HIGHTLIGHTS OF CHANGES in this 19th edition

I make only one family changes in this 19th edition. The addition is family Salpornithidae, the Spotted Creepers. Further, I've resequenced the list of bird families to follow the current 2024 Clements checklist. There are a few minor changes in sequence among Non-passerines, particularly affecting Flamingos and Grebes, but none (except to add the Spotted Creepers) in the Passerines.
    My 18th edition, posted one and-a half years ago, also added just one family, the Elanidae, following Starikov & Wink (2020) who opine, based on molecular evidence, that "mitochondrial and nuclear markers . . . combined with morphological, cytogenetic, and ecological date" warrant the elevation of the Elanin kites to family Elanidae. These involve the Elanus and Chelictinia kites, and Pearl Kite Gampsonyx swainsonii. Their data suggest these kites diverged from the rest of Accipitridae ~21 million years ago. This divergence date is quite similar to divergence dates in families within the Charadriiformes, for example (see Cerny & Natale 2022 for one recent time-dating hypothesis).
    The deletion is to follow Christidis & Boles (2008), and all updated global checklists, in merging the Australo–Papuan Butcherbirds and allies into the woodswallow family Artamidae. Behaviorally, woodswallows (genus Artamus) and the two peltops (Peltops) are distinctive sit-and-wait predators of flying insects, compared to the more corvid-like omnivores — characteristics that make them easily separable — but a series of studies have shown that together they are a strongly supported clade within the Corvoidae (summarized in Winkler et al. 2015).

Net result: one change in total families from the 18th edition [now 261 extant families]

    There has been a trend towards higher numbers of Families in recent years. Following recent decisions by the AOS-NACC, IOC, Clements, Birdlife International, and Winkler et al. (2015) — outlined in my 17th edition —I finally accepted as a fait accompli the elevation to Family level of all the New World nine-primaried passerine families first proposed in Barker et al. (2013). This was with reluctance, as I had hoped ornithologists could reach some reasonable standard by which families could be measured, perhaps something like a divergence date of 18-20 million years ago (mya), at least for passerine families. This hasn't happened. Even the monotypic Yellow-breasted Chat [Icteriidae] was moved near the Icterids and elevated to Family level, making it the youngest family of all bird families at only ~11 mya. It also created a formal Family name [Icteriidae] that will be confused with that of the Orioles and allies [Icteridae]. It remains disappointing that a lack of consistent in application of thought and a discussion (or lack thereof) or divergence times in deciding what is, or is not, a Family.
    There remains uncertain about some avian relationships. In the 17th edition, I resurrected the Skimmer family [Rynchopidae] because the current SACC retain the Skimmers as a family, and do not merge them with the Laridae (Gulls and Terns). Some data suggest that noddies and White Tern are not within the traditional Terns (and might be entitled to Family status), so it is wisest to retain the Rynchopidae as a Family awaiting more research. In this way my list of bird families included all the families currently accepted by either AOS or SACC. Since then, Cerny & Natale (2022) continued to place gulls in Laridae and skimmers in Rynchopidae, but they also moved all terns to Rynchopidae. It will take some time to determine whether gulls, terns, and skimmers are best placed in one Family or divided into 2 or 3 families.

The newest Bird Families book [Winkler et al. 2015] had 243 families. My list in this edition has 261 families, 18 more than the Bird Families book: Skimmers [split by SACC, see above], Ground-Hornbills [also split by Clements, IOC], Elanin Kites (Starikov & Wink 2022), Old World Parrots & Lories [Psittaculidae; also split by Clements, IOC, AOU, SACC], Sharpbill [Oxyruncidae; split by SACC, Clements], Royal Flycatchers [split by AOU], Shrike-babblers and Silktails [both splits recommended by Jønsson et al. (2016) on evidence of ancient divergences], Erpornis, "Bristle-flycatchers" [Erythrocercidae; also split by Clements and IOC] are now generally called Yellow Flycatchers, White-crowned Shrikes (Fuchs et al. 2019), the Alcippe Fulvettas (Cai et al. 2019), Hylias, Wallcreeper [Tichodromidae; also split by Clements, IOC], Parrotbills & allies [Paradoxornithidae; also split by IOC and others], Cinnamon Ibon (based on ancient divergence), and the newest, the Spotted Creepers. In short, this list incorporates all of the extant families adopted by Clements, AOU, SACC, or IOC [except Bananaquit].