Pelecanae II

The 45 Orders








Musophagidae: Turacos Lesson, 1828

6 genera, 23 species HBW-4

Following Hacket et. al (2008), the turacos are considered sister to the Aequornithes, although other positions are possible. The arrangement of the Turacos is based on a combination of Veron and Winney (2000) and Njabo and Sorenson (2009). Both use essentially the same data set (except for bannermani), but analyze it differently, with mostly the same results.

As in previous phylogenies of the turacos, there are three subfamilies: Corythaeolinae, Criniferinae, and Musophaginae. Corythaeolinae is monotypic. Musophaginae variously ends up sister to each of the others, so I treat this as an unresolved trichotomy. Within Criniferinae, Veron and Winney (2000) and Njabo and Sorenson (2009) found that the White-bellied Go-away-bird is sister to the rest. This demands a change of genus for it, in this case to Criniferoides (Roberts, 1926).

They also found that the Purple-crested and Ruwenzori Turacos are sister species, and basal in the Musophaginae subfamily. Veron and Winney (2000) also recommend placing them in the same genus. In that case Gallirex has priority.

For the rest, the tree here leaves two main naming options. One is to put them in one genus (Tuaraco). This does a poor job of reflecting phylogeny. The other option is the one followed here, using a more narrowly circumscribed Tuaraco. The name Menelikornis (von Boetticher 1947) applies to the White-cheeked Turaco, while Proturacus (Bates 1923) has priority for the Bannerman's Turaco group. Finally, given the difference in appearance between the two Musophaga and the Yellow-billed Turaco, I perfer to put the latter in a separate genus. It becomes Pseudopoetus (von Boetticher 1947).

Corythaeolinae: Great Blue Turaco Verheyen, 1956

Criniferinae: Go-away-birds and Plantain-eaters Verheyen, 1956

Musophaginae: Turacos Lesson, 1828


This brings us to the main subject of this page, the waterbird clade, Aequornithes. The Aequornithes include 7 closely related orders: Gaviiformes (loons), Sphenisciformes (penguins), Procellariiformes (petrels and shearwaters), Ciconiiformes (storks). Pelecaniformes (pelicans, hamerkop, shoebill), Suliformes (frigatebirds, boobies, cormorants, darters), and Ardeiformes (herons and ibis).

There is a lot of support for grouping these birds together (e.g., Cracraft et al, 2004; Ericson et al., 2006a; Gibb et al., 2007; Morgan-Richards et al, 2008). The orders are arragned as in Hackett et al. (2008).


This has been attributed to Wetmore & Miller, 1926, but Coues had already used Gaviae as a suborder in the second edition (1903) of his “Key to North American Birds” (pg. 1047). The term Colymbiformes has also been used. However, the ICZN eventually suppressed the genus Colymbus due to confusion about whether it applied to loons or grebes. Because of this, I have not tried to attribute priority to some earlier form of the order based on Colymbus, even though some case may be unambiguous. An account of this may be found on Wikipedia's Loon page.

Gaviidae: Loons J.A. Allen, 1897 (1840)

1 genus, 5 species HBW-1


Spheniscidae: Penguins Bonaparte, 1831

6 genera, 19 species HBW-1

The penguin taxonomy follows Baker et al. (2006). Although the members of the pairs Macaroni/Royal and Snares/Fiordland are considered separate biological species, the pair Little/White-flippered are not. Christidis and Boles (2008) opined that it was premature to split them, and subsequent analysis have proven them correct. The complicated situation of the Little Penguin is analyzed in detail by Puecker et al. (2009), and I suspect it is not the last word on this. They found two clades, as did previous workers. However, they sampled many more penguins and found the clades did not divide as expected. In particular, there is no support for treating the White-flippered Penguin, Eudyptula minor albosignata as a separate species. Rather, there is a mostly Australian clade (with some New Zealand birds mostly from Otago and Omaru), and a clade covering the rest of New Zealand. Although most of the birds at Omaru seem to group with the Australian E. m. novaehollandiae, not all do. It appears likely that the type of E. m. minor, which is from Dusky Sound, belongs to the New Zealand clade. The significance of the presence of Australian clade birds at Otago/Omaru is yet to be fully understood. E.g., is there interbreeding? If so, how much? Although some uncertainty remains, it looks like two species are involved. The name Little Penguin has been official in Australia for some time, while Blue Penguin has been used in New Zealand, so it makes sense to call them Little Penguin, Eudyptula novaehollandiae, and Blue Penguin, Eudyptula minor.

