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In pursuit of the Rook

The views expressed are those of the author and are not necessarily those of Scientific American.


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Splendid Rook; photo by Heinrich Mallison.

Any adventures about the more rural parts of the UK typically involve (for me, anyway) a lot of looking at the Rook Corvus frugilegus, a remarkable Old World corvid that occurs from the far western shores of the UK and France all the way east to Japan (it’s generally absent from the cold northern parts of Eurasia, only visits the Iberian Peninsula and most of southern Europe during the winter, and is absent from much of tropical Asia). The east Asian birds represent the distinctive subspecies C. f. pastinator (sadly, not the more awesome sounding dastinator*, as it says in one particularly famous book on crows). I’ve been loosely ‘collecting’ Rook images over the years and thought it high time to put a bunch of them together.

* That word really reminds me of the sort of thing Dr Doofenshmirtz would refer to in Phineas and Ferb.

Rooks are highly social birds that nest in large colonies called rookeries. They are, as would seem useful for a colonial nester, essentially non-territorial, only defending their nest and mate: all of this is remarkable and unique for a Corvus crow. It seems that Rooks rely heavily on the successful foraging of other members of the species, following them to fruitful patches within 2.5 km of the colony and massing together when rich food sources are located (Green 1996).

Rook pair on a fence, waiting for humans to drop food at an adjacent picnic area. Note shaggy belly feathers blowing to the right on the bird at the back. Image by Heinrich Mallison.

To quote Franklin Coombs from his excellent 1978 The Crows, “Few bird colonies can have aroused as much interest as rookeries. The activities of rooks need to be watched from nest level as Lewis Harding (1848) did from his window, or better still from a hide among the nests” (Coombs 1978, p. 74). Harding’s story is an interesting one. He “returned from a distant climate … in a very imperfect state of health”, and was told by his doctor – Jonathan Couch (1789-1870) – to observe and record the habits of Rooks throughout the months of the year; in other words, to engage in what we now call occupational therapy. Harding’s notes cover both sides of more than 300 sheets of paper and his observations were both accurate and detailed, despite his lack of telescope or binoculars. See Coombs (1978) for a lengthy discussion of Harding’s work.

So far, I’ve personally only had the opportunity to watch rookeries from ground-level, but it’s obvious that lots of interesting stuff is going on up there. Like all corvids, Rooks are smart and display obvious problem-solving abilities. In one case, two captive Rooks in a laboratory co-ordinated their string-pulling movements such that they were able to slide a tray into their enclosure, and they performed this task as well as did captive chimpanzees (Marzluff & Angell 2012, and refs cited therein). Admittedly, single Rooks did not perform so well, however, since they started the string-pulling before their partner arrived (whereas chimps were more patient and seemed to understand the requirement of a two-part team). Rooks are also known to drop stones into water-filled containers so that floating food items can be raised up to within reach (validation of Aesop’s fable).

Rook observed trying to fish something out of the water (photo taken at Marwell Wildlife, UK). Photo by Darren Naish.

The 'fishing' Rook again. Photo by Darren Naish.

The Rook is a black crow (that is, a member of the genus Corvus), so unusual compared to the other Corvus species that Goodwin (1986) wrote that “its relationships within the genus cannot be deduced on present evidence” (p. 71): his phylogram depicts the Rook as the sister-taxon to the remainder of Corvus. However, genetic data indicates that the species is deeply nested within Corvus, closely related to the Eurasian raven C. corax and its kin (Ericson et al. 2005).

Adult (at top) and juvenile Rook of the nominate form. Illustration by Peter Hayman, from 1976 book The Illustrated Book of Nature: A Seasonal Guide to the Habitats of the British Isles. Adults of C. f. pastinator resemble the juvenile condition typical of C. f. frugilegus.

Rooks are famous for their bare, pale faces and bill-bases (the east Asian subspecies C. f. pastinator differs in having a feathered face and bill-base). The vernacular name Bare-faced crow was apparently used for the species in the past (Coombs 1978). Claims that the bare face only occurs due to the soil-probing behaviour practised by this species are not correct: you can read more about this issue in the Tet Zoo ver 2 article linked to below. A tall forehead and shaggy, loose flank feathers that give the bird a so-called ‘baggy trousered’ look are also distinctive. Males and females look the same (though males are slightly larger) and there are no seasonal changes in plumage.

Rooks are seemingly monogamous and pairs stay bonded for years and – supposedly – even for life (Madge & Burn 1999). As is typical (or ubiquitous) in ‘monogamous’ animals, extra-pair copulations are common and some are forced rapes, the male copulating (or attempting to copulate) with a female already incubating her own clutch (Goodwin 1986). Additional birds frequently intervene when such acts occur, though exactly what their motives are is uncertain. Mating occurs on the ground as well as in the rookery [image below from full sequence available here].

This photo - one of a long sequence - shows a mating Rook pair on the ground (in this case, the mating was probably consensual). Part-way through, a third bird intervened and a fight errupted. Eventually, the third bird flew off. Photo by naughty voyeur Heinrich Mallison.

A complex and diverse repertoire of postural displays are present in these birds, and if you know what to look for you can usually get some idea of the sorts of signals they’re conveying. A series of movements that involve bowing, drooping the wings and fanning and drooping the tail signal various stages in assertiveness and/or submissiveness. So-called ‘full-forward’ or ‘forward threat’ poses signal aggression associated with nest defence or squabbles over food, and ‘flight intention’ movements of the sort seen throughout corvids (this is where the wings are repeatedly flipped and tucked away again) seem to signal uncertainty or nervousness.

