A pesticide called DDT - dichlorodiphenyltrichloroethane was found to be the culprit.
It caused thinning of their eggshells which then cracked during incubation.
The female peregrine is considerably larger than the male. As the chicks grow rapidly during May there is an increase of activity around the nest, with both birds bringing back food.
You can cycle there in just a few minutes along the riverside path. We are grateful to the following individuals who recently made donations to keep our project and the webcams running, or have given other support in kind.But before you buy, why not politely ask other peregrine watchers if you can try their equipment? Derby Museum and Art Gallery contains an exciting wildlife gallery, showing many of the habitats and species that live here.Come and stand close to a peregrine falcon in the Derbyshire Nature Gallery, then go and watch one flying free over the City Centre. Precey; the BBC, plus the many peregrine watchers and, of course, to the vergers and authorities of Derby Cathedral without whom none of this would have been possible.Three web cameras now let you monitor their progress, day or night, all year round.During last year's breeding season our cameras and blog brought all the action and updates to over half a million visitors.Look for birds on the east (rear) face of the tower where the nest platform is located half way up.