Social media sleuths are trying to solve the mystery of why dozens of birds crashed to their deaths in the Mexican state of Chihuahua.

“Pls not bird flu,” quipped American Conservative Union boss Matt Schlapp after watching the footage, which gained attention online Saturday.

The birds — later identified as yellow-headed blackbirds — were discovered lifeless on sidewalks by residents of Cuauhtémoc City, the Spanish-language El Heraldo de Chihuahua reported.

The migratory fowl arrived from northern Canada and had been wintering in Mexico. The cause of the mass death remains unclear, but some speculated the birds may have been suffering from the effects of high pollution, which has plagued the region lately.