Mating flights (sometimes involving groups of birds numbering 10 or 12) feature specific stiff-winged wing flaps where the wings are raised at an especially high angle on the upstroke. Like many colonial nesters, Rooks sometimes engage in ‘dreads’ or ‘outflights’. The colony goes quiet and nothing much seems to be happening. All of a sudden, there’s a burst of cawing and most or all of the birds take off in unison. This behaviour might be initiated by concern about a local predator (or perceived predator).

Pleasing Rook illustration, photographed at Horn Tavern, Lyme Regis (while I and colleagues were there for the duration of a conference). Apologies for not knowing the name of the artist: they didn't sign the piece!

There seems to be some sort of relationship between Rooks and falcons, with Common kestrels Falco tinnunculus and Lesser kestrels F. naumanni both being well-known for their habit of sometimes nesting right within a rookery. Even better, breeding in Red-footed falcons F. vespertinus and Amur falcons F. amurensis is (sometimes) seemingly dependent on the presence of rookeries and these species – which are colonial nesters themselves – don’t start their nesting activities until the Rook nesting season is underway. They then move in and either take over disused Rook nests, or else evict Rook adults, nestlings and eggs from their nests before claiming them as their own (Madge & Burn 1994). Long-eared owls Asio otus and Ospreys Pandion haliaetus have also nested within active rookeries on occasion, and rookeries are sometimes mixed with active nests belonging to herons, cormorants and ibises.

Numerous anecdotes describe unusual bits of behaviour in this species, most of which can be interpreted as sensible (and plausible) responses to stimuli. Burton (1978) described an instance in which a flying Rook dove at a Sparrowhawk, forcing the hawk to release a live Starling it had captured, and another in which a breeding pair seemingly enlisted helpers to quickly re-build a nest a few hours after the original one had been destroyed by a person.

Check out the naked, gnarly face and very slender upper jaw tip in this Rook (the unworn bill tip shows that this bird indulges in relatively little - or no - probing behaviour). This individual had a damaged leg and was unable to walk or perch properly. Photo by Darren Naish.

Rooks are terrestrial foragers that feed in grasslands and agricultural fields, though they also forage on shores, tidal mudflats and garbage dumps if those occur nearby. Again, they’re highly unusual compared to other Corvus crows in that they aren’t generalists that habitually feed on anything, but specialists that probe into the ground for worms, insect larvae and other arthropods, and seeds and edible roots. Earthworms seemingly form the bulk of their diet followed by tipulid fly larvae (known popularly as leatherjackets). During the breeding season, the male’s bill becomes shortened due to extensive probing behaviour while that of the female (she is solely responsible for incubation) increases due to relative lack of wear (Green 1996).

Whether Rooks are beneficial or damaging to agriculture has been much-discussed. Their avid consumption of tipulids surely makes them highly beneficial, since these larvae are significant crop pests. Food intended for transport back to the nest is collected in a buccal pouch that, due to the lack of feathering at the base of the bill, is especially obvious relative to that of other corvids.

Some of the best books on corvids (with Carrion crow skull for scale). Photo (taken in the Tet Zoo library) by Darren Naish.

I’ve watched Rooks a lot. At wildlife parks and other outside attractions they’re typically abundant and also relatively unafraid of people, hence some of the close-range photos you see here. However, I really want to spend appropriate time properly observing the goings-on at an active rookery. And one day I will, in my extensive and copious spare time.

For previous Tet Zoo articles on crows and other corvoid passerines, see…

Next: ICHTHYOSAURS!!

Refs – -

Burton, M. 1978. Just Like An Animal. Biddles, London.

Coombs, F. 1978. The Crows. B. T. Batsford, London.

Ericson, P. G. P., Jansén, A.-L., Johansson, U. S. & Ekman, J. 2005. Inter-generic relationships of the crows, jays, magpies and related groups (Aves: Corvidae) based on nucleotide sequence data. Journal of Avian Biology 36, 222-234.

Green, P. 1996. The communal crow. BBC Wildlife 14 (1), 30-34.

Goodwin, D. 1986. Crows of the World. Trustees of the British Museum (Natural History), London.

Madge, S. & Burn, H. 1999. Crows and Jays: A Guide to the Crows, Jays and Magpies of the World. A & C Black, London.

Marzluff, J. & Angell, T. 2012. Gifts of the Crow: How Perception, Emotion, and Thought Allow Smart Birds to Behave Like Humans. Free Press, New York.

Darren Naish About the Author: Darren Naish is a science writer, technical editor and palaeozoologist (affiliated with the University of Southampton, UK). He mostly works on Cretaceous dinosaurs and pterosaurs but has an avid interest in all things tetrapod. His publications can be downloaded at darrennaish.wordpress.com. He has been blogging at Tetrapod Zoology since 2006. Check out the Tet Zoo podcast at tetzoo.com! Follow on Twitter @TetZoo.

The views expressed are those of the author and are not necessarily those of Scientific American.





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  1. 1. BrianL 12:54 pm 05/12/2013

    Ah, the Rook. Is the degree of sociality in this species truly very different from other *Corvus* species or is it more at the extreme of a trend? Surely, other members of the genus can be fairly social at times, though admittedly not breeding in colonies? Of course, that also depends on wether or not you include jackdaws within the genus. They are clearly very social, like rooks.

    Is it known if the high degree of sociality in rooks is due to their specialised feeding habits or if there might be any sort of connection between the two?

    I think that the difference between the *pastinator* subspecies and ‘typical’ rooks shows once again what difference feathers can make for the overall look of a bird. With a naked face, the rook is an unusual *Corvus* indeed whereas with a feathered face it just looks like a normal crow. Is it likely that *pastinator* represents the ancestral look of rooks as would seem most logical or are we actually looking at a paedomorphic rook, by the way?

