Calvin Harris Says His Rooster Was Killed by 'Idiot' Neighbor's Dog

Calvin Harris just can't let Taylor Swift have her big day ... because hours after she announced a new album, he announced the death of his rooster -- and Calvin says the cock was murdered!!!

The musician, who is among Taylor's famous exes, hopped on social media Tuesday and claimed his "majestic" cockerel Smokey was dead.

Calvin claims the rooster was "murdered" by his "idiot" neighbor's "grimey dogs" ... and he says Smokey's death has left him "absolutely gutted."

Harris shared an old photo of him and his chicken -- on the property of what looks like his home in the Cotswolds -- and said ... "Raised this lad from a chick to a majestic cockerel."

Taylor announced her newest album hours before Calvin's post ... she's calling the upcoming album "The Life of a Showgirl" ... and now he's calling attention to his dead cock.

Calvin's tragic loss comes on the heels of some good news for his family ... he recently revealed his wife gave birth to their first child.