Island Thrush (2 Viewers)

I am tired of waiting for the long overdue break up of the Island Thrush species complex, now the largest single unspllt assemblage remaining, so on my 5 hour flight to Ulan Bataar I made speculative predictions for what is currently the species with the most races. I have based it simply on geographic proximity and the existence of endemic species there in other groups. I was being been conservative with the Fiji birds but would not be at all surprised to see 3 or 4 species there alone, and given how the other endemics break out have gone the whole way- 28 species out of 49 taxa!
Be interesting to see how the DNA experts make this work- I recall one study some years back pronounced them all the same, which simply can't be correct-, but I’d make a case on morphology, island endemism and maybe vocals from the few I know. I was surprised BirdLife ducked the issue with the Tobias criteria. Watch this space but don’t hold your breath, at the rate they are going other taxa will have evolved before they pronounce!
Some checklists have split the isolated Taiwan Thrush already, but the rest remain lumped, and many are very poorly known, with some endangered (New Caledonia Thrush) and a couple sadly extinct (Norfolk Island and Lard Howe Island Thrush).

Island Thrush Turdidae Turdus poliocephalus Latham, 1801 OR, AU, PO : Sumatra and Philippines to Fiji Islands
Christmas Island Thrush T. p. erythropleurus Sharpe, 1887 Christmas I. (s of Java)
Sumatran Thrush T. p. loeseri Meyer de Schauensee, 1939 n Sumatra
T. p. indrapurae Robinson & Kloss, 1916 sc Sumatra
Javan Thrush T. p. fumidus Müller, S, 1844 w Java
T. p. javanicus Horsfield, 1821 c Java
T. p. stresemanni Bartels, 1938 ec Java
T. p. whiteheadi (Seebohm, 1893) e Java
Sabah Thrush T. p. seebohmi (Sharpe, 1888) n Borneo
Taiwan Thrush T. p. niveiceps (Hellmayr, 1919) Taiwan
Luzon Thrush T. p. thomassoni (Seebohm, 1894) n Luzon (n Philippines)
T. p. mayonensis (Mearns, 1907) s Luzon (s Philippines)
T. p. mindorensis Ogilvie-Grant, 1896 Mindoro (nw Philippines)
Negros Thrush T. p. nigrorum Ogilvie-Grant, 1896 Negros (sw Philippines)
Mindanao Thrush T. p. malindangensis (Mearns, 1907) nw Mindanao (s Philippines)
T. p. katanglad Salomonsen, 1953 c Mindanao (s Philippines)
T. p. kelleri (Mearns, 1905) se Mindanao (s Philippines)
Sulawesi Island Thrush T. p. hygroscopus Stresemann, 1931 s Sulawesi
T. p. celebensis (Büttikofer, 1893) sw Sulawesi
Timor Thrush T. p. schlegelii Sclater, PL, 1861 w Timor (s Lesser Sundas)
T. p. sterlingi Mayr, 1944 e Timor (s Lesser Sundas)
Seram Thrush T. p. deningeri Stresemann, 1912 Seram (w of New Guinea)
Papuan Thrush T. p. versteegi Junge, 1939 w New Guinea
T. p. erebus Mayr & Gilliard, 1952 ec New Guinea
T. p. keysseri Mayr, 1931 ne New Guinea
T. p. papuensis (De Vis, 1890) se New Guinea
Bismarck Thrush T. p. tolokiwae Diamond, 1989 Tolokiwa (Bismarck Arch.)
T. p. beehleri Ripley, 1977 New Ireland (Bismarck Arch.)
Mussau Thrush T. p. heinrothi Rothschild & Hartert, 1924 St. Matthias (Bismarck Arch.)
Goodenough Thrush T. p. canescens (De Vis, 1894) Goodenough (D'Entrecasteaux Arch.)
Bougainville Thrush T. p. bougainvillei Mayr, 1941 Bougainville (n Solomons)
Kolombangara Thrush T. p. kulambangrae Mayr, 1941 Kolombangara (c Solomons
Guadalcanal Thrush T. p. sladeni Cain & Galbraith, ICJ, 1955 Guadalcanal (s Solomons)
Rennell Thrush T. p. rennellianus Mayr, 1931 Rennell (s Solomons)
Vanuatu Thrush T. p. vanikorensis Quoy & Gaimard, 1832 islands of n Vanuatu
T. p. placens Mayr, 1941 Ureparapara and Vanua Lava (Banks Islands in n Vanuatu)
T. p. whitneyi Mayr, 1941 Gaua I. (Banks Islands in n Vanuatu)
T. p. malekulae Mayr, 1941 Pentecost, Malekula and Ambrym Is. (c Vanuatu)
T. p. becki Mayr, 1941 Paama, Lopevi, Epi and Emae Is. (c Vanuatu)
T. p. efatensis Mayr, 1941 Efate and Nguna Is. (sc Vanuatu)
T. p. albifrons (Ramsay, EP, 1879) Erromango I. (s Vanuatu)
T. p. pritzbueri Layard, EL, 1878 Tanna I. (s Vanuatu) and Lifou I. (Loyalty Is.)
New Caledonia Thrush T. p. mareensis Layard, EL & Tristram, 1879 Mare I. (Loyalty Is.)
T. p. xanthopus Forster, JR, 1844 New Caledonia
Norfolk Island Thrush T. p. poliocephalus Latham, 1801 Norfolk I.
Lord Howe Island Thrush T. p. vinitinctus (Gould, 1855) Lord Howe I.
Fiji Island Thrush T. p. layardi (Seebohm, 1891) w Fiji Is.
Kadavu Thrush T. p. ruficeps (Ramsay, EP, 1875) Kadavu I. (s Fiji)
Vanua Levu Thrush T. p. vitiensis (Layard, EL, 1876) Vanua Levu (n Fiji)
T. p. hades Mayr, 1941 Gau I. (c Fiji(
Taveuni Thrush T. p. tempesti Layard, EL, 1876 Taveuni I. (ne Fiji)
Samoan Thrush T. p. samoensis Tristram, 1879 w Samoa

