Hide and Seek

Voices bounced throughout the central Iowa marsh as Erik ventured into waist-deep water. A storm was rolling in, and it was hard to tell if the marshwater had topped his waders or if he was just drenched in sweat. 

This is never going to work, he thought. 

A seasonal employee at the time, Erik Murry had been hired by Iowa DNR Waterfowl Biologist Orrin Jones for temporary field work to support a new research project. He’d been given ten GPS transmitters and a task: attach each to a Sandhill Crane. 

Sandhill Cranes are widely distributed with several different subspecies and subpopulations, each group marked as distinct based on behavior and range. Iowa is at the western periphery of the eastern population of the larger subspecies, the Greater Sandhill Crane (Antigone canidensis tabida). It is thought members of this eastern population primarily breed within Minnesota, Wisconsin, Michigan and Iowa — states around the Great Lakes. But do they ever overlap with the mid-continent population that congregates along the Platte River in Nebraska each spring? When it’s time to migrate, do they ever travel straight south to mix with resident cranes in Mississippi? How many cranes call Iowa home? Do the ones who hatch here stay?

No one knew the answers — yet. While Sandhill Cranes are native to Iowa, they were extirpated in the late 19^th century and absent for nearly 100 years. They slowly began popping up in Iowa here and there, and the first breeding effort in Iowa was recorded in 1992. Today, cranes are not an altogether uncommon occurrence in the state, but sightings — especially of their young, called colts — are still noteworthy.  

Questions abound as these graceful giants lay claim to Iowa’s shallow wetlands once again. Today’s biologists are still on the cusp of their understanding of Iowa’s recolonizing breeding cranes: simple biological and ecological information is lacking and population size or trends are mere guesses. Any current Iowa crane information is anecdotal, and that makes it hard to know how to best support their recovery. 

Orrin was well aware of Iowa’s crane knowledge gap. Ten or so years ago, he and his counterpart at Iowa State University, Bob Klaver, learned about a field research project taking place in Minnesota examining interactions between subpopulations, and, knowing something similar was needed in Iowa, they conceptualized a pilot project facilitated in partnership between the Iowa DNR and ISU. It took a couple years to get funding, but in 2019 they received a modest grant from U.S. Fish and Wildlife Service’s Office of Conservation Investment (formerly known as Wildlife and Sport Fish Restoration) and with additional support from the Iowa Fish and Wildlife Trust Fund, the quest to better understand Iowa’s cranes was underway. The first step to getting answers? Catch cranes and outfit them with transmitters. 

After getting the right permits, equipment, and receiving training in crane capture and handling techniques from crane experts with the U.S. Fish and Wildlife Service, Orrin assembled a team. Bob had made a career studying remote sensing data and population biology, and his knowledge would be valuable for this project. Matt Garrick, IDNR’s Waterfowl Research Specialist, joined the effort and managed to capture five cranes during their first field season in 2020. It was a great start. 

Life led Matt to another position with Nebraska Game and Parks, so the project needed to find another person with experience in capturing and banding birds. Erik had the resume — he had run Raptor Resource Project’s banding station in Wisconsin’s Wyalusing State Park, catching evasive birds like Rough-legged Hawks, American Kestrels and Golden Eagles. 

But Matt had taken his crane catching technique with him and getting ahold of a four-foot-tall, wetland-dwelling bird with a six-and-a-half-foot wingspan is about as easy as it sounds. So, on this June morning, Erik and the rest of the team met up with Iowa DNR wildlife management staff at Otter Creek WMA in Tama County with the goal of catching a young colt, just a couple months old. 

It was abundantly clear that the two-month-old had the upper hand.  

“We were beat. This crane was just running us in circles,” Erik laughs. “We were ready to give up.”

By some small miracle, eventually the young colt briefly tangled with some cattails, and Erik made the catch. His first capture. But, from that moment on, he knew they’d never attempt this in a marsh again. 

This was just the start of their crane catching learning curve. Night-lighting, decoy trapping, rocket nets, leg snares… none of these standard bird capture methods were proving reliable. And it couldn’t be just any bird — it needed to be big enough to handle wearing the transmitter, but not so big to put up a real fight. 

Eventually, they found the sweet spot: the brief period where the colt is on its feet, but not yet able to fly. Cranes nest on the ground in wet areas like marshes, swales or ephemeral pools. These wetlands provide food like tubers, snails or other aquatic life, but cranes will also forage in open areas like agricultural fields, feeding on waste grain, seeds and insects. A flightless colt in an open area, without easy access to cover, is a much easier target than one in a marsh. But no dilly dallying on making a move — within days of hatching, a colt can travel up to two miles.  

