The ravens at the Tower of London, and ravens native to this country are known as common ravens, this is because they are found in most countries around the world. Apart from the continents of South America, Africa, Australia and the Antartic region.There are eight other species of raven.

These are.

 In Africa.

The white neck raven

The thick billed raven

The Brown necked raven

The Dwarf Raven

Pied/white chested raven

The Fantailed raven.

In Australia.

The Australian raven

 The Forest Raven

The Little Raven. 

In America.

Common raven

Chihuahuan raven