How long have the herons been on the hilltop?

A map may indicate naturalists were aware of the nest colony decades ago.

Heron Zumbro River.JPG
A great blue heron, seen through a trail guardrail, stands in the Zumbro River in near downtown Rochester Sunday, Sept. 19, 2021. John Molseed / Post Bulletin

Discovery of a great blue heron nest colony in the path of a proposed development west of Rochester came as a surprise to the developers, township leaders and wildlife officials.

It seemed the only people who were aware of the birds’ nesting colony were the people who lived near the site.

However, that might not be the case.

The heron nesting colony, known as a rookery, may have been on the radar of the Minnesota Department of Natural Resources for more than two decades.

A 1997 Minnesota Biological Survey map of Olmsted County shows a “colonial waterbird nesting site” in Rochester Township approximately at the site of the proposed development.


The map is part of a statewide effort to document natural communities and rare species. The colonial waterbird nesting site in Rochester Township is the only one identified in Olmsted County on that map.

DNR officials have not yet responded to my requests for information about the site — when it was first documented, species observed, the size of the colony.

Carrol Henderson, former head of the Minnesota Department of Natural Resources' non-game wildlife division, said he is unsure why further study and documentation of the site wasn’t done.

“It is quite possible there has been a colony all those years, but no one has been tracking it,” Henderson said.

Despite the indicator on the map, Carrol said he first learned of the rookery after neighbors filed an injunction against the development, Pavilion Estates, headed by developer Aderonke Mordi.

Carrol said the rookery was the first heron nesting colony he had heard of to be confirmed in an upland woods site and not along a major body of water.

“I wish there was a really squeaky clean answer to how that site fell through the cracks,” Henderson said. “I think it was just not investigated.”

Henderson said GPS technology wasn’t as common or as accurate as it is now and that pinpointing the location of the nest colony might not have been accurately documented on maps for researchers to find later for follow-up study.


“I think it was simply overlooked at the time,” Henderson said.

The colony is not documented in Minnesota’s breeding bird atlas which compiled data and observation from 2009 to 2013.

Henderson said revelation of the rookery in Rochester Township shows there are flaws in the documentation process.

“Now we’re playing catch up,” he said.

Meanwhile, development plans are paused for now. The Rochester Township Board accepted an Environmental Assessment Worksheet of the site Sept. 9. The EAW was conducted to find if there would be significant wildlife impacts from the project and whether a more detailed investigation into those impacts and alternatives or alternatives to the project should be explored in an environmental impact statement.

Under Minnesota regulations, it’s up to the township board to decide whether the findings in the environmental worksheet warrant an environmental impact statement. Township board member Jeff Orth said the board is not requesting such a study.

Under Minnesota regulations , advocates for doing the study can appeal the decision of a regulating authority, in this case, the township board, to the Minnesota Court of Appeals.

That’s one of the options advocates for saving the rookery are exploring, said Jenna Didier, a member of a group called “The Rookies” advocating sparing the rookery from development.


Didier said litigation isn’t the group’s preferred method for their mission, but Didier said the group has found it tends to be the only avenue they have had so far in the governmental process.

"We just feel like we're always scrambling," she said. "We're not interested in litigation, we're interested in doing what we can do to make our habitat resilient."

One solid fact the group has to appeal for an environmental impact statement is that the land use permit for the development issued by the Olmsted County Board was issued while worksheet was still ongoing. State regulations specify project permitting is to be paused pending the assessment.

Didier said the group’s preference would be to purchase the site at a price to make the landowner and developer whole and donate the land and portions of surrounding private property to Minnesota as a state scientific and natural area. That would take collaboration with the DNR which has remained relatively quiet regarding the project. However, a DNR response to the environmental worksheet, written by Melissa Collins, DNR regional environmental assessment ecologist, contained the strongest language the organization has officially issued so far regarding the project saying it could have a “significant impact to local wildlife.”

John Molseed is a tree-hugging Minnesota transplant making his way through his state parks passport. This column is a space for stories of people doing their part (and more) to keep Minnesota green. Send questions, comments and suggestions to .

John Molseed joined the Post Bulletin in 2018. He covers arts, culture, entertainment, nature and other fun stories he's surprised he gets paid to cover. When he's not writing articles about Southeast Minnesota artists and musicians, he's either picking banjo, brewing beer, biking or looking for other hobbies that begin with the letter "b." Readers can reach John at 507-285-7713 or
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