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  2. 2. Heinrich Mallison 12:54 pm 05/12/2013

    and here is the full rook pr0n series.

    Link to this
  3. 3. naishd 1:11 pm 05/12/2013

    Sorry, Heinrich, I’d forgotten that the full sequence is already online.

    Darren

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  4. 4. vdinets 1:37 pm 05/12/2013

    In central Yakutia (the part of Siberia with the most extreme climate) there is an isolated rook population that breeds in the so-called “alas” meadows, large meadow patches surrounded by larch taiga. These meadows are supposedly leftowers from the Pleistocene megafauna-dependent landscape, currently maintained by Yakut horses and cows. This is probably the only place where rooks still don’t use agricultural fields. In other parts of the range it is difficult to figure out what their original habitat was.

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  5. 5. Heinrich Mallison 1:57 pm 05/12/2013

    Darren, how can even begin to think I could bypass dinosaur sex? ;)

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  6. 6. AlexanderBerg 3:24 pm 05/12/2013

    As being a somewhat more of a hexapod than tetrapod person, I shuddered at the term “tipalid”, surely you mean tipulid, as in Tipulidae (Diptera; Nematocera)?
    ;)

    Nice article, Rooks are such charismatic birds, I particularly enjoy them in early spring when they are faffing about looking particularly silly with their baggy trousers, fanned tails and bobbing gait. And that they seem to think that we humans are interested in stealing their acorns, haha..

    Here in southern Sweden they are generally disliked however, being seen as noisy (I quite like the sound of nearby rookeries personally), polluting, unhygienic etc.. :/

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  7. 7. naishd 3:43 pm 05/12/2013

    Tipulid it is, whoops.

    Darren

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  8. 8. Perisoreus 5:39 pm 05/12/2013

    Finally, Corvids! (Although I’m still waiting for the “Gifts of the Crow” review)

    I might add some points: based on DNA barcodes, the rook has been placed (bn two independent studies from 2012, Haring et al. and Jonsson et al.) as sister to the Hawaiian Crow (C. hawaiiensis), which makes sense, given the geographical proximity. Unfortunately, there are no sequences for the two extinct Hawaiian crows (C. impluviatus and C. viriosus) to compare. C. frugilegus and C. hawaiiensis were retrieved as sister to the (Holarctic and African, not the Australian) ravens.

    Sociality is an interesting aspect in this species, but this is true for most of the Corvid species I’ve dealt with so far. Of course, nesting is here especially remarkable, tool use – in my view – not so much. What is not so clear from your account, Darren, is that C. f. pastinator loses its nasal tufts with age (so the base of the bill may indeed be feathered, but not the nostrils).

    And concerning the books: I’d regard none of the titles as a cutting-edge work on corvids (can’t say much about Coombs, though). I usually recommend Goodwin (1986) to corvid newcomers, since it is written by an enthusiast with a lot of experience in the field and it gives a wonderful overview on their behaviour and relation to man. The species and genus accounts, however, are rather outdated, as are Goodwins systematic hypotheses (although, as a good observer, he was right in some crucial points).

    Madge & Burn (1994) was certainly a good work when it was published, but reading it, I found some crucial points missing when I compared it to Goodwin (1986). Some very meager accounts could have easily been filled with Goodwins information and papers available at that time, as a large part of it is taken from Goodwin anyway. Besides that, the corresponding volume of the Handbook of the Birds of the World (Lynx Edicions) is available since 2009, and it covers the whole Madge & Burn (1994) while providing an excellent family account and updated species accounts and distribution maps. The best regional species accounts for corvids are given by the Birds of North America, Cramp’s and Simmon’s (1994) “Birds of the Western Palearctic” and (for those speaking German) Glutz von Blotzheim’s (1993) “Handbuch der Vögel Mitteleuropas”. For Australia, the “Handbook of the Birds of Australia, New Zealand and the Antarctic” (HANZAB) is, as usual, the first address.

    I’m not too happy with Marzluff’s and Angell’s (2012) latest work, at least not when I compare it to their previous “In the Company of Crows and Ravens” (2005). While the latter was an ambitious attempt to cover all the ways that corvids affect prehistoric, ancient and modern humans, the former feels a lot like neuro-reductionism. It tries to explain corvid behaviour largely in terms of neurophysiology and brain size, and I think this misses the point. John Marzluff is professedly interested in corvid culture, but I find that “The Gift of the Crow” captures this field even when I compare it to his initial “The Pinyon Jay”. It’s hard to put my finger on the why, but I think Marzluff is lacking some recent anthropological theory when discussing culture, innovation or tool use. Be that as it may, I’ll come back to it, should there ever be an extensive review. :)

    In any case, thanks for the article (and regards to HMallison, I didn’t expect you here – although I should have)

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  9. 9. naishd 6:00 pm 05/12/2013

    Perisoreus (comment # 8): thanks for the lengthy comment. Some quick responses…

    – Phylogeny: yes, the link with Pacific crows is very interesting. I was mostly trying to emphasise the fact that the Rook is deeply nested within indisputable Corvus, not a disparate outsider.
    – I didn’t know that C. f. pastinator loses its nasal tuft – interesting. Have only ever heard that it keeps the facial feathering otherwise lost in other Rook populations. This is relevant to what BrianL asks in comment # 1.
    – On the uniqueness of the Rook … of course tool use is well known in other members of the group; I certainly didn’t mean to imply that the Rook is at all special in that regard. Its colonial nesting habit surely is unusual, however, and evidently an extreme version of the more limited sociality present in other corvids.
    – The corvid books I showcase above are shown because they’re neat, not because they’re meant to be “cutting edge” :) The accounts in Madge & Burn are indeed obviously based on those provided by Goodwin. If you don’t have Coombs’s volume it’s well worth hunting down – what a classic (and very nicely illustrated) book. Incidentally, I own The Pinyon Jay and did think about including it in the image as well…
    – And, yes, I do need to review Gifts of the Crow at some stage. Still haven’t finished reading it. Love the anecdotes; not so keen on all the brain anatomy stuff.

