Roughly 10 percent of the world’s birds — about a thousand species — are songbirds belong to a group called “nine-primaried oscines,” so named because the 10th primary feather on their wings is greatly reduced compared with most other birds and for the complex sound-producing structures in their throats (oscine is from a Latin word referring to song). For those of us in the Americas, nine-primaried oscines are among our most familiar and beloved birds: finches; sparrows, juncos, and towhees; warblers; blackbirds, meadowlarks, and orioles; cardinals and grosbeaks; and tanagers. Above is a beautiful member of this group, the Painted Redstart (Myioborus pictus), a warbler.
Because this group is so rich in species, so readily able to exploit a wide range of environments and food sources, debates about how to classify these birds have smouldered for decades. Some scientists have lumped them all into one enormous family (e.g., Sibley and Monroe 1990), but more often, they have been treated as several families. This approach, though, has lead to much confusion over which birds belong in which families (remember when we learned that Piranga tanagers are actually cardinals?), and some of the odder members of the group have never really seemed to belong anywhere in the traditional family structure.
Summer Tanager (Piranga rubra) by David J. Ringer
A new and long-anticipated paper, “Going to Extremes: Contrasting Rates of Diversification in a Recent Radiation of New World Passerine Birds,” by Dr. Keith Barker, et al., provides the most comprehensive look to date at relationships within this group of birds, studying multiple genes in every genus belonging to the group.
The results upheld traditional families within the group but still couldn’t crack some of the interrelationships of those well-recognized groups, nor place several of the oddball taxa, including Yellow-breasted Chat, Wrenthrush, and some of the Caribbean “warblers” and “tanagers.” So, the authors have perhaps “gone to extremes” themselves, by proposing that once the finches are left aside, the remaining several hundred species of predominantly New World birds could be divided into not five or six but 16 different families:
- Calcariidae: longspurs, snow buntings (a family recently recognized by the American Ornithologists’ Union)
- Rhodinocichlidae: the Rosy Thrush-tanager
- Emberizidae: now restricted to Old World buntings
- Passerellidae: the New World sparrows
- Spindalidae: Caribbean spindalises
- Nesospingidae: Puerto Rican Tanager
- Phaenicophilidae: Hispaniolan palm-tanagers and allies
- Zeledoniidae: Wrenthrush
- Teretistridae: Cuban Teretistris warblers
- Parulidae: New World wood-warblers
- Icteriidae: Yellow-breasted Chat
- Icteridae: New World blackbirds, orioles, meadowlarks, etc.
- Calyptophilidae: Hispaniolan chat-tanagers
- Mitrospingidae: three disparate “tanager” genera united by genetic similarities
- Cardinalidae: cardinal-grosbeaks
- Thraupidae: tanagers
Barker et al. argue this approach actually preserves taxonomic stability, by continuing to recognize long-established families, rather than lumping huge numbers of species into very large families and demoting long-recognized groups like blackbirds and warblers (as Sibley and Monroe did in 1990).
John Boyd adopts what he calls a “compromise phylogeny” of 10 families, noting that uncertainty remains. For example, rather than putting Yellow-breasted Chat in its own family, Boyd puts it within the blackbird family.
So what do you think? Is preserving “traditional” bird families worth doubling or tripling the number of families in this section of the avian tree? (And if we do it here, why not elsewhere in the tree?) Or does it make more sense to have fewer families, even if it means groups like blackbirds and wood-warblers become subfamilies within a larger family?
I think 16 families is too much for me — after all, we’re not talking about groups of birds that have wildly different morphologies or life strategies, here. Could we live with a family that combines tanagers and cardinals? Or blackbirds and warblers? I think so. How about you?
Red-winged Blackbird (Agelaius phoeniceus) by David J. Ringer