Peregrine

Californian Peregrine falcon by Kevin Cole

We are blessed in Lewes by having had peregrines, Falco peregrinus, nesting on the chalk cliffs just south of the Cuifail tunnel opposite the Railway Land. They share the cliff, after a fashion, with hundreds of jackdaws and a long-suffering pair of ravens. The peregrines really don't like the ravens and spend a significant portion of their non-hunting time dive-bombing the unfortunate corvids. Sadly they sometimes take the raven chicks before they fledge. 
There are a lot of superlatives applied to this bird and if you get the chance to spend time getting to know them you will understand why. It's fastest recorded speed is 242 miles per hour, making it easily the fasted animal on the planet.
My first experience of them was in Melbourne. A pair nested on a skyscraper in the central business district. We were walking up the main drag when a dead pigeon fell from the sky, landing on the pavement about six feet from us. Today I saw a pristine male (tiercel) sitting on a ledge on a cliff in an old chalk pit. He had bright yellow legs and bill and looked, to use an over-used adjective perhaps appropriately, awesome.
They were nearly wiped out by poisoning from pesticides in the 1950s and 60s. DDT was the main culprit. Last year I picked up a fine first edition of J A Baker's classic The Peregrine which immediately made it into the top ten 'next books to be read' list.
They have a fairly distinctive cry in flight: