Whooping cranes - those huge, white, rare birds - are on the move from their summer breeding grounds in Canada to their winter homes in the marshes of the Texas Gulf Coast.

None have made it as far south as North Dakota yet, but they are coming, Martha Tacha, of the U.S. Fish and Wildlife Service, said Thursday.

"I got an e-mail yesterday from Brian Johns, of the Canadian Wildlife Service, and he saw eight cranes in three groups and 20 cranes in two groups" over the last few days in Saskatchewan, said the coordinator for the whooping crane monitoring project in Grand Island, Neb. "They are moving."

Their 2,500-mile migration route from Wood Buffalo National Park on the Alberta-Northwest Territories border in Canada to Aransas National Wildlife Refuge and its nearby coastal marshes in Texas takes many cranes over North Dakota.

Whooping crane watchers are hoping to see 250 or more of the rare birds arrive at Aransas. The population numbers 236 adult birds, and a record 84 chicks hatched from 65 nests at Wood Buffalo this summer.

"There may be more than 250, but we don't want to get our hopes up too high. We don't know how much mortality there will be during migration," Tacha said.

One whooping crane, a 23-year-old, died during the spring migration. Its carcass was found near Almont.

Last year's total of 237 cranes was the largest whooping crane tally since biologists began counting the birds in 1938. Only 18 cranes were counted at Aransas that winter. This year's count will be totaled after all of the birds have arrived and settled into a routine at Aransas, probably in mid-December.

Whooping cranes are protected under the Endangered Species Act, and they are classified as endangered.

Standing about 5 feet, whooping cranes are the tallest birds in North America.

They are mostly white, but have black wingtips, which are visible only in flight. Their wingspan is about 7 feet.

In flight, cranes extend their long necks straight forward, and their slender legs trail beyond their tails. Whooping cranes typically migrate singly or in family groups, but flights of 10 or more have been reported. Whooping cranes sometimes accompany flocks of sandhill cranes, which are smaller and darker.

Johns hadn't seen any twins in the family groups yet, Tacha said, but sightings should pick up soon.

"It will depend on the weather. Migration is so weather dependent that it's hard to predict," Tacha said.

(Reach outdoor writer Richard Hinton at 701-250-8256 or richard.hinton@bismarcktribune.com.)