The HBW website (https://www.hbw.com/species/island-thrush-turdus-poliocephalus) says, about that:

Recent detailed preliminary review assigned 52 subspecies to one of 12 plumage types, then used distributional and limited morphometric data to suggest that 31–38 (concept-dependent) species might be recognized...

Click to expand...

You've got nearly 30 so maybe your list matches the review, which is

Geographic variation in size and coloration in the Turdus poliocephalus complex: a first review of species limits. Univ. Kansas Publ. Mus. Nat. Hist. 40: 1–17.

Click to expand...

But then the web page goes on to give reasons why it might not be possible to turn the preliminary review into something more concrete.

With regard to the Philippine Island Thrushes, as far as I know, only thomassoni has had its song recorded. It is on xeno canto. It seems very few other of the T. p. taxa seem to have had their songs recorded.
T. p. thomassoni does not respond at all to a pre recorded song of niveiceps. I think some of the other Philippine taxa have had their calls recorded - but these are just typical thrush chack chack type calls.

I've seen three of these, probably the most easily seen three, Sabah, Taiwan and Mindanao.

Paul Clapham said:

The HBW website (https://www.hbw.com/species/island-thrush-turdus-poliocephalus) says, about that:



You've got nearly 30 so maybe your list matches the review, which is



But then the web page goes on to give reasons why it might not be possible to turn the preliminary review into something more concrete.

Click to expand...

Thanks Paul, I remember they pointed the way but dod not take it further forward, sadly, I am hoping someone else can do it formally now as it is clear there are multiple species involved.

dnsallen said:

With regard to the Philippine Island Thrushes, as far as I know, only thomassoni has had its song recorded. It is on xeno canto. It seems very few other of the T. p. taxa seem to have had their songs recorded.
T. p. thomassoni does not respond at all to a pre recorded song of niveiceps. I think some of the other Philippine taxa have had their calls recorded - but these are just typical thrush chack chack type calls.

Click to expand...

Thanks Des, I have two Fiji taxa which seem pretty different as well, but I have nothing for the New Guinea birds oddly and they are damn hard on many of the Pacific Islands.

I think it's got to be worth splitting Goodenough Thrush. With a name like that, species rank should be obligatory.

