Sparrows of the West

Recent decades have seen significant shifts in the classification of birds, particularly among the Passeriformes, the perching birds. These shifts have lead to the recognition of a number of major groups that were previously obscured. Among these recent elevations are the New World sparrows of the Passerellidae.

Gambel's white-crowned sparrow Zonotrichia leucophrys gambeli, copyright Gregory Smith.

The New World sparrows are part of a broader radiation known as the nine-primaried songbirds, along with such luminaries as finches, tanagers, and their Old World namesakes. The name 'nine-primaried' refers to the number of well-developed primary feathers (the long outer ones) in the wings; most other perching birds have ten distinct primaries. Though the nine-primaried songbirds have long been recognised as a coherent group, there has been a lot of disagreement over their subdivision. Historically, these subdivisions were strongly influenced by different bill shapes representing different diet specialisations, but recent molecular phylogenies have demonstrated that bill shape is more labile than previously recognised. The New World sparrows were usually regarded previously as a subgroup of the generalist seed-eating family Emberizidae, along with the buntings of the Old World, but molecular phylogenies have asserted the division between the hemispheres. Not all New World representatives of the old Emberizidae have shifted to the Passerellidae: a significant component of the Neotropical fauna (including the finches of the Galapagos islands) have instead proven to be closer to the fruit-eating tanagers of the Thraupidae. As currently recognised, the passerellids are a fairly coherent group of about 140 species distributed around North and South America.

Goldwn-winged sparrow Arremon schlegeli schlegeli, copyright Nick Athanas.

In general, the passerellids are small birds with simple, conical bills. Most are dull brownish in coloration though many are strikingly patterned, particularly around the head. Some are more distinctive: the South American sparrows of the genus Arremon often stand out as particularly colourful. Most passerellids are fairly retiring in their usual habits, foraging at or close to ground level. As noted before, they are mostly generalist feeders. Their short bills are excellently suited for milling the small seeds which make up a large part of their diet. However, they will also take insects and other small invertebrates. One widespread North American species, Ammodramus savannarum, has earned the vernacular name of "grasshopper sparrow" as a result. Notable outliers dietwise are the Neotropical bush-tanagers of the genus Chlorospingus which are primarily berry feeders. These largely greenish birds were previously classified with the Thraupidae as a result before molecular data led to their reassignment.

Common bush-tanager Chlorospingus flavopectus, copyright Becky Matsubara.

Whereas Neotropical members of the Passerellidae are mostly sedentary, North American species are often migratory, moving north with the approach of summer. However, migration is commonly related to environmental conditions. A number of species are migratory in the northern parts of their range but may be found in their southern territories year-round. In some species, migrating populations will leap-frog over resident populations, moving further south than any resident individuals during the winter months. Many passerellid species are strong singers and courting males will often select an exposed branch to sing from in contrast to their usual skulking habits. Other species, particularly those inhabiting open habitats where trees and shrubs are in short supply, may have prominent aerial displays. Males of one of these latter species, the lark bunting Calamospiza melanocorys, moult during the breeding season into black plumage with contrasting white patches on the wings and tail. During the remainder of the year, they are dull in coloration like their females. Nesting is conducted close to ground level like feeding with the nest often being a small cup in the ground concealed under vegetation. Where breeding has been studied in detail, passerellids are commonly what has been called "socially monogamous". Males and females will form what appear to be monogamous pairs with one male remaining close to one female (though construction of the nest and incubation are done by the female alone). However, genetic studies on nestlings have found that chicks are not uncommonly not the child of their apparent 'father', indicating that females have not remained faithful to their mate.

Yellow-striped brush-finch Atlapetes citrinellus, copyright Ron Knight.

Prior to molecular studies, authors had suggested a possible division of North American passerellids between two evolutionary lineages based on ecology and behaviour, the grassland and brushland sparrows. A molecular study of passerellids by Klicka et al. (2014) identified eight well-supported clades within the family. Two further species, the large-footed finch Pezopetes capitalis of Central America and the Zapata sparrow Torreornis inexpectata of Cuba, were not robustly assigned to a clade. Identified relationships were comparable to but not entirely congruent with prior hypotheses. For instance, most 'brushland sparrows' (of the genera Passerella, Zonotrichia and Junco) belonged to a single clade but the remaining 'brushland' genus Melospiza was placed in a clade mostly made up of 'grassland' species. The diverse South American genus Arremon was supported as monophyletic but others were not. In particular, the North American Ammodramus was divided between two widely separated clades. This lead to the resurrection of the genus Ammospiza for a group of saltmarsh-breeding species. Deeper relationships within the family deserve further investigation.

REFERENCES

Hoyo, J. del, A. Elliott & D. A. Christie (eds) 2011. Handbook of the Birds of the World vol. 16. Tanagers to New World Blackbirds. Lynx Edicions: Barcelona.

Klicka, J., F. K. Barker, K. J. Burns, S. M. Lanyon, I. J. Lovette, J. A. Chaves & R. W. Bryson, Jr. 2014. A comprehensive multilocus assessment of sparrow (Aves: Passerellidae) relationships. Molecular Phylogenetics and Evolution 77: 177–182.

The Australasian Not-Robins

I've complained in the past about the decided lack of imagination displayed by many British naturalists when describing the fauna of Australasia. So many animals got lumbered with the names of European species to which they bore a superficial resemblance but of which they were not necessarily close relatives. So we got warblers that are not warblers, cod that are not cod, and the subject of today's post: robins that are not robins.

Male scarlet robin Petroica boodang, copyright Patrick Kavanagh.

Petroica is a genus of small perching birds found widely in Australasia, including species on various islands of the south Pacific. They are dumpy little birds whose males often have contrasting colour patterns with a dark dorsum and a light underside, though a couple of species are uniformly black. A number of species have red patches on the forehead and/or breast, and it is not too difficult to see why British naturalists chose to compare them to the European robin. They are insectivores, gleaning prey from vegetation or on the ground.

Over a dozen species are recognised in the genus Petroica, though the exact number varies depending on the author. Phylogenetic studies indicate four main lineages within the genus (Kearns et al. 2018) with some correlation between phylogeny and distribution. An Australian clade includes the scarlet robin P. boodang, the flame robin P. phoenicea, the pink robin P. rodinogaster and the rose robin P. rosea. As is indicated by their names, these are all red- or pink-chested forms, and they are found in woodlands in southeastern and southwestern Australia where they usually feed from leaves and branches. Females are duller in coloration, mottled grey or brown above and having the red on the underside lessened or lost; for the most part, the same pattern applies to females of the species described below.

