As might be obvious from several of the more recent Tet Zoo articles, I’ve lately been to Rio de Janeiro, in Brazil. And what could I do there but look at – and photograph (or try to photograph) – birds. Well, I was there for the 2013 International Symposium on Pterosaurs, but I didn’t spend 100% of my time talking about, or listening to people talk about, pterosaurs. Anyway, I managed to get a reasonable number of fairly good images of the birds I saw, the vast majority being species that were totally new to me. Let’s look at them. Oh, before I start – I didn’t ever get out into the wilds of Brazil: all the wildlife I saw was in the town, or around the edges of the town. Even so, I hope you’ll be pleasantly surprised.
Immediately on my arrival in Rio, I was thrilled to witness large numbers of Black vultures Coragyps atratus and Magnificent frigatebirds Fregata magnificens. I suppose native Brazilians don’t take a second glance at these familiar and commonplace birds, but their constant appearance was pretty incredible to me.
The vultures start their day by sitting up high on street lighting, pylons and other such places, and once it’s warm enough they cruise over the city on their great black and grey wings. Frigatebirds seem to spend their entire time on the wing (this is more or less correct: they’re known to sleep on the wing, and in fact the data showing that they do is more convincing than is the oft-mentioned idea that swifts might do likewise) and great groups of both birds wheel and soar in the thermals that form over buildings, Sugarloaf Mountain and other local features.
The vultures aren’t difficult to encounter on the ground if you go to the right places. I was staying near Guanabara Bay; here, local people collect great masses of mussels from the rocky coastal places every day (as per usual when it comes to the exploitation of marine animals, I can’t believe for a minute that this is sustainable), and they leave huge numbers of dead mussels dumped around the bay edges. Groups of vultures would gather to eat this waste, and I was able to get pretty close. Black vultures famously scavenge at rubbish dumps and other such places. They’re not wholly restricted to a scavenging lifestyle since they’ve been recorded ganging up to kill live animals including opossums and skunks (McIlhenny 1939). Various reports describe possible predation efforts directed at newborn calves, though we should be sceptical about these accounts since the vultures definitely have an interest in consuming afterbirth. Like other vultures (both Old and New World), they love to eat mammal dung. Some vultures famously sequester the carotenoids in dung and use it to make themselves pretty.
I get the impression from the behaviour that I witnessed that Black vultures are highly social and pretty friendly to their associates and relatives. Birds sitting together on lamp-posts would often preen one another (this is known as allopreening) and the masses of birds feeding on the discarded mussels weren’t aggressive towards one another.
While at the zoo in Quinta da Boa Vista* (hey, that’s a story for another time), I saw something especially interesting: wild Black vultures hanging out in the same enclosure as some deer (I think they were Sambar Rusa unicolor) and grooming their fur. The only photos I have aren’t great, but here’s the better one. As it happens, interspecific allopreening is known to occur between Black vultures and Crested caracaras Caracara plancus, a remarkable bit of behaviour given that predatory animals generally hate members of other predatory species. Souto et al. (2009) suggested that this might occur for the same reason that intraspecific allopreening occurs: to strengthen social bonds between the birds concerned, with both benefiting in some way from a partnership that involves food-finding. Black vultures are also on record as groomers of Capybara Hydrochoerus hydrochaeris (Sazima 2007) and even domestic dogs (Sazima 2010). Lord Geekington produced a great article on this and associated aspects of Black vulture behaviour: check it out here.
* The grand public park that contains the Museu Nacional and much else besides.
I mentioned the frigatebirds. They were typically so high up that getting good closeup images was impossible: here’s the best one I have. The red throat sac shows that we’re looking at a male, and check out the missing primaries at one of the wing tips (was he moulting, or is this battle-damage?).
Four of the world’s five frigatebird species can be seen around the coasts of Brazil. They’re notoriously difficult to separate. However, by far the commonest and most widespread is the Magnificent frigatebird, the largest (its wingspan can be 2.3 m). Males are typically all-dark in this species (females have white chests and juveniles have white heads and bellies too), whereas males in the Great frigatebird F. minor and Lesser frigatebird F. ariel have pale or white markings on their wings or undersides. Forget about using size to differentiate them – unless you’re a genius it’s about impossible to reliably judge the size of a bird soaring in an otherwise empty sky.
