There are few diversions more delightful than the footnotes in author Mary Roach’s books, which are anything but boring—instead, like the rest of her work, they take the reader to places both informative and hilarious. “It’s material that doesn’t really fit the narrative, but I can’t bear to leave out. So it’s just me being indulgent,” Roach told us in 2014 of her process for deciding what becomes a footnote. “If [I] have something ... in a folder and I can’t find a way to fit it in that isn’t distracting or annoying for the reader, I’ll put it in a footnote.”

The footnotes in Roach’s latest offering, Fuzz: When Nature Breaks the Law, are as funny and interesting as ever; from Clark Gable's mountain lion to the incredible aim of seagulls, below are a few of our favorites. —Erin McCarthy

1. You may be wondering: When you live off your own fat, do you need to use the toilet? If you are a bear, you do not. Hibernating bears reabsorb their urine and form a "fecal plug." Cubs, on the other hand, let it go inside the den. Not a problem, because the mother bear eats it—partly as cleanup, but mostly as food. She is nursing, after all. While hibernating. Black bear hibernation isn’t the same as sleep. They’re just sort of slowed down and out of it. Surreally, black bear sows give birth halfway through their hibernation. They deliver a couple of cubs, snack on the placenta, then go back into hibernation, nursing and tending their cubs in a state of semi-alertness until spring. According to a scientist who has taken blood samples from hibernating black bears, they do not have sleep breath and their dens don’t stink. They smell like roots and earth and that is all.

2. That elephants are reliably spooked by fire and sudden loud noises limited their usefulness in war. Though the sight of armor-sided "elephantry" with swords lashed to their trunks conferred, from a distance, a psychological advantage, this quickly evaporated as the two sides drew closer. Records exist of elephants turning and breaking ranks at the sound of musket fire or the sight of flaming arrows. A fleeing, sword-waving elephant storming its own battalion likely racked up as many causalities as it would have inflicted on the enemy.

3. "Mountain lion," "cougar," and "puma" are regional names for the same species. Florida calls them "panthers," and in South Carolina they’re "catamounts." The name "Rowdy" applied to just one, a cub captured by Clark Gable on a 1937 hunting expedition. Rowdy was one of two cubs Gable intended to bring back to surprise paramour Carole Lombard, who had jokingly told him to bring her back "a wildcat or two." According to Stanley P. Young, co-author of The Puma, Rowdy escaped the first night, in his new collar with the engraved nameplate (only to be bagged a year later, collar intact, by a mystified hunter). Rowdy’s sibling was presented to Lombard and soon thereafter donated to the MGM Studios zoo. Lombard had earlier given Gable an enormous ham with Gable’s face pasted to the wrapper, so the cougar appears to have been the victim of misguided gift-giving one-upsmanship.

4. To get the monkey stuff, Catherine VandeVoort’s team at the California National Primate Research Centers developed a low-intensity penile electroejaculator. Why not just use a vibrator? "Oh, we tried. Oh my god, we tried. You could get a good erection but they wouldn’t ejaculate." They also tried a dummy mount with an artificial vagina. Not happening. "A monkey is not smart enough to understand what we want from him, but too smart to have sex with a dummy." She emphasized that the device does not hurt or burn. Quite the opposite. She told me about an orangutan who’d come running at the sound of her voice. It was memorably uncomfortable: "Having an orang gaze longingly into your eyes as you try to set up your gear."

5. To clarify, a turkey vulture is a vulture, not a turkey. Though turkeys, too, have crashed into planes. But only wild ones. Supermarket turkeys have never hit planes, but supermarket chickens have, because they are fired at jet parts to test their ability to hold up to birds strikes. The device that fires them is called, yes it is, the chicken gun.

6. My favorite lethal reinforcement story involves Scarey Man, a scarecrow version of those floppy fan-inflated tubular attention-getters you see at strip malls. Unlike those things, Scarey Man also screams and is inflated only intermittently, bursting up like a jack-in-the-box. Birds start to habituate to Scarey Man in about a week, a 1991 USDA study found. Two of the researchers, Allen Stickley and Junior King, then tested whether lethal reinforcement could make Scarey Man scary longer. They’d dress up in a vinyl poncho and sit unmoving on the shore of a cormorant-plagued fish farm. When Scarey Man went off, the man would leap up alongside, "emit a high- pitched wail and bob up and down," and then fire a shot at the cormorants. The log of hours spent "impersonating Scarey Man" resides in the NWRC archives, along with Stickley’s field notes. The birds seemed more entertained than scared. "March 1, 1992. 1456 hrs: Three birds came in and sat and watched me do my thing." Junior got bored and began wandering away from his post and shooting random birds. "I reminded him that the object is to make birds think Scarey Man is shooting," Stickley wrote, disgustedly. What is it with guys called Junior?

7. And good luck if it’s you. In addition to beaking your head, gulls can be, as Julie C. Ellis, senior research investigator at the University of Pennsylvania, phrased it, "very adept at aiming their feces." She shared the story of a student on Appledore Island who, hoping to protect herself while traversing a nest-dense canyon, put on a raincoat and pulled the hood up tight. "A gull managed to shit directly into her mouth."

Excerpted from Fuzz: When Nature Breaks the Law by Mary Roach. Copyright (c) 2021 by Mary Roach. Used with permission of the publisher, W. W. Norton & Company, Inc. All rights reserved.