MEXICO CITY -- When hundreds of birds were found dead along Mexico's Pacific coast earlier this year, experts immediately suspected avian flu.

       But the government said Thursday that the warming Pacific ocean currents associated with El Ni？o, not bird flu, were responsible for the mass die-off.

       Mexico’s Agriculture Department said Thursday that tests on the dead birds revealed they had died of starvation, not flu.

       The department said that warming surface water in the Pacific caused by El Ni？o can drive fish into deeper, cooler water, making it harder for birds to find food.

       Most of the dead birds were Sooty Shearwaters, seagulls and pelicans. They died in states ranging from Chiapas, on the border with Guatemala, all the way north and west to Baja California.

       “According to autopsies carried out be veterinarians and specialized biologists, it was found that the animals died of starvation,” the department said. “The most probable cause of this epidemiological event is the warming of the waters of the Pacific due to the El Ni？o meteorological effect, which causes fish to seek deeper, colder waters, preventing sea birds from catching food.”

       El Ni？o is a natural, temporary and occasional warming of part of the Pacific that shifts weather patterns across the globe.

       In May, U.S. National Oceanic and Atmospheric Administration climate scientist Michelle L’Heureux said El Ni？o had formed this year a month or two earlier than usual, which “gives it room to grow,” and there’s a 56% chance it will be considered strong and a 25% chance it reaches supersized levels.