Frigatebirds are famously piratical but they’ll also grab food items from the surface of the sea. They’re slow-growing, long-lived, with some of the lowest wing-loadings of any bird. There’s a ton of interesting stuff to say about their biology and anatomy, and I’ll try and remember to come back to them at another time. That thing about them being unable to swim? It’s not true. They just avoid swimming if they can.
Numerous tame Neotropic cormorants Phalacrocorax brasilianus spend all day every day (all day every day) around the edges of the lake in Quinta da Boa Vista. They’re smaller than the cormorants I’m used to (Great cormorants P. carbo): some (but not all) individuals have white borders around the edges of the beak. Check out this close-up shot of an individual doing the wing-drying thing.
Egrets, night-herons and things that you might regard as either egrets or herons
I saw herons belonging to three species. The most impressive was the Great egret or Great white egret Ardea alba: a very neat species (and easy to identify due to its size and all-black legs and feet*), but one that I’ve seen before here in the UK.
The idea that the Great egret actually is a member of the Ardea heron clade has always seemed weird to me, but then it has also been regarded as a member of Egretta at times. Its position in phylogenies is unstable, since it has sometimes been recovered as being close to the bizarre Agami heron Agamia agami and Tigrisoma tiger herons (McCracken & Sheldon 1998) and is not found within, or definitely close to, Ardea proper. Revival of the old name Casmerodius might therefore be appropriate, and some authors (e.g., Sheldon et al. 2000) have done just this (in which case the full name is Casmerodius albus). The Great egret is one of several herons that routinely swims.
* Though, of the four subspecies, two of them don’t have all-black legs during the breeding season. E. a. alba of Eurasia has yellowish or pink on its legs at times, and E. a. modesta has pink or red legs when breeding.
Of the two other heron species I saw, were the small, white, yellow-footed egrets Little egrets Egretta garzetta or Snowy egrets E. thula? When in breeding plumage, these two are hard to differentiate: the main difference concerns the form of the head plumes (two thin plumes in the Little egret; a bushy crest in the Snowy egret). I get the impression that the individuals I saw (there were a few of them, sat together in some waterside plants) were Snowy egrets. The soft keratinous parts of the Little egret are more greenish than those of the Snowy egret, so the birds I saw (with very bright yellow features) were more likely to be Snowy egrets.
Snowy egrets use a more diverse repertoire of feeding behaviours than any other herons: they use their feet to startle, attract or stir up prey, they walk quickly in search of prey at times and stand still awaiting ambush at others, they do the bill-vibrating trick, and they also grab prey from the water while in flight (Hancock & Kushlan 1984). Brief bouts of hovering allow them to dart at prey near the surface, and they sometimes trail their feet in the water while flying (this is called foot dragging, though how it allows them to catch prey, I don’t know). Hey, there are even herons that plunge, head-first, into the water from flight, and I’m sure you know about the baiting behaviour practised by Green-backed herons Butorides striatus. They use bits of bread and other edible material to attract fish.
I also saw a juvenile heron that I initially identified as a Black-crowned night-heron Nycticorax nycticorax. However, the small size of the spots on the wings, the fact that we can clearly see the tarsal joint, and the black and grey (rather than yellowish) bill later led me to believe that this is a juvenile Yellow-crowned night-heron Nyctanassa violacea. I'm reliable informed (see comments below) that my first identification is correct.
The surprising world of pigeons
Feral pigeons (that is, Rock doves or Rock pigeons or whatever you want to call them: Columbia livia) were everywhere. It’s always worth looking closely at feral pigeons since they often give you some idea as to the sort of weirdness local people are breeding into racing pigeons (many racing pigeons go AWOL and live among, and breed with, their wild relatives). The Rio pigeons were darker than the European and north African ones I’m used to, with more subtle versions of the iridescent neck patch.
I saw members of two other pigeon species. Often feeding among the feral pigeons, and sometimes alongside finches and parakeets, were tiny, sparrow-sized Ruddy ground-doves Columbina talpacoti (a male is shown here: females are longer-tailed, browner overall, and with black – rather than rufous – underwing coverts). Columbina pigeons appear to be closely related to the Scardafella species (in fact, these are increasingly included within Columbina these days) as well as to the Metriopelia and Claravis ground doves: traditionally, all of these taxa were regarded as close relatives of other New World pigeons (Goodwin 1967) but a surprising result from some molecular work is that this ‘small American ground dove’ clade is in fact the sister-group to all other crown-columbiforms (Johnson & Clayton 2000). A later study by Pereira et al. (2007) recovered this same topology in some trees, but not all.
