Juncos nest on the ground (usually; sometimes they will nest higher, even reusing old robins’ nests, but I’ve never seen this myself. It’s probably because I’m short). This makes their nests tricky to find, since in the first place, there is a lot of “the ground” to search, and in the second place, you have to be really careful where you step while you search.
They don’t just nest on the ground, though: they often hide their nests underneath things. Some of them are quite good at it.
YABI’s nest. What do you mean, you can’t see it – it’s right there!
See, there it is!
The season of the summer disaster movie is upon us: Godzilla is stomping San Francisco, and I’m sure we’re all eagerly anticipating the premiere of Sharknado 2. To liven up the cinemas a bit, as a relief from the overabundance of sequels (I mean really, Sharknado 2!), I would like to propose a new genre mash-up: the animated talking birds disaster movie. It would be like those dancing penguin movies, or the solemn-looking owl movie (I have seen none of these…), plus disasters. The first one could be called Hailstorm!
It would not be a children’s movie. It would be terrifying.
It hailed on us a few days ago for about half an hour. The hail was mostly small, not larger than 1 cm in diameter, and the only animal reaction I saw was a decidedly alarmed chickaree—although to be fair, chickarees almost always look alarmed. I saw no evidence of damage afterwards; all of the junco nests we were monitoring weathered the storm just fine.
You know the hail isn’t too bad when you can safely hide from it in a tent.
But sometimes hail is a sharper-fanged beast.
Everyone knows ducklings: yellow fuzz, big flat bills, big flat feet, cute little waddles all in a line after Momma, and superpowers.
Photo by Farrukh*
What, didn’t you know that last part?
Several duck species nest high above the ground in tree cavities. This is safer than nesting on the ground, predator-wise, but it also means that the ducklings hatch very, very high up. And then they have to get down.
When they hatch, the ducklings weight very little, which helps: the less you weigh, the less you are hurt by falling. Terminal velocity—the fastest that gravity will make you fall—depends on weight, so small creatures are essentially safe from falling no matter how far they fall. The cushiony leaf litter on the ground helps the ducklings too. And notice how they flatten out, spreading their little legs out behind and their wing stubs out front, their bodies as spread out as possible: they are gliding—albeit not as well as a true glider like a flying squirrel, but nevertheless slowing their descent so that they can land safely.
Last year, I started the field season as soon as the university spring semester ended, because my field assistants were undergraduates and needed to take their finals before heading off into the mountains. That turned out to be too late, as we found that some of the juncos had started breeding without us. So this year I found some awesome non-undergraduate volunteers and went out earlier.
But I might have started a little too early.
My tent, our first morning in the field.
We’d known it was going to rain, and I thought it had – a particularly light-sounding rain pattering on my tent throughout the night. When I woke up I thought my tent had been covered in seeds washed loose by the rain. Then I stuck my head outside.
In fact it was better than rain: drier, and still permitting us to boil water for breakfast.
Our stoves boiling water for breakfast.
Recently I was lucky enough to spend some time in Spain, where the land is dotted with hilltop castles and the winding narrow streets of the old cities are encircled by sturdy stone walls. I crouched behind crenellations, pretending to be a bowman awaiting attack, and climbed dark winding staircases glad that no defending army waited at the top.
Winding staircase in the Olvera castle.
Photo by Q. Stedman
It’s exciting and romantic to imagine castles and walled cities in the flush of functionality, but it’s hard to ignore that the motivating force for those structures was real, unromantic, gut-knotting peril and fear. The people who lived in those cities put up thick stone walls with their hands because they thought other people were going to come and unromantically kill them—which they sometimes did.
Gulls standing guard over Tarifa.
When birds build nests, they’re responding to that same threat. Eggs and baby birds are easy targets for anything from mice to snakes to deer to toucans. To keep them safe, birds too rely on stout walls, secret passageways, and defending armies.
For some reason, lots of junco nestlings and young fledglings really believe they can fly.
Sorry, little guys. You are definitely wrong about this.
BBAR can totally do this.
Here’s a puzzle: you’ve gone to all the bother to evolve fins, then limbs, and then even limbs with all these complicated joints and toes and whatnot—and then you lose them. Limbs all gone.
You’re just a head and a tail now. Why, corn snake, why?
This seems counterproductive, to say the least. Yet it isn’t just the snakes going in for the serpentine body plan: caecilians, amphisbaenians, and legless lizards lost their legs, too, and they aren’t evolved from snakes—these limbless animals all lost their limbs independently.
To understand how being snake-shaped might be adaptive, we’ll also consider some animals that are almost—but not exactly—snake-shaped: the mustelids, or weasels.
Least weasel. Photo by Sergey Yeliseev*