ORONO, Maine — When a three-year study of the state’s ruffed grouse population began back in 2014, scientists were looking to find out if Maine’s three-month hunting season put too much pressure on vulnerable birds when they began perching in trees and eating buds in November and December.
Instead, researchers found that very few grouse are harvested by hunters late in the season, and that the Maine Department of Inland Fisheries and Wildlife’s management plan for the upland game birds was sound and sustainable.
“There was a concern, at least among some hunters, that [grouse sitting in trees that have no leaves to hide them] could lead to overharvest during that later part of the season,” said Erik Blomberg, an assistant professor in UMaine’s Department of Wildlife, Fisheries and Conservation biology, who helped oversee the study.
The research paper, “Survival and harvest of ruffed grouse in central Maine, USA” — which was recently published in The Journal of Wildlife Management — was conceived to fill a data gap: Though ruffed grouse have been extensively studied, Maine-specific data on late-season harvest totals had not been compiled. Unlike Maine’s big game animals such as deer and moose, hunters are not required to register or “tag” upland birds after they’re shot.
Maine’s ruffed grouse hunting season is roughly three months long. This year it stretches from Oct. 2 to Dec. 31.
A significant finding of the study: The annual harvest of ruffed grouse in October is double the number taken by hunters in November in December combined.
The team was also able to determine the mortality rate of the ruffed grouse populations in its study groups. Simply put, that number indicates how many grouse that are alive on Oct. 1 are still alive a year later. The answer: 30 percent.
“So 70 percent of birds are killed over the course of a year,” Blomberg said. “Some amount of that is because [hunters] shoot them, for harvest. But the remainder is almost exclusively predation.”
Grouse make tasty table fare, and are large enough that even a couple birds can provide the makings of a good meal for two. But they also have quite a delicious reputation among the state’s predators.
“They’re like the cheeseburger of the forest,” Blomberg said. “There’s a large number of things out there that want to eat grouse.”
So if 70 percent of the state’s grouse die every year, why does Maine allow hunting? Because those birds that don’t survive are replaced by new grouse.
“It’s kind of impressive, because we nevertheless have pretty strong ruffed grouse populations in Maine,” Blomberg said.
An average female grouse lays 10 eggs, and is tenacious in its attempts to re-nest should its first effort fail, Blomberg said.
“So on the reproductive side of the coin they can offset those losses by just being highly productive,” he said.
Researchers from UMaine and the DIF&W between 2014 and 2016 trapped and radio-marked 248 grouse in two study areas: The Frye Mountain Wildlife Management Area and industrial forestland off the Stud Mill Road east of Old Town. Both locations are popular with upland game hunters.
The radio collars were marked with a toll-free phone number that hunters would use to report the bird as harvested.
That 248-bird sample was designed to represent the population of each given study area.
Over the three-year study, the team found that on Frye Mountain, the October harvest rate was 14 percent, while the Stud Mill Road harvest rate was 7 percent.
During the combined months of November and December, Frye Mountain’s harvest rate was 7 percent, while Stud Mill Road’s was 3 percent.
“Our overall harvest rate, when you look at all the birds we marked over the course of three years, at two study sites, was 16 percent,” Blomberg said.
The study was led by graduate student Samantha Davis, who was assisted by fellow grad student Joelle Mangelinckx, Blomberg, and DIF&W biologists Brad Allen and Kelsey Sullivan.
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