Passeriformes I

Passerines

The 44 Orders

Paleognaths

Galloanserae

Metaves

Pelecanae

Charadriae

Passerae

PASSERIFORMES

There are not only more passerines than any other order of birds, there more passerines than all of the other orders put together. Nearly 60% of all extant bird species are Passeriformes.

Although we have long known which birds are passerines and which are not, their relationships have been poorly understood. A comparison of Clements 5th edition (which uses an old taxonomy) and Howard-Moore 3rd edition (more recent, but not current) shows how much revision has been necessary. There are still many passerines that are classified in the wrong family (and genus) which makes it harder to determine proper family boundaries and relations. Recent work on passerine taxonomy has done much to clarify the situation, and these pages are an attempt to incorporate the latest information.

New Zealand Wrens: Acanthisitti

Until recently the New Zealand wrens were considered suboscines. However, the passerines have a basal split between the New Zealand wrens and all other songbirds (Barker et al., 2002; Barker et al., 2004). The common ancestor of the suboscines and the oscine passerines comes after the split between the New Zealand wrens, so we cannot put the New Zealand wrens in the suboscines. That not only forces them into their own family, but into their own suborder, Acanthisitti.

The Acanthisittidae are endemic to New Zealand. Together with the oldest splits among the suboscines and oscines, this suggest a southern origin for the Passeriformes. Attempts to date the split between the Acanthisittidae and the other passerines suggest that it may date to the period when New Zealand separated from a still-joined Australia and Antarctica (see Ericson et al., 2002a).

Acanthisittidae: New Zealand Wrens

2 genera, 4 species HBW-9

Suboscines: Tyranni

The next split is between the oscines and suboscines. The oscines have roots in Australia. The origin of the suboscines is less clear. One group, the ancestral Tyrannides, went to the Americas (probably South America), while the ancestral Eurylaimides went to the Old World (India?). Although South America and India were once joined with Australia-Antarctica as Gondwana, the separation between them seems to long predate the split between the oscines and suboscines.

One possibility is that all originated when Australia, New Zealand, and Antarctica were still joined, with the ancestral Acanthisittidae in the portion that became New Zealand, the ancestral oscines in the Australian part, and the suboscines in the Antarctic part (which may have had a subtropical climate then). The western suboscines (ancestral Tyrannides) could have easily made their way to South America. The Eurylaimides remain a problem. One suggestion is that the eastern suboscines spread onto the now-submerged Kerguelen Plateau, and thence to India (see Moyle et al., 2006a). They could then ride along as India drifted into Asia.

The oscine group is bigger, so we consider it the main trunk, and investigate the smaller suboscine branch first. It has two parts, the Old World Eurylaimides and the New World Tyrannides.

Old World Suboscines: Eurylaimides

Eurylaimides tree Like the passerines as a whole, the suboscines have generally been identifiable as suboscine, but teasing out the relationships between the suboscines has been difficult. The next division is between the Old World subsocines (Eurylaimides) and the New World suboscines (Tyrannides). The Old World suboscines, the pittas, asities, and broadbills have recently been reorganized (Irestedt et al., 2006b; see also Moyle et al., 2006a). The Sapayoa, Sapayoa aenigma, has finally found a new home in this group as the only New World representative of the Eurylaimides (see also Fjeldsa et al., 2003; Chesser, 2004). However, whether it is closer to the Calyptomenidae or Philepittidae and Eurylaimidae remains unresolved. Using different genes, Irestedt et al. (2006b) find it sister to Calyptomenidae, while Moyle et al (2006a) find it sister to Philepittidae + Eurylaimidae. In either case, the split is quite ancient. The antiquity of the split, together with uncertainty about its closest relatives, justifies separate family status for Sapayoa.

The main split among the Eurylaimides is between the pittas and the rest. Moyle et al. found that the broadbills were not a natural grouping. Some are more closely related to the Sapayoa and the asities than they are to the other broadbills. This list considers the broadbills to consist of two families, one of them sister to the asities, the other sister to the rest of the broadbills, asities, and Sapayoa. In contrast, the SACC treats all of the broadbills, including the asities and sapayoa, as one family, Eurylaimidae.

Calyptomenidae: Calyptomenid Broadbills

2 genera, 6 species Not HBW Family

The division between Smithornis and Calyptomena is quite deep, and it would not be unreasonable to put them in separate families.

Sapayoidae: Sapayoa

1 genus, 1 species Not HBW Family

The Sapayoa has been long separated from the other Eurylaimides, probably since the early Eocene. There were likely many more members of its clade, with it the only survivor.

Philepittidae: Asities

2 genera, 4 species HBW-8

Eurylaimidae: Eurylaimid Broadbills

7 genera, 9 species HBW-8

Pittidae: Pittas

3 genera, 32 species HBW-8

Pitta taxonomy follows Irestedt et al., (2006b), who recommended resurrecting the genera Erythropitta and Hydrornis.

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