Red-capped robin Petroica goodenovii, copyright Patrick Kavanagh.

More arid parts of Australia are inhabited by the red-capped robin Petroica goodenovii which is more terrestrial in habits than the preceding species. The red-capped robin forms a clade with two insular species, the Norfolk Island robin P. multicolor and the Pacific robin P. pusilla, the latter being found over a wide range from the Solomon Islands to Samoa (with a subfossil record from Tonga). The Norfolk Island robin is endangered with only an estimated 400 to 500 pairs surviving, a position whose severity was not fully appreciated until recently owing to the Norfolk Island and Pacific robins previously being regarded as conspecific with the Australian scarlet robin (Kearns et al. 2016). Kearns et al. (2016, 2018) also identified a strong genetic divergence between Pacific robins from the Solomon Islands and the eastern part of their range, suggesting the possibility of a further species division. However, they did not support such a divergence for the Samoan population which had previously been suggested as a candidate species by plumage and song characters.

Snow mountain robin Petroica archboldi, copyright Papua Expeditions.

The third clade includes two montane New Guinean species, the subalpine robin Petroica bivittata and the snow mountain robin P. archboldi. The male subalpine robin has a black back and white breast, without any red patches, and the species is found in high mountain forests and shrublands. The snow mountain robin, on the other hand, is a large Petroica species that is mostly slate-grey in coloration with a small red patch on the upper breast. It is found at the highest altitude of any bird in New Guinea and is the only bird found there in rocky scree habitats above the tree line. Both the New Guinean Petroica species, but particularly P. archboldi, have disjointed, localised ranges, and Kearns et al. (2018) expressed concern about the snow mountain robin's likelihood of future survival in the face of mining pressures and temperature rises.

North Island robin Petroica longipes, copyright Tony Wills.

The fourth and final clade, albeit a weakly supported one, unites the New Zealand Petroica species. Historically, most authors have recognised three Petroica species in New Zealand that, with the typical pithiness often associated with discussions of the somewhat depauperate New Zealand fauna, were generally known simply as the robin P. australis, the black robin P. traversi, and the tomtit P. macrocephala. However, multiple subspecies have been recognised within both the robin and the tomtit and recent years have seen calls for all to be recognised as distinct species (potentially raising the number of species in New Zealand to nine). Acceptance of these proposals has been varied: the North Island robin P. longipes now seems to be generally accepted as a separate species from the South Island P. australis but I have seen less recognition of more than one species of tomtit. The New Zealand robins are largely terrestrial feeders, and are noticeably longer-legged than other Petroica species. Male New Zealand robins are also duller in coloration with brownish backs. The more arboreal tomtits are the more similar in overall appearance to Petroica species from elsewhere. Most tomtit males are black above and white or yellow below. For the most part, female tomtits resemble other Petroica species in being duller than the males, brown above rather than black, but the female Auckland Island tomtit P. (macrocephala) marrineri is closer in appearance to the male. The Snares Island tomtit P. (macrocephala) dannefaerdi is uniformly black in both sexes. In this it resembles the larger black robin of the Chatham Islands, some distance east of New Zealand's South Island. Black robins are most reknowned for their conservation history with introduced predators reducing the entire species' population to only five individuals in 1980, including only a single breeding female. An intensive management program was instituted beginning with the capture and transfer of the entire population to a predator-free island. Higher breeding rates were encouraged through the removal of egg clutches from robin nests, with the bereaved birds laying a new batch to replace them and the original clutch placed in a nest of the local tomtit race to be raised cuckoo-style. As a result of this effort, population numbers increased until the current black robin population numbers about 250 individuals. Obviously, that's by no means enough to count their survival assured (and questions still linger about what, if anything, will be the long-term effects of inbreeding from such a minute founding populations) but it's still one heck of a lot better than what it was.

REFERENCES

Kearns, A. M., L. Joseph, L. C. White, J. J. Austin, C. Baker, A. C. Driskell, J. F. Malloy & K. E. Omland. 2016. Norfolk Island robins are a distinct endangered species: ancient DNA unlocks surprising relationships and phenotypic discordance within the Australo-Pacific robins. Conserv. Genet. 17: 321–335.

Kearns, A. M., L. Joseph, A. Thierry, J. F. Malloy, M. N. Cortes-Rodriguez & K. E. Omland (in press 2018) Diversification of Petroica robins across the Australo-Pacific region: first insights into the phylogenetic affinities of New Guinea's highland robin species. Emu.

Finches in Drag

Green-headed tanager Tangara seledon, copyright Dario Sanches.

In many parts of tropical South America, it is common to see small flocks of brightly coloured small birds foraging among vegetation, plucking off berries or hunting for insects. In many cases, these flocks may contain individuals of multiple or even several species. These are the tanagers, one of the Neotropical region's most characteristic bird families.

Tanagers are members of the bird clade known as the nine-primaried songbirds (so-called because their wings have nine functional primary feathers rather than the ten of other songbirds) that also includes the finches, buntings and cardinals. The largest genus of tanagers, and indeed one of the larger genera of birds in general, is Tangara. This genus includes about fifty species found in various parts of the neotropics. In their overall structure, they are fairly uniform: small, sturdy birds with a stout, moderate-length bill and an average-length tail (Hilty 2011). In other words, they have a fairly unremarkable, finchy-type appearance. In colour and patterning, however, they are considerably more varied, to the extent that I am at a loss to know where to begin. There are species of a rich, deep blue and of a bright, emerald green. There are species with bold, contrasting patterns of blues, blacks, greens or golds; there are species of a solid, uniform brilliance. There are species with caps or chests of orange or black. There are even a few, such as the plain-coloured tanager Tangara inornata, that eschew the gaudy pigments of their congeners entirely in favour of more restrained patterns of greys and beiges. In many species, males and females show little or no difference in appearance; however, in the black-capped group (including species such as the black-capped tanager T. heinei), the males have contrasting patterns of black and blue or yellow whereas the females are largely green and grey.

Golden tanager Tangara arthus, copyright Alejandro Bayer Tamayo.

