SAN FRANCISCO (KCBS) — Wildlife officials have a mystery on their hands after dozens of shorebirds in the East Bay were found covered with a strange gooey substance this week.

As of Sunday morning, 89 birds have been contaminated and 20 were found dead, according to the International Bird Rescue blog.

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Alexia Retallack, with the Department of Fish and Wildlife spill-prevention agency, she told KCBS her team was called in Friday after receiving reports that dozens of birds were in distress along the bay shore from Hayward north to Alameda.

Contaminated Birds

Two birds being treated for a mysterious gooey substance coating their feathers. (Chris Filippi/KCBS)

Retallack says the response team started scooping up the birds which were still alive in order to help rehabilitate them. At the same time, they began testing the substance coating their feathers.

Retallack says the substance does not appear to be petroleum-based but it’s still oily and able to coat the feathers, which affects birds’ buoyancy and ability to stay warm. Several of the birds have died from hypothermia.

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She says because of the Marin Luther King holiday, testing won’t occur until Tuesday.

Once they identify exactly what the substance is, rescue officials can develop a better response procedure.

Bufflehead Contaminated

One of the shorebirds covered with the mysterious substance in the East Bay. (International Bird Rescue Photo)

Though this is not a public safety risk, officials are advising people not to touch affected birds.

Dozens of people were helping to look for more birds this weekend, led by members of the International Bird Rescue foundation.

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To get involved in the clean up, visit the Bird Rescue’s website.