One of the most common things I get around this time of year from well-meaning friends and family is a statement like this "Spring is here - I saw a Robin"!!! Usually, their faces are so full of joy at the prospect of a cold winter being over and they are so enthusiastic to share something "bird" with me, which anyone who has been around me more than a day knows I love birds, that I don't say anything other than "yay! that's great - bring on the better weather!" When in fact, I'd like to share this post with them to share the knowledge that I have about the truth of the matter.
Actually, as time goes on, I tend to want to share more than leave them in ignorance. So whether it is I who pointed you here or a friend or family member - read this knowing that we LOVE that you want to share your excitement and passion for spring with us. We just want to dispel the myth that for the majority of North America, all robins migrate south and return in Spring.
(photo courtesy of National Audubon Society)
Here is how many of us picture arguably the most identifiable bird in North America: the American Robin (
Turdus migratorious) [heck it even has the word migratory in it's Latin name!]. A medium sized song bird hopping around on the grass with a huge worm in it's mouth. This is in fact how most people see them most of the time. They do love worms, it's true. They especially love feeding worms to their young - like most songbirds, they feed their young the nice protein-rich food of invertebrates to sustain them. In our yard-loving society (a topic for another day), robins are plentiful. Thus leads to the argument people often have with the concept of Robins being year round species - how in the heck do they get worms out of my backyard that looks like this!:
(my backyard this winter)
That's just it - they don't. They're not hopping around on the snow and we typically don't see them as we expect. So we assume they are gone - ie went south for the winter. Until one early spring day, the temperatures reach 50 degrees, the sun is shining, the ground begins to unfreeze, and back they come again - looking for worms on the ground. We jump around, get excited, "The robins are back!! They came back!! It's spring!!"
In all truth, a high percentage of them have been around all winter. True, they have "come back" - come back to their quintessential place as the yard hoppers most people think they are. And there are some that migrate every year - but usually not as far as we think. A bird has to make a choice: migrate or not? -more about this later-
But first, you might be questioning my credibility at this point. Have I seen them this winter? Yes. Have I seen them every winter? Since I've been an out-in-the-woods birdwatcher, yes (I say this mainly to differentiate that before the age of roughly 18 I saw most of my birds from behind glass looking at bird feeders - not that there's anything wrong with this, mind you - it just limits how many birds you see and behaviors you witness). But beyond personally, how do we know about this for a fact? First, a scientific way - mist netting, aka bird banding. Bird banding is an ornithological technique by which individual birds are caught in a hard to see net, measured and weighed, and fitted with a lightweight band that identify them with a unique number. Some are recaught, thus telling us where they've been and how they've changed. These studies help researchers greatly and give us a ton of information that we'd otherwise not know about birds.
I encourage everyone to check out a bird banding demonstration if they ever get the chance - it is very cool. Another awesome tool that you can use right now in the privacy of your own home is eBird. eBird is an online resource that many citizen scientists (ie amateur bird watchers) have entered data in for over 10 years now. I can get lost for hours on the thing, exploring data. I definitely encourage you to take a look. But here is a graph I quickly pulled up, showing American Robins observed in December and January for the past 10 years, as a percentage of checklists submitted - the darker the purple, the higher the percentage.
I know this image is not the cleanest - I strongly suggest you go to the weblink to check it out for yourself. While you're there, play around with some of the parameters - this is for December and January for the past 10 years.... but you can change the date range, zoom into your area, even change the species. This is an amazing tool that I just love... ok enough reading, go check it out!
Welcome back! So let's assume that you've taken my word for it, checked out some data showing there is evidence that some robins do, in fact, over winter in your backyard. Now, I know you're asking - where are all the birds if they aren't eating worms? They group together in large groups called flocks. Sometimes they are even in mixed flocks with other species - typically Eastern Bluebirds (or other bluebirds if you are in a different region than I am), sometimes even Cedar Waxwings or Yellow-rumpted Warblers. The primary advantage of a flock is that they can find food faster. And this time of year, what are robins mostly looking for? Berries! They love fruit - and great news - you can provide it in the form of berry-producing shrubs in your yard (preferably natives - that is definitely for another post).
(photo courtesy of Kim Smith)
It is actually not that uncommon for a species to change it's food source to what's more prevalent at particular times of years. Even humans did this before modern transportation and refrigeration allowed us the luxury of eating anything we want, whenever we want (that my dears is a topic for another blog!). There are a few species that do not do this, but by and large, the majority of species of birds shift their food preferences to what's available. The other option is to follow your food source - and that is the essence of migration.
Growing up, I always thought migration was about staying warm, but really it's about food. Sure, these birds can freeze to death, but in a roundabout way that goes back to food too. Food produces energy, which powers these birds and keeps them unfrozen (they are warm blooded, like you and me) - well and some nice places to roost help too. Birds are much less active in the winter - I'll admit it, I am too! - another reason why we don't see them as much. But if you want to find them, you can, you just have to know where to look. Look for berry bushes/trees - sumacs, high bush cranberries, junipers... there is a wide variety that they like.
[Another tip for seeing bluebirds in winter - they still like to bathe! Put out a unfrozen body of water and robins will come! And you might also get other species too - especially bluebirds. Honestly, putting out a bird bath in winter is one of the best things you can do.]
The thing about migration is it takes a TON of energy and there are great risks. Every year, birds decide to either migrate or stay put. I don't really think they mentally decide - it's probably instinct, but mostly it's about food availability. The best way to describe this, I feel, is through an analogy. Say you love crawfish. Straight up, love them. You know all the best crawfish restaurants in town - even sometimes making special trips just to try a new place. Well then imagine a catastrophe strikes and crawfish become rare. You start to pack your bags, stock up on what food you have left, and get ready to make the thousand mile trek down to Louisiana where they are still plentiful. Yet, you start looking around and seeing all this other food that is all around you - maybe you should try some chicken instead. You decide the favorite food isn't worth the effort (and risk) and decide to just eat chicken until crayfish become more plentiful (and easy to find) again.
I know, this is a silly thought, but it works as analogy - some birds migrate, some don't. There are birds that make thousand mile trips every year - it really is a fascinating subject. Some robins migrate - some don't. The ones that do face the risks of travel, while the ones that stay face the risks of the cold and running out of food. In mild winters, many will survive - in harsh winters, not so many. The benefit if you survive? You have spent less energy AND you are already near your territory and are thus more likely to mate and be successful.
Another bird that falls into this category of a harbinger of spring is the Red-winged Blackbird - similar thing here folks. They spend the winter in MASSIVE mixed species flocks with other blackbirds, feeding primarily on waste grain in the fields. Come spring, they will be back to their usual posts at the side of any and all bodies of water.
(photo courtesy of New Jersey Audubon)
I will end by saying that robin behavior can be a good harbinger of spring, if not the robin itself. When the weather changes enough that the ground unfreezes and grass greens, the robins change their behavior. They will unflock and find their respective territories - males singing their hearts out to any female who will listen (and other males they what to keep away). That IS spring - new life stirring in the remains of the bitter winter. It is my favorite time of the year.
Resources:
Weidensaul, Scott. Living on the Wind: Across the Hemisphere with Migratory Birds, 2000.