Why Evolution is True is a blog written by Jerry Coyne, centered on evolution and biology but also dealing with diverse topics like politics, culture, and cats.
Many readers sent me this video made by engineer and inventor Mark Rober about his attempt to build a Rube-Goldberg-like bird feeder that would foil squirrels. (This is the ultimate pandemic project.) Thanks to all who sent this; it’s truly awesome (as the kids say), and “viral”, with over 14 million views in four days! (This may reflect people looking for cute videos while they’re quarantined.)
It’s a truly impressive project, but what impressed me even more was both the agility and the cleverness of the hungry rodents. If you’re one of the rare people who haven’t seen this, do watch. It’s a lot of fun.
You may remember Rober as the guy who devised a glitter/stink bomb package to punish those who steal boxes off people’s porches.
I really like this video, as it recalls a similar incident that happened to me in India. In the very short video below, posted on “Twitch” (whatever that is), a hawk swoops in and, with unerring accuracy, nabs a girl’s sandwich. I watched it several times to see how it swooped in. Those things have awesome vision!
Similarly, once in some godforsaken small-town railway station in India, when I was waiting for a train, I bought a bun filled with some hot-pepper filling. As I stood on the platform eating it, a hawk simply snatched it from my hands. I hope it burned its tummy! And once in St. Ives in England, I bought a pastie and was eating it by the shore when a seagull took it away from me. (Tourists are warned not to eat food in the open, but I didn’t see the sign.)
Well, animals deserve to eat, too—but not buns and pasties!
Today we have a video of an interspecific brawl sent by Swiss biologist Jacques Hausser and taken by his daughter in law in the town of Bassins (also Switzerland) last Friday. With permission, I put the video on YouTube so I could embed it.
Jacques’s title and notes are indented below. There are also three bonus photos:
Interspecific fighting for a nesting hole
This afternoon, Deny, my daughter-in-law, heard a great commotion, followed by a thump, and saw two birds fighting on the ground. She videotaped part of the scene, then brought me the two birds still clutching to each other. Unable to get them apart (the sharp claws of the swift were firmly hooked in the starling’s flesh) I had to bring them to a rehab center.
Why this fight? The neighbor’s house was partly renovated this winter, and, quite typically, several nesting opportunities disappeared in the process, including probably the one of this frustrated swift coming back from Africa, who tried to expel the starling from its nest – I found some eggs broken on the soil, too. I had planned to built swift nesting boxes, but with the Covid-19, my plans remained at the paper stage…
The cast of characters (be sure to put the sound up):
Starling: Starling, Sturnus vulgaris, and Common swift, Apus apus. Interested onlooker and would-be actor: Domino, my cat [Felis catus]. Vocals: mostly carrion crow, Corvus corone, very interested too.
I asked Jacques if the birds would be okay, and apparently the swift was released swiftly (that’s a “Tom Swifty“, making it a double pun), but the starling, with a wound in the chest, will require more days of care, though she too will pull through (see below):
it was something not observed every day. The video was taken by my daughter-in-law Denielle Hausser. According to the staff in the rehab, the starling will be OK after some more days of care.
More information from Jacques:
Looking at the picture below from Professor David Norman of the Merseyside ringing group (reproduced with permission), you can understand the suffering of the starling! Although “Apus” means footless, swift have rather special “pamprodactyl” feet, with the four fingers usually kept more or less parallel in the front direction – to hang on vertical walls – but they can oppose fingers 1-2 to fingers 3-4 to grasp something – including perhaps each other in their aerial mating. Remember that swifts can stay in the air up to 9 months, loving, hunting, sleeping, and drinking on the wing. They land only for breeding, or when they are caught in a bad or cold weather.
Look at those swift talons!
I have a picture of the male (?) starling from the same pair.
The swifts are hard to photograph, but I have a very bad picture I like nevertheless.
We have two PBS videos today. First, a lovely video that uses a tiny “hummingbird drone” to fly inside a monarch butterfly swarm in their Mexican mountain destination. Look at how thickly the trees are festooned with butterflies!
And, as a treat, here’s a video of a real tiny hummingbird, in fact the smallest bird on Earth: the bee hummingbird (Mellisuga helenae). It’s endemic to Cuba and the Isla de la Juventud.
How big is it? Wikipedia says this:
The bee hummingbird is the smallest living bird. Females weigh 2.6 g (0.092 oz) and are 6.1 cm (2.4 in) long, and are slightly larger than males, with an average weight of 1.95 g (0.069 oz) and length of 5.5 cm (2.2 in). Like all hummingbirds, it is a swift, strong flier.
In other words, it would take 175 females to weigh a pound. And they have the typical hummingbird metabolism, eating half their weight each day in nectar and the occasional insect.