    Thanks for all comments so far, keep ‘em coming.

    Darren

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  10. 10. Dartian 10:56 pm 05/12/2013

    Perisoreus:
    which makes sense, given the geographical proximity

    The geographical proximity between the Palearctic and the Hawaiian islands? Rather than making sense, that’s highly unexpected, IMO.

    And correct me if I’m wrong, but almost all Hawaiian land birds are ultimately of New World origin. It’s thus also quite unexpected if the Hawaiian crow, of all birds, really is an exception.

    How old is the rook-Hawaiian crow split according to those papers you cite, and how old are the Hawaiian islands?

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  11. 11. naishd 3:15 am 05/13/2013

    Dartian (comment # 10): the postulated link between the Rook and the Hawaiian species is relatively poorly supported and there have been appropriate caveats about its reliability. Haring et al. (2012) stated…

    “The closer relationship of C. hawaiiensis and C. frugilegus as suggested by the short CR sequences has to be considered with caution. A preliminary genetic analysis by Fleischer and MacIntosh (dos Anjos et al. 2009) suggests that the former species might be more closely related to C. corax than to other Corvus species. However, in their study they included only a few species, thus these relationships are rather vague. The isolated geographical range of C. hawaiiensis does not allow any assumption based on biogeographical considerations. Due to the short sequence length analysed the current results can only be taken as a weak hypothesis that should be further investigated. If this relationship is confirmed by further sequence data, this would provide a nice opportunity to calibrate a rough molecular clock based on the age of the Hawaiian archipelago.”

    Haring, E., Daubl, B., Pinsker, W., Kryukov, A. & Gamauf, A. 2012. Genetic divergences and intraspecific variation in corvids of the genus Corvus (Aves: Passeriformes: Corvidae) – a first survey based on museum specimens. Journal of Zoological Systematics and Evolutionary Research 50, 230-246.

    Darren

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  12. 12. Perisoreus 3:36 am 05/13/2013

    Dartian (Comment #10)

    Well, Hawaii is remote by every respect, yet it harbours (or harboured) a number of species that were able to cross an enormous distance. Of course, a lot of the radiations took place in situ (which explains the huge number of small passerines), but some species are obviously descendants of migratory ancestors (take, for example, the extinct harrier Circus dossenus). To present knowledge, North America is rather new ground for Corvus (see for example Jonsson et al. 2012: Brains, tools, innovation and biogeography in crows and ravens) while the Old World is where they emerged. It’s true that Hawaii is somewhat closer to North America today, but remember that during the Miocene and Pleistocene, there was a land bridge connecting today’s Eurasia and North America, and it was directly adjacent to the Rooks present range.

    In Addition, there are a lot of stepping stones in the western Pacific while the Eastern pacific is essentially bare. It was apparently easier to reach island this way for birds, compare for example the Mascarenes, which show a surprising lack of genuine African taxa.

    So the best candidates for colonizing the pacific among Corvus are large, rather unspecialized and migratory species. The ancestor of the Hawaiian Crow was apparently a “proto-raven” (I don’t think it was very similar to the rook), so it was then among the largest crows. Possibly, it was a seasonal migrant, as all the other wide-ranged generalists among this genus are migrants today. Most of this is true for the Rook, not so much for ravens. I wouldn’t expect any of the smaller and less migratory American species in Hawaii and the Common Raven is rather a disperser than a migrant.

    But yes, a lot of this is free-hand speculation and I might miss a lot of the crucial aspects. The split between Rook and Hawaiian Crow is very deep and old: in Jonsson’s study, it dates back to the Miocene when Hawaii didn’t even exist (but probably some other islands in the same region). But as I indicated: North America has a rather short Corvus history, while obviously a lot was going on in the western Pacific region.

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  13. 13. David Marjanović 6:15 am 05/13/2013

    Coming from a place with rooks but no rookeries, this was particularly interesting for me! In Austria, they arrive in large flocks when the leaves have fallen, and fly off to Russia or thereabout when the winter ends.

    phyllogram

    Phylogram. Tribe, not leaf. :-)

    the “Handbook of the Birds of Australia, New Zealand and the Antarctic” (HANZAB)

    The Hand-Australia-New-Zealand-Antarctic-Book? …Oh. The Handbook of Australian, New Zealand and Antarctic Birds. Now it makes sense. :^)

    The split between Rook and Hawaiian Crow is very deep and old: in Jonsson’s study, it dates back to the Miocene

    Obligatory question: how was this calibrated?

    Link to this
  14. 14. vdinets 7:20 am 05/13/2013

    Actually, Hawaiian birds are a mix of species of North American, Polynesian and Palearctic origin. The ancestor of the largest local radiation, the Hawaiian honeycreepers, was apparently a Palearctic finch. It looks like the ones of North American origin tend to be the most recent arrivals.

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  15. 15. Dartian 8:42 am 05/13/2013

    Perisoreus:
    there are a lot of stepping stones in the western Pacific

    True, and, contrary to what I wrote above, some members of Hawaii’s avifauna do indeed seem to have come from that direction (and not from the Americas): for example, honeyeaters, monarch flycatchers, and Acrocephalus. At the same time, however, many bird and bat taxa typical of the western Indo-Pacific realm have failed to reach Hawaii (e.g., columbiforms, psittaciforms, and megachiropteran fruit bats).