As noted above, tanagers feed on a mixed diet of fruit and insects. The fruit part is dominated by small berries that they can either swallow whole or mash with their bills before swallowing them piecemeal. Studies on the mixed-species flocks formed by Tangara species have found that while different species show very little variation in how they obtain the fruit component of their diet, they usually show very distinct specialisations in how they forage for insects. Some hunt for insects along branches, others prefer to look on leaves. Branch-hunting species may differ in the thickness and density of branches preferred, or in the mode of searching employed. For instance, the golden tanager T. arthus and flame-faced tanager T. parzudakii can both be found foraging on moss-covered branches, but the flame-faced tanager usually catches insects by probing directly into the moss whereas the golden tanager usually either focuses on the moss-free sections or catches insects sitting on the moss surface without probing. A few species catch insects aerially, making short sallies from a perch.

Blue-grey tanager Thraupis episcopus, indicated by phylogenetic analysis as a species of Tangara, copyright Mdf.

Somewhat unexpectedly for a genus of this size and diversity in a group as taxonomically challenging as the tanagers, molecular phylogenetic studies have largely corroborated Tangara's monophyly. They have also supported the monophyly of most of the species groups recognised within the genus of the basis of similarities in plumage patterns (Sedano & Burns 2010). The only exception has been the discovery that many of the species previously included in the genus Thraupis form a clade nested within Tangara, leading to the suggestion that these two genera should be synonymised (apart from in informal discussions online, I'm not aware of anyone suggesting the alternative that Tangara be split). The 'Thraupis' species are larger and plainer in coloration than most other Tangara species. A few taxonomists have also suggested that the colourful green tanagers of the genus Chlorochrysa should be included in Tangara, but this relationship has not been supported by molecular data. Chlorochrysa species are glossier than the often more matt-coloured Tangara, and they have an acrobatic mode of foraging involving postures such as regularly hanging upside-down that differ from any Tangara species.

REFERENCES

Hilty, S. L. 2011. Family Thraupidae (tanagers). In: del Hoyo, J., A. Elliott & D. Christie. Handbook of the Birds of the World vol. 16. Tanagers to New World Blackbirds pp. 46–329. Lynx Edicions: Barcelona.

Sedano, R. E., & K. J. Burns. 2010. Are the northern Andes a species pump for Neotropical birds? Phylogenetics and biogeography of a clade of Neotropical tanagers (Aves: Thraupini). Journal of Biogeography 37: 325–343.

The Hawaiian Honeycreepers: Diversity in Danger

'Apapane Himatione sanguinea, copyright Peter LaTourette.

In 1938, avian malaria was discovered to have affected pigeons in the city of Honolulu (Amadon 1950). This might have seemed like a minor detail—except among breeders, pigeons do not normally elicit much concern from the average person—but it was to prove a disaster. From the pigeons, the disease spread into native birdlife of the Hawaiian archipelago and wreaked havoc. Many species living at lower elevations were wiped out, unable to withstand the disease's effects. Others were forced into remnant populations above an elevation of 1500m, where the disease's mosquito vectors were unable to survive.

Among the malaria's victims were several species of the Hawaiian honeycreepers, a group of small birds unique to the archipelago. The honeycreepers have become recognised as one of the classic examples of an island adaptive radiation, like the Madagascan vangas or the Galapagos finches. From the original colonisation of the archipelago by what was probably a fairly generalised finch-like bird, perhaps some five or six million years ago (Lerner et al. 2011), the Drepanidini have diversified into a disparate array of seed-eaters, insectivores and nectar-feeders. Some have evolved massive reinforced bills to crush the seeds of local trees such as koa or naio. Other have long slender bills that they use to reach into the depths of flowers or prise insect larvae from holes in bark. Currently, about fifty species of honeycreeper are known to have been present in the Hawaiian archipelago prior to human settlement; new ones continue to be described from fossil or subfossil remains. Sadly, due to factors such as habitat loss, competition with and predation by introduced fauna, and diseases such as the aforementioned malaria, only about twenty species remain alive today and many of those are critically endangered.

Maui 'alauahio Paroreomyza montana, copyright Markus Lagerqvist.

Older references will refer to the Hawaiian honeycreepers as their own family, the Drepanididae, due as much to long-standing uncertainty about their relationships to other birds as to their own distinctiveness. Many authors, such as Amadon (1950), argued for a connection between the honeycreepers and the South American flowerpiercers of the tanager family, believing that the nectar-feeders among the Drepanididae were closer in appearance to the group's original ancestor. However, recent studies, both molecular and morphological, have been unified in supporting a connection between the honeycreepers and the finches of the Fringillidae, leading to the demotion of the 'family' Drepanididae to a 'tribe' Drepanidini of the fringillids. In his original studies on the honeycreepers, Perkins recognised two subgroups: the 'melanodrepanines' were mostly nectar-feeders and were largely black and/or red in coloration, whereas the 'chlorodrepanines' were mostly seed-eaters or insectivores and usually yellow or greenish. Recent studies have supported the 'melanodrepanines' as a clade but identified the 'chlorodrepanines' as paraphyletic.

Po'o-uli Melamprosops phaeosoma, copyright Paul Baker.

One unusual feature of many Drepanidini is that they carry a distinctive scent that has been referred to as the 'drepanidine odour' (this site describes it as a sweet, musty smell). Two primarily insectivorous genera, the po'o-uli Melamprosops phaeosoma and the ʻalauahios Paroreomyza, lack this 'drepanidine odour', and on the basis of this and a couple of other points it has been questioned whether they are properly assigned to the Drepanidini. However, the osteological analysis of Drepanidini by James (2004) confirmed their position as drepanidines, a result that has since been corroborated by molecular analyses. It seems likely that Melamprosops and Paroreomyza are basal drepanidines outside an 'odoriferous' clade (Pratt 2014). Together with the akikiki Oreomystis bairdi, these species form a basal grade of generalist feeders with fairly slender bills. It is possible that the akikiki and the Maui ʻalauahio Paroreomyza montana are the only members of this grade surviving.

Laysan finches Telespiza cantans, copyright S. Plentovich.