Here’s a far larger bird, a Picazuro pigeon Patagioenas picazuro, easily identified thanks to its diagnostic ‘scaly’ neck patch. To my European eyes, this is a ‘wood pigeon’-like species, and indeed the names Argentine wood pigeon, Scaly-necked wood pigeon and Brown wood pigeon have all been used for it on occasion. Goodwin (1967) says that it “[h]as been recorded as regularly visiting slaughtering grounds and gathering at skinned carcases of domestic animals, although unfortunately the observer did not ascertain what the pigeons so-doing were eating” (p. 98). Weird.
Goodwin (1967) included the species in Columba as a close relative of the South and Central American Scaled pigeon C. speciosa and the mostly Caribbean Red-necked pigeon C. squamosa and White-crowned pigeon C. leucocephala. Of course, most authors – historically – have included these American Columba-like pigeons within Columba. However, some molecular phylogenetic studies find this American group to be substantially separated from ‘true’, Old World Columba pigeons, hence the use of the generic name Patagioenas for the American birds (Johnson et al. 2001, Pereira et al. 2007).
The hawk in the garden
I said that we’d come back to raptors. While standing in the garden of the Universidade Federal for a coffee break I saw a mid-sized, ventrally barred hawk alight in one of the trees. I pursued with camera in hand and was treating to many minutes of observation as the bird sat there, allowing many close-up photos. It was longer-billed than I’d expect for an Accipiter. Brazil has a really impressive collection of ventrally barred, hawk-like raptors: they include Accipiter species as well as the Hook-billed kite Chondrohierax uncinatus, Crane hawk Geranospiza caerulescens, Grey or Grey-lined hawk Buteo nitidus and others. With its combination of yellow cere and legs, pale eye, dark tail barring (without white barring) and brownish bars on the chest and belly, I reckon that this is a Roadside hawk Rupornis magnirostris, specifically the nominate form (12 subspecies are recognised for this widespread species) [UPDATE: nope! Instead it seems to be the form R. m. magniplumis. See comments].
Most texts these days don’t give the Roadside hawk its own genus; rather, it’s treated as a member of the ‘buzzard’ genus Buteo. However, Riesing et al. (2003) supported the view that Rupornis should be recognised as one of several ‘sub-buteonine’ genera outside of Buteo. Lerner & Mindell (2005) found the Roadside hawk to group with the Harris hawk Parabuteo unicinctus, both being less close to Buteo proper than were Leucopternus and Geranoaetus. More recent work hasn’t supported quite the same relationship: the position of the Roadside hawk is uncertain with respect to the Harris hawk, the Rufous-thighed hawk Buteo leurorrhous (or Percnohierax leucrorrhous) and remaining buteonines (Lerner et al. 2008). If the Roadside, Harris and Rufous-thighed hawks are all outside the clade associated with the name Buteo, one solution is to retain the names Rupornis, Parabuteo and Percnohierax for these species. This is my preferred option (it’s subjective, but I simply think it makes more sense to keep the Harris hawk and other ‘sub-buteonines’ outside of Buteo). However, the idea that all of these taxa might best be absorbed into a more inclusive version of Buteo is preferred by others.
Parrots and the many, many passerines
Monk parakeets Myiopsitta monachus were a frequent sight in the park where I did most of my bird-watching, and many individuals were building – or sitting in – the communal stick nests they manufacture in the tops of trees (they will also build on pylons and other man-made structures). The natural range of this species is actually Bolivia, Uruguay, Argentina and only the southern part of Brazil, and it isn’t a native of the Rio region. How a feral colony become established here is unknown to me, but it’s well known that there are feral colonies elsewhere: in Florida, New York, Puerto Rico and even Berlin, Austria and elsewhere in Europe. The communal nests built by Monk parakeets can be several metres across and be used by perhaps 100 pairs (Juniper & Parr 1998). Other names for this species include Quaker parrot and Cliff parakeet.
Let’s now move on to passerines, the group that contains about 60% of all living bird species. Tropical America is of course inhabited by numerous passerine groups that are wholly absent from Europe, and I was thrilled to find that several members of the groups concerned were easily and regularly encountered. I’m talking in particular about members of the suboscine groups Furnariida and Tyrannida.
