Pied wagtails are fairly common at Druridge. There is however another form of this wagtail called the white wagtail (which is confusingly not white). The main difference between the two is that adult pied wagtails have a black back, and adult white wagtails have a distinctly pale grey back. Juveniles tend to be all sorts of shades of grey so you can't easily distinguish them until they are fully grown. They often feed around the feet of livestock (there were horses in the field at the time).