populations are under assault. changing farming practices, pollution and climate change are all taking their toll, says the bird protection charity the rspb. we do a piece of work called the state of nature which is a report on all the reasons for this decline. we've lost about 38 million birds over the last 50 years, that's about a fifth of our breeding bird population here in the uk. and not every species is declining, but overall more species are declining than others, particularly farmland birds. woodland birds aren't doing very well. can you hear that? loads of birds there, and that is what this is all about. this is about us all going into our gardens, looking out of our windows, on our balconies, counting the birds we can see to survey the bird population. really important information about what is happening to the country's birds. and the rspb wants you to help them by taking part in their big garden bird watch. it is the biggest citizens�* survey anywhere in the world and all they are asking