Snake Island
Copyright© 2026 by James Foster Reed
Chapter 8: Expected Variation
The rain came through Wednesday night and took Thursday morning with it, and by the time the front cleared the survey week was down a day. Evan Thayer sat in the map room at the East Quabbin Field Station with the datasheets from Tuesday spread in front of him and the window open to the smell of wet gravel, and he did what he always did with a survey week that had lost a day. He corrected for effort and kept going.
Tuesday had been good. He would have said that to anyone who asked, and it would have been true. Fifty-two encounters across two observers and six hours, which for the second week of June was above the running mean. The gravid females were staging where gravid females staged, on the warm broken rock at the south end of the Shelf, and he had confirmed four of the seven he expected to see there, including 2019-F-11, who had wintered in the same crevice for three years running and had apparently decided to make a career of it. Tomasz had photographed a big yellow-phase male neither of them had laid eyes on since the fall before last, looking heavy and unbothered in the juniper at the ledge’s east shoulder. The female whose transmitter had died in April, eleven hundred dollars of telemetry gone quiet while its carrier went on living, had turned up again in almost exactly the place the last good fix had put her, which was the kind of small vindication the work handed out maybe twice a season. You took it and said thank you.
He entered Tuesday’s sheets line by line, because he did not trust anyone else to read Tomasz’s fours, and it was in the entering that the number surfaced.
Young males.
The encounter data sorted itself into classes the way it always did: gravid females, non-gravid females, adult males, and the loose category he still thought of the way his own graduate advisor had taught him to, the three-to-five-year males, big enough to be past most of their predators and young enough to still be figuring out where they lived. In a June survey they usually ran somewhere near a fifth of encounters. It varied. Everything varied. But across nine years of June sheets the class had a shape, and this June it did not have that shape. Four encounters out of fifty-two. His three-year June mean said nine, maybe ten.
He sat with that for a moment, then pulled the recapture side, because encounters alone were weather and recaptures were closer to climate. Going into the season the database carried seventeen marked males in that class presumed alive: clipped, tagged, photographed, most of them handled at least twice. By the second week of a normal June he would have re-encountered six or seven of them. He had re-encountered three.
Evan took his glasses off, which he did not need to do, and cleaned them on the hem of his shirt, which did not need doing either, and put them back on and looked at the number again. It had not moved.
The first thing he did was try to break it. That was the job. A number you liked got written down. A number you did not like got interrogated, because the numbers you did not like were the ones most likely to be your own error wearing a lab coat.
Effort first. They had lost Thursday to rain, so the week’s coverage was thin, and thin coverage bit hardest on exactly this class, because the young males did not sit on the ledge waiting to be counted. The gravid females staged in the open where the survey went. The young males went where the chipmunks went, into the interior, under the hardwood canopy, into the old orchard slope on the west side where the deer swam over for the apples, terrain the transects only sampled at the edges. He ran the effort correction twice, once conservative and once generous. Conservatively the gap held. Generously it narrowed and still held.
Detection, then. June was the leanest month for that class on principle. They dispersed off the ledge into summer range, they moved through cover, and their detection probability was the worst of any class he tracked, a fact he had written into the monitoring protocol himself in year four. He pulled the year-four memo and reread his own sentence. Encounter rates for subadult and young adult males in June surveys should be interpreted with caution owing to low and variable detectability. His own hand, nine years younger, telling him to calm down.
Shed. Two of the missing fourteen had been in early shed when last handled in May, blue-eyed and irritable, and an animal in shed holed up and stayed holed up. That accounted for two, potentially.
And then the strongest piece, the one that mattered, which was 2022. He went back into the archive and found it because he remembered it was there, and it was. In June of 2022 the young-male class had come up almost this thin, five encounters against an expectation of nine, and he had flagged it that year too, in milder language, and by the August survey the class had filled back in like water finding its level. Wet spring that year. Different weather, same shape. The system had a documented history of producing exactly this gap and then closing it.
So there it was. Low detectability by design, a rain-shortened week, two animals in shed, and a documented precedent for a June trough that self-corrected by August. Any one of those was an adequate explanation. Together they were more than adequate. A reviewer would have accepted it. He would have accepted it from a student, and he was harder on students than reviewers were.
He typed the line for the Friday summary the way he typed all such lines, plainly. Encounter and recapture rates for males in the three-to-five-year class ran below the three-year June mean; given reduced survey effort, seasonally low detectability for this class, and a comparable trough in June 2022 that resolved by late summer, the deficit is within expected variation. Recommend standard follow-up at the August survey.
Which was true. Every clause of it was true, and the recommendation was the correct one, and August was seven weeks away.
He read the paragraph over once and moved on to the parts of the summary that needed no defending. The count of forty-one animals before noon in April, still the best single morning in the project’s history, went in as it had gone into every draft since April, unexamined, a fact so friendly it had never once been asked to show its work. 2019-F-11 and her crevice went in. The recovered female and her dead transmitter went in, with a note that the replacement unit could come out of the existing equipment line. Two animals refound after two seasons of absence went in, and he noticed, in passing, that he had just cited two seasons of absence followed by reappearance as good news in one paragraph and had spent forty minutes upstream of it establishing that absence followed by reappearance was the system’s normal behavior, and the two thoughts sat near each other for a second and then filed themselves in their separate drawers, the way thoughts do when a man has somewhere to be.
It was past four by then. Most Thursdays the summary went out by five, a day ahead of its Friday deadline, a habit so old that the central office had probably recalibrated its expectations around it. This Thursday he saved the draft instead of sending it. He told himself he wanted to recheck the effort correction with fresh eyes, and that was even true, in the way that the second reason for a thing is always true.
He closed the map room window against the evening damp. Out past the equipment bay the sky had scrubbed itself clean behind the front, and the light coming off the water through the trees was the hard clear kind that followed rain, the kind that made distances honest. He stood looking at it for a moment without thinking anything in particular, and then he locked up and drove home, where his girlfriend was quiet at supper and his girlfriend’s daughter wanted to talk about a rumor going around school, a rattlesnake out on Old Reservoir Road, and he gave Maggie the same answer he would have given a room full of selectmen, because it was the answer and she deserved the real one. Milk snake, probably. And even if it were the other thing, dispersal is not the same as establishment. She recited the second half along with him, deadpan, the way she had since she was eleven, and he laughed, and meant it.
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