    Birds that have surely colonised to Hawaii from the New World are more numerous. At least Branta, the herons, Buteo, Asio, Fulica, Himantopus, Myadestes, and the honeycreepers (in reality carpodacine finches) are of American origin, as is the bat Lasiurus; Gallinula, Porzana and the ancestor of the extinct ibis Apteribis probably are/were of New World origin too. (Anas is equivocal in this regard, as are the two cosmopolitan raptors, the osprey and the peregrine falcon.)

    So there is a fairly obvious New World bias regarding the origin of Hawaii’s birds. No members of Hawaii’s avifauna would clearly seem to be of Palearctic origin, though.

    As for where this leaves the crows; given that there is a large Corvus radiation in the western Indo-Australo-Pacific region, I’d intuitively consider this as a far more likely source of origin for the Hawaiian crow than temperate Eurasia (or perhaps even North America). How many phylogenetic studies have been done that include both the rook, the Hawaiian crow and at least some of the various tropical crow species in SE Asia/Australasia?

    Link to this
  16. 16. Perisoreus 10:37 am 05/13/2013

    David Marjanović (Comment #13)

    Thanks for the correction :)

    Obligatory question: how was this calibrated?

    Quote: “To estimate the relative divergence times within Corvus, we used BEAST v.1.6 and assigned the best fitting
    model, as estimated by MRMODELTEST, to each of the four partitions. We assumed a Yule Speciation
    Process for the tree prior and an uncorrelated lognormal
    distribution for the molecular clock model. We used default prior distributions for all other parameters and ran MC3 chains for 50 million generations. The program Tracer was used to assess convergence diagnostics. To obtain absolute date estimates we calibrated the tree using secondary calibration points derived from Barker et al. who used various approaches to date the all Passeriformes tree. Thus we used the age of Acanthisittidae versus other passerines at 76 ± 8 My SD (age within 95% confidence intervals = 62.8–89.2 My) and the split between Menura noveahollandiae and all other oscines 63 ± 2 My SD (confidence intervals = 59.7–66.3 My). In order to apply these calibration points, some additional taxa were included in the dating analyses (see Table 1). We also compared our age estimates with the classic mitochondrial 2% rule”

    Source.

    I don’t trust molecular clocks too much, but even without questioning methodology here, I think the split is really older than today’s Hawaiian archipelago. But there are predecessors (Emperor Islands) of course.

    Dartian (Comment #15)

    I’m skeptical when it comes to theories about “main sources” of an avifauna, especially one that assembled over a million year’s timespan. Given that a lot of Hawaiian taxa are extinct and no longer accessible for DNA analysis (the Grallistrix owls, for example), I’d also be cautious with regards to western or eastern bias on Hawaii.

    Regarding the Indo-Pacific-Australian crows, there’s an interesting pattern in the two studies who have dealt with the genus extensively (Darren has given the quotation for Haring et al. above, the link to Jonsson et al. is in my response to David). The genus apparently moved from the southeastern palearctic down to what is today Australia and radiated from the respective mainland to the smaller isles: the indonesian crows stem, as it seems, from repeated colonisations, while the more remote species seem to have taken the shortest road: the Mariana Crow is closely related to the Philippine Jungle Crow C. macrorhynchus philippinus (itself belonging to a messy wastebin species), while the Solomon and Bismarck crows group with the New Guinean ones. The Caledonian Crow’s (C. moneduloides) affinities are not quite clear, it is somewhat close to the Slender-billed Crow complex but might be closer to the New Guinean-Solomon-Bismarck assemblage. And then there are the extinct New Zealand and Chatham species, of course, for which the Australian C. cornoides is considered the closest living relative (see this).

    So most of the crows of the western Pacific seem to have dispersed south- and then eastwards to the Pacific islands. A similar pattern can be observed in North America, where crows colonised the Carribean and Central America from the northwest (however, they were probably halted by the Cyanocorax jays further south).

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  17. 17. BrianL 10:50 am 05/13/2013

    @Dartian:

    You can add your ‘honeyeaters’ to your North American list. Moho’s have been recovered as bombycilloids some years ago. They seem to be closest to silky flycatchers, if I’m not mistaken.

    I don’t know wether you included moa nalo and *Talpanas* among *Anas* since the moa nalo at least seem to be derived from that genus in its traditional composition. Do realise that the current trend seems to be to split up traditional *Anas* into a number of genera that were previously sunk into it (hence *Mareca*, *Querquedula*,*Sibrionetta*, etc.) According to the TIF checklist, moa nalo should be considered the basal divergence here. If so, this doesn’t help spectacularly. According to TIF, moa nalo are sister to traditional *Anas* species plus *Salvadorina*, *Tachyeres*, *Lophonetta*,*Amazonetta* and *Speculanas* Of these, *Salvadorina* is New Guinean, while the others are South American. The whole shebang including moa nalo is sister to *Calonetta* from SA. My guess is that the moa nalo ancestors did come from North America, but who knows?
    As for *Talpanas* (and let’s not forget mysterious *Geochen*)…your guess is as good as mine.

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  18. 18. Heteromeles 7:11 pm 05/13/2013

    Ah, I love it when zoologists talk about Hawaii. Everyone is so romantic.

    I just spend a week in a condo on Maui, and there are scads of doves (spot-necked and zebra doves) all over the place. There are also mynas (which seem to have taken over the corvid scavenger role), house sparrows, and francolins around the condos. We didn’t see any native landbirds below about 7000 feet, unless you want to count the black-necked stilts in a reserve.

