Mexico says mass bird deaths likely caused by El Niño's hotter waters

Authorities had initially suspected bird flu, but a joint effort from the country's agriculture and environment ministries concluded the most likely reason was warmer oceans resulting from El Niño.

The periodic natural phenomenon, which lasts between months and years, warms the Pacific Ocean fuelling tropical cyclones, floods and rainfall across the Americas and elsewhere.

The U.S. National Oceanic and Atmospheric Administration (NOAA) earlier this month declared that an El Nino is now under way, after three years dominated by the cooler La Nina pattern.