Use of English PRO

There are many different kinds of birds (0) WHICH successfully share our cities with us, but (1) ............ of the most intelligent are crows. This bird has been carefully tested by scientists in (2) ............  manner of ways, and the results are clear for everyone to see. Even their success in (3) ............  they have adapted to our civilization would seem to confirm this. Despite past attempts to kill them all, crows, (4) ............ are very common in land used by farmers, can still be seen in towns and cities, going about their daily business. They are sociable, especially (5) ............ not looking after their babies, and often gather as a group on winter nights. Sometimes thousands of them gather (6) ............  in one place. Most crows are able to adapt to different conditions, and they are quite trusting, (7) ............ though they are often shy where people attack them. Some become friendly when in towns, and then they regularly visit gardens, and it is not strange for them to become friends (8) ............ humans.