    Yes, I enjoyed seeing a few honeycreepers as much as anyone else I did drive up Haleakala to see them (didn’t see a nene, sadly). Thing is, Hawaii is a romantic isle for evolutionary biologists, romantic in the sense that we go there not to see the present, but to experience our imagination of how it was supposed to be, back in a little-known and fairly hypothetical past. Given this, you have to be just a little bit careful about over-romanticizing about the whole thing.

    Conversely, if you want to study incipient insular adaptive radiation, there’s likely a ton of it going on in the lowlands right now. I’ll bet that, in 10,000 years, there will be separate mongoose species on each island, and a swarm of new anolis species. Won’t that be great?

    Link to this
  19. 19. Dartian 10:30 pm 05/13/2013

    Perisoreus:
    I’d also be cautious with regards to western or eastern bias on Hawaii

    But it’s not just the birds (and the bats). Many, and perhaps most, of Hawaii’s insect and plant taxa also have obvious New World affinities. It seems a bit like grasping at straws to expect a few as-of-yet phylogenetically unstudied extinct Hawaiian birds to substantially alter this overall pattern.

    Incidentally, that reference by Jønsson et al. (thanks for it, by the way) have this to say regarding the relationships of the Hawaiian crow and Hawaii’s avifauna generally:

    “[T]he Hawaiian crow (C. hawaiiensis) is not a member of [the Indo-Pacific crow] clade, instead it clusters with the Palaearctic C. frugilegus (Clade IV) and so we infer it to have colonized Hawaii from East Asia. This is unexpected because the Hawaiian biota generally evolved through colonization from America whereas that of the rest of the Pacific was mostly colonized from Asia and Australo-Papua”

    Emphasis mine. I highlighted the authors’ use of the word ‘unexpected’ because I used it too in comment #10 – without having been aware of this reference until now. ;)

    Brian:
    You can add your ‘honeyeaters’ to your North American list. Moho’s have been recovered as bombycilloids some years ago. They seem to be closest to silky flycatchers

    Thanks for that. I had managed to completely forget about that study.

    I don’t know wether you included moa nalo and *Talpanas* among *Anas*

    What I mostly had in mind were the suggestions that the ancestors of the Laysan duck Anas laysanensis are of Indo-Pacific and the ancestors of the Hawaiian duck Anas wyvilliana are of North American origin – thus representing two separate colonisation events of Hawaii by dabbling ducks.

    Link to this
  20. 20. vdinets 2:13 am 05/14/2013

    Aren’t Drepanidids Palearctic in origin? I definitely remember reading something about it, but I have limited internet access at the moment.

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  21. 21. Perisoreus 3:50 am 05/14/2013

    vdinets (comment #20)

    Not necessarily, at least not according to Helen James’ osteological study.

    The Carduelini, grouping as sister to the Drepanidini in this analysis, are of holarctic distribution.

    Link to this
  22. 22. Perisoreus 3:59 am 05/14/2013

    Dartian (Comment #19)

    But it’s not just the birds (and the bats). Many, and perhaps most, of Hawaii’s insect and plant taxa also have obvious New World affinities. It seems a bit like grasping at straws to expect a few as-of-yet phylogenetically unstudied extinct Hawaiian birds to substantially alter this overall pattern.

    I don’t argue against an overall pattern (which I do not doubt), but against inferences from that pattern to obviously aberrant members of this fauna. The ancestry of finches and ducks can’t tell us anything about harriers, owls, or, for that matter, crow. I’d expect a large crow as colonizer of Hawaii (just as with New Zealand and the Marianas), but the large corvids of NA are rather young species, especially the ravens and the American/Northwestern Crow. The Eurasian crows, on the other hand, have been around for a little longer and the western Pacific islands are full of them.

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  23. 23. naishd 4:32 am 05/14/2013

    Enjoying the discussion, thanks to all for comments. I just want to point out how the general idea that members of an avifauna all (or, at least, mostly) came from the same area reminds me of similar discussions that used to be held about the Mascarene avifauna. Wisdom had it that all the birds on the Mascarenes came from India. But studies later showed that the Mascarene birds are a hodge-podge of animals from diverse sources. The falcons, ibises, sheldgeese and coots are from Africa, the white-eyes came from Asia, Africa and Madagascar, the harriers might be from Australia, some of the pigeons are from southeast Asia, some are probably from India, and so on.

    I realise, of course, that the case of isolated Hawaii is very different from that of the Mascarenes, but it’s right to be sceptical of the idea that components of a fauna all have the same approximate geographical origin.

    Darren

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  24. 24. Lars Dietz 4:42 am 05/14/2013

    Perisoreus: Actually, the phylogeny in that paper shows Carduelinae (Carduelini in their taxonomy) as paraphyletic towards Drepanidini, with Pinicola enucleator as their closest relative. Molecular results (Lerner et al. 2011, Zuccon et al. 2012 show Drepanidini as closest to Old World rosefinches (Carpodacini). Of course, they still could have evolved from an extinct North American ancestor, but Carduelinae in general are clearly of Old World origin with multiple dispersals to North America.

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  25. 25. David Marjanović 5:52 am 05/14/2013

    To obtain absolute date estimates we calibrated the tree using secondary calibration points derived from Barker et al. who used various approaches to date the all Passeriformes tree. Thus we used the age of Acanthisittidae versus other passerines at 76 ± 8 My SD

    What the vertical gene transfer!?!

    It’s from 2012!!! Is it even possible they didn’t know about Shaul & Graur (2004), “Reading the entrails of chickens”?!? Massive failure of peer review, too!

    *sigh* How did Barker et al. calibrate their tree, then? Cretaceous passeriforms hardly make any sense.

