A Darwin finch in the Galapagos. The subfamily that is unique to the islands has been threatened by an invasive parasite that first appeared in 1997. Education Images/UIG via Getty Images hide caption

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A Filipino chicken vendor in Quezon City, east of Manila, Philippines. Researchers say Pacific island chicken are genetically similar to the variety found in the Philippines, but different from South American chicken. Rolex Dela Pena/EPA/Landov hide caption

itoggle caption Rolex Dela Pena/EPA/Landov

Hundreds of thousands of people crowd Copacabana Beach in Rio de Janeiro on Sunday as Pope Francis celebrates the final Mass of his visit to Brazil. Security lapses, traffic chaos and other logistical snafus marred the visit. AFP/Getty Images hide caption

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