The next clade of drepanidines to diverge in molecular phylogenies includes the Hawaiian finches, an assemblage of often seed- or fruit-eating species with thick, strong bills (Pratt 2014). James' (2004) osteological analysis did not resolve the finches as a single clade, instead intermingling them with the aforementioned grade. Again, the finches have been hard hit by extinction, with the only survivors being the palila Loxioides bailleui, the Laysan finch Telespiza cantans and the Nihoa finch T. ultima. Amadon (1950) noted that the Kona grosbeak Chloridops kona was extremely rare even when first discovered in the late 1800s, being restricted to an area of only 'a few square miles' in the Kona district of Hawai'i. The grosbeaks of the genus Chloridops and the koa finches of the genus Rhodacanthis had particularly strongly developed bills for cracking seeds, looking almost parrot-like in the case of Chloridops (James 2004). Of uncertain relationships to the finches are two unusual extinct species, the 'o'u Psittirostra psittacea and the Lanai hookbill Dysmorodrepanis munroi. The 'o'u was a fruit-eating, large-billed bird that was once widespread on the main islands of the Hawaiian archipelago (in contrast to most other honeycreeper species, which were mostly restricted to a single island). It was last definitely recorded in 1989 and continued survival is considered unlikely. The Lanai hookbill was a particularly bizarre species in which the mandible and maxilla were curved toward each other, so that the base of the bill gaped open even when the beak was closed. The single known specimen is unusual enough that Amadon (1950) did not accept that it represented an actual species, expressing the opinion that it was probably a deformed 'o'u specimen; current authors accept it as a good species.

Crested honeycreeper Palmeria dolei, from the US Geological Survey.

As noted above, the nectar-feeding 'melanodrepanines' form a well-supported clade including three surviving species: the 'i'iwi Drepanis coccinea, the crested honeycreeper or akohekohe Palmeria dolei and the 'apapane Himatione sanguinea, the last of which is one of the more abundant living honeycreepers. The melanodrepanines have slender bills, which in the species of Drepanis (the 'i'iwi and two extinct species of mamo) are long and downcurved. Also probably belonging to the melanodrepanines is the extinct ʻula-ʻai-hawane Ciridops anna, which shared their black and red plumage despite being a fruit- rather than a nectar-feeder.

Kaua'i 'akialoa Akialoa procerus (front) and Kaua'i nukupuu Hemignathus hanapepe (rear), from Keulemans (1890).

The final group of drepanidines to be considered here is also the largest, and contains the most surviving species: the 'amakihis of the genus Chlorodrepanis, the 'akepas Loxops, and related taxa. These are slender-billed insectivorous forms with the more generalist species being similar in appearance to the basal genera Paroreomyza and Oreomystis. Indeed, the classification of drepanidines by Amadon (1950), which was decidedly more lumpy than the current norm, subsumed the latter two genera in an expanded Loxops. Possibly related to this group are the extinct 'akialoas of the genus (wait for it...) Akialoa, which had an extremely long down-curved bill. Two other genera of this group, Hemignathus (including the ʻakiapolaʻau Hemignathus wilsoni) and the Maui parrotbill Pseudonestor xanthophrys, are unique among passerines in having a maxilla that significantly overhangs the much shorter mandible. The Maui parrotbill, despite being primarily an insectivore, has a heavier bill somewhat reminiscent of the finch group, and James' (2004) morphological analysis (which was primarily based on skull features) associated it with Psittirostra and Dysmorodrepanis rather than with Hemignathus; the latter association, however, is supported by molecular analyses, indicating a single origin for the unequal bills.

The loss of this remarkable radiation can be regarded as nothing short of a tragedy. Only two species of Hawaiian honeycreeper are currently regarded as not threatened (as given in the IUCN listings at Wikipedia), the 'apapane and the common 'amakihi Chlorodrepanis virens. Even these species could become endangered as a warming climate allows malaria-carrying mosquitoes to encroach further on their highland refuges. And something truly wonderful could be lost from the world.

REFERENCES

Amadon, D. 1950. The Hawaiian honeycreepers (Aves, Drepaniidae). Bulletin of the American Museum of Natural History 92 (4): 151–262.

James, H. F. 2004. The osteology and phylogeny of the Hawaiian finch radiation (Fringillidae: Drepanidini), including extinct taxa. Zoological Journal of the Linnean Society 141: 207–255.

Lerner, H. R. L., M. Meyer, H. F. James, M. Hofreiter & R. C. Fleischer. 2011. Multilocus resolution of phylogeny and timescale in the extant adaptive radiation of Hawaiian honeycreepers. Current Biology 21: 1838–1844.

Pratt, H. D. 2014. A consensus taxonomy for the Hawaiian honeycreepers. Occasional Papers of the Museum of Natural Science, Louisiana State University 85: 1–20.

The Parulidae: Not-warblers, Not-ovenbirds and Not-redstarts

Black-crested warbler Myiothlypis nigrocristata, photographed by Mikko Pyhälä.

There is no denying the current status of English as the de facto lingua franca of the world*. And yet, I feel that a complaint must be laid at the feet of the Brits: they're a bit unimaginative when it comes to animal names. Many a British explorer, upon being presented with some hitherto unfamiliar product of the natural world, proceeded to label it with the name of whatever inhabitant of his native Europe he felt bore some vague resemblance. And hence, even today, there are significant groups of animals such as the Parulidae that are almost without a vernacular name to genuinely call their own.

*The potential irony of this sentence is not lost on me.

The Parulidae are a family of birds found throughout the Americas, though in the northern United States and Canada they are represented by migratory species that retreat further south in the cold months. Many of the migratory species have males with brightly coloured breeding plumage and are consequently idolised by North American bird watchers; non-migratory species, on the other hand, tend to have similarly subdued males and females (Update: see comments below). Members of the Parulidae are generally referred to as 'warblers' or 'wood warblers', despite not being at all closely related to the European warblers. Instead, parulids are members of the 'nine-primaried oscines', the passerine clade that also includes such birds as finches, buntings, sparrows, cardinals and tanagers. Within the nine-primaried oscines, parulids are closely related to the Icteridae, another American clade containing its fair share of representatives doomed to masquerade under stolen names (Barker et al. 2013).

Ovenbird Seiurus aurocapilla on its nest, photographed by M. C. Donald.

