Wildlife researchers and a gardener spotted the endangered rusty-patched bumblebee, Henslow's sparrow and nine threatened grassland bird species on two swaths of Maplewood land, posing new challenges to potential county plans to build on the property.

Environmental groups say the results of an independent natural resources report released this week are proof Ramsey County, the property owner, should rethink possible plans to redevelop the shuttered 88-acre Ponds at Battle Creek golf course and a second 77-acre grassland site north of the county correctional facility. "It basically reinforces what we have been saying all along, that this grassland has some unique natural value," said John Zakelj, president of Friends of Maplewood Nature and a member of the St. Paul Audubon Society. "The report makes the point there is nothing else like this in Ramsey County or perhaps the entire metro area."

Ramsey County has been studying possible redevelopment of the properties, less than a mile apart on Century Avenue, for the past year with an eye toward much-needed affordable housing.

But even before the discovery of the federally endangered bumblebee and the sparrow, which is on Minnesota's endangered species list, the two sites had become the latest battleground between environmentalists and development interests.

The St. Paul Audubon Society, joined by the nonprofit Friends of the Mississippi River and the Legacy of Nature Alliance, have asked county leaders to save the grassland site and incorporate it into adjacent Battle Creek Regional Park. Members of the Friends of the Parks and Trails of St. Paul and Ramsey County have expressed interest in preserving both sites.

County leaders hired Midwest Natural Resources to survey the birds, bees and plants on both properties. Before it was complete, the county issued a request for development interest on the two parcels, calling it a "prime development opportunity" and frustrating groups trying to preserve them. Three developers submitted proposals for the golf course; none were received for the grassland.

County leaders have said no decisions have been made about the future of the properties.

"This is one piece of information we solicited to help inform future decisionmaking," said Ramsey County spokesman John Siqveland.

The county is now reviewing the proposals for the golf course behind closed doors.

Colleen O'Connor Toberman, river corridor program director with Friends of the Mississippi River, said the results of the natural resources report make one thing clear: The county needs to slow down.

"This report is just a first step in what clearly needs to be studied more," she said. "We don't know anything about the potential impacts of the redevelopment of these sites on these species. We do know many of these bird species are sensitive to habitat size."

Toberman said there's concern that the county may attempt to develop part of the site, inadvertently destroying the habitat's benefits.

According to the natural resources report, 53 bird species were discovered on the grassland site, including the endangered Henslow's sparrow. Seven of the species are in greatest conservation need, including the bobolink and Eastern meadowlark. The site is monitored by corrections staff and is not accessible by the public.

Scientists found 39 bird species on the golf course, including two in greatest conservation need. They also determined the rusty-patched bumblebee has been spotted and photographed at the golf course by a gardener. The gardener's sightings were submitted to and confirmed by Bumble Bee Watch, a community science project that track bees in North America.

Maplewood Mayor Marylee Abrams, who has said she supports keeping the golf course, said she has been eagerly awaiting the natural resources report. The city has zoning authority over the two properties.

"This report confirms the environmental importance of these two parcels to the city of Maplewood and our residents," Abrams said.

Sightings of state and federal endangered species on a property doesn't automatically preclude development, experts say.

The rusty-patched bumblebee was listed as endangered in 2017, said Georgia Parham, a spokeswoman with the U.S. Fish and Wildlife Service.

Parham said she can't speak to this particular project, but explained that "what the Endangered Species Act does is it prohibits take — which is killing, harming or harassing. If there is an issue with a listed species, we work with the folks who are working on the project. What we are focused on is preserving habitat and food sources for rusty-patched bumblebees and other pollinators."

In the case of the Henslow's sparrow, which was added to the state endangered list in 1996, developers are precluded from disturbing nesting birds but can start construction when the birds leave for the season.

Entomologist Elaine Evans, a bee researcher and extension educator at the University of Minnesota, said a pipeline construction project in Virginia was halted after the discovery of rusty-patched bumblebees in the area. Last year, Minnetonka — under the threat of a lawsuit from the nonprofit Center for Biological Diversity — agreed to plant wildflowers and native grasses to settle a dispute over a new mountain bike trail that cut through the bees' habitat.

"I would like to see more protections for [rusty-patched bumblebees] where they do exist," Evans said.

Evans said she doesn't know enough specifics to discuss the Ramsey County sites but said scientists haven't yet uncovered the secrets of the species' life cycle. The nature of the species also makes protecting it a challenge.

"Bees are very mobile. They are tiny and people don't notice them," Evans said.

Collette Adkins, a senior attorney with the Center for Biological Diversity and lead in the Minnetonka case, said it's often groups like hers that demand enforcement of the Endangered Species Act.

According to the U.S. Supreme Court, the law should be "interpreted very broadly," which includes the impacts of development, she said.

"It is quite a big deal to have an endangered species on land slated for development," she said. "Ramsey County needs to be working closely with U.S. Fish & Wildlife to make sure the bee isn't harmed."