Sandhill cranes thrive in the San Joaquin Valley wetlands

The Fresno BeeNovember 23, 2013 

— Six sandhill cranes landed gracefully and strolled two-by-two with their mates into an autumn scene worthy of a Norman Rockwell painting.

The sandhill crane couples, members of a species that mates for life, were joining a dazzling array of birds amid November foliage at the Merced National Wildlife Refuge, a carefully tended artificial wetland.

Each fall, thousands of sandhill crane couples have a date to join the honking, squawking and even dancing in the San Joaquin Valley's wetlands. The wetlands are open on this dry year, thanks to water from the federal Central Valley Project and groundwater wells.

A steady supply of water for refuges is a higher priority than some farm water, according to a 1992 environmental reform law, the Central Valley Project Improvement Act.

So in the midst of California's two-year dry spell, refuges have gotten 100 percent of their water allotments, unlike some farmers who have suffered deep cutbacks due to environmental restrictions and drought.

"The drought has an effect on us, because the ground takes in more water and it can result in fewer acres of refuge this year," said recreation planner Jack Sparks of the U.S. Fish and Wildlife Service. "But there are a lot of birds."

Take the self-guided tour at the Merced refuge, which is part of the San Luis National Wildlife Refuge Complex in Merced County. You'll see snow geese, black-necked stilts, great egrets, tri-colored blackbirds, American coots and dozens of other species.

But the sandhill crane — here for the winter because the breeding grounds in Alaska and Canada freeze over — can steal the show.

With up to 20,000 of them at Merced and other area refuges, they dance together, hopping and flapping their wings. Biologists say the dance is connected to courtship, but not always.

"Sometimes there's a whole family of them dancing, letting off steam and showing exuberance," said Mike Savino, president of the Sacramento-based Save Our Sandhill Cranes, a nonprofit group dedicated to maintaining habitat for the bird. "Truth is, we don't really know all the reasons they dance."

The sandhill crane is a big, gray bird, with a wing-span up to six feet, and it is known for lively family chattering.

The bird is not a federally threatened or endangered species, though California considers one subspecies of the crane to be threatened.

Scientists say fossils dating back several million years are structurally identical to the sandhill crane, meaning this resilient species might be the oldest surviving bird on the planet.

Before the Central Valley was extensively farmed and developed, sandhill cranes and hundreds of other species had 4 million acres of wetlands to visit each year. More than 90 percent of the natural wetlands have been drained.

The 10,200 acres at the Merced wetlands are the oldest part of the 45,000 acres of the San Luis complex, which includes San Luis and San Joaquin River refuges. The Merced site was established in the early 1950s.

Before dams were built on Sierra Nevada rivers, the wetlands were fed by melting snow running down through local rivers and streams. Now, the remaining wetlands are mostly supported with Northern and Central California river water captured at reservoirs.

The refuges must be managed to mimic nature, said Sparks and Tara Wertz, assistant manager at the Merced refuge. Grassy wetlands plants, such as tules and bullrush, would take over the wetlands if they were not mowed down periodically. Birds flying overhead must see ponds of water to be attracted in large numbers.

Wertz said there are three cornfields on the Merced refuge to help supply food for birds. There also is a cattle grazing program.

"The grazing keeps down the grass to lower heights so the area remains open," said Wertz.

Before farming and development, nature would clear out excess brush and grass with periodic fires or the occasional scouring flood. One small section of the Merced refuge is charred from a prescribed burn this year.

Small islands are part of the managed landscape around the ponded water. Hundreds of shorebirds gather there, feeling safer because they can see the approach of predators, such as coyotes.

The sandhill cranes scatter at dawn to find food, then slowly return. Some continue to browse the refuge's offerings, a smorgasbord of tubers, insects, amphibians and rodents.

As the sun sets, they will begin to roost in the water overnight.

"They roost in the water for protection," said Sparks. "Coyotes can't sneak up without making some kind of noise. The water is very important."

 

http://www.fws.gov/refuge/san_luis/

http://www.soscranes.org/index.php?page=crane-education

 

The reporter can be reached at (559) 441-6316, mgrossi@fresnobee.com or @markgrossi on Twitter.

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