Every spring, the great blue herons return to a secluded patch of forest near Cascade Creek outside Rochester to nest in the treetops and rear their young.
Neighbors — the only people who knew about the hidden colony — say the herons have nested there for decades. The wild oasis with as many as 40 or 50 nests sits on the edge of the fast-growing city.
"It's amazing," said Pat Adamson, who lives near the heron rookery. "We look forward to seeing them every year."
The great blue herons are now cause célèbre in a dispute over a proposed housing development in Rochester Township. And with a "Save the Rookery" campaign in full swing, the clash is exposing fault lines as the rapidly growing home of the Mayo Clinic struggles to balance relentless growth with natural spaces and declining bird populations.
The Rochester developer seeking to build Pavilion Estates characterizes the battle over the birds as an 11th-hour tactic to stop a project that neighbors have simply opposed. The company says most of the heron nests are not on the 30 acres slated for development.
Neighbors, birders and concerned citizens say the construction will destroy an irreplaceable natural resource. They are pushing for an official environmental impact review. One lawsuit, a temporary restraining order and petition later, the development has skidded to a halt.
Because of the controversy, the Olmsted County Board has tabled a decision to change the land's use to allow for suburban development.
"We are upset at being accused of destroying the [great blue herons] when we have no intention of taking eggs or birds," developer Aderonke Mordi said. "We are as environmentally conscious as our future neighbors."
Until the dispute, first reported in the Rochester Post-Bulletin, is resolved, the future of the colony and the development remain uncertain.
Some residents welcome the pause.
"This is a wonderful opportunity for people to take on the hard decisions, and maybe even realizing their own role in wanting to have a suburban lifestyle and what it actually means," said Brett Ostby, a Rochester environmental consultant. "We're so detached from our natural world."
Important nesting site
Great blue herons are easily identifiable with their head plumes and pale orange beaks. They grow up to 4½ feet tall and have a wing span of about 6 feet.
Local birders said they're surprised that such a large heron rookery was able to remain so isolated.
Lance Vrieze, a board member of the Zumbro Valley Audubon Society, said he visited soon after learning about it. He said he easily counted 20 nests as he stood in one spot in the forest. They look like large squirrel nests, he said, jumbles of sticks perched precariously at the very tops of trees.
"I know of no other nesting site in Olmsted County," Vrieze said. "It would be devastating to have the project remove the nesting site."
Although bird numbers are plunging across the United States, great blue herons are not a threatened species. Their numbers across the middle and eastern United States are fairly stable, according to Tom Cooper, regional Migratory Birds Program chief at the U.S. Fish and Wildlife Service in Bloomington.
But the Rochester Township colony is large, Cooper said, and "kind of rare" in that it's not on an island or in a marshy area but in more of an upland forest.
"Heron colonies are definitely pretty neat features on the natural landscape and we certainly want to protect them where we can," Cooper said.
Great blue herons are protected under the Migratory Bird Treaty Act of 1918, which the U.S. Fish and Wildlife Service enforces. The agency has not stepped in, however. While the act prohibits disturbing active nests with chicks and/or eggs during breeding season, it does not cover empty nests, nor does it necessarily cover nests during nest building, he said.
"There's nuance there," Cooper said.
Rookery vs. growth
Adamson and his neighbor Leal Segura say the heron rookery needs protection. They live in the fern-filled forest next to the 30 acres slated for development, land owned by Byron resident Steven Connelly, who declined to comment. The rookery spreads across all three properties.
In a complaint filed last month in Olmsted County District Court, Adamson and Leal call it a unique natural resource protected under the Minnesota Environmental Rights Act. They want the court to declare that the rookery can't be disturbed and that no trees within 1,000 feet of a nest can be removed.
"The eggs or fledglings currently in the nests will be killed or abandoned if their rookery is disturbed," the complaint said.
The court has extended a temporary restraining order related to the lawsuit; the next hearing is April 29.
In the meantime, more than 1,100 people immediately signed a "Save the Rookery" petition sent to the Minnesota Environmental Quality Board calling for a review of the project's impact on the environment. That board determined Rochester Township must make the decision on doing a review, and it forwarded the petition to that local body on April 6. The township has 15 business days to make a decision, the state board said.
Rochester Township Board Chairman Matthew Kitzmann said the heron matter will be discussed more fully at the next monthly meeting on May 13.
Mordi said her company, International Properties LLC, feels blindsided by the public controversy. The birds never came up earlier in the process, she said.
In a written response to questions, she said the state and federal wildlife officials whom they contacted "tell us that rookeries are not protected because [great blue herons] are common birds that are resilient and move their nest sites often."
Mordi agrees the birds and their eggs are protected under the Migratory Bird Treaty but said that it doesn't protect trees with empty nests.
The company remains committed to the 10-lot development with a private road, she said, and has signed a contract to buy the 30 wooded acres from Connelly for $1.4 million.
It's also considering voluntarily conducting an environmental review, she said, and will save "as many nest trees as possible."
Meanwhile, the "Save the Rookery" supporters are plotting their next move.
"It all happened so fast," said Lynn Cornell, a bird enthusiast who created the savetherookery.com website and is new to such activism.
"I'm thrilled Rochester is growing, that we have restaurants to go to," said Cornell. "I want us to grow in a way that still respects the natural environment."
Jennifer Bjorhus • 612-673-4683