RIO DE JANEIRO, Brazil – Hundreds of baby penguins swept from the icy shores of Antarctica and Patagonia are washing up dead on Rio de Janeiro’s tropical beaches, rescuers and penguin experts said Friday.

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.

While it is common here to find some penguins – both dead and alive – swept by strong ocean currents from the Strait of Magellan, Pimenta said there have been more this year than at any time in recent memory.

Experts 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.”

Niteroi, the state’s biggest zoo, has already received about 100 penguins for treatment this year and many are drenched in petroleum, Muniz said. The Campos oil field that supplies most of Brazil’s oil lies offshore.

Pimenta suggested pollution is to blame.

“Aside from the oil in the Campos basin, the pollution is lowering the animals’ immunity, leaving them vulnerable to funguses and bacteria that attack their lungs,” Pimenta said, quoting biologists who work with him.

But biologist Erli Costa of Rio de Janeiro’s Federal University suggested weather patterns could be involved.

“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.