I have never been able to get close to a cuckoo (Cuculus canorus), they are very nervous birds. This photo reflects a fairly typical view that one might get of one. I sometimes wonder if they are nervous because they are up to no good and do not want anyone to know! Most birds, though, are nervous and easily disturbed so the cuckoo is no exception really.
Often heard but not seen, the cuckoo resembles a bird of prey in flight; a bit like a kestrel in some ways being of similar size. When it lands the tail is often 'cocked' at an angle to the rest of the body. It likes a perch with a good view because it is, of course, looking for nests of other birds that it can use to lay its eggs in. Surely there can be very few people not familiar with the life cycle of the cuckoo?
Once one of our most familiar birds, the true herald of spring, people used to write to the Times newspaper to report their first cuckoo heard each year. In recent years, sadly, the cuckoo has declined sharply in numbers and now is heard far less frequently.