A few years ago, inspired by A. T. Peterson 2007, Geographic variation in size and coloration in the Turdus poliocephalus complex: A first review of species limits (see #2), I, like sicklebill, whiled away some time in speculation and a desire to create distinctive English names, and divided T. poliocephalus (then based on H&M 3 (2003)) as follows:
Turdus erythropleurus Sharpe, 1887. Christmas Island Thrush
T. loeseri Meyer de Schauensee, 1939. Atjeh Mountain Thrush
T. indrapurae Robinson & Kloss, 1916. Korinchi Mountain Thrush.
T. fumidus S. Müller, 1843. Gedeh Mountain Thrush
T. javanicus Horsfield, 1821. Javan Thrush.
T. whiteheadi (Seebohm, 1893) (incl. stresemanni M. Bartels Jr. 1938). Whitehead's Thrush
T. niveiceps (Hellmayr, 1919). Taiwan Thrush
T. thomassoni (Seebohm, 1894) (incl. mayonensis (Mearns, 1907)). Luzon Mountain Thrush
T. mindorensis Ogilvie-Grant, 1896. Mindoro Mountain Thrush
T. nigrorum Ogilvie-Grant, 1896. Negros Mountain Thrush
T. malindangensis (Mearns, 1907). Malindang Mountain Thrush
T. katanglad Salomonsen, 1953. Katanglad Mountain Thrush
T. kelleri (Mearns, 1905). Apo Mountain Thrush
T. hygroscopus Stresemann, 1931. Latimodjong Mountain Thrush
T. celebensis (Büttikofer, 1893). Bonthain Mountain Thrush
T. schlegelii P. Sclater, 1861. Mutis Mountain Thrush
T. sterlingi Mayr, 1944. Ramelan Mountain Thrush
T. deningeri Stresemann, 1912. Seram Mountain Thrush
T. versteegi Junge, 1939. Oranje Mountain Thrush
T. heinrothi Rothschild & Hartert, 1924 (incl. carbonarius Mayr & Gilliard, 1951 (= erebus M & G, 1952); keysseri Mayr, 1931; tolokiwae Diamond, 1989; beehleri Ripley, 1977; bougainvillei Mayr, 1941; sladeni Cain & Galbraith, 1955; rennellianus Mayr, 1931). Melanesian Thrush
T. canescens (DeVis, 1894). Goodenough Island Thrush
T. papuensis (DeVis, 1890). Papuan Mountain Thrush
T. kulambangrae Mayr, 1941. Kolombangara Island Thrush
T. vanikorensis Quoy & Gaimard, 1830 (incl. whitneyi Mayr, 1941; malekulae Mayr, 1941; becki Mayr, 1941). Vanuatu Thrush
T. placens Mayr, 1941. Charming Thrush
T. efatensis Mayr, 1941. Efate Thrush
T. pritzbueri Layard, 1878 (incl. albifrons Ramsay, 1879). Pritzbuer's Thrush
T. mareensis Layard & tristram, 1879. Mare Island Thrush
T. xanthopus Forster, 1844. New Caledonian Thrush
T. poliocephalus Latham, 1802. Norfolk Island Thrush
T. vinitinctus (Gould, 1855). Lord Howe Island Thrush
T. layardi (Seebohm, 1890). Layard's Thrush
T. ruficeps (Ramsay, 1876). Kandavu Thrush
T. vitiensis Layard, 1876. Vanua Levu Thrush
T. hades Mayr, 1941. Hades Thrush
T. tempesti Layard, 1876. Taveuni Thrush
T. samoensis Tristram, 1879. Samoan Thrush

I am impressed by the general concordance with sicklebill.

FWIW Clements has already split off the Taiwan (Island) Thrush. They also recognize 38 "Groups" in the remaining species.

That's true, they did. But their groups are surprisingly different from sicklebill's proposed species.

First of all they split sicklebill's Sumatran, Javan, Luzon, Mindanao, Sulawesi, Timor, and Papuan into a lot of mostly monotypic species.

On the other hand they have a "North Melanesian" group which lumps a lot of sicklebill's species.

And then they split sicklebill's Vanuatu (with 8 ssp) into four species. They even split New Caledonia into two species.

However I've noticed that when the splitters break up a large species, their splits don't necessarily align with the Clements groups. So when (or if) they finally split Island Thrush it will be interesting to see how it goes!

niveiceps was split, I believe, based on genetic data (Nylander et al 2008 https://doi.org/10.1080/10635150802044003) that placed it completely outside of the island thrush complex. (I don't think (?) any further analysis has been done on this taxon since, though, and they sequenced a single bird. To be safe, this should ideally be replicated.)
So far as I know, all the other taxa of the complex that have been sequenced were always found to cluster together. IOW, for these taxa, evidence similar to that which was used to split the Taiwan bird doesn't seem very likely to be out there waiting to be found.

