Field of Science

Showing posts with label Suboscines. Show all posts
Showing posts with label Suboscines. Show all posts

Meet the Tityrids

South America may be the most biodiverse continent in the modern world. More species are known from the northern half of South America than from any comparable region of the planet. And yet, for whatever reason(s), many notable groups of South American animals remain distinctly under-represented in pop-culture depictions of biology.Take, for instance, the group of birds known as the New World suboscines. With something in the area of 1200 known species, this is an incredibly diverse group, but many popular bird books will devote far less attention to them than warranted in comparison to the more recognisable songbirds.

Masked tityra Tityra semifasciata costaricensis, copyright Nick Athanas.


Indeed, there are entire families of New World suboscines that barely raise a blip in the popular recognition stakes. Once such group is the Tityridae, a family of small to medium-sized insectivorous and fruit-eating birds found in tropical and subtropical regions of North and South America. Granted, part of this lack of representation may be due to tityrids not being recognised as a group until the late 1990s. Previously, the 30-odd species now placed in this family were divided between three larger related families: the Tyrannidae (tyrant flycatchers), Cotingidae (cotingas) and Pipridae (manakins). Nevertheless, it had long been recognised that each tityrid species was a poor fit in its original family, and in 1989 a group including most of the current tityrids (excluding only the genus Tityra) was proposed based on features of the syringeal anatomy (Barber & Rice 2007). Molecular data would later add Tityra into the mix and eventual inspire recognition of the family in its current form.

Brown-winged mourner or brown-winged schiffornis Schiffornis turdina wallacii, copyright Nick Athanas.


As recognised by Ohlson et al. (2013), the Tityridae includes seven genera divided between two subfamilies. The mourners of the genera Schiffornis, Laniisoma and Laniocera make up the subfamily Schiffornithinae (which has sometimes been labelled by the junior name Laniisominae). The Tityrinae includes the tityras Tityra, the purpletufts Iodopleura and the becards of the genera Xenopsaris and Pachyramphus (an earlier recognised becard genus Platypsaris is now generally synonymised with Pachyramphus). Some authors have also included the sharpbill Oxyruncus cristatus and three flycatcher genera Onychorhynchus, Myiobius and Terenotriccus in the Tityridae. A clade uniting these latter four genera with the tityrids was supported by Ohlson et al. (2013) though they chose to separate the latter taxa into distinct families, making this largely another taxon calibration question. It should be noted, however, that the name Oxyruncidae has priority over Tityridae so should properly be the name used if the broader clade is recognised as one family. Most recent authors who have united the two have insisted on ignoring this priority but their arguments for doing so seem generally handwavy and weak, based on the equally handwavy and weak concept of a 'traditional classification'.

Buff-throated purpletuft Iodopleura pipra, copyright Rick Elis Simpson.


For the most part, the tityrids are not brightly coloured birds. Perhaps the most dramatically coloured members are the tityras which are patterned in black and white and/or pale grey. The mourners are mostly more or less olive green; a couple of species are cinnamon brown and the Laniisoma species have yellow underparts and black caps. The dumpy little purpletufts get their name from bright patches of violet feathers on the shoulders of males but these are often concealed when the wings are closed. Becards, the most speciose subgroup with nearly twenty species in the genus Pachyramphus, come in a range of patterns from uniformly dark grey or cinnamon brown to grey or green and white to green and yellow. Males of a couple of species have a red bib on the throat. In those becard species previously placed in the genus Platypsaris, the males have patches of bright white feathers on the shoulders that are normally held concealed, only being revealed when the male is displaying to a female during courtship (Miller et al. 2015).

Green-backed becard Pachyramphus viridis viridis, copyright Cláudio Dias Timm.