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  26. 26. Chabier G. 6:03 am 05/14/2013

    The Rook is an enigmatic bird for Spanish ornithologists. Nobody knows why this species only breeds in very located places in the province of León (NW Spain), and not elsewhere. It’s difficult to be explained, dealing with such an adaptable bird, in a country where all the other Corvidae species are quite widespread and abundant.

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  27. 27. Perisoreus 6:04 am 05/14/2013

    naishd (comment #23)

    The falcons, ibises, sheldgeese and coots are from Africa, the white-eyes came from Asia, Africa and Madagascar, the harriers might be from Australia, some of the pigeons are from southeast Asia, some are probably from India, and so on.

    Do you remember the source for that alleged Australian ancestry of the Reunion Harrier? My latest state of knowledge (Simmon’s Harriers of the World, if I remember correctly, which isn’t the best source in this respects) had the Reunion and the Madagascar Harrier as sisters to the Palearctic (Western) Marsh Harrier, while the Australian Swamp harrier was the sister to that group. Interesting, by the way, that crows never reached the Mascarenes until recent times.

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  28. 28. naishd 6:45 am 05/14/2013

    Re: inferred Cretaceous passerines (comment # 25)… yikes, I’d missed that (not that such an inference is unique to this study). For those interested in the ‘entrails of chickens’ paper that David mentions, it’s…

    Graur, D. & Martin, W. 2004. Reading the entrails of chickens: molecular timescales of evolution and the illusion of precision. Trends in Genetics 20, 80-86.

    Darren

    Link to this
  29. 29. Dartian 6:50 am 05/14/2013

    Darren:
    it’s right to be sceptical of the idea that components of a fauna all have the same approximate geographical origin

    It is, and for the record, I was never suggesting otherwise in my earlier comments. I was just expressing (fully justified, IMO) surprise at the idea of a sister-species relationship between a temperate Eurasian and a tropical Eastern Pacific island-living species. AFAIK, such a thing is virtually unheard of among passerines, or perhaps* even birds in general.

    * I inserted the ‘perhaps’ there for a reason. Isn’t there an extinct Hawaiian species of sea eagle Haliaeetus that’s supposedly most closely related to the Palearctic white-tailed eagle H. albicilla? (Of course, sea eagles are much stronger fliers than crows, so their transoceanic dispersal is perhaps slightly less unexpected.)

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  30. 30. naishd 7:37 am 05/14/2013

    Perisoreus (comment # 27), re: “alleged Australian ancestry of the Reunion Harrier?”, turns out I was sorta mis-remembering what Cheke & Hume (2008: Lost Land of the Dodo) said. Citing Simmons* (2000: Harriers of the World), they imply a sister-group relationship between the two Indian Ocean forms and the Swamp harrier C. approximans, and they explicitly discuss a trans-Indian Ocean migration.

    However, I checked Simmons (2000) and the phylogeny therein depicts a sister-group relationship between the two Indian Ocean forms and C. aeruginosus; the Swamp harrier C. approximans is then the sister-taxon to all three. Sorry for being misleading!

    * They accidentally use ‘Simmonds’.

    Darren

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  31. 31. Jerzy v. 3.0. 3:29 pm 05/14/2013

    I have somewhat different problem, which is bugging me for some time.

    Rooks, magpies etc. pass mirror self-recognition and some other intelligence tests which only humans and very few animals pass. Should corvids get some protection because of their advanced minds, together with great apes, elephants and dolphins? E.g. protection from shooting as vermin?

    Usually birds get special protection because they are endangered species. Should corvids, although common as dirt and sometimes nuisance, get special protection because of their ape-level intelligence?

    After some thinking, I cannot see an argument against.

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  32. 32. Jerzy v. 3.0. 3:34 pm 05/14/2013

    @29
    There was an extinct subspecies of Gadwall on one Pacific Island.

    Migrant temperate species are actually rather good candidates for vagrancy and colonizing remote islands.

    Link to this
  33. 33. vdinets 4:34 pm 05/14/2013

    It is worth noting that virtually all vagrant or migrant birds recorded on Hawaii today are from North America. Apparently the pattern used to be different, probably because the earliest colonizers arrived on islands further west that are now mostly submerged. Note that the only non-Drepanidid songbird on those tiny islets is not from North America, and the same might be true for Laysan teal.

    Jerzy: Corvids are not mammals. Archosaurs are our competitors, not brothers. We shouldn’t encourage them to get too smart (and protecting species based on their human-like intelligence would create strong selective pressure in the long term). Corvid takeover is a very real possibility, we shouldn’t encourage it. Have you read The War on Salamanders?

    Chabier: could it have something to do with parasitism by the great spotted cuckoo? I was under impression that it’s more of an issue in Spain than elsewhere in Europe.

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  34. 34. Heteromeles 4:54 pm 05/14/2013

    Personally, I think protecting intelligent corvids exhaustively is an excellent strategy for keeping them from developing human-level intelligence. After all, we are talking about selective pressure. If they are a real threat, I’d rather have help them evolve into harmless moochers.

    The opposite is what we’ve done with everything from malaria to Staphylococcus aureus to cockroaches, rats, and raccoons–try to wipe them out. All this has done is make them that much tougher, to the point where we could only control them with great and continual efforts. These are red queen races, in other words.

    BTW, this is one of my favorite arguments for conservation. I’d much rather have rich landscapes of species that we enjoy, that we can exploit, and that depend on us in some part for their ultimate survival. The alternative is a landscape of species that we can’t control, that take advantage of us or otherwise inconvenience us, and that decrease our quality of life. To put it simply, I’d much rather camp in a field of wildflowers with birds, than a field of thistles with fire ants. Unfortunately, this seems to be a minority view…

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  35. 35. Dartian 3:34 am 05/15/2013

    Vladimir:
    could it have something to do with parasitism by the great spotted cuckoo?