The Macaroni/Royal and Snares/Fiordland pairs breed on different islands. The differences in appearance and DNA to are sufficient to allow treatment as separate species. In fact, the DNA difference seems to be less than between the Eudyptula clades (Baker et al., 2006), but the Eudyptula plumage differences are smaller and the situation on the breeding grounds is unclear.

Jouventin et al. (2006) make a good case for splitting Rockhopper Penguin into two biological species. I did not find the case for a three-way split compelling (Banks et al, 2006).


Austin (1996), Austin et al. (2004), Kennedy and Page (2002) and Penhallurick and Wink (2004) were useful in organizing the Procellariiformes. Concerning the latter, the comments by Rheindt and Austin (2005) should be noted. Information concerning the Storm-Petrels and Gadfly Petrels was too ambiguous, so they follow Howard-Moore (except for the split of the Galapagos and Hawaiian Petrels).

Oceanitidae: Southern Storm-Petrels Forbes, 1882

5 genera, 9 species Not HBW Family

Oceanitidae tree

The split of the Storm-Petrels into two families was suggested by Nunn and Stanley (1998). See also Hackett et al. (2008).

I've added the Pincoya Storm-Petrel, Oceanites pincoyae, described by Harrison et al. (2013).

I've also added the New Zealand Storm-Petrel, which was rediscovered in 2003 (Gaskin and Baird, 2005; Stephenson et al, 2008a). Details of the capture of one are on the Pterodroma Pelagics web site. Some uncertainty remained as to its identity after the initial reports, but a comparison with museum specimens (Stephenson et al, 2008b) removed any doubt that it was a New Zealand Storm-Petrel. A recent genetic analysis by Robertson et al. (2011), based partly on data from Nunn and Stanley (1998), showed that it belongs in genus Fregetta rather than the monotypic Pealeornis.

Robertson et al. (2011) also found that the Fregetta race leucogaster, often considered a subspecies of the White-bellied Storm-Petrel, is actually much more closely related to the Black-bellied Storm-Petrel. Whether it is a subspecies or distinct species is unclear at this point.

Diomedeidae: Albatrosses G.R. Gray, 1840

4 genera, 21 species HBW-1

Traditionally, the 24 recognized albatross taxa have been grouped into 13 species.

Traditional Albatross Species Limits

24 taxa, 13 species

  • Laysan Albatross, Phoebastria immutabilis
  • Black-footed Albatross, Phoebastria nigripes
  • Waved Albatross, Phoebastria irrorata
  • Short-tailed Albatross, Phoebastria albatrus
  • Royal Albatross, Diomedea epomophora
    • Diomedea epomophora sanfordi
    • Diomedea epomophora epomophora
  • Wandering Albatross, Diomedea exulans
    • Diomedea exulans dabbenena
    • Diomedea exulans amsterdamensis
    • Diomedea exulans antipodensis
    • Diomedea exulans gibsoni
    • Diomedea exulans exulans
  • Sooty Albatross, Phoebetria fusca
  • Light-mantled Albatross, Phoebetria palpebrata
  • Yellow-nosed Albatross, Thalassarche chlororhynchos
    • Thalassarche chlororhynchos chlororhynchos
    • Thalassarche chlororhynchos carteri
  • Grey-headed Albatross, Thalassarche chrysostoma
  • Black-browed Albatross, Thalassarche melanophris
    • Thalassarche melanophris melanophris
    • Thalassarche melanophris impavida
  • Buller's Albatross, Thalassarche bulleri
    • Thalassarche bulleri bulleri
    • Thalassarche bulleri platei
  • Shy Albatross, Thalassarche cauta
    • Thalassarche cauta cauta
    • Thalassarche cauta steadi
    • Thalassarche cauta eremita
    • Thalassarche cauta salvini

Robertson and Nunn (1998) suggested a radical new taxonomy for albatrosses, elevating all 24 taxa to species level. This has caused a certain amount of controversy, and has not been universally accepted (e.g., Penhallurick and Wink, 2004; Penhallurick, 2012). The 4th edition of the highly regarded Howard and Moore checklist (Dickinson and Remsen, 2013) also continues to follow traditional albatross taxonomy. Their version is shown above.

Nonetheless, many other sources have moved toward the Robertson and Nunn taxonomy, and the TiF list uses a 21 species version. IOC 3.3 uses the same 21 species list as TiF. BirdLife International (ver. 5) additionally splits T. cauta and T.steadi for 22 species. The AOU's SACC has adopted the 3-way split of Thalassarche cauta used here (see proposals #155 and #255. Clements 6.7 accepts only this split and uses a 15 species list. The SACC also considered splitting Diomedea exulans into 4 species (see proposal #388). This was unable to gain the required 2/3's majority (the vote was 6-4 in favor of the split). Penhallurick (2012) makes a case for retaining the traditional classification.

