This is the White-tailed Hawk (Geranoaetus albicaudatus), a bird of prey species that is resident throughout much of the tropical or subtropical environments across the Americas.
Last year, I was recording a specimen of this bird singing at the top of a tree in an early morning. At a specific moment of the recording, a Southern Lapwing (Vanellus chilensis) catches sight of the White-tailed Hawk, and starts calling and attacking the bird of prey.
This video was recorded in Itatiba / São Paulo - Brazil using a Panasonic HDC-HS80.
Hope you enjoy it!!!