KEARNEY — Fewer migrating whooping cranes that used the Central Platte River as a resting place may have been an unexpected result of last spring’s extremely wet weather.
Dave Baasch, the Platte River Recovery Implementation Program director of biological and ecological services, said there were only nine confirmed whooping crane sightings in and along the Platte River from Lexington to Chapman last spring, compared to 118 in spring 2018.
He told PRRIP Governance Committee members at Tuesday’s quarterly meeting in Kearney that high river flows may have been a factor in the drop.
Several committee members said the same weather conditions provided a lot of water for area wetlands also used by whooping cranes, particularly in the Rainwater Basin south of the Platte.
“So maybe the Platte wasn’t as important to them this year,” Baasch said.
Whooping cranes — listed as endangered under the federal Endangered Species Act — that use the Central Flyway for spring and fall migrations are monitored by program biologists and other Nebraska conservation organizations. In the spring, most whoopers usually arrive soon after approximately 600,000 sandhill cranes have left the area.
Unlike sandhill cranes that stay for several weeks to rest and feed in the Central Platte Valley each spring, whooping cranes generally stop in the area for only a few days.
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Baasch had a chart Tuesday that showed highs and lows in whooping crane sightings in spring and fall. All-time highs were around 10 percent of the Central Flyway population in the fall and 25 percent in spring; lows for both seasons were in the single digits.
The last count of the Central Flyway whooping cranes, which winter at Aransas National Wildlife Refuge along the Texas Gulf Coast, was 505 in January 2018. Baasch estimated current flock numbers at 540-550.
“We are looking at (habitat) use and river flows with whooping cranes as well,” he said, not just numbers, to better understand their preferred conditions.
Tern, plover trends
The Central Platte also provides nesting habitat for endangered interior least terns and threatened piping plovers.
Earlier Tuesday, PRRIP Deputy Executive Director Chad Smith said tern and plover numbers are up, but mostly at off-channel nesting sites such as sandpits retired from commercial use provided by the program.
Baasch said nesting pairs are up for both species — the highest for plovers since 2001 and second highest for terns — but fledglings per nest have dropped the past five years.
The decline rate for terns allows for some population growth, he said, but the rate for plovers isn’t sustainable.
One factor is the development of fewer off-channel sites by the program than when those efforts started in 2007. However, Baasch said the biggest issue is a growing number of predators, particularly other birds, at nesting areas.
Mammal trapping has been successful. He said several hundred raccoons have been trapped in some years, although numbers were down during the 2019 nesting season.
Cameras set up at nesting sites in 2017 and 2018 revealed the extent of the avian predator problem.
“It’s hawks, owls, kestrels, juvenile bald eagles. It’s everything,” Baasch said, and some predators are building nests in trees near the nesting sites.
PRRIP Executive Director Jason Farnsworth said, “It’s just one of those surprises you deal with.” He added that while some things can’t be controlled, it’s possible to collect data on avian predation and try solutions.
Baasch said possible solutions might include avian predator trapping or using strobe lights at night, but more discussions are needed before he makes suggestions to the Governance Committee.
Another benefit of cameras at nest sites is monitors can read identification bands carried by some birds. Baasch said tern and plover banding hasn’t been done since 2016.
Approximately two-thirds of banded terns and half of banded plovers return to Central Platte nesting sites.
“We haven’t seen a lot of change,” he said. “Some years we’re pulling birds from other places and some years we’re not.”