Furnariida includes ovenbirds, woodcreeper and antbirds. I frequently saw tiny, acrobatic, foliage-gleaning, brown passerines that I reckoned were members of this group, but – despite copious and maddening efforts – I was never able to get any good photos. A plain and widespread ovenbird of open habitats, the Rufous hornero or Red ovenbird Furnarius rufus, was often seen at parks and on the beach. This is the national bird of Argentina and Uruguay and is well known for associating with humans. In the parks, you can see horneros foraging in close association with Cattle tyrants (read on) and feral pigeons.
Tyrant dinosaurs of the Anthropocene!
Tyrannida includes the brilliant tyrant flycatchers (or tyrannids), cotingas, and manakins. No cotingas or manakins for me, sadly (remember that I didn’t really get out of the town: everything I saw was encountered in urban, suburban or coastal settings), but two tyrant flycatchers – the Masked water-tyrant Fluvicola nengeta and Cattle tyrant Machetornis rixosa – were seen frequently, often at close quarters. The Masked water-tyrant is one of several black and white, or black, white and grey Fluvicola species associated with water. The tyrannid radiation is vast and complicated; Fluvicola is one of the ‘core’ members of a fluvicoline clade (traditionally regarded as a ‘subfamily’) that also includes the Myiophobus flycatchers, the ground-tyrants (Muscisaxicola), the White-headed marsh-tyrant (Arundinicola leucocephala) and the monjitas (Xolmis) (Ohlson et al. 2008). A Eurocentric person might describe a Fluvicola tyrant as looking something like a cross between a wheatear and a wagtail.
The Cattle tyrant - Machetornis - is a strongly terrestrial tyrant flycatcher that occurs throughout grasslands and parklands, its yellow underside, grey head and striding, terrestrial foraging habit making it essentially unmistakable.
It isn’t a fluvicoline tyrant; beyond that, there have been several competing views as to exactly what it is. A close affinity with kingbirds has been suggested on occasion due to overall morphology and behaviour: Ohlson et al. (2008) found strong genetic support for this grouping, specifically finding Machetornis to be the sister-taxon to the Great kiskadee Pitangus sulphuratus (read on). If this is true, Machetornis is a remarkably unusual member of its clade since just about all of the others are aerial hawkers that grab prey before returning to a perch. Furthermore, kingbirds and their relatives are well known for possessing a specialised syrinx that uniquely contains both internal cartilaginous divisions and a pair of muscles termed the obliqui ventrales; Machetornis lacks these features, and it also lacks some bony cranial features present in kingbirds (Lanyon 1984). Either some weird transformations happened in kingbird phylogeny (and that’s ok: weirdness is everywhere in evolutionary history), or our phylogenetic hypotheses are wrong.
Incidentally, everyone seriously interested in suboscines must surely own a copy of Guy Kirwan and Graeme Green’s Cotingas and Manakins (2011, Helm) by now. I have mine. It’s incredible (and in the to-be-reviewed-soon pile).
Brazil is home to a respectable number of passerines (well, eight) that share the same distinctive livery: the underside is bright yellow, the back, wings and tail are brownish or olive, and the head is boldly marked with black and white, with black stripes passing through the eye region and across the crown. Some of these birds are close relatives (like the Conopias flycatchers) but the others aren’t, leaving me wondering why these birds look so superficially similar: is it just a coincidence, or is there some sort of mimicry going on here?
The most frequently seen of these species is the Great kiskadee Pitangus sulphuratus, one of the most famous, conspicuous and adaptable of the world’s tyrant flycatchers. It’s big, reaching 27 cm or so, and is named for its call, which sort of sounds a bit like kis-ka-DEE! (other interpretations are available). Pitangus is a tyrannine tyrant flycatcher, typically considered part of the ‘kingbird assemblage’ (that is, as a close relative of Tyrannus, the kingbirds) (Lanyon 1984, Birdsley 2002). I saw kiskadees at many places: on the beach, at birdfeeders, and at various locations in parks and at the roadside.
