American Robins are on everyone's minds right now as a new season draws near, and we await the familiar song of these harbingers of spring to fill the air once again. In the meantime, let's learn some interesting facts about these humble thrushes (yep - thrushes)!
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| American Robin (Turdus migratorius) |
1. Some stick around all year long.
Harbingers of spring? Maybe not. The wintering range of the American Robin is largely affected by weather and food supply. Most birds can survive frigid temperatures as long as they have a reliable source of food, and in this area our native fruit-bearing plants typically have a bounty available for robins to eat throughout the winter. Robins maintain a body temperature of about 104℉ no matter the temperature outside. In the winter they generate body heat by shivering, and maintain their warm temperature by fluffing their feathers which acts as a shield from blowing wind and snow. All of this temperature regulation takes a lot of energy, which they get from their food. Studies suggest that more robins over-winter here than we may realize, and rather than migrating, they simply change their behaviour. In the winter months robins are non-territorial and will gather in nomadic flocks to feast on berries, while in the spring the flocks will disband to seek out and claim suitable nesting territory. Once nesting territories are established, American Robins will aggressively defend their areas until the last chicks of the season have flown the coop, flocking together once again when fall blows in. So while many do migrate south, because of their nomadic tendencies through the winter & solitary nature in the spring and summer, there may be more robins who over-winter here than we see. Click here to learn more about winter robins. 2. They have a pocket for storing extra food.
No, it's not tucked inside of that orange vest of theirs, it's in their throats. American Robins have evolved to posses an exceptionally stretchy esophagus that acts as a storage compartment. This compartment is especially useful in the winter, when they pack it full of fruits for the long, cold nights. Some fruits you could expect to find in there would be crab apples, mountain ash berries, and juniper berries. The availability of this extra food can play a vital role in a robin's ability to survive low nighttime temperatures.
3. Birds of a feather flock together - sometimes by the thousands.
While it's common to see half a dozen or so robins searching for worms together in your backyard during breeding season, roosting groups don't really establish themselves until winter. Adult males will roost (rest in trees) in small flocks during the breeding season, with females following once the season is over, and both later joined by juveniles once they are able to travel to the known roosting area. These roosts are typically comprised of 20 to 200 individuals, but can include as many as 250 000 birds. These flocks will sometimes include other species as well, including European Starlings and Common Grackles.
3. Birds of a feather flock together - sometimes by the thousands.
While it's common to see half a dozen or so robins searching for worms together in your backyard during breeding season, roosting groups don't really establish themselves until winter. Adult males will roost (rest in trees) in small flocks during the breeding season, with females following once the season is over, and both later joined by juveniles once they are able to travel to the known roosting area. These roosts are typically comprised of 20 to 200 individuals, but can include as many as 250 000 birds. These flocks will sometimes include other species as well, including European Starlings and Common Grackles.
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| American Robin feeding mealworms to its young |
4. Robins are nesting champions.
If it seems like you're seeing baby robins all spring and summer long, it's because you are. Robins are prolific nesters, raising up to three broods of 3-5 chicks each throughout the nesting season. Not only do they produce and raise a large number of their own offspring each year, but they sometimes raise foster chicks as well. Robin nests are commonly parasitized by Brown-headed Cowbirds, who lay their eggs in the nests of other species, leaving them to be incubated and raised by the foster parents. If you've ever seen a family of robins hopping around your yard with one fledgling who looks like an odd one out, and is a bit bossier than the rest, it was most likely a Brown-headed Cowbird.
5. Sometimes they get drunk.
After a long, hard week of answering to demanding babies & digging up worm after worm, sometimes robins like to let loose with a nice fermented berry or two. Just kidding, they don't actually mean to get drunk (or maybe they do?). The first frost of the year causes berries to ferment, which in turn, turns them into bird-sized pints of alcohol. If birds binge on these berries - as robins often do - they can become intoxicated, which alters their perception and ability to fly properly. This becomes even more of an issue in the spring when the fermented fruits thaw. The cold temperatures of the winter concentrate sugars in the fruit, and increasing temperatures cause the sugars to breakdown at an accelerated rate. This forms a very potent alcohol within the fruits, similar to vodka. If you come across a bird you think might be under the influence, it likely just needs some time to recoup in a dark and quiet area, but it's always best practice to contact your nearest wildlife rehab facility for advice just in case.
After a long, hard week of answering to demanding babies & digging up worm after worm, sometimes robins like to let loose with a nice fermented berry or two. Just kidding, they don't actually mean to get drunk (or maybe they do?). The first frost of the year causes berries to ferment, which in turn, turns them into bird-sized pints of alcohol. If birds binge on these berries - as robins often do - they can become intoxicated, which alters their perception and ability to fly properly. This becomes even more of an issue in the spring when the fermented fruits thaw. The cold temperatures of the winter concentrate sugars in the fruit, and increasing temperatures cause the sugars to breakdown at an accelerated rate. This forms a very potent alcohol within the fruits, similar to vodka. If you come across a bird you think might be under the influence, it likely just needs some time to recoup in a dark and quiet area, but it's always best practice to contact your nearest wildlife rehab facility for advice just in case.
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| American Robin feeding on crab apples |
I don't know about you, but I don't care what anyone says - robins mean spring, and spring can't come fast enough this year! 😉
Happy trails!
- Shayna
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Another great one!!!
ReplyDeleteThanks Ramon! Kristen :)
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