Birders, from left, Vic Leipzig, 65, Tere Ross, 73, Fiona Parker, 65, and James Stacy, 68, use their eyes and ears to identify various bird species at Shipley Nature Center in Huntington Beach. (KEVIN CHANG, HB Independent / January 31, 2014)

The sound of twigs snapping and leaves rustling was in the air as Vic Leipzig and his team of bird watchers walked through a vegetated pathway in Shipley Nature Center on Friday morning.

The bustling traffic on Goldenwest Street struck a discordant note amid the rustic ambience, but that didn't bother the 13 birders as they conducted their monthly bird survey on the 18-acre plot across from the Huntington Beach Central Library.

Leipzig, 65, a former Surf City mayor and former Independent columnist, and his group of volunteers were too busy focusing on identifying the various species of chirping birds to let outside noise distract them.

"There are a lot of birds that we don't expect to see, but we listen for [them] because they're species that tend to hide in the brush," he said. "And even the ones that we can see, the vocalization is the important clue that it's there and gives us a chance to see it."

Bird surveying is one of the volunteer-driven activities at Shipley Nature Center managed by the nonprofit Friends of the Shipley Nature Center.

People can assist by pruning the vegetation around the trails or by answering phones in the interactive center.

Administrative coordinator Carol Williams said many Boy Scouts conduct their Eagle Scout projects at Shipley.

Some Scouts have built cabinets and shelves while others have created benches for the park's outdoor amphitheater, she said.

On Friday, the volunteer birders split up into four groups to cover different sections of the park. Leipzig and his crew — Fiona Parker, James Stacy and Tere Ross — were in charge of monitoring the northeast quadrant.

Every so often, they would stop dead in their tracks and strain to hear the faintest peep. As soon as one would spot a bird flying overhead, the rest were quick to draw their binoculars.

Spotting the winged creatures proved difficult during the overcast morning. Despite seeing a few hawks perched on branches in the distance, members of the group mainly relied on their ears to identify the birds.

"There's a combination of different features of any sound," Leipzig said. "Pitch is one; speed and repetition [are] another."

They were able to recognize the calls of several bushtits and finches without a problem, but other species were trickier to pin down.

"There were some birds burbling back there that might be marsh wrens, maybe a pair," said Parker, 65, who lives in Fountain Valley.

"I did not hear marsh wrens," Leipzig replied.

Similar friendly disagreements between the two experienced birders broke out as they walked along the trail.

Leipzig and Parker spent several minutes during the survey debating if the bird they heard was a song sparrow or a Hutton's vireo.

Back and forth they went, arguing over the pitch and volume of the weeps they heard.

"I want it to be a Hutton's vireo. Can I have it?" asked Parker.

"Fine, you can have it," Leipzig conceded during their unofficial competition. Parker cheered.