Here’s a smaller tyrant flycatcher that possesses the same livery: the Social flycatcher Myiozetetes similes (one of four or five Myiozetetes species). According to Ohlson et al. (2008), Myiozetetes is also a tyrannine and actually isn’t far in the phylogeny from the Great kiskadee, nor from the similarly coloured and patterned Boat-billed flycatcher Megarhynchus pitangua. If these species are as close as Ohlson et al. (2008) found, the distinctive livery would - in this case - seem to be a shared character that was lost or modified in the ancestors of the Cattle tyrant, the Variegated flycatcher Empidonomus varius and the kingbirds (Tyrannus).
Seen at distance, I first assumed that the Social flycatcher shown above was another kiskadee, but as I got closer I realised that it was very different, with its shorter, more delicate bill, orange-red crown patch, and different proportions. For whatever reason, this individual was repeatedly perching on a car’s windshield and wing mirror.
And yet another passerine that again has that yellow-bellied, stripey-head thing going on is the small, nectarivous Bananaquit Coereba flaveola. I had good views of Bananaquits on several occasions and managed to get two half-decent photos (both shown in the montage here). Bananaquits are famously enigmatic when it comes to their phylogenetic affinities.
The grey, ‘finch-shaped’ passerine shown at the top of the adjacent montage – seen several times but never staying still long enough to permit a good photo – is, I think, a Palm tanager Thraupis palmarum [UPDATE: nope. Calyptura (see comments) says it's more likely to be a Sayaca tanager T. sayaca]. Like most of the birds discussed here, both the Palm and Sayaca tanagers are widespread across Brazil and known for their association with towns and secondary forest growth of the sort promoted by human activity. We also see here (at bottom left) a Chalk-browed mockingbird Mimus saturninus.
Here (at right) is another neat passerine: a Red-cowled cardinal Paroaria dominicana, one of three similar, red-headed, mostly black and white cardinals that occurs in Brazil. The white strips on the primaries are diagnostic, as is the red ‘bib’.
Another passerine that I saw on numerous occasions was the unmistakeable Rufous-bellied thrush Turdus rufiventris, Brazil’s national bird (shown above, at left). The Rufous-bellied thrush is deeply nested within a predominantly South American thrush clade that was hypothesised to have its closest relatives in Africa by Voekler et al. (2007) (though see Nylander et al. (2008) for a more complex picture). It’s thought that repeated trans-Atlantic dispersal events happened in thrush evolution during the Miocene, and indeed thrushes clearly made numerous over-water dispersals (from a Eurasian centre of origin) throughout their history (Voekler et al. 2009).
I saw hirundines of a few species while in Rio. Some were big and some were small. A fairly poor photo of a
Tawny-headed swallow Alopochelidon fucata Southern rough-winged swallow Stelgidopteryx ruficollis was featured previously in my ‘mystery birds from Brazil’ article; here’s a better photo, this time of a fairly large, white-throated, white-bellied hirundine. It can only be a Brown-chested martin Progne tapera: the apparent absence of the greyish or brownish chest band expected for that species is, I think, a trick of the light.
And that brings us to an end of our photographic mini-tour of the birds of Rio. As I said earlier, I saw several additional species but failed to photograph them, including (unidentified) hummingbirds, Southern lapwing Vanellus chilensis, Kelp gull Larus dominicanus and a mid-sized, pale-headed tern that was probably a Yellow-billed tern Sterna superciliaris (or Sternula superciliaris). I also saw a large, dark-masked falcon perched on a street light at the side of the road. I thought that it was an Aplomado falcon Falco femoralis but didn’t know at the time that this species occurs across much of Brazil, including in and around Rio, so this is probably what it was.
Finally – I went out to Brazil without a field guide and have been identifying the birds from my photos while here at home. The book I’ve been using as my primary source of information is Ber van Perlo’s A Field Guide to the Birds of Brazil (2009, Oxford University Press).
I cannot recommend this book highly enough: anybody interested in bird diversity, or specifically in the birds of South America or Brazil, really must get hold of a copy. I just love seeing all those antbirds, woodcreepers and so many others - so rarely illustrated elsewhere – depicted together in fieldguide format. Buy the book here on amazon! Ok, I’m done; I hope you found this interesting.
For previous Tet Zoo articles on South American birds, or on the groups of birds discussed here, see...
- “Like a normal blog”… and rabbit-eating herons
- To the Sahara in quest of dinosaurs (living and extinct) (includes discussion of egrets)
- Heron tries to swallow giant lamprey. Chokes. Dies. Second heron tries same trick. Also chokes. Also dies.