Eggs the size of coffee beans! 80 wingbeats per second! A nest smaller than a golf ball, and beautifully festooned with what looks like liverworts. This, like all hummingbirds, is one of the most marvelous products of natural selection.
Here we have what’s supposedly the world’s largest beetle, the Hercules beetle (Dynastes hercules), though Wikipedia says it’s “the longest beetle” and “one of the largest flying insects in the world.” How big?
Adult body sizes (not including the thoracic horn) vary between 50 and 85 mm (2.0 and 3.3 in) in length and 29 and 42 mm (1.1 and 1.7 in) in width. Male Hercules beetles may reach up to 173 mm (7 in) in length (including the horn), making them the longest species of beetle in the world, if jaws and/or horns are included in the measurement. The size of the horn is naturally variable, more so than any variation of the size of legs, wings, or overall body size in the species. This variability results from developmental mechanisms that coincide with genetic predisposition in relation to nutrition, stress, exposure to parasites, and/or physiological conditions.
They can weight about 2 ounces.
Reports suggest the Hercules beetle is able to carry up to 850 times its body mass. Actual measurements on a much smaller (and relatively stronger: see square-cube law) species of rhinoceros beetle shows a carrying capacity only up to 100 times their body mass, at which point they can barely move.
That’s the equivalent of a 150-pound male carrying nearly 64 tons! The males use their big horns to fight. I’ve put a video of a male battle below:
They eat rotting wood, and of course they can fly (you can see the elytra, or wing covers, pull back when this one’s forced to flap its wings). It seems to me that they’re torturing the poor beetle!
In Why Evolution is True, I begin the chapter on natural selection with the example of the Asian giant hornet (Vespa mandarinia). I used that example because it shows both the amazing adaptations of animals, and it’s also a tale that wasn’t well known then. But it’s better known now that the giant hornets have been found in the U.S., where the native honeybees are defenseless. The hornets are pure bee-killing machines, two inches long, each capable of decapitating 40 bees per minute. But native Asian bees have evolved a a defense. As I said in the book:
The hornets are fearsome hunting machines, and the introduced bees are defenseless. But there are bees that can fight off the giant hornet: honeybees that are native to Japan. And their defense is stunning—another marvel of adaptive behavior. When the hornet scout first arrives at their hive, the honeybees near the entrance rush into the hive, calling nestmates to arms while luring the hornet inside. In the meantime, hundreds of worker bees assemble inside the entrance. Once the hornet is inside, it is mobbed and covered by a tight ball of bees. Vibrating their abdomens, the bees quickly raise the temperature inside the ball to about 47degrees C. Bees can survive this temperature, but the hornet cannot. In twenty minutes the hornet scout is cooked to death , and—usually—the nest is saved. I can’t think of another case (save the Spanish Inquisition) in which animals kill their enemies by roasting them.
There are several evolutionary lessons in this twisted tale. The most obvious is that the hornet is marvelously adapted to kill—it looks as though it were designed for mass slaughter. Moreover, many traits work together to make the wasp a killing machine. They include body form (large size, stings, deadly jaws, big wings), chemicals (marking pheromones and deadly venom in the sting), and behavior (rapid flight, coordinated attacks on bee nests, and the larval “I am hungry” behavior that prompts the hornet attacks). And then there is the defense of the native honeybees—the coordinated swarming and subsequent roasting of their enemy—certainly an evolved response to repeated attacks by hornets. (Remember, this behavior is genetically encoded in a brain smaller than a pencil point.)
Here’s a video showing the brutal attacks of the hornets on honeybees. The counterattack by bees on the hornet “advance guard” begins about four minutes in:
Several readers in the comments noted that this hornet can also take down praying mantids. But sometimes the mantis wins. Watch this mantis chomp down on a hornet, ingesting it in minutes. Look how the hornet tries to sting the mantis, but the mantis knows just where to grab it so that fearsome stinger can’t strike. (I do have my suspicions that the hornet was drugged or something, as it looks lethargic.
I was going to do a somewhat complex post on consciousness today, but Duck Farming has been onerous and, as Matthew and I discovered on a Skype call today, we’re both having trouble concentrating during this period. Consciousness shall thus be postponed until tomorrow and instead we’ll have something not mindless but simple and biological.
This informative 4½-minute clip from BBC Earth features not only real-time X-rays of hamsters being bendy in their Habitrails, but also of them stuffing their famous cheek pouches, which in this species go all the way back to the hips! And they can push the stored food out of their pouches with their paws.
Readers with hamsters are welcome to share their experiences.
Lagniappe: This clip, which I found online, purports to be from the 2003 movie The Cat in the Hat, and the video was posted ten years ago. Prescient or what?
