It's probably a safe bet that average 5-year-olds wouldn't know a meadowlark if one hit them in the head. But Bob Janssen did.

Seventy-odd years ago, he was riding his bike near a marshy swamp in Minneapolis, "and this bird flushed right into my face and it was a meadowlark. And I turned my bike around and ran home to my mother and said, 'Mom I saw a meadowlark.' But how did I know that bird was a meadowlark?

"To this day, I don't know how. I didn't own a bird book. I didn't get my first field guide to birds 'til I was 10 years old."

Bob Janssen Elizabeth Baier | MPR News

Ever since that introduction, the 83-year-old Janssen has devoted his life to birds. He wrote two bird books while working a corporate job. He later led the state's Ornithologists Union. And 18 years ago, a few years after retiring, he got an inquiry from the Department of Natural Resources.

"Do you know anybody who would like to tell us at State Parks about the birds in the state park?" the called asked. "And of course I said, 'How about me?'"

So Janssen committed to 14 visits to four state parks every year for four years: William O'Brien, Afton, the Minnesota Valley State Recreation Area and Fort Snelling. And as a diehard birder, he kept detailed records of the various birds he saw and shared them with the DNR.

"After three years of this," Janssen recounted, "they said, 'Why don't we do this for all the state parks?'"

No one had ever documented the birds found in state parks. So Janssen set out to do just that. He gathered existing data and records for about half the state's parks. For the other half, he had to go to the parks and start counting. It took him eight more years to conduct the hundreds of bird surveys he needed.

"I've got sheets and Excel spreadsheets, which show each date we were there and what birds we recorded. And from that I created this checklist," he said.

That work led to 75 checklists — one for every state park and state recreation area. Every list includes scores of bird species and their abundance in each of the four seasons.

Earlier this year that work was published as a book, thanks to $45,000 in funding from the DNR and the state's nongame wildlife fund. Proceeds go to the state parks. Janssen receives no royalties from book sales.

Carrol Henderson, the DNR's nongame wildlife supervisor, helped Janssen turn the list into a book.

"At the point that he was wrapping this up," Henderson said, "I said, 'Bob, the real story here is what's special about every state park. Because each park has different habitats and different species of birds are specialties that people would love [to] see. And so we started coming up with this vision of a book that would basically point out the best of the best birding opportunities at each state park."

Of Minnesota's 439 documented bird species, 310 — or about 70 percent — have been recorded in the state's parks. Henderson said that's in large part due to Janssen's work. Henderson said Janssen is a rarity among bird experts.

"I don't think there's probably anyone else out there who can come close to this encyclopedic knowledge that he has about our bird life," Henderson said. "I mean, there's a lot of wonderful people who are studying birds. They study certain kinds of birds, or they specialize in a certain kind of area. But Bob has this vast understanding of statewide birds."

And Janssen still has a vast appreciation of birds, even after years of painstaking work to type, count and document them all over the state.

"Birds are beautiful objects," Janssen said. "They're everywhere you go. They are ever-changing, ever-beautiful, ever-intriguing, ever-mysterious. So I became a provincial Minnesota birder."

And even with his magnum opus now in print, Janssen isn't finished yet. He said he may think up another book about Minnesota birds while he recovers from some knee surgery in coming weeks.