Amelia: Look, there’s a flock of dark-eyed juncos hopping on the snow below my bird feeder. If I’m very quiet, I wonder if I can step a little closer…
Dark-eyed junco: Abort, abort! Fly for the trees!
A: Darn, why do you always do that? I just want a closer look.
D: I didn’t get this old without being very careful. I spend my most of my life on the ground, and oddly enough, there are a lot of predators down there.
A: A tiny bird that lives on the ground? That seems like a poor life choice.
D: Excuse you! I’m an extremely successful species found all over North America.
A: If you’re so common, how come I only see you in the winter?
D: For the simple reason that we spend our summers in coniferous or dense forest – not where you humans typically live. In the winter we fly south to warmer areas, looking for seeds and sleeping insects in more bushy open areas, like roadsides, farm fields and suburbs. We do like these birdfeeders you put up, even though we prefer the seeds the fall on the ground.
A: Why do you spend so much time on the ground?
D: It’s where all the good food is! Grasses and weeds have delicious seeds. And don’t get me started on ants, flies, spiders and caterpillars! It’s a veritable buffet down here. In addition, hopping after insects is good exercise.
A: I guess that’s true. When your flock flew away, I noticed your tails have flashy white feathers. They look pretty, but do they serve a larger purpose?
D: Yes. First, they help us stay together as a flock. Seeing flashes of white lets me know I’m still with my group. They also help us escape predators.
A: Really? Don’t they make you more visible to predators?
D: It’s all part of the “flash and hide” trick. If a hawk starts chasing me while I’m flying, its eyes are following those flashes of white. But once I fly into the brush and close up my tail, the white disappears, and the hawk loses track of me. Cotton tailed rabbits do the same thing.
A: Huh, I would never have thought that would work.
D: Yep. It’s such a successful feature that all 15 subspecies in North America have it, even though the rest of their markings come in a rainbow of greys, pinks and browns.
A: Hold on, not all dark-eyed juncos are grey and white like you?
D: Nope. We’re actually one of world’s best examples of diversification and rapid evolution.
A: What do you mean?
D: It means we look different based on where we live. We started from one ancestor bird that spread out across North America between 10,000-13,000 years ago, after the last ice age. Since then, populations in different parts of the continent have evolved different colourings.
A: But doesn’t evolution take a long time?
D: Usually, it does. But feather colour is more flexible than many other traits – a quick change in one gene is all it takes. Change that superficial can happen relatively fast, evolutionarily speaking. Humans thought we were separate species for a long time, until genetic testing in the 1980s proved otherwise. We can still interbreed where our populations border each other, and during winter migrations we’ll often flock with other subspecies. But if we stay apart long enough, we may indeed become separate species. You’re watching evolution in action in your own backyard!
A: Okay, that’s pretty cool. Besides colour and where you live, are there other differences between the subspecies?
D: Not lots- we all hop on the ground, feed on insects and seeds, have cute pink beaks, migrate, and make our nests on the ground.
A: Hold on, you nest on the ground? I don’t want to judge, but that sounds like another awful life choice. Don’t your eggs and babies get eaten?
D: Well, yes they do. Repeatedly. We do our best to chase away squirrels, snakes and chipmunks, but anything bigger than that is not going to listen to a tiny songbird.
A: Wait, chipmunks eat eggs and baby birds?
D: Definitely. Isn’t that common knowledge? They are stripy menaces.
A: Okay, I learned something new. It must be tragic to lose your babies.
D: Oh it is, but we’re nothing if not determined. If a nest fails, we’ll try again up to five times in a season to raise a successful brood.
A: Wow, that’s impressive! Though I still question your judgement on the whole nesting on the ground thing.
D: It’s not as if the nest is in plain sight. It’s usually hidden under a bush, under tree roots, or in a rocky hollow.
A: Okay, so who makes the nest?
D: I do. The female is responsible for choosing the nest site and building the nest. I may attempt to build up to seven different nests before I settle on the perfect one.
A: Once you make that nest, do you use the same one every year?
D: Are you kidding? Nests on the ground don’t last that long! They’re also full of bugs and parasites. I start fresh every year.
A: Sounds like a lot of work. Does your mate help raise the babies?
D: Oh yes, he helps me feed them. We’re a devoted pair, even if some of the babies aren’t his.
A: What? I thought you were monogamous.
D: We prefer the term “socially monogamous.” It means we raise a family together, but we’re both sleeping around with the neighbours. This works out well for me because if my mate dies during the breeding season, one of the neighbours will take me as his second mate and help raise my babies. The next year I’ll find a new mate. We’re nothing if not persistent when it comes to raising babies!
A: You are certainly committed.
D: Also, I bet you didn’t know that I’m a sparrow.
A: Really? You’re not brown and stripy like most sparrows.
D: That’s because stripy sparrows live in grasslands where the stripes help them blend in. I live in coniferous forest, where stripes would not help at all.
A: That makes sense. I’d better get back inside- it’s cold out here. Will I see you again next winter?
D: Probably, if you keep putting out this delicious birdseed!