Volume 12 features a lengthy foreword on fossil birds by Kevin J. Caley. This volume covers the following families: Picathartes (Picathartidae); Babblers (Timaliidae); Parrotbills (Paradoxornithidae); Australasian Babblers (Pomatostomidae); Logrunners (Orthonychidae); Jewel-babblers and allies (Eupetidae); Whistlers (Pachycephalidae); Australasian Robins (Petroicidae); Fairywrens (Maluridae); Bristlebirds (Dasyornithidae); Thornbills (Acanthizidae); Australian Chats (Epthianuridae); Sitellas (Neosittidae); Australasian Treecreepers (Climacteridae); and Tits and Chickadees (Paridae).