density food resource there as well.

So, why spend all the energy to migrate and have to compete with the locals and other migrants, when you can stay put with a nice dependable fruit crop at home and be first with the best nest site in the spring?  Winter Robins are so smart.

"I am so smart..S-M-R-T".

“I am so smart..S-M-R-T”. (Homer Simpson)

15 thoughts on “The Robin in Winter…or why Robins don’t migrate

  1. You must have some very hardy robins that far north. I usually get a few per week that stop by my yard looking for berries on my Eastern Cedar trees. Not sure if there is much left, the Waxwings have usually plucked the trees clean by now.

    • I agree–they must be tough to put up with this weather. I have to admit I have never paid attention to whether they stayed here all winter before this year.

  2. The waxwings played through Salt Lake a couple of weeks ago but didn’t show much interest in frozen crabapples – they like Pyrus fruits. Robins are stripping the crabapples, and I keep a heater in the birdbath so they can drink and swim.

    • They drink from the bird bath here, but it would probably be lethal to get wet in this weather. I think I read that waxwings prefer fruit with higher lipid content, and robins prefer the higher sugar fruits.

  3. Well, that’s timely information, I was just hiking today, and wondering how the flock of robins I had seen were managing to get by with the ground frozen beneath snow. But in these Rhode Island woods there are winterberry, green brier, bittersweet and others. I even visited a holly tree with only a single berry on it. I thought the cedar waxwings had been at it – but maybe it was the robins.

    • Interesting. Sometimes I see mixed flocks of robins and waxwings, but I know they do have different fruit preferences. Lots of fruit left here so far, but there are still 5 months or so to go before the ground will defrost.

  4. Beautiful shots, Sue, but I am not sure that I can change the image in my mind that robins are harbingers of spring. There may be enough food for them, but I’m not sure that I would want to endure the cold there (as a human or as a bird).

  5. Robins have been eating the berries off a tree in our front yard. I’ve never seen so many robins as this winter. They look huge too…all puffed up. Our feeder in the back has been very busy with other visitors too …brrr…what a cold winter!

    • I think Robins adopt the Goldfinch strategy in winter and hang out in big flocks together. More eyes to search for the remaining fruit, perhaps. I hope there is enough fruit left to sustain them through the rest of the deep freeze this winter.

  6. I’ve read, too, that in many areas the robins you see in winter aren’t the same ones you see in spring…a given area’s warm-weather robins migrated south in fall and were replaced by others migrating in from the north! So I guess one can still consider them harbingers of spring…even if at a glance we can’t tell one robin (in general) from another!

  7. Pingback: Rockin’ robins | Mike Powell

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