How to treat slightly differentiated allopatric taxa, where the breeding ranges do not overlap, is often a thorny issue. If you read SACC proposal #388, you will see just how contentious it is.

My take on it is that there is some evidence of restricted gene flow between many of these taxa—a sign of legitimate biological species. Although the evidence is a long way from being convincing, I think it is enough to barely tip the scale in favor of the 21-species treatment below, at least for the present.

Burg and Croxall (2004), Bried et al. (2007), and Rains et al. (2011) provided support for most of the Robertson and Nunn splits in the Wandering Albatross group (except for D. antipodensis gibsoni), while Burg and Croxall (2001) examined the Black-browed/Gray-headed Albatross group. The Shy Albatrosses were studied by Abbott and Double (2003a, b). Interestingly, the Wandering Albatross in the narrow sense remains widespread even after the other taxa in the group (Tristan, Antipodes, and Amsterdam Albatrosses) are split off.

The phylogeny used here is based on Nunn and Stanley (1998) and Chambers et al. (2009). Finally, the term platei is often used for the northern populations of Buller's Albatross. It is said to refer instead to a juvenile of the southern population, in which case a new name is needed for the northern population (e.g., Chambers et al., 2009).

Hydrobatidae: Northern Storm-Petrels Mathews, 1912-13 (1865)

4 genera, 17 species HBW-1

The Hydrobatidae have been rearranged based on Nunn and Stanley (1998) and Penhallurick and Wink (2004). This entails moving the Fork-tailed Storm-Petrel, Oceanodroma furcata, to the genus Hydrobates. Since O. furcata is the type species of Oceanodroma, it is helpful to give other genus names to the other three Hydrobatidae clades. Fortunately, the supply of available names is more than adequate. Those that are relevant are Cymochorea (Coues 1864, type leucorhoa) and Halocyptena (Coues 1864, type microsoma), and Thalobata (Matthews and Hallstrom 1943, type castro).

I've grouped melania and matsudairae together as they are sometimes considered conspecific. That pair is sister to the microsoma/tethys pair, and all join Halocyptena. I've also grouped two other possibly conspecific pairs, tristrami and markhami, and monorhis and leucorhoa. Homochroa might be close to the leucorhoa group. All of these go in Cymochorea. It's not clear where hornbyi goes, and it is provisionally placed somewhere in Cymochorea too.

That brings us to the basal group, the contentious Band-rumped (Madeiran) Storm-Petrel, Thalobata castro. Traditionally, it has been thought almost undifferentiated across the Atlantic and Pacific. Now we find that the genes reveal both substantial geographic and seasonal structure, enough that some recommend dividing it into a number of species (see Bolton (2007); Bolton et al., 2008; Friesen et al., 2007; Smith and Friesen, 2007; Smith et al., 2007).

In several locations, Band-rumped Storm-Petrel breeds in both the hot and cool seasons. Recent studies have found that the hot-season population is different from the cool-season population (e.g., Bolton, 2007; Frisen et al., 2007). The following table shows the island groups where Band-rumped Storm-Petrels breed, the season they breed, and applicable subspecific names. There may also be a population breeding on or near Sao Tome, but breeding sites have never been located. Further, it is unknown how closely the St. Helena and Ascension birds are related.

The breeding locations and seasons are:

Location Season Subspecies TiF Species
Ascension &
St. Helena Islands
hot helena castro
Azores hot monteiroi monteiroi
castro castro
Cape Verde Islands protracted
jabejabe jabejabe
Galapagos Islands both bangsi cryptoleucura
Hawaiian Islands hot cryptoleucura cryptoleucura
Japan hot kumagai cryptoleucura

Because they breed in the same location, there is a tendency to think of these as sympatric populations. Since they don't interbreed, they must be distinct species. QED.

Some have even suggested that castro be restricted to the birds breeding in Madiera (Desertas and Selvagem) during the hot season. The rest would be separated as Grant's Storm-Petrel, which does not yet have a scientific name. I find this hard to swallow. Based on Friesen et al. (2007) and Smith et al. (2007), the genetic distances appear to be quite small. Any separation between them is quite recent, perhaps within the Holocene.

Although Friesen et al. (2007) suggest the ancestral birds bred in the hot season, I don't really see this. The Cape Verde population is sister to the others and has a prolonged breeding season. If the ancestral population spread from there, one could easily see it adapting to local conditions that variously support breeding in the hot and/or cool seasons.

