07/22/2010 02:47 pm ET | Updated May 25, 2011

Penguins Stranded On Brazilian Beaches, Pollution And Overfishing To Blame (VIDEO)

Magellan Penguins annually leave their colonies in Patagonia and Antarctica to undertake a thousand-mile journey in search of food. But in recent years, the penguins have been increasingly washing up on Brazilian shores, mysteriously sick, disoriented, and unable to return home.

Giselda Condiotto, president of Niteroi Zoo, has been rescuing stranded penguins since 1999. At first she would only receive two or three a year. That number escalated to 100 penguins in 2004, exponentially rising to 700 penguins in 2008, she tells CNN in the video below.

Unfortunately, many penguins don't even survive long enough to make it into to Condiotto's care, AP reports. Recently, over 500 penguins turned up dead on Brazilian beaches in the span of just 10 days, an extremely startling number.

Thiago do Nascimento, a biologist at the Peruibe Aquarium in Brazil, thinks overfishing is primarily to blame, diminishing the penguins' food supply. Nascimento said only about 10 dead penguins shows up on the beach in the average year. Autopsies revealed that many of those penguins had empty stomachs, and may have starved to death.

Scientists are looking into other factors that may be at play. Climate change could be adversely affecting ocean conditions for the birds, while Maria das Gracas de Souza of Brazil's environmental agency, IBAMA, believes pollution is affecting the penguins.

Some of the rehabilitated penguins are returned to their natural habitats, but others become so accustomed to human care that experts are afraid they won't be able to survive on their own.

WATCH the rehabilitation of the penguins on CNN: