School roosters

In Harry Potter and the Chamber of Secrets, when Hagrid charges into Dumbledore's office to defend Harry, he is seen carrying a dead rooster in his hands. In the extended cut of the movie, Hagrid mentions that someone is killing the school roosters. In the harry potter lore, the sound of a rooster is fatal to a basilisk. That’s why Ginny killed them under Tom Riddle’s control. It was also the rooster’s blood that was used to write on the walls.