This suggests that considering them as sympatric gives the wrong impression. Rather, these populations occupy different niches that in some cases are separated temporally rather than geographically. They are better regarded as being adjacent (or even isolated) rather than overlapping.

This changes the picture. If we think of these populations as potential allospecies, they may not make the grade. There's not much differentiation. More evidence is needed, and there is more for some populations. Bolton (2007) used tape playback to explore whether there are pre-mating barriers to interbreeding. He investigated populations on the Cape Verde, Galapagos, and Azores islands. Although birds responded to calls of birds from their own islands, response to birds from other islands was weak and often no more than to unrelated control species.

This suggests that at least the subspecies tested — jabejabe (Cape Verde), bangsi (Galapagos), monteiroi (Azores hot season), and castro (Azores cold season only) — are distinct biological species. What about the other populations? We first consider the remaining Atlantic populations. Table 3 in Smith et al. (2007) addresses this issue. It shows that the northern Atlantic populations other than monteiroi are quite closely related (estimated divergence times from 100(!) to 17,000 years). Accordingly, I keep them all in T. castro. It also suggests that the birds from Ascension (and St. Helena?) are fairly close to the main populations of castro (divergence time 15,000-30,000 years, as opposed to about 100,000 years between monteiroi and castro, and 200,000-300,000 between jabejabe and either castro or monteiroi). Accordingly, I also treat helena as a form of T. castro.

Click for Storm-Petrel tree
Click for Storm-Petrel tree

That brings us to the Pacific populations. We start with the hot and cool season breeders at the Galapagos Islands. Bolton (2007) found they did not respond to the calls of band-rumped storm-petrels from the Atlantic. Moreover, Smith et al. (2007) found divergence times of over 200,000 years between them and the Atlantic breeders. Finally, Smith and Friesen (2007) found only weak evidence that these involve a cryptic species, and suggested they are only as distinct from each other as subspecies. Here they are treated as part of the same species, distinct from the Atlantic species. The analysis of Freisen et al. (2007) found that the Japanese and Galapagos breeders form a separate clade. Returning to Table 3 of Smith et al. (2007), we also see that the Hawaiian breeders belong in this group. Moreover, the divergence time of 150,000-200,000 years does not compel us to treat them as separate species from each other (absent further evidence). Accordingly, I treat the Pacific populations of band-rumped storm-petrels as a single species, T. cryptoleucura, including bangsi (Galapagos) and kumagai (Japan).

When all is said and done, I treat the band-rumped storm-petrels as 4 species. These species are separated not only by breeding location, but by whether they breed in the hot or cool season. In some cases there is little genetic differentiation between hot or cool season breeders, or across islands. When there is no other evidence they form separate species, those populations are lumped together, either as T. castro or T. cryptoleucura.

Pelecanoididae: Diving-Petrels G.R. Gray, 1871 (1850)

1 genus, 4 species HBW-1

Pelecanoididae tree The diving-petrels are traditionally considered a separate family from the petrels (Procellariidae). In many ways, including size, shape, and flight style, they are a southern counterpart of the smaller auks.

Procellariidae: Petrels, Shearwaters Leach, 1820

15 genera, 92 species HBW-1

Click for Procellariidae tree
Click for Procellariidae tree

The relationships of the Pterodrominae remain somewhat murky, although the group from mollis to deserta is in decent shape. The taxa shown in brown are subspecies that may deserve species status.

Among the Petrodroma, I've elevated the Desertas Petrel, Pterodroma desertas to species status based on Zino et al. (2008) and Jesus et al. (2009).

The Northern Fulmar, Fulmarus glacialis, has been split into the Atlantic Fulmar, Fulmarus glacialis and the Pacific Fulmar, Fulmarus rodgersii, based on Kerr and Dove (2013), who estimated their most recent common ancestor ocurred about 3 million years ago. Although the separation was clear enough in mitochondrial DNA, it didn't show in nuclear DNA. Presumably they simply looked a slow-evolving gene.

Pterodrominae: Gadfly Petrels Verheyen, 1958 (1856)

Fulmarinae: Fulmars Bonaparte, 1853

Pachyptilinae: Prions Oliver, 1930

Procellariinae: Procellarine petrels Leach, 1820

Puffininae: Shearwaters Reichenbach, 1850

The division of Puffinus into species is based on Austin et al. (2004). Since it is doubtful that the two clades of Puffinus (here called Ardenna and Puffinus) are more closer related to each other than to Calonectris, they are placed in separate genera.

