Treehugger Tuesday

From the Nebraska website Omaha.com:

Early-arriving Sandhill Crane Migration has Experts Curious

By Robert Pore / World-Herald News Service | Posted: Sunday, March 6, 2016 1:00 am
Sandhill cranes


Sandhill cranes land in a field of corn stubble in Hall County last week. Numbers of birds now in the region are near the usual mid-March peak.

GRAND ISLAND, Neb. — A record number of early-arriving sandhill cranes in the Platte River valley have experts eager to see just how long the migrating birds will stay.

Sandhill crane migration generally runs from mid-February through mid-April. During that period, more than 500,000 sandhill cranes migrate through the area. The migration normally doesn’t peak until mid-March.

“What we are seeing now is nearing our numbers for peak migration,” said Brice Krohn, Crane Trust vice president.

The latest aerial count of cranes along the Platte River from Chapman to Overton — taken on Monday — showed 213,600 cranes, the largest number recorded in February since weekly crane inventories during migration season began in 1998, Krohn said.

Since data collection efforts began 18 years ago, he said, the most sandhill cranes previously recorded in the area during February was 30,000 in February 2005.

“I think it is the weather pattern we have been seeing,” he said. “We don’t know what triggers the migration mechanism in the sandhill cranes, but once they start their process, they don’t stop. So a lot of it could be a weather pattern.”

Since an early February snowstorm dumped 18.3 inches of snow in Grand Island, temperatures in the region have been well above normal. The average daily temperature in February in Grand Island was nearly 7 degrees above the 30-year average.

“What we are interested to see is if they are going to stay like they normally do,” he said. “Do they come early and stay for the month? We don’t know. We are excited to learn from that and keep running our flights every Monday and document what we see.”

Andrew Caven, the Crane Trust’s lead biologist, said how long the sandhill cranes stay in Nebraska could be influenced by several local factors. For example, the amount of waste corn and natural forage available play a role since the cranes stop along the Platte River to fuel up and rest before completing their journey north to their nesting grounds.

He said producing natural forage is an essential function of conservation properties such as the Crane Trust at the Alda exit on Interstate 80, Audubon’s Rowe Sanctuary, the Nature Conservancy and the Platte River Recovery and Implementation Program.

“We provide a source of protein and nutrients that agricultural systems cannot with the native prairies and wet meadows we protect and conserve,” Caven said.