I’ve been neglecting my blog-writing duties lately, preoccupied with the annual Big Grant Proposal Deadline. My grant proposal is on sexual selection in juncos. What part of juncos is sexually selected, you ask? Why, that flashy tail, of course! They’re practically peacocks!
LANK showing off his sexy tail
You’re not quite there yet, little one…
I’ve also been TAing a class on animal behavior, so while I don’t have many extra words to spare right now—I need them all for that grant proposal—I do have a wealth of animal videos that have been brought to my attention by my fellow animal behavior fans. Please accept some videos in lieu of words.
Here is a video of a bird even drabber than a junco who attracts females with his sexually selected aesthetic tastes in things like flowers, shiny beetles, and slightly… er… less attractive items as well: the Vogelkop Bowerbird.
And here are some flies that—well, you should just watch it to believe it. It starts with them gulping air bubbles into their heads, and that’s not even the weird part.
Why are they like that? Sexual selection! Females in this species prefer their males as hammerheaded as possible.
Hey, why not?
Mammals—including us—use facial muscles to communicate, by, say, smiling or frowning. Reptiles and birds don’t do that: they don’t have the right muscles for it. If you think a bird looks grumpy, or angry, or has any similar human-type facial expression, you’re projecting your human perceptions onto an animal that really doesn’t work like that. (Now, whether the bird actually is grumpy is a different matter; I’m just saying that you can’t tell if it is by looking at its face.)
So the appearance that all these junco chicks have of possessing some serious attitude is merely an entertaining illusion.
What are you looking at?
They were strewn all along the beach, these transparent, tripartite things. At first glance they looked like plastic trash, but they felt organic in my fingers.
Fortunately I happened to be beachcombing with a world expert on marine invertebrates. “Ooh,” he said, “Velella!”
Velella velella, or by-the-wind sailor: a living sailboat, a jellyfish on a stiff frame. In their preferred state, i.e. when not washed up on beaches, these animals float on the ocean surface with their tentacles just below the water, to catch food, and their upright sails above the water, to catch the wind.
Hummingbirds are amazing fliers. They fly forward at up to 26 miles per hour; they fly backward; they hover. They beat their wings 50 times a second, so all you see is a blur, with that enameled little body floating serenely in the middle. They are flight acrobats. They are flight artistes. How do they do that?
Rufous Hummingbird. Photo by M. LaBarbera
It helps that they are quite small. The amount of power that you can get out of your muscles increases as muscle mass (size) increases—bigger muscles, more power—but the amount of power increases less quickly than mass does. That is, if you double the size of the muscle, you get less than twice the amount of power out of it. This means that as an animal gets bigger, its ratio of muscle power to muscle mass decreases. An ant can carry enormous things for its size. A small bird can generate enough power with its muscles to hold its own body aloft and still in the air—to hover. A California Condor? Not so much. Hummingbirds’ small size means that they are, relative to their own body mass, very strong.
Small size is a Rufous Hummingbird’s secret weapon.
Photo by M. LaBarbera