The Calonectris shearwaters have been studied by Gómez-Díaz et al. (2006). They found that the three Atlantic taxa, borealis, diomedea, and edwardsii, form distinct clades that are roughly equidistant genetically, with diomedea perhaps closer to edwardsii. Their study of morphology found diomedea and borealis very close, with edwardsii somewhat more distant. I've treated this as an unresolved trichotomy on the tree. Following the recommendations of Sangster et al. (2012), the three Atlantic taxa are considered distinct species. The Mediterranean population takes the name Scopoli's Shearwater, Calonectris diomedea, the Cape Verde population becomes Cape Verde Shearwater, Calonectris edwardsii, while Cory's Shearwater is now restriced to Calonectris borealis.

The Cory's/Scopoli's split is of potential interest in the ABA area as there are several specimens of Scopoli's from New York in the early 20th century (Bull, 1974). More recently, Scopoli's has been photographed off the North Carolina and Florida coasts.

That brings us to the Puffinus species swamp. Although Austin et al. (2004) went a long way toward clarifying matters, not all of their results were conclusive, and an inability to extract DNA from certain specimens meant that some taxa were not included (specimens of auricularis, bannermani, and gunax did not yield usable DNA, while heinrothi was not sampled at all). They only examined a single gene: cytochrome-b. Although cytochrome-b is usually pretty reliable at this level of analysis, we would be happier if it were confirmed by a multi-gene analysis. Moreover, some clades have weak support, and additional genes might clarify the situation there.

Several extinct Puffinus taxa have been identified. Olson (2010) makes a strong osteological case that fossil bones from Bermuda previously named P. parvus actually belong to Boyd's Shearwater, P. boydi. It appears likely it was extirpated from Bermuda following human occupation. Interestingly, Audubon's Shearwater then briefly colonized the island, but was extirpated in the 20th century. Ramirez et al. (2010) attempted to examine DNA from the extinct Lava Shearwater, P. olsoni, and the Dune Shearwater, P. holeae. Although they were successful with with olsoni, which is probably best regarded as a form of the Manx Shearwater, P. puffinus, they were unsuccessful with holeae.

One interesting thing about the various Puffinus races is the limited overlap in breeding range. Only the Manx Shearwater, P. puffinus even shares an island with other types of Puffinus. This happens even when two or more Puffinus are present in the same area. This helps strengthen the case for species status of a number of races.

Heinroth's Shearwater, Puffinus heinrothi, differs in plumage from most of Puffinus (in our narrow sense). No DNA information is available. It's probably relatively basal and I've listed it first to highlight the uncertainty.

Of the taxa we have DNA for, the Christmas (nativitatis) and Galapagos (subalaris) Shearwaters are basal. They may be more closely related to each other than the rest of Puffinus, but this is not entirely clear (compare Austin et al., 2004 and Ramirez et al., 2010). In any event, the remaining species form a clade, with Hutton's (huttoni) and Fluttering (gavia) Shearwaters of New Zealand grouping together. All of these taxa are monotypic.

The rest of the Puffinus shearwaters are more tightly grouped, but divide into two parts: an Audubon/Manx group and a Tropical Shearwater group. However, there is some ambiguity in the analysis, and the Manx group may actually be basal (or two basal groups). In any event, the inferred timing of the split between Manx (puffinus), Yelkouan (yelkouan), and Balearic (mauretanicus) Shearwaters post-dates the refilling of the Mediterranean Sea about 5 million years ago. Further, the split between the Atlantic Manx/Audubon two clades may have been driven by the closing of the Isthmus of Panama which completed about 3 million years ago. If the isthmus hypothesis is correct, I wonder whether there was one widespread small shearwater prior to the cleavage of the oceans, or whether groups separated on either side of the isthmus then diversified east or west into their respective seas, finally meeting again near the Tropic of Capricorn north of New Zealand.

Besides the Manx group, the Atlantic part includes the Little/Audubon's group. The southerly Little Shearwater (assimilis), includes assimilis, tunneyi, kermadecensis, haurakiensis, and elegans. Arguably elegans should be raised to species level as Subantarctic Shearwater. However, the sampling of elegans did not adequately reflect its range, and I prefer to wait for more information (the brown color on the tree indicates this uncertainty). The northerly Audubon's group includes 4 taxa: Audubon's Shearwater (P. lherminieri lherminieri and P. l. loyemilleri (if valid)), Barolo Shearwater (P. baroli, and Boyd's Shearwater, P. boydi.

