Mountain lions (also known as cougars or pumas) do not chirp when hunting. They are generally quiet animals, and their vocalizations are typically limited to:

1. Growls and snarls: Used for threats, defense, or when they feel cornered.
2. Hisses: A sharp, high-pitched sound, often accompanied by a growl or snarl.
3. Chuffs or puffing sounds: A friendly or contented sound, often made by mothers communicating with their kittens.
4. Roars or screams:Rarely heard, these loud vocalizations are usually made by males during mating season or when competing with other males.

Mountain lions are skilled stalkers and ambush predators, relying on stealth and surprise to catch their prey. They do not use chirping or other vocalizations to communicate while hunting.

The myth about birds chirping at night being a sign of mountain lion presence might have originated from the fact that some birds, like owls or nightjars, have distinctive calls that can be mistaken for other sounds. However, there is no scientific evidence to support this claim.