A pesticide called DDT - dichlorodiphenyltrichloroethane was found to be the culprit.It caused thinning of their eggshells which then cracked during incubation.Only after was banned, and peregrines given legal protection, did their numbers slowly start to recover. In 2006 a young pair showed strong signs of wanting to breed on Derby Cathedral, but there were no suitable ledges.
During last year's breeding season our cameras and blog brought all the action and updates to over half a million visitors.
You can view Derby Peregrines live on our Peregrine Webcam Pages.
Follow this external link to our Peregrine Blog for all the latest news from the Peregrine Project Team.
Derby lies in the centre of England, and the ancient stone tower of its cathedral dates back over 470 years.
Records suggest that peregrine falcons have roosted and hunted from the tower at many times over the centuries.
But then in the mid-20th century their numbers crashed suddenly.
They were virtually wiped out from many parts of Britain and the world.
Please Note: we are aware of connection issues which have affected our live cameras in recent weeks.
These are being investigated as a matter of priority as other services are also being affected.
Important: Please see the Derby Cathedral Peregrine Project blog for important news about the webcams.
Peregrine Falcons first nested on Derby Cathedral in 2006.