The last group contains the rest. These birds breed in the Indian and Pacific Oceans, from the east coast of Africa to the west coast of the Americas. The second portion is relatively clear-cut. It includes the recently discovered Bryan's Shearwater, Puffinus bryani (Pyle et al., 2011), the monotypic Black-vented (P. opisthomlelas) and Townsend's (P. auricularis) Shearwaters, and Newell's Shearwater (P. newelli, plus myrtae). The 10 remaining taxa appear to be closely related. The unsampled Bannerman's Shearwater, P. bannermani, of Japan is treated as a separate species, as is the Persian Shearwater (P. persicus plus temptator). The remaining races are very closely related and are treated as a single species: Tropical Shearwater, P. bailloni. However, this species is sometimes split further into a Pacific group, Atoll Shearwater (dichrous, plus polynesiae, colstoni, nicolae, and presumably gunax), leaving bailloni and the possibly redundant atrodorsalis as Baillon's Shearwater.

CICONIIFORMES Bonaparte, 1854

Hackett et al. (2008) found that the storks were basal in the remaining Pelecanae. Slikas (1997) did not come to a definitive conclusion on how to arranged the genera of the Ciconiidae. I've adopted her maximum likelihood tree. However, it may not be correct, and there were indications that Ciconia itself may not be monophyletic.

Ciconiidae: Storks Sundevall, 1836

6 genera, 19 species HBW-1

SULIFORMES Sharpe 1891

AOU officially adopted the term Suliformes in the 51st supplement. Sharpe had previously used Sulae as a suborder. For that matter, he also had Fregatae and Phalacrocoraces as suborders. The Suliformes had previously been considered part of the Pelecaniformes, a tradition that dates back to their naming by Sharpe.

The Suliformes were traditionally considered part of the Pelecaniformes (as were the tropicbirds). After all, how likely was it that such unusual features as a totipalmate foot and gular pouch would arise independently? They also share the location of the salt-excreting gland and all lack an incubation patch. These similarities lead Linneaus to put all but the tropicbirds (which lack the gular pouch) in the same genus.

It wasn't until the mid-20th century that ornithologists started to suspect that maybe these birds didn't all belong together. Hedges and Sibley (1994) used DNA hybridization to argue that not only did the pelicans and frigatebirds not belong with the group, but that the tropicbird also didn't belong.

In fact, their Figure 2 is quite interesting. If you try to map it onto the tree I'm using, you find that the tropicbirds are outside the Pelecanae entirely. More recent DNA analyses based on sequences usually put the frigatebirds (but not pelicans) in a group with the boobies, gannets, cormorants, and darters. We follow that here. Note that morphological support for this clade is not strong (Mayr, 2008).

Fregatidae: Frigatebirds Degland & Gerbe, 1867 (1840)

1 genus, 5 species HBW-1

The frigatebird taxonomy follows Kennedy and Spencer (2004).

Sulidae: Gannets, Boobies Reichenbach, 1849 (1836)

3 genera, 10 species HBW-1

Click for Sulidae tree
Click for Sulidae tree

Sulid taxonomy follows Patterson et al. (2011), which is similar to Friesen et al. (2002), except that Papasula is considered basal. The extinct Tasman Booby, often considered a separate species, is here considered a subspecies of the Masked Booby following Christidis and Boles (2008). More recently, Steeves et al. (2010) provides strong evidence for this treatment. They further argue that Sula dactylatra tasmani is identical with the still extant subspecies S. d. fullagari, in which case both should be referred to as S. d. tasmani.

Anhingidae: Anhingas Reichenbach, 1849 (1815)

1 genus, 4 species HBW-1

Phalacrocoracidae: Cormorants Reichenbach, 1849-50 (1836)

2 genera, 41 species HBW-1

The arrangement below is based on the DNA analyses of Kennedy et al. (2000, 2001, 2009) and the osteological analysis of Siegel-Causey (1988). Where the studies overlap, there is considerable disagreement, and I have followed Kennedy et al. in these cases. You can click on the tree diagram for a hypothetical phylogeny. The species in black were included in Kennedy et al.'s analysis, while no DNA data is available for species marked in blue on the tree. In those cases, I've followed Sigel-Causey when possible. The placement of Bank Cormorant remains quite uncertain. The most recent effort by Kennedy et al. (2009) resolved the long-controversial status of the Flightless Cormorant. They found it is sister to the Neotropic and Double-crested Cormorants.

On the tree, I've included available genus names that could be used to subdivide Phalacrocorax. Unless they are generally adopted, they are perhaps best thought of as subgenera.

Although work has been done on the phylogeny of the blue-eyed shag complex, it remains murky. There are eight Phalacrocorax taxa involved: albiventer, atriceps, bransfieldensis, georgianus, melanogenis, nivalis, purpurascens, and verrucosus.