Though the nine-primaried oscines as a whole are fairly stable in their membership, recent years have seen a fair bit of shuffling back and forth between the clade's constituent families. As a result of this shuffling, the name 'Parulidae' has come to be associated with a core clade that excludes a number of more uncertainly placed taxa previously included in the family, such as the Central American wrenthrush Zeledonia coronata. A recent comprehensive study of the molecular phylogeny of the core parulids by Lovette et al. (2010) also resulted in a proposed shifting of many generic boundaries within the clade. According to Lovette et al., the basalmost member of the Parulidae is the ovenbird Seiurus aurocapilla, a migratory but monomorphic, relatively large parulid of North and Central America. Just to confuse matters, the name 'ovenbird' has also been used for an unrelated group of South American birds of the genus Furnarius. To be charitable, this is not a case of inappropriate name-saking, but refers to the construction by both groups of domed nests resembling an old earthernware oven. The next member of the parulids to split off was the worm-eating warbler Helmitheros vermivorus, a relatively long-billed species that migrates between the eastern United States and Central America.

Swainson's warbler Limnothlypis swainsonii, photographed by Greg Lavaty.

Next comes a clade of eight species classified in the genera Parkesia, Vermivora, Mniotilta, Limnothlypis and Protonotaria. The black-and-white warbler Mniotilta varia is noted for its distinctive feeding behaviour: it crawls along branches like a nuthatch or creeper, gleaning insects from the bark. The prothonotary warbler Protonotaria citrea is a bright yellow species that Kurt Vonnegut devoted some time to in Jailbird: "The song of a prothonotary warbler is notoriously monotonous, as I am the first to admit...Still—they are capable of expressing heartbreak—within strict limits, of course" (I personally feel the same about skylarks). The waterthrushes of the genus Parkesia are larger, terrestrially-feeding species.

Chestnut-sided warbler Setophaga pensylvanica, photographed by Cephas.
Other North American species are placed by Lovette et al. in the larger genera Geothlypis, Oreothlypis and Setophaga. The last genus contains the species previously included in Dendroica, but the recognition that the American redstart Setophaga ruticilla (again, no relation to the European redstart) is nested within Dendroica leads to the use of the older name. These genera include some of the most colorful parulids. The remaining genera Myiothlypis, Basileuterus, Cardellina and Myioborus form a mostly Neotropical clade. Myioborus species are also known as redstarts, presumably by comparison with the European birds as not one of them actually possesses a red tail. The name 'whitestart' has supposedly been proposed instead, but the only time that name appears to see use is when it is referred to by someone explaining why they are not using it...

REFERENCES

Barker, K. F., K. J. Burns, J. Klicka, S. M. Lanyon & I. J. Lovette. 2013. Going to extremes: contrasting rates of diversification in a recent radiation of New World passerine birds. Systematic Biology 62 (2): 298-320.

Lovette, I. J., J. L. Pérez-Emán, J. P. Sullivan, R. C. Banks, I. Fiorentino, S. Córdoba-Córdoba, M. Echeverry-Galvis, F. K. Barker, K. J. Burns, J. Klicka, S. M. Lanyon & E. Bermingham. 2010. A comprehensive multilocus phylogeny for the wood-warblers and a revised classification of the Parulidae (Aves). Molecular Phylogenetics and Evolution 57: 753-770.

Birds of the Sun

Handsome sunbird Aethopyga bella, photographed by Tonee Despojo. This species was only recently separated at species level from the lovely sunbird Aethopyga shelleyi; one of the distinguishing features of the two is the purple ear-patch in A. bella.

The sunbirds are definitely forerunners in the tally of the world's most brilliantly coloured birds. This family of long-billed nectar-feeders, found in tropical regions of the Old World, is often compared to the New World hummingbirds. Like hummingbirds, the males of most sunbirds shimmer with brilliant iridescent colours (the exceptions are the spiderhunters of the genus Arachnothera); the females are much more restrained, generally shades of olive-green or brown. However, though hummingbirds are committed aerialists (as befits their relationship with the swifts and nightjars), sunbirds are, as Passeriformes, more likely to feed while perched on a stem alongside their chosen flower. Also, while sunbirds are primarily nectar feeders, they also feed to a fair extent on small insects (this is also true of hummingbirds).

Male (above) and female (below) of fork-tailed sunbird Aethopyga christinae. Male photographed by Frankie Chu, female by Neil Fifer.

Sunbirds are also a rather less diverse group than hummingbirds, both in number of species and in external appearance. Because of their structural similarity, authors have differed in the number of genera recognised in the family, but one group that has generally been differentiated is the Aethopyga sunbirds of southern Asia. Aethopyga species tend to be smaller than other sunbirds, with relatively short but strongly downcurved bills. The male has the central tail-feathers elongate (Ali & Ripley 1999). Aethopyga species are also distinguished from other sunbirds by the structure of the tongue. As with other sunbirds, the tongue is elongate, with the sides curved inwards to form a double tube. Differing from others, the end of the tongue is divided into two inwardly open tubes but with a basal bifurcated plate connecting the tubes:

Tongues of sunbirds of different genera showing differences in morphology, from Cheke & Mann (2001).

Cheke & Mann (2001) listed seventeen species of Aethopyga, with an eighteenth species being added by Mann (2002). Several of these species are also currently recognised as polytypic, with multiple subspecies. Though Mann's (2002) 'new' species was simply derived from the elevation of previously-recognised subspecies, one entirely new species of Aethopyga, A. linaraborae from Mindanao in the Phillippines, was only described as recently as 1997. No large scale analysis of the interrelationships between Aethopyga species appears to have been published as yet, but centres of diversity are the Philippines and the Himalayas.

Elegant sunbird Aethopyga duyvenbodei, photographed by Marc Thibault. Having been informed by their vernacular names that Aethopyga sunbirds are, in turn, handsome, lovely and elegant, it is all the sadder to say that this last species from Sangihe, near Sulawesi, is regarded as endangered.

REFERENCES

Ali, S., & S. D. Ripley. 1999. Handbook of the Birds of India and Pakistan, together with those of Bangladesh, Nepal, Sikkim, Bhutan and Sri Lanka, 2nd ed., vol. 10. Flowerpeckers to Buntings. Oxford University Press.

Cheke, R. A., & C. F. Mann. 2001. Sunbirds: A Guide to the Sunbirds, Flowerpeckers, Spiderhunters and Sugarbirds of the World. A & C Black Publishers.

