clipped from news.yahoo.com

Three normally white polar bears at Higashiyama Zoo and Botanical Gardens in central Japan changed their color in July after swimming in a pond with an overgrowth of algae.

High temperatures in July and August and less-frequent water changes because of the zoo's conservation efforts caused an algae growth in the bear pond and safety moat, Kurobe said.

Algae that enters hollow spaces in the bears' fur is hard to rinse off, he said.

The bears are expected to return to their natural color when the algae growth subsides in November, Kurobe said.