Following SACC, the King Cormorant, Phalacrocorax albiventer is considered a color morph of the Imperial Cormorant, Phalacrocorax atriceps (aka Blue-eyed Shag). Rasmussen (1991) makes a strong case. The key points are in the abstract: frequent hybridization and non-assortative mating in the contact zones. The genetic distance as measured using allozymes also seems very small.

However, Antarctic Shag, Phalacrocorax bransfieldensis and South Georgia Shag, Phalacrocorax georgianus are split off as separate species (Siegel-Causey and Lefevre, 1989). They present evidence that the breeding range of the Antarctic Shag formerly included the area around Tierra del Fuego, part of the breeding range of P. atriceps. They argue that there is no sign of interbreeding, indicating they are separate biological species. The South Georgia Shag seems more distinct, and is arguably also a separate species. These cluster together to the exclusion of the Kerguelen Shag in Siegel-Causey (1988), in which case it would also seem to be a separate species.

That still leaves 3 taxa to deal with. Unfortunately, there seems to be little solid information to work with. Christidis and Boles (2008) note all this, but consider these three taxa to be subspecies of P. atriceps. There is one piece of evidence. The genetic distance between purpurascens and albiventer is small enough for them to be a single species. However, it's also large enough to be different species. In HBW-1, Orta (1992) takes the opposite tack and splits them.

In version 2.17 I followed Christidis and Boles concerning melanogenis, nivalis, purpurascens. This left me with the same four species as Sibely and Monroe (1990). I gather I'm not the only one uncomfortable with that solution. It just doesn't make biogeographic sense to have birds breeding on the other side of the world lumped into atriceps when the physically closer taxa are considered separate species. In the absence of definitive information, this version follows Orta in considering them as three species, and presumes all three are closer to the Kerguelen Shag than to the Imperial Cormorant.


The status of two monotypic families, the Shoebill and the Hammerkop, has been a perennial issue. The analysis of Ericson et al. (2006a) indicates that both are relatives of the pelicans. Indeed, their tree allows them to be lumped into the same family. We keep them separate not only because of their uniqueness, but also because the division between them seems to be ancient.

Scopidae: Hammerkop Bonaparte, 1849

1 genus, 1 species HBW-1

Balaenicipitidae: Shoebill Bonaparte, 1853

1 genus, 1 species HBW-1

Pelecanidae: Pelicans Rafinesque 1815

Pelican tree
Pelican species tree

The pelicans have been studied by Kennedy et al. (2013). The arrangement on the tree and order below reflects the relationships they found. Note how the New World Pelicans and Old World Pelicans form sister clades. They also found that the Pink-backed, Dalmatian, and Spot-billed Pelicans are quite closely related.

1 genus, 8 species HBW-1


It's not entirely clear that the herons and ibises are sister clades. Should the ibises and spoonbills turn out to form a separate clade, the name Plataleiformes (Newton 1884) has priority for that clade.

Threskiornithidae: Ibises, Spoonbills Poche, 1904

13 genera, 35 species HBW-1

Threskiornithidae tree The traditional treatment of the ibises and spoonbills as sister subfamilies is just wrong. The spoonbills are not the sister group of the ibises. Rather, they are most closely related to Threskiornis and perhaps Pseudibis. Krattinger's MA thesis (2010) shows this fact clearly. Chesser et al. (2010) is consistent with this idea, and it already appeared in Sibley and Ahlquist (1990; esp. Fig. 367). Oddly, Sibley and Ahlquist did not comment on it. Perhaps they found it too unbelievable.

Interestingly, there had been other hints that the spoonbills should not be treated as a subfamily. Matheu and del Hoyo (1992=HBW-1) mention that the Eurasian Spoonbill has been known to hybridize with Black-headed Ibis,Threskiornis melanocephalus. Unfortunately, they did not make the connection with Sibley and Ahlquist's results.

Krattinger (2010) also estimated divergence times. His results suggest that the spoonbill clade originated about 15 million years ago (with large error bars). That time span is more than sufficient to evolve even such a distinctive bill. The Hawaiian Honeycreepers evolved theirs in half that time (Lerner et al, 2011).

Krattinger did find a deep division in Threskiornithidae, but it was between the exclusively New World genera (Eudociminae) and the rest (Threskiornithinae), not between the ibises and spoonbills. The treatment as subfamilies emphasizes this radical change in taxonomy of the ibises and spoonbills.

Krattinger (2010) examined DNA from just over half of Threskiornithidae. The exact position of some of the Old World genera was not conclusively resolved (Bostrychia, Lophotibis, Nipponia), but this tree is a reasonable interpretation of what Krattinger found. The resulting tree is also consistent with Chesser et al. (2010) and Sibley and Ahlquist (1990). Question marks indicate genera that were not sampled. The order within the spoonbills is based on Chesser et al. (2010), which included all of the spoonbills.

