The sound of gunshots alarmed some runners and cyclists on Stevens Creek Trail Saturday, but it turns out the bullets were recreational.

From around the Bay Area, hunters headed to the Don Edwards San Francisco Bay National Wildlife Refuge as duck hunting season began a half hour before sunrise. At one salt pond, where the Stevens Creek Trail met the Moffett Bay Trail, about 33 hunters had signed in before noon Saturday, and some of the "early birds" were already calling it a day.

There were also plenty of cyclists, runners and walkers passing by on the trails. One hunter said there's room for everyone, and there have been no incidents in the past.

That's because the range of a bullet from a shotgun is about 100 feet, and the water provides a 300-foot buffer zone between the duck blinds and the trails, according to refuge manager Eric Mruz. He pointed out that when duck hunting, hunters aim their shotguns into the air, not on the horizon where people are most likely to be.

"So it is safe for the public to use the trail while hunting is occurring," he said.

The hunting season is regulated through permits and licenses, which is checked by law enforcement. Fees from the hunters, including ammunition tax, go toward paying for the duck hunting facilities, as well as conservation.

According to Mruz, some studies have shown that duck hunting helps keep the populations healthy, thinning out the stock in a survival-of-the-fittest kind of way. There are several types of ducks that pass by this area, including mallards, pintails, midgeons, and northern shovelers.

Eldon Hoge, a member of the hunting and conservation club Ducks Unlimited, was one of four men heading out on Saturday. The hunters had come from all over the region—San Mateo, East Palo Alto, Hayward and Redwood City. They'd arrived at the refuge at 2 a.m. and after a few hours had only caught three ducks (out of a seven-duck-per-person quota), a disappointing morning. 

"On a good day we would have caught 28," Hoge said.

Though there's no science to a winning strategy, Hoge decided to go "tailgate hunting" or "bench hunting," which is when Hoge sits in his truck and waits for the sunrise. When it's time to hunt, he chooses from among 25 duck blinds—wooden shacks in the salt pond that camouflage the hunters.

"It's pure guesswork," Hoge said, explaining how to pick a good duck blind.

While most people tend to grumble about bad weather, gray skies help duck hunters, because they keep the migrating waterfowl moving.

"The weather kicks them up and keeps them moving south," Mruz said. "When it's cold and misty, they'll continue flying toward warmer weather."

From the salt pond, NASA Ames Research Center and Moffett Field are visible from one side and the Google headquarters from the other. This is the first year the Moffett Bay Trail along the salt pond has been open. The 2.3-mile trail is part of the Bay Trail network and connects Mountain View to Sunnyvale.

Some walkers on the trails that morning, getting a dose of nature, said they felt terrible for the ducks—and their own nervous systems.

"I just find it so incredible this is protected area for migrating waterfowl," said Diane Ingolia from Palo Alto, who was out walking with a friend. The sound of gunfire didn't stop the two from exercising along the trail, but the unexpected soundtrack that morning struck a nerve. Ingolia said she has heard the gunshots from her house in previous seasons.

The intermittent sound of gunshots will be heard until Jan. 30, when the season ends. The office workers and residents nearby should know that duck hunting is limited to three days of the week—Wednesday, Saturday, Sunday—from sunrise to sunset.