At last, the Odedi revealed: the most mysterious bush warbler

I come back to you now, at the turn of the tide. Or, to put it another way, the thesis has finally been submitted. It was hard work, it involved staying up most nights to 4 or 5 in the morning, and it meant no time for blog posts or for extraneous side projects, but it’s done. So the next step is the viva (that’s the word we use in the UK for ‘thesis defence’, if you’re wondering). Fingers crossed (go here to see what happened).

Although I have more than my fair share of work that I need to catch up on, what the hell….

In March of this year Mary LeCroy and F. Keith Barker published their description of the Odedi Cettia haddeni, a bush warbler from Bougainville Island of the North Solomons Province in the SW Pacific (LeCroy & Barker 2006). Bougainville Island will be familiar to you if you’ve read about obscure and/or recently extinct birds, as it was famously home to the Moustached kingfisher Actenoides bougainvillea (a species which hasn’t been seen for four decades, and may well be extinct), among others.

Cettia, the bush warbler genus, is represented by 14 species, most of which live in SE Asia, but there are also several species that inhabit the islands of the SW Pacific. We have one member of the genus here in Europe: Cetti’s warbler Cettia cetti (though it’s not a European endemic, as it also occurs across Asia). People here don’t ordinarily call it ‘Cetti’s bush warbler’, but they do elsewhere in the world (in India for example, where it’s but one of eight Cettia species). Cetti’s warbler is a skulking bird that tends to stay hidden in river-bank foliage, its distinctively explosive song giving its location away. Will and I used to go find them along overgrown canals when we lived in Gosport (well, I used to go find them. Will just came along for the ride).

Incidentally, it’s a good example of a bird whose range has increased substantially within recent history. Early in the 20th century it was apparently restricted to the Mediterranean region, but it’s been gradually spreading northward and today occurs as far north as Sweden (or at least that’s what some of the books say: in the field guides it isn’t shown as extending further north than southern Britain).

Bush warblers are particularly newsworthy right now (to my mind at any rate) given that the just-published oscine supertree of Jønsson & Fjeldså (2006) found Cettia to be diphyletic, with C. cetti grouping with the tesias* and Urosphena (the stubtails) while the Japanese bush warbler C. diphone grouped with the Broad-billed flycatcher-warbler Tickellia hodgsoni and Orthotomus (the tailorbirds). Admittedly, the idea that Cetti’s warbler might group with tesias and stubtails, both of which are radically short-tailed, seems odd, but then total evidence is the game.

* Tesias are one of a number of poorly-known tropical passerines for which the common name is the same as the technical generic name. Other examples include prinias, yuhinas, minlas, newtonias, oxylabes, niltavas, liocichlas, apalis, camaropteras, eremomelas… the list goes on.

Results contrary to those of Jønsson & Fjeldså (2006) were found by LeCroy & Barker (2006): based on cytochrome b sequences, they found Cettia to be monophyletic, with C. cetti as a basal member of the clade and stubtails as the sister-group. The island endemic forms of the SW Pacific formed a subclade within Cettia, thereby supporting Orenstein & Pratt’s (1983) contention that this was probably the case. It’s been suggested that the island-endemic bush warblers descended from a wide-ranging colonizing ancestor that originated from a continental source. This is the standard stepwise dispersal model favoured for the evolution of island endemics: it’s recently been shown that, remarkably, some continental passerine radiations descended from island passerine clades (Filardi & Moyle 2005), but there’s no indication that this occurred in bush warblers.

Anyway, if island-endemic bush warblers have descended from a widespread colonizing ancestor, then the members of this clade are somewhat patchily distributed in the region, and their absence from some islands and island groups (such as New Guinea and the Bismarck Archipelago) seems odd. Maybe bush warblers were present on these islands and have since become excluded by more recently evolved species (the ‘taxon cycle’ model), or perhaps they’ve been made extinct by people. Such is supported by the fact that extinct bush warbler species have been reported from Tonga (Steadman 1993, 1995). Or… maybe bush warblers actually do inhabit some of these islands, but await discovery. This is possible given that other members of the group are recent discoveries: there’s the Odedi of course, but also C. carolinae from Tanimbar in the Moluccas. It was only named in 1987 (Rozendaal 1987).