Current thinking is that the extinct Reunion Solitaire was actually an ibis! Moreover, it seems to have been closely related to the sacred-ibises (see Mourer-Chauviré et al., 1995). Accordingly, it appears at the head of Threskiornis.

You may think it odd that the family is called Threskiornithidae when Eudociminae is a much older name. The family was once referred to as Ibididae (based on Ibis Cuvier 1816), but the oldest use of the genus Ibis actually refers to the Mycteria storks. Ibididae had to be replaced, and everyone ultimately settled on basing it on Threskiornis, which replaced Cuvier's version of Ibis. Ultimately, the ICZN ruled on this (Opinion 1674) and the family is called Threskiornithidae.

Eudociminae Bonaparte, 1854

Threskiornithinae Poche, 1904

Ardeidae: Herons, Egrets, Bitterns Leach, 1820

20 genera, 72 species HBW-1

Ardeidae tree The Boat-billed Heron was previously considered to be the only member of the Cochlearidae, but is now just another heron. The list here is pieced together from the limited DNA evidence available (Chang et al., 2003; Sheldon et al., 2000) and more traditional morphological evidence.

The DNA evidence puts the tiger-herons first (only one was included), followed by the Boat-billed Heron. Then there is a group that includes Zebrilus, Botaurus and Ixobrychus. Chang et al. (2003) found the Black Bittern embedded in Ixobrychus. It's sometimes put in a monotypic genus Dupetor, which is here considered part of Ixobrychus.

It's not at all clear what happens with the night-herons. I've grouped them into a clade, but that has only weak genetic support. Still, the other options did not fare better.

The remaining genera mostly fall into two main clades. Butorides probably goes in one or the other, but the DNA is quite equivocal, so I put them in-between. I'm also guessing that Agamia is near Ardeola, but there's no DNA evidence, and the other evidence is pretty vague.

We consider the Ardea clade first. The Great Egret is sometimes put in a separate genus, Casmerodius. The 12S rRNA tree of Chang et al. puts them sister to the Intermediate Egret, and both sister to Ardea. Sheldon et al. (2000) didn't include the Intermediate Egret, but also found Casmerodius sister to Ardea. This is also why the Intermediate Egret is placed in Mesophoyx. Note that both of these are sometimes put in Egretta, but the DNA says no on this. The placement of Bubulcus follows both Chang et al. and Sheldon et al.

Kushlan and Hancock (2005) and Christidis and Boles (2008) suggested treating the Great Egret as two species: Casmerodius albus and Casmerodius modestus. Certainly, the genetic distance between some of the Great Egret subspecies is quite large, comparable to that between Great and Intermediate Egret (Sheldon, 1987), but the subspecies analyzed are egretta and modestus. This suggest no significant gene flow between albus and modestus, that they are distinct biological species. But how do the other subspecies (albus and melanorhynchos) fit in? Both Kushlan and Hancock, and Cristidis and Boles, suggest that egretta should be grouped with albus and melanorhynchos. However, Pratt (2011) argues that the split should be between egretta and the rest, mainly on the basis of breeding plumage. The evidence is just not there to draw a definitive conclusion. However, it seems clear enough that the Great Egret actually includes two or more species. I think this needs to be acknowledged, and that Pratt's arrangement makes more sense. In other words, the Great Egret has been split into the monotypic American Egret, Casmerodius egretta, and Great Egret, Casmerodius albus (including melanorhynchos and modestus).

The status of the Great White Heron, Ardea herodias occidentalis, remains controversial (e.g., Stevenson and Anderson, 1994). It is very near the borderline for species status. Genetically, it is nested within the larger Great Blue Heron clade. However, in their overlap zone in extreme south Florida, there seems to be little interbreeding between the dimorphic Great White Herons (the dark morph is sometimes called Würdemann's Heron) and the monomorphic Great Blue Herons (McGuire, 2002). Moreover, the Great Blue Herons of the Florida peninsula (wardii) are more closely related to those of the northern US (herodias) than to occidentalis. However wardii and herodias are closer to occidentalis than any of them are to fannini. For the present, I'm following AOU by treating them as one species although I'm not convinced this is correct.

The other group is the Ardeola-Egretta clade. Syrigma seems to belong here according to the DNA. That makes it natural to include Pilherodius too, but the relationships between all of these are unclear. As mentioned above, I'm guessing that Agamia belongs with this group, but there is not much to go on.

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