Mann, C. F. 2002. Systematic notes on Asian birds. 28. Taxonomic comments on some south and south-east Asian members of the family Nectariniidae. Zool. Verh. Leiden 340: 179-189.

More than Four and Twenty Blackbirds

The Tristan thrush or Starchy, Turdus eremita, an endemic bird of the remote Tristan da Cunha group of islands in the South Atlantic, scavenging on a dead penguin (starchies have decidedly more catholic tastes than other thrushes). Photo by Lex.

Turdus, the thrushes, is a large cosmopolitan genus of birds found throughout the world except for Australia. The extent of the genus' circumscription has varied between authorities, though most recent authors exclude the ground-thrushes of the genus Zoothera. Conversely, phylogenetic studies have indicated that the previously monotypic genera Cichlherminia lherminieri of the Caribbean and Nesocichla eremita from Tristan da Cunha should be subsumed within Turdus (Voelker et al., 2007). At present, it seems unlikely that Turdus will be further subdivided; as the basalmost species in the genus is likely to be the mistle thrush Turdus viscivorus, which happens to also be the type of the genus, any subdivision would require that Turdus be reduced to a single species and all other species placed in new genera.


The blackbird Turdus merula, a species found throughout northern Eurasia (and introduced to New Zealand). Only the males are black; the females are dark mottled brown and have grey rather than yellow beaks. Photo by Bence Mate.

Of the 60+ species remaining in Turdus, many are widespread and divided into a number of subspecies that may or may not be promoted to separate species by future researchers. As an extreme example, a study on variation between geographically separated populations of the island thrush Turdus poliocephalus, whose distribution extends from Sumatra and the Philippines east to Norfolk Island* and Vanuatu, suggested that there may be grounds for dividing them between nearly forty diagnostic taxonomic units (Peterson, 2007).

*At least, it did. The Tasman Sea populations of T. poliocephalus have, unfortunately, since shuffled off this mortal coil.


The St Lucia forest thrush, Turdus lherminieri sanctaeluciae. Like T. eremita, this is a distinctive species that was previously placed in its own genus. Photo by Jean-Michel Fenerole.

The base coloration of most species of Turdus can be described as 'mottled brown', though notable exceptions (at least as males) include the grey and red American robin T. migratorius and the blackbird T. merula. Most members of the genus are more highly regarded for their voices rather than their looks, an attribute honoured in both the vernacular and scientific names of the song thrush Turdus philomelos* ("lover of song"). As with other speciose songbird clades, variation in song has turned out to be significant in separating closely related species. Both the Príncipe thrush T. xanthorhynchus (Melo et al., 2010) and the black-throated thrush T. atrogularis (Sangster et al., 2009) differ in their songs (among other things) from species with which they were previously considered conspecific.

*Older references may one of the names Turdus musicus or Turdus ericetorum for this species. Both these names have since been suppressed by the ICZN. The history of Turdus musicus is particularly turgid, as authorities had disagreed over whether the name should be applied to the song thrush or to the redwing (now Turdus iliacus) (Mayr & Vaurie, 1957). Both T. musicus and T. iliacus appeared in Linnaeus' 1758 Systema Naturae. Unfortunately (whether because he was unclear on the distinction between the species, or by a simple composition error), Linnaeus confused the two species' descriptions: under T. musicus, he gave a description of the redwing but provided sources referring to the song thrush, while the entry for T. iliacus attached a description of the song thrush to references referring to the redwing! (The significance of Linnaeus' sources to his descriptions has previously been discussed in the sperm whale nomenclature post.) Mayr & Vaurie's (1957) application buried the name Turdus musicus and designated a neotype to fix Turdus iliacus firmly to the redwing.

REFERENCES

Mayr, E., & C. Vaurie. 1957. Proposed use of the plenary powers to suppress the specific name "musicus" Linnaeus, 1758, as published in the combination "Turdus musicus" and to approve a neotype for "Turdus iliacus" Linnaeus, 1758, the Eurasian redwing (class Aves). Bulletin of Zoological Nomenclature 13 (6): 177-181.

Melo, M., R. C. K. Bowie, G. Voelker, M. Dallimer, N. J. Collar & P. J. Jones. 2010. Multiple lines of evidence support the recognition of a very rare bird species: the Príncipe thrush. Journal of Zoology 282 (2): 120-129.

Peterson, A. T. 2007. Geographic variation in size and coloration in the Turdus poliocephalus complex: a first review of species limits. Scientific Papers, Natural History Museum, The University of Kansas 40: 1-17.

Sangster, G., A. B. van den Berg, A. J. van Loon & C. S. Roselaar. 2009. Dutch avifaunal list: taxonomic changes in 2004–2008. Ardea 97 (3): 373–381.

Voelker, G., S. Rohwer, R. C. K. Bowie & D. C. Outlaw. 2007. Molecular systematics of a speciose, cosmopolitan songbird genus: defining the limits of, and relationships among, the Turdus thrushes. Molecular Phylogenetics and Evolution 42: 422-434.

Name the Bug # 7 - Apalopteron familiare hahasima

Apalopteron familiare hahasima - photo by Outsuka Hiroyuki.

Apalopteron familiare, the Bonin honeyeater, is a small bird of the Japanese Ogasawara (or Bonin) island group in the north-west Pacific. Phylogenetically speaking, it's been shuffled around a bit over the years - originally described as a species of bulbul, it seems to have been regarded by many authors as some sort of timaliid (babbler) until Deignan identified it in 1958 as belonging to the Meliphagidae (honeyeaters), mainly on the basis of its branched, brushed tongue. There it stayed until molecular analysis re-identified it as a member of the white-eyes (Driskell & Christidis, 2004). There are two funny things about this - (1) Apalopteron really does look like a white-eye (albeit a large one), so identifying it as one is hardly surprising; (2) further phylogenetic analysis has also placed the white-eyes (previously regarded as a separate family) within the Timaliidae (Gelang et al., 2009), making Apalopteron's older position correct after all.

