More than 400 penguins, most of them young, have been found dead on the beaches of Rio de Janeiro state over the past two months, according to Eduardo Pimenta, superintendent for the state coastal protection and environment agency in the resort city of Cabo Frio.
Rescuers and those who treat penguins are divided over the possible causes.
Thiago Muniz, a veterinarian at the Niteroi Zoo, said he believed overfishing has forced the penguins to swim further from shore to find fish to eat "and that leaves them more vulnerable to getting caught up in the strong ocean currents."
But biologist Erli Costa of Rio de Janeiro's Federal University suggested global warming could be involved.
"I don't think the levels of pollution are high enough to affect the birds so quickly. I think instead we're seeing more young and sick penguins because of global warming, which affects ocean currents and creates more cyclones, making the seas rougher," Costa said.
Source: The Associated Press