What makes the Odedi further interesting is that, prior to 2004, it was a mystery animal known only from ethnic reports and from its vocalisations, and in fact in the annals of obscure ornithology it has a relatively long and interesting history. In 1975 Jared Diamond noted his 1972 discovery of an unknown mountain-dwelling passerine on Bougainville Island, known to the local speakers of the Rotokas language as the kopipi, and to the Nasioi speakers as the ódedi. Diamond never saw the bird but did describe its thrush-like song (Diamond 1975). Over the following years several other ornithologists were to learn about and encounter the Odedi, including Don Hadden and Bruce Beehler, both well known specialists of the birds of the Solomons and surrounding Islands. Hadden heard the bird calling on many occasions between 1977 and 1980, usually during misty and/or wet weather, but he was never able to catch one. Beehler (who I’d say is best known for his work on birds-of-paradise) published a brief paper on the bird in 1983 and thought it most likely that it was a species of Vitia (Beehler 1983), a genus regarded nowadays as synonymous with Cettia (Orenstein & Pratt 1983).

Hadden was eventually able to obtain photos of the species, and he included one in his 2004 book Birds and Bird Lore of Bougainville and the North Solomons (Hadden 2004). Even better, at long last, he managed to obtain a specimen in January 2000, and subsequent specimens were procured later in the year and in 2001. As Hadden and others had predicted, the Odedi proved to be a rather plain, short-winged, chestnut-coloured bush warbler. Compared to other bush warblers of the SW Pacific, it is huge (fully 4 grams heavier than any other bush warbler), notably dark, with a wider bill, a more robust tarsus and longer toes.

So in view of Hadden’s long quest for this species, culminating in its discovery, it is fitting that LeCroy & Barker (2006) have named it after him.

Given that the Odedi was known from its vocalizations and from ethnic reports prior to the procurement of the first specimen, does this mean that - pre-2000 - it was a cryptid? I would say yes. And if people who are regarded without question as card-carrying zoologists of the utterly ordinary type are actually out there chasing down ethnoknown species like the Odedi, are they actually cryptozoologists? That’s less easy to answer, because cryptozoologists are more usually regarded as dedicated to the pursuit of cryptids alone, whereas Hadden and others don’t search for species like the Odedi to the exclusion of all others. But I personally don’t see any problems with the idea that ‘ordinary’ zoologists actually do engage in cryptozoological research at times, it’s just that they tend not to identify the research as such. As it happens, there are actually a few small passerines known from observations or photos, but not (yet) from specimens. Future post on that to come. Among others.

The photo above was borrowed from…

http://www.camacdonald.com/birding/JapaneseBush-Warbler(JJ).jpg

It doesn’t depict an Odedi (sorry), but a Japanese bush warbler C. diphone.

Refs - -

Beehler, B. 1983. Thoughts on an ornithological mystery from Bougainville Island, Papua New Guinea. Emu 83, 114-115.

Diamond, J. 1975. Distributional ecology and habits of some Bougainville birds (Solomon Islands). Condor 77, 14-23.

Filardi, C. E. & Moyle, R. G. 2005. Single origin of a pan-Pacific bird group and upstream colonization of Australasia. Nature 438, 216-219.

Hadden, D. 2004. Birds and Bird Lore of Bougainville and the North Solomons. Dove Publications Pty (Alderley, Queensland).

Jønsson, K. A. & Fjeldså, J. 2006. A phylogenetic supertree of oscine passerine birds (Aves: Passeri). Zoologica Scriptca 35, 149-186.

LeCroy, M. & Barker, F. K. 2006. A new species of bush-warbler from Bougainville Island and a monophyletic origin of southwest Pacifc Cettia. American Museum Novitates 3511, 1-20.

Orenstein, R. I. & Pratt, H. D. 1983. The relationships and evolution of the southwest Pacific warbler genera Vitia and Psamathia (Sylviinae). Wilson Bulletin 95, 184-198.

Rozendaal, F. G. 1987. Description of a new species of bush warbler of the genus Cettia Bonaparte, 1834 (Aves: Sylviidae) from Yamdena, Tanimbar Islands, Indonesia. Zoologische Mededelingen 61, 177-202.

Steadman, D. W. 1993. Biogeography of Tongan birds before and after human impact. Proceedings of the National Academy of Sciences, USA 90, 818-822.

- . 1995. Prehistoric extinctions of Pacific Island birds: biodiversity meets zooarchaeology. Science 267, 1123-1131.