San Francisco Zoo management and the union representing zookeepers sparred Thursday over whether an open-mike feature on employees’ walkie-talkies was used as a bugging system, exposing private conversations without the workers’ knowledge.

The zoo’s executive director, Tanya Peterson, acknowledged Thursday that such a feature exists, but said she disabled it in January, weeks before managers allegedly used it to eavesdrop on a private conversation. The incident, which Peterson suspects may be a misunderstanding, was brought to the attention of the union last week.

The dustup is the latest episode in the feud between the Teamsters 856 and zoo management that came to a head last year during contentious contract negotiations.

Part of the collective bargaining agreement was a deal to get workers a state-of-the-art radio system that would include a “code red button,” which zookeepers could use to alert security if they were attacked by an animal. Peterson said the zoo “bought the best radio system it could,” and warned staffers that the radios would mean less privacy.

But according to union representative Tim Jenkins, employees were never told their radios could be monitored remotely. He said they learned about the feature March 12 after an unnamed manager revealed to union officials that he had overheard other managers, including Vice President of Operations Robert Icard, “making fun” of someone talking on the radio.

“On Monday, we met with management and asked if this is technically possible,” Jenkins said. “They said it was, and that it was installed on radios without people even knowing.”

The person allegedly being eavesdropped on, Jenkins said, was Joe Fitting, the zoo’s director of conservation.

Fitting was promoted Thursday to deputy director, according to an e-mail obtained by The Chronicle. Peterson, though, said there was no connection between the eavesdropping allegations and the promotion, adding that Fitting has been her “right-hand man” and that they have been talking about giving him a bump since December.

She also said the alleged bugging incident would have happened months after the remote monitoring feature was disabled.

“It is often easy to hear a partial conversation” when the walkie-talkies are being used in normal communications, she said. “I’m hoping this is a misunderstanding.”

According to the user manual for the model of Motorola two-way radios used by employees, the remote monitoring feature allows a user to “turn on the microphone of a target radio,” which can be used to “monitor, remotely, any audible activity surrounding the target radio.”

Union representative Nicole Casey said Thursday in a statement that “because of the need to respond to animal emergencies, employees carry their radio with them at all times during work — including lunch and bathroom breaks — and were never told their private conversations could be monitored.”

She added that “essentially, employees could be bugged at any time. An additional concern is that the radios are GPS-enabled. It would be possible, for instance, to know who is taking lunch together and then decide to listen to their conversation.”

Peterson said when the radios went into use last year, the capability for remote listening was enabled only for her, Icard and a dispatcher at the zoo.

“Zoo management has no interest in monitoring conversations of its employees,” Peterson said in a statement Wednesday. “Safety is a top priority for the zoo, and this new radio system was installed to ensure zoo employees are working in the safest possible environment.”

She said the well-being of workers is paramount for the zoo, especially after the incident on Christmas Day in 2007 when a Siberian tiger named Tatiana jumped out of its enclosure, fatally mauled a teenager and injured two others.

Peterson said the radio system was geared more toward law enforcement. She thought it could be helpful in emergency situations, she said, but felt uncomfortable with it.

“Emergency monitoring on the zoo’s new radio system was a vendor feature designed to assist with medical and safety emergencies,” Peterson said. “When I was made aware of the radio's capabilities, this feature was disabled."

As for the allegations that managers used the system to listen in on Fitting, she said the zoo had hired a lawyer to look into it and interviewing employees about it. The union has also hired an attorney to see if the system was in “violation of any state or federal laws.”