    Wouldn’t the colonial nesting habits of the rook offer good protection against the cuckoos? It would certainly be much more difficult for the cuckoo to sneak an egg into a rook’s nest inside a colony without being detected (and presumably attacked and chased away).

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  36. 36. David Marjanović 5:47 am 05/15/2013

    *facepalm* Where did I get “Shaul” from?!?

    I’m really not used to keeping track of people. The only reason at all I remember the names of scientists I haven’t met is to cite their papers.

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  37. 37. Chabier G. 5:47 am 05/15/2013

    Vdinets:
    Great spotted cuckoo is fairly common here, but its main host species is the magpie, and magpies populations don’t seem to suffer by that parasitation. Other possible explanation could be competence with red billed chough, another insectivorous corvid. In Spain this species thrives not only in the mountains, but also in steppe, moor and corn plains, nesting in old buildings. I think in other European countries choughs are confined to mountains.

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  38. 38. Perisoreus 5:57 am 05/15/2013

    There’s another great book on corvids that I forgot and I don’t think it was mentioned before:

    It’s Tony Angell’s (1978) Ravens, Crows, Magpies and Jays, a predecessor in many respects to his later collaborations with John Marzluff. It contains a lot of exquisit drawings and focuses on the corvids of North America (also covering those left out by the Birds of North America), also providing short species accounts of about a page. The rest of the book is of rather anecdotal character, but I think that’s what makes it so nice to read.

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  39. 39. Perisoreus 6:09 am 05/15/2013

    Chabier G. (comment #38)

    I think in other European countries choughs are confined to mountains.

    An interesting point, since Spain is in fact the last European stronghold of the Red-billed Chough. It has virtually disappeared everywhere else west of the Balkan; there are but about 50 breeding pairs left in the alps (where its congener, the Yellow-billed Chough is thriving) and they only breed at the Atlantic coast in France, Britain and Ireland. Back in the 19th century, it was still widespread in the region, and it is said to have nested at the northernmost point of the danube in medieval times. It’s indeed a curious circumstance that it still persists in Spain while the Rook is confined to a very small area.

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  40. 40. vdinets 6:41 am 05/15/2013

    Dartian: magpies are loosely colonial in many places, too (not sure about Spain).

    Chabier: that’s really strange, considering that Spain is a warm, dry place compared to most of Europe, and r-b chough is generally a species of higher elevations which tends to be replaced by y-b chough in drier mountains of Central Asia.

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  41. 41. Chabier G. 7:17 am 05/15/2013

    Well, I know it sounds strange,indeed red billed chough is a symbol of the mountain wildlife. But in the Ebro Valley, where I live, this species roamed the arid steppe of Monegros, probably the driest place in Europe, with 250 mm of annual rainfall, more than 40ºC in the summer, and a vegetation that ressembles that of the Middle West or Maghreb shrublands. They nest in old sheep sheds and other ancient buildings, forming colonies of several tens, and gathering in flocks of hundreds in the winter months. Even around the city of Zaragoza, the distinctive sound scream of the choughs is a part of the landscape. The main concern about red billed chough conservation, indeed, is the progressive ruine of these shelters, replaced by new preformed buildings that don´t offer any nest cavity.

    Link to this
  42. 42. vdinets 10:16 pm 05/15/2013

    Chabier: This is probably a silly question, but has anyone looked at the genetic structure? There is a small chance that a cryptic lowland species exists…

    Link to this
  43. 43. Chabier G. 7:55 am 05/16/2013

    Well, AFAIK nobody has investigated chough genetics. I’ve observed for many years choughs in Aragón, in the field and, sadly, in post-mortem examination, and I can’t notice any difference in size, colour, aspect, ethology, anatomy or singing, between mountain and steppe choughs. Nobody, among the ornithologists I know, has noticed differences. But, well, now we know enough about crytovariation to don’t trust too much in the common sense. Nobody noticed the very different song of Iberian chiffchaff until it was determinated as a separated species, and the same happens with bat cryptic species, once the new taxon is described, somebody finds unique features as different sound frequences.
    Chough genetics could be an interesting line of investigation. In past years our wildlife rescue center sent samples of some species to the laboratory. Unfortunately, in our current situation, genetic analysis has been restricted to our “totemic” species, the bearded vulture.

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  44. 44. naishd 8:39 am 05/16/2013

    There are a few studies on Red-billed chough phylogeography (including a PhD study – Marius Wenzel’s. Anyone know if it’s been published yet?). I don’t think any of these studies sampled choughs from the Ebro River region, but it would be interesting to know.

    Darren

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  45. 45. glynyoung 9:45 am 05/16/2013

    Is this the one? Pronounced genetic structure and low genetic diversity in European red-billed chough (Pyrrhocorax pyrrhocorax) populations. Conservation Genetics
    http://link.springer.com/article/10.1007%2Fs10592-012-0366-6
    There are some other chough populations worth a good look at too like the one in Ethiopia

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  46. 46. Perisoreus 8:33 am 05/18/2013

    There is a study based on morphometry and vocalizasation by Laiolo et al. (2004) (see here https://de.wikipedia.org/wiki/Alpenkrähe#Literatur) and one of genetic diversity in Britain, it should be mentioned by Wenzel et al. (2012).

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  47. 47. llewelly 2:05 pm 05/19/2013

    Very good interview with the author of _Gifts of the Crow_ here

    http://skepticallyspeaking.ca/episodes/213-bird-brains

    Link to this

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