The two subfamilies of tityrids differ from one another in their breeding behaviour (Barber & Rice 2007). Where breeding has been observed, the Schiffornithinae are polygamous with males not taking any part in nesting and rearing the chicks. The Tityrinae, in contrast, are generally monogamous with both parents doing their bit to feed their offspring. In Iodopleura species, parents may even be further assisted by offspring from previous clutches that have not yet begun breeding themselves. The ancestral nest type for Tityridae, as found in Schiffornithinae, Iodopleura and Xenopsaris, seems to have been a cup shape. Cup nests in Schiffornithinae are bulky and constructed from leaves; those of Iodopleura and Xenopsaris are more compact and woven from materials such as fungus, plant fibres and spider webs. In Tityra, the nest is cup-shaped but loose and concealed within a cavity in a tree. Finally, Pachyramphus species build globular nests with entrances at the side and below, and they may place their nest alongside a beehive just for that little bit of extra protection. The two groups also differ in their preferred habitats: schiffornithines are mostly found deep in forest interiors whereas Tityrinae tend to prefer more open habitats (Ohlson et al. 2013).

REFERENCES

Barber, B. R., & N. H. Rice. 2007. Systematics and evolution in the Tityrinae (Passeriformes: Tyrannoidea). Auk 124 (4): 1317–1329.

Miller, E. T., S. K. Wagner, J. Klavins, T. Brush & H. F. Greeney. 2015. Striking courtship displays in the becard clade Platypsaris. Wilson Journal of Ornithology 127 (1): 123–126.

Ohlson, J. I., M. Irestedt, P. G. P. Ericson & J. Fjeldså. 2013. Phylogeny and classification of the New World suboscines (Aves, Passeriformes). Zootaxa 3613 (1): 1-35.

The Elaenia Elaenias

Yellow-bellied elaenia Elaenia flavogaster, photographed by Félix Uribe.


We are all aware that there are some truly stunning birds out there: majestic eagles and vultures, vibrant parrots and hummingbirds, eye-catching cranes and pelicans. But those of us who spend a lot of time contemplating the nature of bird diversity, whether as bird-watchers or ornithologists, will soon admit that the greater proportion of this diversity is composed of what are affectionately or not-so-affectionately referred to as Little Brown Jobs. In particular, the tyrant flycatchers or Tyrannidae of the Americas are one family of birds that is notorious for including some of the littlest, the brownest, and the jobbiest.

Elaenia is a genus of about twenty or so species of tyrannid found in Central and South America (Sibley & Monroe, 1990, listed eighteen, but phylogenetic studies suggest that some of these should be divided into more than one species—Rheindt et al. 2009). The name 'elaenia' does double service for these guys as both genus and vernacular name, though the members of some related genera are also labelled in the vernacular as 'elaenias'. As a result, Ridgely & Tudor (2009), without a trace of apparent irony, referred to the species of this genus as 'Elaenia elaenias'.

Mottled-backed elaenia Elaenia gigas, showing its distinctive divided crest, photographed by Nick Athanas.


The various species of Elaenia elaenias are notoriously difficult to distinguish, and none are particularly eye-catching. They are mostly greenish, though the slaty elaenia Elaenia strepera is dark grey, and the brownish elaenia E. pelzelni is (surprisingly) brown. Underparts may be white, or they may be yellow. One species in particular is labelled as the yellow-bellied elaenia E. flavogaster, but in this case it is not any more strikingly yellow than a number of other species, leading one to suspect whether its vernacular name is any sort of moral judgement. A number of species have some degree of white streak on the crown, and some have a small crest of feathers (the mottle-backed elaenia E. gigas has a well-developed, bifurcated crest). Elaenias are best distinguished by their calls, but that of course requires the bird in question to be calling.

Great elaenia Elaenia dayi, photographed by Thiago Orsi.


