BERLIN (AP) — The Berlin Zoo shut its doors to visitors after one of its aquatic birds tested positive for avian flu, the facility said Friday.

A routine check on a hamerkop - a medium-sized wading bird - that had died last week found that it was positive for the disease.

The zoo will remain closed for the time being as a “precautionary” measure, the zoo said in a statement. In the meantime, caretakers are working to quarantine and separate the remaining bird populations.

"The primary goal is to prevent the spread of avian flu,” Berlin's climate ministry said in a statement.

Zoos in other German cities, including Greifswald, Karlsruhe, Rostock and Heidelberg, have also recently been hit with cases of avian flu.