SILVERTON (AP) — It’s beginning to sound a lot like Christmas at tree farms up and down the Willamette Valley, with the whir of helicopter blades in the air.

Silver Bells Caroling That, too.

But in the Willamette Valley, where the lion’s share of the nation’s Christmas trees are grown, several local aviation companies, as well as out-of-state operators from as far away as Alaska and Montana, take part in the harvest.

During the five-week window when the work is in full swing, speed is of the essence. Oregon growers have 8 million perishable trees to deliver to customers across the country and in other countries.

And helicopters are the only practical way to move trees at some big farms.

The harvest goes faster with helicopters, and fewer workers are needed to lug trees. Helicopters also reduce the need to build and maintain all-weather roads on farms.

Fewer roads mean growers save on capital expenses. There’s also more space for cultivating Douglas fir and noble fir, the predominant Christmas tree varieties grown in Oregon

Growers pay anywhere from $600 to $800 per hour to hire helicopter companies for harvest. Operators are quick to point out that maintenance costs for their hard-used machines take a large bite out of profits.

These days, the sight of helicopters in Christmas tree country is a familiar one for many local people, but three decades ago using choppers to bring in the harvest was new and experimental.

Jerry Harchenko, a pilot who helped pioneer the technique in Oregon, said Washington Christmas tree farmers were the first to try helicopters in the Northwest. Word quickly spread about how well it worked.

Jim Heater, owner of Silver Mountain Christmas Trees, a Sublimity-area tree farm, was among the first to make helicopters part of the annual shipping frenzy. In 1976, choppers began hovering over Heater’s fields.

Skeptics claimed the cost of using helicopters was too expensive, said Heater, a past president of the National Christmas Tree Association. Undeterred, Heater did the math and found that helicopters increased his farm’s productivity.

“Manpower (cost) is unbelievably high when you’re carrying to a road every 200 feet,” Heater said.

Now, he estimates that 70 percent of the Northwest tree harvest is done with helicopters.

But some growers aren’t sold on helicopters.

Charlie Grogan, of Silver Bells Tree Farm near Silverton, said that hand-carrying is easier on trees and his wallet.

“We feel we come out dollars ahead and with a better product,” said Grogan, another past president of the National Christmas Tree Association.