Passeriformes I

Passerines

Tyranni: Suboscines

Passeri: Oscines

Passerida

Sylvioidea
Muscicapoidea and allies
Passeroidea

The 46 Orders

Paleognathae

Galloanserae

Columbimorphae

Otidimorphae

Strisores

Opisthocomiformes

Gruiformes

Mirandornithes

Ardeae

Charadriiformes

Telluraves

Afroaves

Australaves

PASSERIFORMES Linnaeus, 1766

The name Passeriformes (in the form Passeres) has been attributed to Linnaeus, 1766. In the absence of a code for order-level names, I rather reluctantly continue that because other choices may create nomenclatural havoc. However, it suffers from a problem. Linnaeus did not base it on a genus name he used. Indeed, he already used in in 1758. In 1766, he at least mentions the genus Passer, citing Brisson. However, he considered the House Sparrow to be Fringilla domestica, not Passer domesticus. Thus Passeres is not properly based on a genus name. According to Brodkorb (1978), who does attribute Passeriformes to Linnaeus, Nitzsch, 1820 is next in the priority line, but I have similar doubts about his use of Passer also. I think strictly enforcing the requirement that the order-level name be based on one of the genera used in the text would end up giving priority to Corviformes or Hirundiformes (Wagler, 1830).

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 and 4th editions shows how much revision has been necessary. Many passerines have been classified in the wrong family (and genus) which made it harder to determine proper family boundaries and relations. Recent work on passerine taxonomy has done much to clarify the situation, although some issues still remain.

Jarvis et al. (2014) estimate that the Passeriformes-Psittaciformes split occurred approximately 55 mya, but that the basal split within Passeriforems (between Acanthisitti and the rest) dates to only 39 mya. Selvatti et al. (2017) give an earlier date for the basal split, about 50 mya. Regardless of when it occured, the fossil record suggests that there was more going on than we presently see.

The earliest fossils that may belong to the Passeriform crown group date from the Oligocene, but there are some Eocene fragments that may be stem group Passeriformes (see Mayr 2009 for more). However, there is a extinct sister group to the Passeriformes, the Zygodactylidae (Mayr, 2008b; Mayr, 2011; DeBee, 2012). Fossils of the Zygodactylidae have been found starting in the early Eocene (Green River Formation, Wyoming; Danish Fur Formation, Denmark) to the middle Miocene (France, ca. 12 mya). Based on the fossil evidence, these were once one of the most abundant small birds (Mayr, 2009) and were widespread in the northern hemisphere.

Unlike modern Passeriformes, Zygodactylidae have a zygodactyl foot. This may indicate their common heritage with the zygodactyl parrots. Boletho et al. (2014), in a study of foot development, indicate how this may have occurred.

New Zealand Wrens: Acanthisitti Wolters, 1977

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 Passeriform crown group. Attempts to date the split between the Acanthisittidae and the other passerines using vicariance suggest that it may date to the period when New Zealand separated from a still-joined Australia and Antarctica (see Ericson et al., 2002a). However, Jarvis et al. (2014) date the split much later, around 2014.

Acanthisittidae: New Zealand Wrens Sundevall, 1872

2 genera, 4 species HBW-9

EUPASSERES Ericson et al., 2002b

The remaining passeriformes are called the Eupasseres. They consist of the oscines (Passeri) and the suboscines (Tyranni).

Suboscines: Tyranni Wetmore & Miller, 1926

The oscines have roots in Australia. The origin of the suboscines (Tyranni) has been less clear, but also appears to be southern. The recent results of Selvatti et al. (2017) suggest that both the Tyrannides and Eurylaimides originally diversified in South America (or Antarctica).

It had previously been suggested 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.

My current view is that these naive vicariance ideas are just wrong, and that the suboscines got where they are by flying. In this case, Selvatti et al. (2017) provide support for my position by finding that the basal split in Eurylaimides is between the South American Sapayoa and the Old World Eurylaimides.

To order the Passeriformes, 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 Seebohm, 1890

Click for Eurylaimides tree
Click for 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 plus Sapayoa (Eurylaimides) and the New World suboscines (Tyrannides). The general arrangement of the Old World suboscines, the pittas, asities, and broadbills, and Sapayoa now follows Prum et al. (2015). They did not include the Sapayoa in their analysis.

