D.W. Field Park in Brockton closed on Friday due to a potential avian flu outbreak, just a week after more than 60 geese, swans, and ducks were found dead at a Plymouth pond 25 miles away.

Avian flu is rampant in poultry farms and in wild birds in the U.S. Every mutation brings the virus one step closer to the brink of human-to-human transmission, but predicting whether a virus will cross that threshold remains an uncertain science.

Dead swans and Canada geese were found on a pond in a park that has since been closed due to avian flu concerns in Brockton and Avon, officials reported.