A maroon SUV bumped up the rise into the turnaround and parked at an angle. She watched a couple get out, a trim middle-aged woman and super-skinny husband in cross-trainers. “Look, they’re here today,” he said in a loud whisper, and they stood at the edge of the precipice holding hands, thrilled with their luck. As if the butterflies might have been elsewhere. None of the visitors had spoken to her today, addressing their questions, if any, to a man in khaki who was passing out leaflets to the intermittent visitors, asking them to take some kind of pledge. He wasn’t one of the Californians like Carlos and Roger. Those boys had gone home, taking their wrecked clothes and good cheer. This man was from another organization in a city she didn’t recognize, and he was no kid, either. He had white hair and a snap-brimmed hat and slightly crossed eyes behind thick glasses. He was here in no official capacity, despite all the khaki. It was his retirement project to travel from place to place distributing the pledge, which Dellarobia had yet to read. He’d actually talked her ear off this morning with rambling tales of people he’d met and unfriendly encounters with officers of the law and with wildlife, always winding up with the baffling declaration, “And that’s all she wrote!” Who was she? This man, Leighton Akins by name, somehow came out ahead as the hero of all his own stories, Dellarobia noticed. A sure sign he was not from the South. Hereabouts, if a man told a story in which he was not the butt of the joke, or worse yet, that contained no jokes at all, his audience would shuffle off at the first appreciable pause. Without that choice, Dellarobia listened awhile, then tuned him out, and finally told Mr. Akins in the politest way possible that she was working as a biologist here and had to concentrate.

She was supposed to watch the roosting colonies and track their flight behavior. The butterflies were showing some signs of restless movement, actually leaving the roost trees in significant numbers. It did take concentration to watch for the small explosions of flyers, then locate individuals with the binoculars and follow the wobbling specks that vanished through gray air. The weighty binoculars made her anxious, probably three or four months’ utility bills right there, highly breakable. But Ovid had hung them around her neck as if it were no high occasion. Costume jewelry, not diamonds.

He wanted to know which direction the flyers were headed, in what numbers, and whether they returned in the afternoon. They might be seeking water or nectar sources. After surviving all other onslaughts in this alien place, it could be the warmth rather than the cold that killed them. The sunny, warmer days that brought them out of dormancy to fly around, as they’d seen, would tax the butterflies in a way that the cool, steady clime of the Mexican mountains did not. They might burn through their fat reserves and starve. Ovid had asked if anything could possibly be flowering here in late February, a question she’d passed on to Hester. Hepatica and skunk cabbage and harbinger of spring and maybe cutleaf toothwort, was her astonishing answer. Could any of these be nectar sources for an insect? Hester didn’t know, but surprised Dellarobia by offering to help her find some flowers. The hypothesis could be tested with live monarchs in the lab.

The sightseeing couple took a barrage of photos with a camera whose very shutter clicks sounded expensive. After chatting cordially with Leighton about his pledge, they set off down the steep trail for a close-up view of the butterflies, as she’d known they would. For her own entertainment she was predicting hikers vs. turnarounds on the basis of body mass and shoe type. She was batting a thousand except for two teenage girls who defied all expectations, charging down the mountain in stiletto boots.

The SUV couple didn’t stay very long. They returned and drove off in short order, possibly daunted by the fog. Almost immediately Dellarobia heard the approach of another vehicle that didn’t sound like a car. A motorcycle, maybe, though what kind of crazy person would try this steep, gravelly track on a motorcycle? She heard it slipping and keeling, its engine revving. And then by way of answer she saw Dimmit Slaughter. She’d gone to high school with Dimmit. He kicked the stand and dismounted his machine, helmetless, his T-shirt stretched to within an inch of its life across his broad belly, where the letters distorted outward like horror movie credits. He hitched his jeans and whistled at the view. Or at something. She tried not to stare at his midsection, but it did draw the eye, ballooning under the yellow shirt he’d tucked into his belt, sub-belly, in the most unflattering way imaginable. As men so often did. How they toted such physiques around so proudly was a mystery to Dellarobia. Women spent whole lifetimes trying to camouflage figure flaws that were basically undetectable to the human eye.

“Well, well, Miss Dell,” he said. “I heard you were hanging around up here. Where’s the Farmer?”

“Not hanging around up here,” she replied. Leighton Akins started to approach with his pledge pamphlet, but reconsidered.

“And are we having fun yet?” Dimmit asked.

“I’m working.”

He looked her up and down in her chair. Probably he’d looked at her the same way on some nasty little screen, that Internet portrait of her as the almost-nude on the half shell. “Nice,” Dimmit said. “If you can get it.”

“What is, work? You ought to try it out some time. For a change of pace.”

“Who pays you for that, the government?”

“Who pays your disability, Dimmit? Santa Claus?” She’d heard about a back injury, a fall out a window. But not while working. “I get paid out of a grant,” she told him. “From the National Science Foundation.”

He picked up a brittle monarch from the muddy ditch at the edge of the gravel and brought it over, flipping it with his thumb onto her notebook. “Here you go, science foundation. Why don’t you perform a dialysis on that to see what it died of?”

Mr. Akins seemed alarmed, but Dellarobia had no fear of Dimmit. He and Cub moved in some of the same circles. She might not be much liked in town these days, but if Dimmit misbehaved, he could find himself disliked a good deal more. “I see you’ve gained some substance in the world,” she observed. “Since I saw you last.”

He cupped the sphere of his belly in both hands, and winked. “Baby, that’s the fuel tank for my love machine.”

She rolled her eyes sideways. She wouldn’t mind having Dimmit’s self-confidence, but would not take that body as part of the deal. Like waking up pregnant every morning till death do you part.