The Ogasawara islands are arranged in three groups - from north to south, these are the Mukojima, Chichijima and Hahajima groups. Shima (which often becomes voiced to -jima when used in a compound) is Japanese for "island", while chichi is "father" and haha is "mother" (other islands in the group include ani and otōto [elder and younger brother] and ane and imōto [elder and younger sister]). Apalopteron familiare was originally found on all three groups, but currently survives only in the Hahajima group. As on many Pacific islands, the Ogasawara fauna has been pretty heavily hit since the arrival of humans due to habitat disturbal and introduced predators - among the endemic species to have become extinct in the group are a heron (Nycticorax crassirostris), pigeon (Columba versicolor), thrush (Turdus terrestris), finch (Chaunoproctus ferrugineus) and bat (Pipistrellus sturdeei) (Iwahashi, 1992). The type subspecies of Bonin honeyeater (Apalopteron familiare familiare) became extinct on Mukojima by the 1940s (Morioka & Sakane, 1978)*. Kawakami et al. (2008) found that dispersal between populations of Apalopteron on separate islands was very low, which would further increase its vulnerability.

*It is possible that a bit of revision may be required here. Suzuki & Morioka (2005) indicated that the type locality for Apalopteron familiare was probably Chichijima rather than Mukojima. Chichijima is considerably closer to Hahajima than it is to Mukojima, raising the question of whether the correct subspecies has been identified as the type.

REFERENCES

Driskell, A. C., & L. Christidis. 2004. Phylogeny and evolution of the Australo-Papuan honeyeaters (Passeriformes, Meliphagidae). Molecular Phylogenetics and Evolution 31 (3): 943-960.

Gelang, M., A. Cibois, E. Pasquet, U. Olsson, P. Alström & P. G. P. Ericson. 2009. Phylogeny of babblers (Aves, Passeriformes): major lineages, family limits and classification. Zoologica Scripta 38: 225-236.

Iwahashi, J. (ed.) 1992. Reddo Deeta Animaruzu: a pictorial of Japanese fauna facing extinction. JICC: Tokyo.

Kawakami, K., S. Harada, T. Suzuki & H. Higuchi. 2008. Genetic and morphological differences among populations of the Bonin Islands white-eye in Japan. Zoological Science 25 (9): 882-887.

Morioka, H., & T. Sakane. 1978. Observations on the ecology and behavior of Apalopteron familiare (Aves, Meliphagidae). Memoirs of the National Science Museum, Tokyo 11: 169-188, pl. 7-8.

Suzuki, T., & H. Morioka. 2005. Distribution and extinction of the Ogasawara Islands honeyeater Apalopteron familiare on Chichijima, Ogasawara Islands. Journal of the Yamashina Institute for Ornithology 37 (1): 45-49.

The Tomb of the Unknown Honeyeater

Some of the birds referred to in this post. Clockwise from top left - Bombycilla garrulus, the Bohemian waxwing, Bombycillidae; Chaetoptila angustipluma, a Hawaiian honeyeater; two true honeyeaters (Meliphagidae), Anthochaera carunculata (red wattlebird) and Prosthemadera novaeseelandiae (tui); and Moho nobilis, the Hawai'i 'o'o, a Hawaiian honeyeater. Painting by John Anderton.

Fleischer, R. C., H. F. James & S. L. Olson. 2008. Convergent evolution of Hawaiian and Australo-Papuan honeyeaters from distant songbird ancestors. Current Biology 18: 1-5.

GrrlScientist brought my attention yesterday to an interesting new publication on the phylogeny of the Hawaiian honeyeaters. Not, I hasten to explain, the Hawaiian honeycreepers, the Drepanidini clade of birds unique to Hawaii that has become famed for their remarkable adaptive radiation into a whole range of ecological niches, but a smaller clade of five species, Chaetoptila angustipluma and the four species of 'o'o (Moho), that is also unique to Hawaii.

The honeyeaters of the family Meliphagidae are a sizable, fairly heterogenous assemblage of songbirds (Oscines) that are found throughout the Australo-Papuan region, with outliers on various Pacific islands such as New Zealand and Samoa. Despite including a diversity of morphologies, meliphagids are well established as a family, united by features such as a brushed tongue used for taking nectar from flowers (hence, of course, the name "honeyeaters"). The five Hawaiian species share many of these features, and are fairly similar in appearance to Australasian meliphagids, so have always been regarded as meliphagids themselves. The study being discussed here found in a DNA phylogenetic analysis that this was not the case.

Conducting a molecular analysis of Hawaiian honeyeaters is a remarkable achievement in itself because, tragically, not one of the five species remains alive today. All became extinct in the last two centuries. The last surviving species was the smallest, the Kauai 'o'o (Moho braccatus), the last male of which was sighted in 1987 (just to turn the pathos up a notch, a short video of this last individual can be seen here). The Hawaiian honeyeaters therefore join an all-too-long list of birds extinct on the Hawaiian islands since human colonisation, such as the moa-nalo. In the absence of living specimens, Fleischer et al. had to extract DNA from museum specimens, but were able to do so for all five species.

Phylogenetic analysis of these samples showed that, as mentioned above, Chaetoptila and Moho were not related to the true meliphagids. As I've explained elsewhere, recent molecular analyses have consistently identified three large clades within the songbirds (as well as a smattering of smaller clades), the Meliphagoidea (including the meliphagids), Corvoidea and Passerida (including most Northern Hemisphere songbirds). The Hawaiian honeyeaters are not members of the Meliphagoidea, but instead belong to an entirely different clade, the Passerida. Within the Passerida, they belong to an assemblage that includes the Holarctic waxwings (Bombycilla), North American silky flycatchers (Ptilogonatinae) and Caribbean palmchat (Dulus dominicus). Most authors have united these birds in the family Bombycillidae, and the name was recently used in this sense by Spellman et al. (2008). While Fleischer et al. (2008) establish a new family Mohoidae for the Hawaiian honeyeaters, that clade would belong within Bombycillidae in the broad sense. Relationships of the Bombycillidae within the Passerida remain largely unresolved.

The Hawaiian honeyeaters have not been the first birds to abscond from the Meliphagidae in recent years. I have previously discussed the discovery that the New Zealand stitchbird (Notiomystis cincta) is related to the New Zealand wattlebirds, and perhaps a basal member of the Corvoidea. The South African sugarbirds of the genus Promerops, long unsettled as meliphagids, belong to the Passerida and are basal members of the Passeroidea assemblage that includes finches and sparrows (Beresford et al., 2005). The Bonin honeyeater (Apalopteron familiare) is also a member of the Passerida, and falls within the family of white-eyes, Zosteropidae (Driskell & Christidis, 2004) - which I wasn't too surprised to hear because, if you ignore the "meliphagid" brushed tongue, Apalopteron really does look like a big white-eye. Still, the Hawaiian honeyeaters are probably the most typically "meliphagid-like" birds to be recognised as non-meliphagids.