- Eurylaimides, Tyrannida and Furnariida: the suboscine passerines
- ‘Mystery’ birds from Brazil
Birdsley, J. S. 2002. Phylogeny of the tyrant flycatchers (Tyrannidae) based on morphology and behaviour. The Auk 119, 715-734.
Gilmore, D. 1967. Pigeons and Doves of the World. British Museum (Natural History), London.
Hancock, J. & Kushlan, J. 1984. The Herons Handbook. Croom Helm, London & Sydney.
Humphrey, J. S., Tillman, E. A. & Avery, M. L. 2004. Vulture-cattle interactions at a Central Florida Ranch. Proceedings - Vertebrate Pest Conference 21, 122-125.
Johnson, K. P. & Clayton, D. H. 2000. Nuclear and mitochondrial genes contain similar phylogenetic signal for pigeons and doves (Aves: Columbiformes). Molecular Phylogenetics and Evolution 14, 141-151.
- ., de Kort, S., Dinwoodey, K., Mateman, A. C., ten Cate, C., Lessells, C. M. & Clayton, D. H. 2001. A molecular phylogeny of the dove genera Streptopelia and Columba. The Auk 118, 874-887
Juniper, T. & Parr, M. 1998. Parrots. Pica Press, Mountfield.
Lanyon, W. E. 1984. A phylogeny of the kingbirds and their allies. American Museum Novitates 2797, 1-28.
Lerner, H. R., Klaver, M. C. & Mindell, D. P. 2008. Molecular phylogenetics of the buteonine birds of prey (Accipitridae). The Auk 304, 304-315.
- . & Mindell, D. P. 2005. Phylogeny of eagles, Old World vultures, and other Accipitridae based on nuclear and mitochondrial DNA. Molecular Phylogenetics and Evolution 37, 327-346.
McCracken, K. G. & Sheldon, F. H. 1998. Molecular and osteological heron phylogenies: sources of incongruence. The Auk 115, 127-141.
McIlhenny, E. A. 1939. Feeding habits of black vultures. The Auk 56, 472-474.
Nylander, J. A. A. Olsson, U., Alstrm, P. & Sanmartn, I. 2008. Accounting for phylogenetic uncertainty in biogeography: a bayesian approach to dispersal-vicariance analysis of the thrushes (Aves: Turdus). Systematic Biology 57, 257-268.
Ohlson, J., Fjelds J. & Ericson, P. G. P. 2008. Tyrant flycatchers coming out in the open: phylogeny and ecological radiation of Tyrannidae (Aves, Passeriformes). Zoologica Scripta 37, 315-335.
Pereira, S. L., Johnson, K. P., Clayton, D. H. & Baker, A. J. 2007. Mitochondrial and nuclear DNA sequences support a Cretaceous origin of Columbiformes and a dispersal-driven radiation in the Paleogene. Systematic Biology 56, 656-672.
Riesing, M. J., Kruckenhauser, L., Gamauf, A. & Haring, E. 2003. Molecular phylogeny of the genus Buteo (Aves: Accipitridae) based on mitochondrial marker sequences. Molecular Phylogenetics and Evolution 27, 328-342.
Sazima, I. 2007. Unexpected cleaners: Black Vultures (Coragyps atratus) remove debris, ticks, and peck at sores of capybaras (Hydrochoerus hydrochaeris), with an overview of tick-removing birds in Brazil. Revista Brasileira de Ornitologia 15, 417-442.
Sazima, I. 2010. Black Vultures (Coragyps atratus) pick organic debris from the hair of a domestic dog in southeastern Brazil. Revista Brasileira de Ornitologia 18, 45-48.
Sheldon, F. H., Jones, C. E. & McCracken, K. G. 2000. Relative patterns and rates of evolution in heron nuclear and mitochondrial DNA. Molecular and Biological Evolution 17, 437-450.
Voelker, G., Rohwer, S., Bowie, R. C. K. & Outlaw, D. C. 2007. Molecular systematics of a speciose, cosmopolitan songbird genus: definining the limits of, and relationships among, the Turdus thrushes. Molecular Phylogenetics and Evolution 42, 422-434.
- ., Rohwer, S., Outlaw, D. C. & Bowie, R. C. K. 2009. Repeated trans-Atlantic dispersal catalysed a global songbird radiation. Global Ecology and Biogeography 18, 41-49.