“It’s a narrow window of opportunity and requires a lot of scouting,” explains Erik. “Lots of windshield time identifying where adults are tending to a nest, lots of repeat visits to check on colt development.”

Though the capture method was refined, it was rarely pretty. Erik, who is now the Depredation and CWD Biologist with the IDNR but still helps with this study, chuckles as he recounts getting bested by a crane on a foot chase through a hummocky field at a popular birding spot, catching it only after falling several times in front of an audience of birders with cameras. And occasionally, colts find some bravery after they’ve been outfitted with their new “jewelry” and turn back around to charge at their captor. 

“Cranes will humble you,” Orrin laughs. He remembers when a foolproof plan yielded nothing — an adult and her two colts, seemingly cornered in a corn field, squatted low and vanished. “That corn was only a foot tall,” he remembers. “They managed to duck low enough to run away down a corn row undetected.”

These birds have to know how to run the gauntlet. In today’s world with lack of habitat and hazards around every corner, they have developed a knack for getting out of tricky spots. 

Though Erik was designated as the primary “crane catcher,” several others joined the effort including Taylor Ballard, a wildlife research technician who also helps with captures and serves as the team’s “data shepherd.” But because birds don’t adhere to property boundaries, the team extends beyond paid employees. Erik had many conversations with landowners about the project in case the chase left public land, which it often did. Initially hesitant about what people might think when he came knocking on their door, Erik describes being pleasantly surprised by “exceptional” public buy-in. 

“I often got tips from farmers or the local county conservation department about where they were seeing birds. That input was so incredibly helpful,” Erik says. “And I still get calls from people asking, ‘How’s my crane doing?’”

So, how are the cranes doing? The value of this study hinges on collecting data over a long period of time — not much can be gleaned about habitat use or migration patterns from just one season. The transmitters are built for longevity, lasting anywhere from three to five years, and deliver a massive amount of very precise data. The units operate on cell tower networks, collecting the bird’s position every 30 minutes. Data is uploaded daily, meaning Taylor, the data shepherd, doesn’t have to wait long to have data to work with. 

Forty-two Sandhill Cranes have been captured over the last several years, with hope for more as the research project continues. While the data is still young, initial findings lead to more questions. 

“One bird comes back to the same exact wetland, uses the same nest location and has success every year,” Orrin explains. “That crane has it dialed in. Others, not so much. Is that experience? Individual decisions? We don’t know.” 

It will take some time before they’re able to deduce population-level information such as survival rate, rate of nesting success, or an approximation for how many cranes breed in the state. But data on the birds’ movements are already proving to be well worth the time and effort invested. 

“Iowa cranes make a big movement eastward, sometimes even northeast before continuing as far south as Florida. They are deliberately going to affiliate with the rest of the eastern population to travel as a group,” says Orrin. “But there are outliers. We’re learning that colts and adults have different migration approaches: adults are much more precise in their travels, while colts make huge, unpredictable prospecting movements.”

They’re also learning that cranes make the trip in segments, noting that Indiana, Tennessee and Alabama are important stopover sites. And the data is providing information about habitat quality and placement here at home, too. 

“I don’t think there’s a species more reliant on shallow wetlands,” remarks Erik.  

Orrin further underscores the importance of habitat, noting that the availability of wetlands is their most limiting factor. 

“They certainly stand to benefit from wetland restoration and habitat protection,” he says.

Still, Sandhill Cranes seem to be expanding distribution and presumably increasing in abundance. It begs the question: if Iowa had more of its historical wetlands or an increased effort to restore wetlands in the right places, what could that mean for the cranes? 

“They are remarkable birds. Seeing all the subtleties of their ecology… I have such a deep respect for them and their ability to navigate this modern landscape,” Orrin remarks. “They are so charismatic.”

If you’ve observed a crane in the wild, it’s likely you’ve also picked up on their charisma. If you haven’t, check out some wetlands this summer — like Brenton Slough in Polk and Dallas counties that INHF was recently able to protect with your support. Some of the colts were captured there, in fact. 

The choreography of their courtship dances exude elegance. Their unmistakable calls are reminiscent of inhabitants of Jurassic Park. And if you’re lucky enough to spot a colt on your excursions, take a moment to wish them well and revel in the fact you’re witnessing the return of a species in real time.

Top photo: Two adult Sandhill Cranes dance in the water at Brenton Slough in Polk County. Photo by Ty Smedes