The sandhill cranes usually start arriving along the central Platte River valley in Mid-February through the middle of April with the peak occurring around the middle of March. But this year has been different.
The cranes started their migration early this year because the river valley is already seeing peak numbers of the birds. “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,” reports Omaha.com.
The largest number of cranes counted in February was 30,000 in 2005. Researchers are thinking the mild winter the country just went through is to blame for the early migration, and this could very well be true, according to Digital Journal on Tuesday. According to NOAA, the average winter temperature in the lower 48 was 4.6 degrees warmer than normal.
“What we are seeing now is nearing our numbers for peak migration,” said Brice Krohn, Crane Trust vice president. “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.”
An early February snowstorm dumped 18.3 inches of snow on Grand Island, and since that time, temperatures have stayed around 7 degrees above normal.
“What we are interested to see is if they are going to stay like they normally do,” Krohn 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.”
How long the cranes do stay is dependent on a number of factors, one of them being the availability of food. The Platte River valley is a key stopover for the migratory flocks, a place where they can rest and store up energy for the rest of their trip north to breed.
Many people don’t know this, but once the cranes leave Nebraska, heading north, they will spread out across the northern U.S. and into Canada and even as far as Siberia. So depending on how much waste corn and natural forage is available will make a difference in how long the cranes stay around.
Some of the oldest birds on the planet
Cranes are among the oldest birds on the planet, and fossil records show sandhill cranes were in Nebraska nine million years ago, long before there was a Platte River. Actually, the river is a youngin’, being only 10,000 years old. Back then, the region was more savanna-like, sort of like modern East Africa today, with varieties of rhinos, camels and elephants, long extinct.
But the cranes survived, and over the millenniums watched as the American bison, pronghorn and wapiti evolved on the American plains. Now the landscape has changed from the open prairies of yesterday to cornfields and concrete.
There are six subspecies of sandhill crane, and three are migratory and three are non-migratory. Two of the non-migratory subspecies, the Mississippi sandhill crane, and Cuban sandhill crane are endangered. The third non-migratory crane is the Florida sandhill crane, and it is doing alright.
All three of the migratory subspecies of sandhill cranes pass through Nebraska, and their populations are doing very well. The most numerous and the smallest is the lesser sandhill crane. Another subspecies is the Canadian or intermediate sandhill crane. It makes up about 15 percent of the cranes coming through Nebraska. The third subspecies, the greater sandhill crane is the largest crane and makes up only five percent of the cranes migrating through Nebraska.
Migratory routes of the sandhill cranes
The sandhill cranes that come through Nebraska winter primarily in Texas, New Mexico, and Mexico. When they leave Nebraska heading North in late March and into the middle of April, they head to their nesting grounds. Depending on the subspecies, they go to different places. The greater sandhill crane ends up in the Great Lakes and the Interlake region of Manitoba, Canada.
The Canadian or intermediate subspecies breeds throughout central Canada, from the Hudson Bay west to the Rocky Mountains. The lesser sandhill crane has the furthest to travel and is a bird of the high Arctic. Their nesting grounds can be found in Alaska and the northern reaches of Canada. Believe it or not, but about 80,000 of the lesser sandhill cranes continue their travels, crossing the Bering Strait and ending up in eastern Siberia.
There are plenty of protected sites where bird-lovers can watch the cranes from afar, such as the Rowe Sanctuary near Gibbon, Neb. The Rowe Sanctuary also feature a Crane Cam on their Web site a http://www.rowesanctuary.org/.
