Adult Peregrine Falcons have a dark grey-and-white plumage.  
Their chest and throat are white and the belly is white with horizontal dark grey stripes.
Juveniles Peregrine Falcons have a dark brown head and their belly is somewhat brownish with heavy vertical (instead of horizontal) dark brown stripes.
Juveniles remain brown-and-cream colored until they are one year old.

The Peregrine Falcon is best known for its diving speed during flight which can reach more than 320 km per hour, making it not only the world’s fastest bird but also the world’s fastest animal.

An adult. Immokalee area, Florida, USA, 23 November 2012