Before the advent of the internet, Robert Janssen's home hotline served as the Minnesota's birding community's information hub. Birders shared their sightings on his answering machine, and then, each Thursday, he'd compile an outgoing message for those making weekend treks to see birds.

"We'd be home after school and the phone would be ringing and people would be leaving messages saying, 'There's a blue spotted something in Waseca, blah, blah,' " remembered his daughter, Carolyn Olson. "My dad would come home from work and get that message and then be gone if it was a bird he didn't have on his list."

Known among local birders as a "pioneer of ornithology in Minnesota" and the community's "institutional memory," Janssen, of Golden Valley, died on Oct. 29 at age 91.

The author of the local birder's bible, "Birds in Minnesota," was thought to have visited every named place in Minnesota to comprehensively document its avian population. He was among the rare birders to have spotted more than 200 species in every one of the state's 87 counties.

Any serious Minnesota birder knew who Janssen was and likely had run into him in the field. ("Once at Le Sueur over a rufous hummingbird and once near Granite Falls when we were both looking for blue grosbeaks," one fellow bird enthusiast recalled.) And Janssen generously shared his encyclopedic knowledge to make birding more accessible and advocate for the environment.

"He thought that if people could know where to find birds and how to identify them, that would enhance their support of birds and all the things that go into maintaining healthy populations," said Janssen's friend Jim Williams, a birding columnist for the Star Tribune.

Janssen identified his first bird at about 5 years old when, riding his bike in south Minneapolis, he spotted a meadowlark and rushed home to tell his mom.

In adulthood, Janssen worked as a sales manager for an envelope company and went birding on weeknights and weekends, as often as he could.

"He got his first pair of binoculars when he was 7 years old, and ever since then, it was his life's everything," Olson said. "It took precedence. He would get up from Christmas dinner."

Janssen collectively drove and walked an untold number of miles, down back roads and through marshes, rescuing injured birds along the way and tucking feathers into his car visor. He thought nothing of driving to Grand Marais to see a bird, turning around and coming home. And if, a few days later, another interesting species was seen in that area, he'd do the same again.

Though Janssen was active in his church, his son, Michael, said his father also found God in nature. "He was very much a seeker, not only of birds and natural history, but he was also a very spiritual man," he said.

Janssen became a leader in the Minnesota Ornithologists' Union and served as the longtime editor of its journal, the Loon. He taught birding classes at the North House Folk School and gave talks around the state.

Janssen's "Birds in Minnesota," a version of which he first published in 1975, with Duluth birder Jan Green, became the go-to handbook describing each species' status and range. He also wrote "Birds of Minnesota State Parks," and, into his 80s, surveyed areas being considered for wind turbine placement to spare bird flyways.

Over his long tenure as a birder, Janssen witnessed many changes, including the return of the bald eagle and trumpeter swan, the arrival of the Eurasian collared dove, the taming of the Canada goose. ("When I was a kid, it was a wild, wild creature — you couldn't get near it," he said in a 2020 interview. "Now they're pooping on your porch!") Now, to see the meadowlark that ignited Janssen's passion, Minnesota birders must travel to South Dakota because of habitat loss.

Though Janssen held a lofty perch in the birding community, he wasn't one to crow. Kim Eckert, author of the state's primary guide to birding locations, reminds the next generation to respect the groundwork Janssen laid.

"I just hope that as people equal his number of species they've seen, they realize that he and others discovered some of those places and birds."

Janssen was preceded in death by his wife, Suzanne, and survived by children Michael, of Hastings, and Carolyn Olson, of Wayzata; four grandchildren; and two great-grandchildren. Services will be at 10 a.m. Nov. 13 at Lakewood Chapel in Minneapolis.