The Oakland A’s got a thumbs down Monday from the Golden Gate Audubon Society, which claimed the proposal to build a ballpark on land owned by the Peralta Community College District is a bad deal for birds.

The influential advocacy group, which has more than 7,000 members in Oakland and nearby cities, said the proposed ballpark in the Eastlake neighborhood would be disastrous for nearly 200 species of ducks, herons, songbirds, nesting cormorants and fish that make their homes in Lake Merritt, the nation’s oldest wildlife refuge.

“We’re not antibaseball. We love the A’s, but we want them to stay where they are,” said Cindy Margulis, the executive director of Golden Gate Audubon. “When you put in a stadium and have all the additional cars and traffic, there will be additional contaminants coming into the lake. Oakland is a creative, imaginative city, and I think they can do better.”

The Audubon announcement put a damper on a rally Monday by Oakland business and civic leaders who declared their support for the ballpark, which they claimed would create thousands of jobs and rejuvenate a stagnant part of the city.

The A’s announced last week that they want to build their future home at a site near Laney College and the Lake Merritt BART Station, not far from Chinatown.

The proposal, however, received a tepid response from Mayor Libby Schaaf and Councilman Abel Guillén, the district representative who said he has a number of concerns that need to be addressed. Some Peralta faculty and community members have also vowed to fight the sports facility, saying it will hurt the college’s educational mission and speed up displacement of low-income renters in the area.

Margulis dashed more cold water on the Peralta site Monday, saying it is ill-suited for a stadium and cannot handle all the needed parking. She said the loud noise and intense light would scare and disorient birds and the trash left by tens of thousands of fans would pollute the narrow channel that connects the lake to the Oakland estuary and San Francisco Bay.

Building the ballpark there, she said, could undo the $198 million in environmental restoration and habitat improvement work done at Lake Merritt under the Measure DD bond funding.

Margulis said she supports renovating the existing Coliseum complex.

“There is a massive footprint that already exists, that already has public transit,” she said. “Throwing that all out and causing more impacts in a different location is not the ecologically responsible thing to do.”

A’s officials said they intend to address Audubon’s concerns.

“We look forward to engaging in a community process where all voices are incorporated into our plan, including Golden Gate Audubon,” said Catherine Aker, vice president of communications for the team.

Local business owners and prominent community leaders are urging residents and city officials to get behind the ballpark and work with the team, rather than rebuff the plan right off the bat.

“I am looking for our mayor and elected leaders to set the right tone for the one shot we have at keeping a sports team in Oakland,” Barbara Leslie, president of the Oakland Chamber of Commerce, said in an email. “This is an honest and refreshing commitment by a sports franchise who cares about and is committed to our city.”

Carl Chan, a board member of the Chinatown Chamber of Commerce, was also critical of the negativity, urging Oakland’s elected leaders to have some “backbone” and face down the opposition.

“Many people would love to focus on the problems,” he said. “But many of us here, we’re going to focus on all the solutions.”

Doug Boxer, co-founder of Let’s Go Oakland — a civic group formed to keep the A’s in town — and the son of former U.S. Sen. Barbara Boxer, said the city is on the verge of doing something great.

“We sit at the precipice,” Boxer said. “We can’t let the pop fly drop.”

Although the ballpark would be privately financed by the A’s owners, it will need authorization from the Peralta Community College District and the Oakland City Council.

Peter Fimrite and Kimberly Veklerov are San Francisco Chronicle staff writers. Email: pfimrite@sfchronicle.com, kveklerov@sfchronicle.com. Twitter: @pfimrite, @kveklerov