Q. What do you mean by Blackcaps?

Blackcaps are small songbirds found throughout Europe. A large population of blackcaps inhabits the forests of Germany. These blackcaps have typically migrated southwest over two mountain ranges to overwinter in Spain, where they feed on fruits and berries. However since the 1960s, blackcaps have been seen in Britain after migrating northwest from Germany. The number of blackcaps migrating to Britain has increased and today about 10% of the German population migrate there, instead of to Spain. In Britain, the blackcaps feed on birdseed provided by local bird-lovers. 

In spring the birds from both Britain and Spain leave at the same time to fly back to Germany to the same breeding grounds. On arrival they select a mate for that season and breed.