PS --
GenBank has Turdus poliocephalus data from three studies. Besides Nylander et al 2008, these are: Voelker et al 2007 [pdf] and Jones & Kennedy 2008 [pdf].
BOLD has nothing.

Population genomics of the island thrush elucidates one of earth’s great archipelagic radiations
Andrew Hart Reeve, Graham Gower, José Martín Pujolar, Brian Tilston Smith, Bent Petersen, Urban Olsson, Tri Haryoko, Bonny Koane, Gibson Maiah, Mozes P. K. Blom, Per G. P. Ericson, Martin Irestedt, Fernando Racimo, Knud Andreas Jønsson
bioRxiv 2022.04.21.488757; doi: https://doi.org/10.1101/2022.04.21.488757

Jacana said:

Population genomics of the island thrush elucidates one of earth’s great archipelagic radiations
Andrew Hart Reeve, Graham Gower, José Martín Pujolar, Brian Tilston Smith, Bent Petersen, Urban Olsson, Tri Haryoko, Bonny Koane, Gibson Maiah, Mozes P. K. Blom, Per G. P. Ericson, Martin Irestedt, Fernando Racimo, Knud Andreas Jønsson
bioRxiv 2022.04.21.488757; doi: https://doi.org/10.1101/2022.04.21.488757

Click to expand...

In which section did you find this manuscript ?

Manuscript link found via google, worked for me: https://www.biorxiv.org/content/10.1101/2022.04.21.488757v1.full.pdf

Jacana said:

Population genomics of the island thrush elucidates one of earth’s great archipelagic radiations
Andrew Hart Reeve, Graham Gower, José Martín Pujolar, Brian Tilston Smith, Bent Petersen, Urban Olsson, Tri Haryoko, Bonny Koane, Gibson Maiah, Mozes P. K. Blom, Per G. P. Ericson, Martin Irestedt, Fernando Racimo, Knud Andreas Jønsson
bioRxiv 2022.04.21.488757; doi: https://doi.org/10.1101/2022.04.21.488757

Click to expand...

[pdf]

Jacana said:

Population genomics of the island thrush elucidates one of earth’s great archipelagic radiations
Andrew Hart Reeve, Graham Gower, José Martín Pujolar, Brian Tilston Smith, Bent Petersen, Urban Olsson, Tri Haryoko, Bonny Koane, Gibson Maiah, Mozes P. K. Blom, Per G. P. Ericson, Martin Irestedt, Fernando Racimo, Knud Andreas Jønsson
bioRxiv 2022.04.21.488757; doi: https://doi.org/10.1101/2022.04.21.488757

Click to expand...

Can you tell me if this study supports the following results? :

James Jobling said:

Turdus erythropleurus Sharpe, 1887. Christmas Island Thrush
T. loeseri Meyer de Schauensee, 1939. Atjeh Mountain Thrush
T. indrapurae Robinson & Kloss, 1916. Korinchi Mountain Thrush.
T. fumidus S. Müller, 1843. Gedeh Mountain Thrush
T. javanicus Horsfield, 1821. Javan Thrush.
T. whiteheadi (Seebohm, 1893) (incl. stresemanni M. Bartels Jr. 1938). Whitehead's Thrush
T. niveiceps (Hellmayr, 1919). Taiwan Thrush
T. thomassoni (Seebohm, 1894) (incl. mayonensis (Mearns, 1907)). Luzon Mountain Thrush
T. mindorensis Ogilvie-Grant, 1896. Mindoro Mountain Thrush
T. nigrorum Ogilvie-Grant, 1896. Negros Mountain Thrush
T. malindangensis (Mearns, 1907). Malindang Mountain Thrush
T. katanglad Salomonsen, 1953. Katanglad Mountain Thrush
T. kelleri (Mearns, 1905). Apo Mountain Thrush
T. hygroscopus Stresemann, 1931. Latimodjong Mountain Thrush
T. celebensis (Büttikofer, 1893). Bonthain Mountain Thrush
T. schlegelii P. Sclater, 1861. Mutis Mountain Thrush
T. sterlingi Mayr, 1944. Ramelan Mountain Thrush
T. deningeri Stresemann, 1912. Seram Mountain Thrush
T. versteegi Junge, 1939. Oranje Mountain Thrush
T. heinrothi Rothschild & Hartert, 1924 (incl. carbonarius Mayr & Gilliard, 1951 (= erebus M & G, 1952); keysseri Mayr, 1931; tolokiwae Diamond, 1989; beehleri Ripley, 1977; bougainvillei Mayr, 1941; sladeni Cain & Galbraith, 1955; rennellianus Mayr, 1931). Melanesian Thrush
T. canescens (DeVis, 1894). Goodenough Island Thrush
T. papuensis (DeVis, 1890). Papuan Mountain Thrush
T. kulambangrae Mayr, 1941. Kolombangara Island Thrush
T. vanikorensis Quoy & Gaimard, 1830 (incl. whitneyi Mayr, 1941; malekulae Mayr, 1941; becki Mayr, 1941). Vanuatu Thrush
T. placens Mayr, 1941. Charming Thrush
T. efatensis Mayr, 1941. Efate Thrush
T. pritzbueri Layard, 1878 (incl. albifrons Ramsay, 1879). Pritzbuer's Thrush
T. mareensis Layard & tristram, 1879. Mare Island Thrush
T. xanthopus Forster, 1844. New Caledonian Thrush
T. poliocephalus Latham, 1802. Norfolk Island Thrush
T. vinitinctus (Gould, 1855). Lord Howe Island Thrush
T. layardi (Seebohm, 1890). Layard's Thrush
T. ruficeps (Ramsay, 1876). Kandavu Thrush
T. vitiensis Layard, 1876. Vanua Levu Thrush
T. hades Mayr, 1941. Hades Thrush
T. tempesti Layard, 1876. Taveuni Thrush
T. samoensis Tristram, 1879. Samoan Thrush

Click to expand...

It would be great to see some integrative taxonomy applied to species limits within this complex. One problem is the often significant variation in plumage within a single population or subspecies. For example, thomassoni have been photographed with hoods ranging from mid-brown through to solid black; the ssp kelleri of southern Mindanao is rather similarly variable with hoods ranging from grey to dark brown. Sspp katanglad and mindorensis are the most distinctive Philippine races and are unexpectedly rather similar in plumage.
The song of thomassoni of N Luzon is known and kelleri seems to respond to it with a very similar song. Meanwhile deningeri of Seram has a song that is recognisably very similar to thomassoni. Songs of the complex in New Guinea and the Pacific islands seem completely different though. The song of Taiwan Thrush is also completely different and thomassoni does not respond at all to it. Otherwise it seems the songs of all the other sspp remain unknown or at least undocumented throughout their ranges.

Jim LeNomenclatoriste said:

Can you tell me if this study supports the following results? :

Click to expand...

Yes and no. The Island Thrush is monophyletic, apart from the unrelated Taiwan Thrush. The authors lable clades A through L in their Figure 1a with the following composition. The radiation is mostly a grade (clades D & E are sisters),from the Philippines, via Sundaland and eastwards.

A. mindorensis (Mindoro)
B. thomassoni (Luzon, plus an unnamed population from Sibuyan)
C. nigrorum, malindagensis, katanglad, kelleri (Mindanao & Negros, plus unnamed population on Panay)
D. erythropleurus, sterlingi, schlegelii, celebensis (Christmas I., Timor & SW Sulawesi)
E. seebohmi, stresemanni, whiteheadi, javanicus, fumidus, indrapurae, loeseri (Borneo, Sumatra, Java)
F. deningeri (Seram)
G. verstegi, papuensis (New Guinea)
H. beehleri, tolokiwae, heinrothi (Bismarcks)
I. bougainvillei (Bougainville)
J. kulambangrae, sladeni (Kolombangara, Guadalcanal)
K. renellianus, efatensis, becki, malekulae, mareensis, placens (Vanuatu & Renell)
L. whitney, placens, albifrons, pritzbueri, xanthopus, vinitinctus, poliocephalus, samoensis, hades, ruficeps, tempesti, vitiensis, layardi (Vanuatu, Lifou, New Caledonia, Lord Howe, Norfolk, Samoa, Fiji)

Whether or not the clades represent species is another question, not discussed in the paper. I would vote no, considering the explosive radiation starting at only 1,3 MYA and plumage inconsistencies.