SAN FRANCISCO (AP)  — Crews demolishing the old eastern span of the San Francisco-Oakland Bay Bridge have run into an unusual challenge: birds that won’t leave.

The California Department of Transportation says cormorants that call the defunct bridge home have not gone away despite encouragement from workers. So the agency is switching to a new tactic that attempts to attract the dark-colored birds to other areas.

Caltrans spokeswoman Leah Robinson-Leach tells KCBS the attraction strategy is part of a contract that is currently out for bid.

The birds have not delayed the demolition so far, but Robinson-Leach says that will change if they are not gone by the end of the year. The work is expected to be completed in 2018.