Glenn Del Giudice, a longtime Department of Natural Resources wildlife researcher known for his yearslong studies of whitetail deer habitat and threats to Minnesota's fragile moose population, has died. He was 68.

"He made a name for himself well beyond the boundaries of Minnesota,'' said Mike Larson, supervisor of the DNR's forest wildlife research group where Del Giudice was a high-ranking senior scientist. "He had a towering reputation … active in teaching and collaborating with scientists across the world.''

Larson said Del Giudice had planned to retire next week. The researcher's death was unexpected but followed a weekslong hospital stay, Larson said.

Larson said it is daunting to try to characterize the scope of Del Giudice's work, but he conducted foundational work in deer and moose ecologies, especially surrounding their winter habitat needs. He strived to incorporate the best and latest technologies in his research, often breaking ground on methodologies.

Many students and professional wildlife biologists alike were trained by Del Giudice in the safe capture and handling of deer and moose for research projects. He also was the DNR's go-to expert on interactions among deer, moose and wolves, Larson said.

In 1996, the Star Tribune noted at the time that Del Giudice was "among a handful of deer researchers employed by the Department of Natural Resources who help keep Minnesota at the forefront of whitetail management worldwide."

He was several years into a 12-year study of whitetails and their dependence on stands of conifers mixed with older aspen to endure harsh winters. Those wintering areas were in decline Up North and Del Giudice was still collecting data on the importance of winter habitat for deer at a research location near Remer.

Tom Rusch, a retired DNR wildlife manager from Tower who worked with Del Giudice for 35 years, said he was a pillar in the whitetail and moose research communities across North America. His loss will be felt immediately next week when DNR crews once again launch the department's aerial moose survey, a vital annual tool that has helped the state track the population decline of the species.

"We'd hand him the data and he'd write it all up and be able to say where the population was heading,'' Rusch said.

Del Giudice, of Forest Lake, also was instrumental in developing Minnesota's Winter Severity Index — a model combining snow depths, duration of deep snow and other seasonal indicators to help estimate deer mortality over winter. Rusch said Del Giudice taught a lot of wildlife managers and hunters that wolves get too much blame for deer population declines when so many other factors are in play.

In the field, Del Giudice was a pioneer in collecting urine samples from moose and deer by capturing it from snow. He used the samples to analyze health levels in the animals.

"He was extremely intelligent and organized,'' Rusch said. "He worked and worked and worked some more.''

Del Giudice also was an adjunct professor in graduate studies at the University of Minnesota. An obituary in the Star Tribune noted that he "was passionate about his research and exploring the natural world, and he often spent his weekends writing, hiking and exploring the outdoors."

Del Giudice is survived by three children. A celebration of life gathering is set from 4 p.m. to 7 p.m. Friday at Mattson Funeral Home, 343 North Shore Dr., in Forest Lake.

Star Tribune staff writer Bob Timmons contributed to this report.