The Sapayoa, Sapayoa aenigma, has found a new home in this group as the only New World representative of the Eurylaimides (see Fjeldså et al., 2003; Chesser, 2004). Selvatti et al. (2017) make the best effort at resolving the position of the Sapayoa and find it is sister to the other Eurylaimides. Note however that the coverage is not as complete as I would like, and that the four other papers that include Sapayoa— Fjeldså et al., 2003; Chesser, 2004; Irestedt et al. (2006b); Moyle et al., (2006a) did not attain consensus on where the Sapayoa goes.

Moyle et al. (2006a) found that the broadbills were not a natural grouping. Some are more closely related to the asities than they are to the other broadbills. This list considers the broadbills to consist of three families, one of them sister to the asities, the other two are sister to each other, and then to the Pittidae. The list starts with the asities.

Sapayoidae: Sapayoa Irestedt et al., 2006

1 genus, 1 species Not HBW Family (HBW-9:167)

The Sapayoa is on its own old branch in Eurylaimides. It is the Old World Suboscine in the Neotropics. There were likely many more members of its clade, with it the only survivor.

Philepittidae: Asities Sharpe, 1870

2 genera, 4 species HBW-8

The Asities of Madagascar are also placed in their own family. Prum et al. (2015) found that the division between the Philepittidae and Eurylaimidae dates to almost 20 mya, while Selvatti et al. (2017) placed it around 22 mya. Both agree the split was in the early Miocene. Selvatti et al. also found that the two subfamilies of Philepittidae split about 16 mya.

Philepittinae: Asities Sharpe, 1870

Neodrepaninae: Sunbird-Asities Shelly, 1880

Eurylaimidae: Eurylaimid Broadbills Lesson, 1831

7 genera, 9 species HBW-8

Except for Grauer's Broadbill, which is African, this family is Indo-Malayan. The division between Grauer's Broadbill and the rest is fairly deep, almost 20 mya according to Selvatti et al. (2017), and Grauer's has been placed in a separate subfamily.

Pseudocalyptomeninae Prum, 1993

Eurylaiminae Lesson, 1831

Smithornithidae: African Broadbills Bonaparte, 1853

1 genus, 3 species Not HBW Family (HBW-8:83-4)

The division between African Smithornis and Calyptomena of Sundaland is quite deep. Prum et al. (2015) estimate put it in the early-Miocene, approximately 20 million years ago. It seems reasonable to put them in separate families.

Calyptomenidae: Asian Green Broadbills Bonaparte, 1850

1 genus, 3 species Not HBW Family (HBW-8:84-5)

Pittidae: Pittas Swainson, 1831

3 genera, 42 species HBW-8

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

I had earlier split the Red-bellied Pitta, Erythropitta erythrogaster, into Northern Red-bellied Pitta, Erythropitta erythrogaster, and Southern Red-bellied Pitta, Erythropitta macklotii

The more extensive splits suggested by Irestedt et al. (2013) have been considered by Collar et al. (2015). As a result, I've further split Northern Red-bellied Pitta, Erythropitta erythrogaster, into

Moreover, Southern Red-bellied Pitta, Erythropitta macklotii, has been split into

I'm not entirely persuaded by these splits. The DNA differences found by Irestedt et al. (2013) are not strong enough to insist on species status. Collar et al.'s (2015) analysis mostly relies on plumage differences, some of them subtle. Finally, Rheindt et al. (2010) pointed to the lack of vocal differences between Sula Pitta, Erythropitta dohertyi, and Philippine Pitta, Erythropitta erythrogaster. Given the importance of vocal differences for most suboscines, one really has to wonder whether these truly represent different species.

Based on Rheindt and Eaton (2010), the Banded Pitta, Hydrornis guajanus is split into three species: Malayan Banded-Pitta, Hydrornis irena, Bornean Banded-Pitta, Hydrornis schwaneri, and Javan Banded-Pitta, Hydrornis guajanus. Since these are allopatric taxa, it is difficult to establish appropriate species limits. In my mind, the fact that irena seems to cross water barriers that are comparable to those separating the other two species suggests that more than water separates them, that they are biological species.

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