Why Mister Grouse Is the Friendliest Bird in the Forest

When Bill Hartline bought 50 acres of forested land outside Muncy, Pa., he was looking for a bit of solitude and a place to eventually build a new home in retirement. But during a camping trip there in early 2020, he discovered the wooded plot wasn’t as lonely as he thought. That evening, a ruffed grouse — a crow-size bird with a tiny mohawk and mottled feathers — appeared at his feet.

“I crouched down and said, ‘Hello.’ He cooed back and started following me around,” Mr. Hartline, 66, said. “Three years later, he’s still following me around.”

That’s putting it mildly. Mister Grouse, as he has named the bird, seems to ingratiate himself into everything Mr. Hartline does. Mister Grouse rides the tractor, hops up on ladders and enjoys the campfire from atop Mr. Hartline’s shoulders.

It’s a far cry from the behavior of most ruffed grouse, whose stealth and elusiveness are why hunters call them the “king of game birds.”

“He is extremely friendly, but in all honesty, he can be a pain, too,” Mr. Hartline said.

When Mr. Hartline or his guests try to drive away, the bird throws himself under the car. “He never wants you to leave, and he’s learned that if he’s under the car, you won’t leave,” Mr. Hartline said.

He can also get “too friendly,” as Mr. Hartline puts it, untying shoelaces or pulling hair.

Still, Mr. Hartline says that he considers Mister Grouse a friend, although he’s curious as to why the bird has chosen him. Researchers may soon have the answer.

During a recent study to ascertain the genetic health of Pennsylvania’s dwindling grouse population, a team of scientists turned up a surprise: A genetic anomaly called a chromosomal inversion was present in a significant number of samples. Such inversions happen when a segment of DNA breaks off and reattaches in reverse order.

Chromosomal inversions in birds can manifest in an obvious trait, such as a difference in appearance or demeanor, according to Julian Avery, an ecologist at Pennsylvania State University and a member of the research team.

“They might be less migratory or interact with other genetic populations differently,” he said. “They’ll have these weird behaviors.”

For ruffed grouse, being unusual is more of the norm.

“Grouse are crazy bizarre,” Dr. Avery said. The birds, who are closely related to turkeys and quail, are lousy fliers and spend most of their time on the ground, where they thrive eating bitter, sometimes toxic plants. In the winter, they grow comb-like extensions from their toes that act like snowshoes, and spend cold nights burrowed in snowbanks.

And then there’s the drumming, a mating display during which the male beats his wings so quickly that the whole forest seems to vibrate. “Imagine a car with bass in the trunk — you feel it,” Dr. Avery said. “It’s an amazing sensation.”

But the newly discovered inversion didn’t correlate to any obvious behaviors, or characteristics like sex or color pattern.

“So we just started wracking our brains about grouse,” said Reina Tyl, a wildlife biologist at the Pennsylvania Game Commission who was also on the research team. “Is there anything weird about just some grouse? The first thing that came to mind was the existence of tame grouse.”

Every year, reports of so-called tame grouse emerge from the woods of Pennsylvania and other Northeastern states. Videos online show docile birds standing near a snowblower in a stranger’s garage, relaxing on the lap of a bemused bowhunter and perching on the steering wheel of heavy machinery, cameras inches from their beaks.

They’ve been given names like Gracie, Grousey and Bob.

There have been a number of explanations for the phenomenon — that the birds are drunk on fermented berries or are attempting to defend mating territory from would-be competitors. Another hypothesis posits that the birds are a “genetic throwback” from colonial days, when they were so fearless that people called grouse “fool hens” and hunted them with sticks and stones.

Could the chromosomal inversion explain the existence of the uninhibited birds?

“It seemed like an obvious behavioral difference we could easily look into,” Ms. Tyl said.

In March, more than 100 people responded after the game commission put out a call for tame grouse sightings. Ms. Tyl then spent months meeting the most extroverted ruffed grouse in Pennsylvania.

Drawing them out of the woods often required an audible stimulus comparable to the males’ drumming — the puttering of an all-terrain vehicle engine, for example.

“I brought a chain saw to a couple sites,” Ms. Tyl said. Once she had the grouse in hand, she determined the age and sex of the birds — all seven that she captured were males — swabbed their mouths for DNA and took photos of their tail fans. The birds were typically released in five minutes or less.

“For the most part, they’d be like, OK, enough. I’m a tame grouse but that was a little too much, even for me,” Ms. Tyl said.

But not Mister Grouse.

While the other birds fled upon release, Mister Grouse “U-turned,” she said, eager for more human company.

While Mr. Hartline awaits results from the Penn State team that could determine, as soon as next year, if Mister Grouse’s friendliness is written in his DNA, he has been researching his own methods for coexisting with a bird that doesn’t always respect his boundaries.

“When I go camping, if I open my tent door, he zips right into it,” Mr. Hartline said. So he bought Mister Grouse his own small screened-in tent. “Now, I’ll sit outside of his tent, and he sits inside,” he added.

So far, the compromise seems to be amenable to both parties. “He’s happy just hanging out,” Mr. Hartline said.