ALDA, Neb. — Many Nebraska eyes are on the skies during the annual spring migration stop that sandhill cranes and other migratory birds make in the Central Platte Valley.
But Crane Trust scientists headquartered southeast of Alda focus year-round on the region's river, wetlands, native prairies and wildlife diversity — measuring the health of critical migratory habitat for endangered whooping cranes.
Preliminary results from the U.S. Fish and Wildlife Service's 2012-13 winter survey indicate that 247 whooping cranes were at their primary wintering grounds in south Texas. Additional observations suggest that there were at least 22 birds in other areas.
That's 279 whooping cranes in the wild that use the same Central Flyway as millions of sandhill cranes, geese and ducks.
Those needle-in-a-haystack numbers are why staff at what originally was known as the Platte River Whooping Crane Maintenance Trust study sandhill cranes to learn things beneficial for whooping cranes.
“We have a basic understanding (of whooping cranes), but because there are fewer birds, we haven't studied them as much,” said Crane Trust wildlife biologist Greg Wright. “Sandhill cranes are the closest surrogate species to whooping cranes.”
“The two species are different in a number of their behaviors,” said Mary Harner, the trust's science director, but both use river environments and open wetlands where they are protected from predators during night roosting.
Managing habitat for both species involves limiting vegetation and maintaining Platte River flows that create wide, shallow channels, said Harner, who oversees research activities by staff and visiting researchers. She also is a wetlands ecologist.
Wright leads on-the-ground biological research, inventory and monitoring activities on Crane Trust lands. During spring migration season, he's also in the air weekly, taking early morning sandhill crane survey flights between Lexington and Chapman.
Wright estimated that 140,000 cranes were in and along the river as of Monday morning's flight. He said the numbers are expected to grow greatly with the south wind in the next few days.
Observations from the air by Wright and lead range technician Evan Suhr will add to the long-term migration season data collected since 1998 about sandhill crane roosts. It's one way to study the effects of habitat management practices.
Wright said a key question is whether sandhill cranes are using certain sites because they are good habitat or just better than somewhere else.
Food also is a big concern for both crane species because they stop in the Platte Valley to rest and put on body fat before continuing migration journeys of 2,500 miles or more.
Sandhill cranes are most known for eating grain from south-central Nebraska cornfields and getting nutrients from wetlands.
“Whooping cranes also eat grain, but they tend to be a little more animalivorous and use the wetlands and wet meadows more,” Harner said. There, they eat invertebrates, amphibians, snakes and fish.
Harner said the Crane Trust has a history of studying wetlands on Mormon and Shoemaker Islands. Monitoring wells helps researchers learn about factors contributing to the rise and fall of groundwater that fills depressions to create wet meadows.
“Wet meadows are the most endangered habitats in the valley and the most used by cranes,” Wright said.
There also have been studies on how amphibians and reptiles respond to those conditions and to land management practices that include grazing, prescribed burning and resting.
Harner said researchers have found five species on the two Platte River islands that hadn't been identified before: four snakes and the non-native American bullfrog.
Biologists also have done sampling surveys of fish, small mammals, amphibians and reptiles at other trust properties — about 6,5000 total acres. “That biological diversity is a real good indicator of the health of the ecosystem,” Wright said.
Harner said the trust also is preserving some of the last native tall-grass and mixed-grass prairies.
New on Mormon Island this spring are 10 cameras that were placed Wednesday in sloughs and uplands to collect more up-close data about sandhill cranes. “Most surveys are viewing from a distance and big patterns,” Harner said.
Video also may be shared with guests at the Nature & Visitor Center at the Alda Interstate 80 exit, which the Crane Trust acquired last year to enhance community outreach and education.
Overwintering sandhill cranes still a mystery
ALDA, Neb. — Several thousand sandhill cranes migrating through the Central Platte Valley in the fall of 2011 did something no one expected: They stayed for the winter.
Or maybe they went south toward their wintering grounds in south Texas, saw drought conditions and returned to Nebraska.
No one knows why the birds wintered in Nebraska in 2011-2012 or why a smaller group did it again this winter. Crane Trust and University of Nebraska at Kearney scientists are studying the mystery.
Crane Trust Director of Science Mary Harner said about 4,000 sandhill cranes spent the 2011-2012 winter in Nebraska. The number is based on driving surveys done between Kearney and Grand Island in December 2011 and January 2012.
“It was a very mild winter here, with very little snow,” Harner said. “So they either just stopped or maybe went down and came back.”
She said UNK associate professor of biology Keith Geluso and Crane Trust wildlife biologist Greg Wright drove the same Kearney-to-Grand Island routes this past December and January and saw an estimated 1,000 cranes.
Wright said they'd “go off the radar” during cold weather, be gone for a couple of weeks and then be found in the same fields.
Geluso and Harner studied Christmas bird count records and the Nebraska Bird Review going back to the 1930s and found accounts of sandhill cranes being spotted in the winter.
But the past two years were different, Harner said: “They stayed for a long period, they stayed in the same area and they stayed in the thousands.”
Researchers continue to see examples that “things with wings” are more adaptable than once thought. “People have looked at them for so long that you think you know everything,” Harner said, “but they change.” — Lori Potter