Monday, January 30th, 2023
Monday, January 30th, 2023

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Illinois researcher discounts rut theories

Lewistown, Ill. — The notion that the deer rut is determined by moon phases is being challenged by an Illinois scholar who has spent more than 50 years observing buck and doe behavior.

Alan Harn also is a deer hunter, and he has followed his 2012 research paper, “Five Decades at the Scrape: Observations on Variation in Whitetail Deer Breeding Patterns in Illinois,” with a new paper on the rut.

“There’s a mind-boggling amount of misinformation out there,” Harn, assistant curator of anthropology at the Illinois State Museum at Dickson Mounds, said. “After reading too many pieces citing moon phases as determining breeding patterns, I realized that I have the data from my research to offer a rebuttal to the idea of moon phases.”

Harn already has given one public presentation on the data that led to the paper, laying out his research during the fall meeting of the Illinois Valley Archaeology Society in September.

Harn’s contention that the calendar – and not the moon – is the only way to accurately predict the deer breeding season is supported by a number of deer observers. Bill Winke, creator of Midwest Whitetail, agreed, noting, “I have not seen a rut predictor that was actually more accurate than the calendar.”

On the flip side, outdoor writer Charles Alsheimer and wildlife biologist Wayne Laroche have long contended that a key factor in the rut is the occurrence of the second full moon after the autumn Equinox.

According to their theory, once this moon hits, most doe estrous cycles kick into gear and the peak of the rut follows.

But Harn, an active bowhunter for six decades, logged more than 7,000 observation hours between 1962 and 2012, taking detailed notes and records on 1,438 mature white-tailed bucks. He debunks the moon phase theory.

“Paralleling my investigations as an anthropological researcher and forensic scientist for (Illinois) DNR now for 52 years, I also compiled structured daily records of deer activity and other factors I observed while hunting during that time,” he said. “The science on this is decisive. A number of scientific, peer-reviewed studies have shown the timing of the rut in any particular location is triggered by photoperiod, or day length – not by the moon, or temperature, or anything else.”

Harn said he thinks hunters often confuse visible rut behaviors – chasing and grunting, for example – with the peak of breeding. His research takes a look at rut patterns, supporting a fact that biologists have long known – that whitetail breeding activity is triggered by decreasing sunlight entering the eye in early fall.

How the misconceptions of the rut period came to be is rather simple, Harn, who has bowhunted in Illinois for nearly six decades, explains.

“As self-fulfilling prophets, hunters tend to hunt at times they perceive as best, and they indeed see most of their deer during those times precisely because that was when they concentrated their efforts afield,” he said. “As hunters, we focus on when the best time to hunt is. Wouldn’t it be good to determine when to avoid hunting?”

Harn also expounds on the fact that the rut is actually three months long, beginning in November. The 28-day cycles are out of a doe’s control. “A female deer cannot manipulate her three fall monthly estrus cycles to correspond with external things such as the moon phase any more than a human female can,” he said.

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