In another interesting recurring theme in oscine phylogeny, the reclassification of Hawaiian honeyeaters, while morphologically unexpected, makes a certain degree of biogeographic sense. Most colonisation of the Hawaiian islands seems to have been derived from North America rather than the western part of the Pacific, with Hawaiian honeycreepers, warblers, geese and violets, among others, all having demonstrated North American (and often northern North American) affinities. As pointed out by a commentator at GrrlScientist's post linked to above, the only Hawaiian bird that still possesses western Pacific affinities is the monarch flycatcher Chasiempis sandwichensis, whose Monarchidae affinities were supported by Filardi & Moyle (2005).

That Hawaiian honeyeaters are such a distinct lineage makes their loss all the more tragic. An extra dose of tragedy that verges on the comic surrounds the most distinct of the mohoids, Chaetoptila angustipluma. Those of my readers who have heard of it before may have noticed that I have deliberately avoided using the vernacular name given to this bird, the kioea. My reason for doing so is that there is reason to doubt whether this name properly belongs to Chaetoptila at all. "Kioea" is actually the Hawaiian name for the bristle-thighed curlew (Numenius tahitiensis), a migratory wading bird and not very much like a honeyeater at all. References to "kioea" as a seabird include the Kumulipo, the epic poem that recited the genealogy of the Hawaiian royal family:

Hanau ke Kioea ka makua,
Puka kana keiki he Kukuluae'o, lele.

The Kioea was born and became parent,
Its offspring was a Kukuluaeo [stilt, Himantopus knudseni], and flew.

--Hawaiian text from here, 1897 translation by Queen Liliuokalani.

Peale (1848) provided no common name for Chaetoptila angustipluma when he first described it (as Entomiza angustipluma - Entomyza is a meliphagid genus). Bryan & Greenway (1944) gave the name "kioea" for this species, but with a question mark, and they also used the name elsewhere for the curlew - I haven't been able to find whether this is the first recorded association between the name and Chaetoptila. Not only has Chaetoptila been cruelly forced out of existence, but it has potentially been subjected to the indignity of a name that is not its own. It truly is the unknown honeyeater.

REFERENCES

Beresford, P., F. K. Barker, P. G. Ryan & T. M. Crowe. 2005. African endemics span the tree of songbirds (Passeri): molecular systematics of several evolutionary ‘enigmas’. Proceedings of the Royal Society of London Series B – Biological Sciences 272: 849-858.

Bryan, E. H., Jr & J. C. Greenway Jr. 1944. Check-list of the birds of the Hawaiian islands. Bulletin of the Museum of Comparative Zoology 94 (2): 92-140.

Driskell, A. C., & L. Christidis. 2004. Phylogeny and evolution of the Australo-Papuan honeyeaters (Passeriformes, Meliphagidae). Molecular Phylogenetics and Evolution 31 (3): 943-960.

Filardi, C. E., & R. G. Moyle. 2005. Single origin of a pan-Pacific bird group and upstream colonization of Australasia. Nature 438 (7065): 216-219.

Peale, T. R. 1848. Mammalia and Ornithology. C. Sherman: Philadelphia.

Spellman, G. M., A. Cibois, R. G. Moyle, K. Winker & F. K. Barker. 2008. Clarifying the systematics of an enigmatic avian lineage: what is a bombycillid?. Molecular Phylogenetics and Evolution 49 (3): 1036-1040.

Products of Kinky Inter-species Sex

Um, maybe I don't want to know what sort of Google search will hit that post title, or who's doing the searching. I can assure you, the following post is both PG and work-safe.

I came across this post today on identifying a hybrid passerine bird. The bird in question is an entirely different individual from the one discussed here, which was also revealed not too long ago. (Offhand, the site linked to via the latter, Don Roberson's Creagrus, is well worth a look for anybody interested in birds.)

Both of these birds belong to the family Parulidae, the so-called American 'warblers' - an entirely distinct and unrelated family from the various 'warblers' of the Old World (previously Sylviidae, but see here - Don Roberson again - for a good summary of the collapse of that family) and from the Australasian 'warblers' of the family Acanthizidae. Interestingly, Parulidae seems to have produced a large number of recorded hybrids over the years (enough that many have been awarded their own common names), and attention has been drawn to the fact that a greater number of recorded hybrids have been between members of different genera than members of the same genus (those that are members of the same genus have invariably been very closely-related species). The same pattern has been recorded in South American manakins (Pipridae) (Stotz, 1993). Even if we admit the point that a 'genus' is simply a grouping defined by the author and has no objective reality, it still remains arguable that hybrids are always between very closely or distantly related species, never between fairly closely related species.*

*My apologies for the revoltingly turgid sentence.

Parkes (1978) commented on this phenomenon, and suggested that barriers to hybridisation may be more heavily selected for between closely-related and sympatric species for which hybridisation may be more of a risk. This theory has also been supported by work on courtship songs in insects where sympatric species of lacewing have very different songs, while different species from Asia and North America have very similar songs, and members of one species will actually respond if they hear songs from the other 'wrong' species (Henry et al., 1999).

Perhaps the best comment on all this, though, comes from my partner - when I told him that I was posting on an interspecific hybrid, he seemed rather incredulous that a bird had mated with a member of a different species, and when considering why commented, "that must be one ugly bird".

REFERENCES

Henry, C. S., M. L. Martínez Wells & C. M. Simon. 1999. Convergent evolution of courtship songs among cryptic species of the carnea group of green lacewings (Neuroptera: Chrysopidae: Chrysoperla). Evolution 53 (4): 1165-1179.

Parkes, K. C. 1978. Still another parulid intergeneric hybrid (Mniotilta × Dendroica) and its taxonomic and evolutionary implications. The Auk 95: 682-690. Pdf here.

Stotz, D. F. 1993. A hybrid manakin (Pipra) from Roraima, Brazil, and a phylogenetic perspective on hybridization in the Pipridae. Wilson Bulletin 105 (2): 348-351. Pdf here.