Henry Fitch holds a snake for 2-year-old Ethan Sharp to admire in this 2005 file photo. Fitch, a longtime professor and naturalist at Kansas University’s Natural History Reservation, died this week at age 99.

Ecologist, naturalist and herpetologist Henry Fitch died this week, leaving his exhaustive work on a 590-acre patch of evolving pasture-turned-woodland northeast of Lawrence to live on for generations.

Fitch, 99, died Tuesday in Stillwater, Okla., where he had lived with his daughter and son-in-law since 2006.

Since coming to Lawrence in 1948, Fitch had focused his professional attention and personal persistence on the Kansas University Natural History Reservation, where he had been hired as its original superintendent and resident naturalist. Fitch also served on the KU faculty, becoming a full professor in 1958.

While he would retire in 1980 as a professor of ecology and evolutionary biology, Fitch’s work as superintendent at the reservation — now known as the Fitch Natural History Reservation — would continue.

There, he would follow blue-tailed skinks, copperhead snakes and seemingly everything in between. Whether it was trapping, tagging and tracking animals, or digesting information about their eating habits or cataloging the changing habitat of the undisturbed site where they lived, Fitch knew it all.

And he wrote it down, filling field books with invaluable information about a single site whose changes are catalogued for the scientific world. Today’s researchers continue to cite Fitch’s observations in their own studies.

“That’s got to be one of the best-known square miles in North America — on the planet — in terms of biodiversity,” said Harry Greene, professor of ecology and evolutionary biology at Cornell University, who worked with Fitch in the 1960s and considered him a ground-breaking mentor. “Think of that as a baseline, a landmark for the future. We couldn’t have known how valuable that would be.

“That’s a huge legacy on his part.”

One example: Fitch maintained 50,000 individual records of snake captures, said George Pisani, an adjunct herpetologist with the Kansas Biological Survey.

“The records themselves provide a baseline that goes back to 1948, and we can’t get there anymore,” said Pisani, who is embracing the task of transferring Fitch’s handwritten records to computer files. “The thing about science is, you don’t know what you may find relevant 50 years into the future. Simply having this information available allows others to expand on it, and add to it. This really will stand the test of time quite well.”

Fitch’s kind demeanor, professional approach and unwavering dedication led many professionals to follow the man who never stopped learning, from his earliest work up through his less-active days in Oklahoma.

Greene noted that a wire trap Fitch had fashioned to capture snakes in the 1950s remains the industry standard even now.

“It’s not an exaggeration to say that Henry’s the father of snake biology,” said Greene, who in 2004 received the Henry S. Fitch Award for Excellence in Herpetology, an honor given by the American Society of Ichthyologists and Herpetologists for outstanding field work. “He’s the guy who got it done in the 1940s, and now we’re all doing it.”

A memorial service is being considered for Fitch and his late wife, Virginia, at a later date, but one thing is settled: The ecologist’s cremated remains will be scattered at the reservation, the place he always considered his permanent home.

“That’s where he belongs,” said Alice Echelle, his daughter.