SAN FRANCISCO (KCBS) — The Bay Bridge has been home to a number of bird species but there is one in particular that is having an impact on the demolition of the old eastern span of the bridge.

Cormorants, the dark colored birds with the long necks, reside under the Bay Bridge and Leah Robinson-Leach with Caltrans said they live under the now-defunct eastern span where workers have tried “encouraging” them to leave.

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“At this point, they have not adhered to our encouragement,” Robinson-Leach said.

Instead, she said, they will be switching from encouragement to attraction and that is now part of a contract that is currently out for bid.

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“We will work with them to ensure that attractors will be put in place that will, in fact, attract the birds to other areas”

About 500 pairs of cormorants as well as seagulls and other birds make their home under the old eastern span and Robinson-Leach said that while the demolition is remains on schedule, the birds will have a significant impact on the work if they don’t move on by the end of the year.

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The demolition is expected to be completed in 2018.