Though members of the tyrant flycatcher family in both affinities and appearance, elaenias consume a fair proportion of fruit as well as insects. In at least some species, fruit make up by far the greater part of the diet (Marini & Cavalcanti 1998). Different species often have different preferred habitats, and the relationship between habitat and phylogeny was examined by Rheindt et al. (2008). Two savannah-dwelling species, the plain-crested elaenia Elaenia cristata and the rufous-crowned elaenia E. ruficeps, appear to be the sister clade to the remaining species that mostly inhabit riparian habitats or montane and temperate forests (Elaenia species are largely absent from lowland tropical forest). The forest species fall into two clades nested among the riparian species. The great elaenia E. dayi, which happens to be the largest Elaenia species by a noticeable margin, inhabits the stunted montane forests of the south Venezuelan tepuis (if you've seen the film Up, this is the habitat in which that film is mostly set). Migratory habits, on the other hand, are less correlated with phylogeny than habitat preferences. A number of Elaenia species migrate between temperate breeding grounds and tropical wintering grounds, but migratory species may be closely related to sedentary species that inhabit the tropics all year round. Indeed, some species are mostly sedentary but have somewhat migratory populations in more temperate parts of their range.

REFERENCES

Marini, M. Â., & R. B. Cavalcanti. 1998. Frugivory by Elaenia flycatchers. Hornero 15: 47-50.

Rheindt, F. E., L. Christidis & J. A. Norman. 2008. Habitat shifts in the evolutionary history of a Neotropical flycatcher lineage from forest and open landscapes. BMC Evolutionary Biology 8: 1193.

Rheindt, F. E., L. Christidis & J. A. Norman. 2009. Genetic introgression, incomplete lineage sorting and faulty taxonomy create multiple cases of polyphyly in a montane clade of tyrant-flycatchers (Elaenia, Tyrannidae). Zoologica Scripta 38: 143-153.

Ridgely, R. S., & G. Tudor. 2009. Field Guide to the Songbirds of South America: The Passerines. University of Texas Press.

Sibley, C. G., & B. L. Monroe Jr. 1990. Distribution and Taxonomy of Birds of the World. Yale University Press.

Taxon of the Week: Cotinginae – Neotropical and Fabulous!

Sure you said just fluffy, but did you ever imagine I could do this with your hair?

When I used to look through one of the various bird family books I knew and loved as a young'un, the cotingas were somewhere I was bound to stop. Cotingas are a diverse family of largely frugivorous birds from Central and South America. Don Roberson refers to them as the "birds-of-paradise of the New World", and while perhaps not quite so incredible as the original birds-of-paradise, cotingas are certainly up there (along with hummingbirds and pheasants) in terms of total drag-queen-esque gaudiness.

Preliminary phylogenetic analysis by Prum et al. (2000) divided the Cotingidae into four reasonably well-supported clades, though relationships within the clades were poorly supported. Prum et al. suggested that these clades be recognised as the subfamilies Tityrinae, Phytotominae, Rupicolinae and Cotinginae. A more recent analysis by Ohlson et al. (2007) effectively supported Phytotominae and Cotinginae, though the Rupicolinae of Prum et al. (2000) were polyphyletic. Authors differ on whether the Tityrinae should be included in the Cotingidae or not, and Ohlson et al. (2007) excluded them. It is with the Cotinginae (the "core cotingas" of Ohlson et al.) that I am concerned today.

The name "cotinga" is actually a rather inappropriate one. It comes from a native Amazon name for one of the species meaning "washed white" (Austin, 1961). Despite this, only a few species of cotinga are significantly white, including the bellbirds of the genus Procnias (male three-wattled bellbird, P. tricarunculata, at left from Encyclopaedia Brittanica). Bellbirds get their name from their bell-like call (a single "bock!" according to Don Roberson), which is reputedly one of the loudest sounds made by any bird. Ohlson et al. (2007) placed Procnias in a clade they referred to as the "canopy cotingas", which also includes (among others) Gymnoderus foetidus (the bare-necked fruitcrow) and Carpodectes nitidus (the all-white snowy cotinga). The genus Cotinga has traditionally been regarded as closely related to these genera, but Ohlson et al. were unable to confirm such a relationship.



Going by the results of Prum et al. (2000), the canopy cotingas probably also include Xipholena punicea, the pompadour cotinga (shown above in a picture from the Field Museum). This species received its common name from Jeane-Antoinette Poisson, Marquise de Pompadour, she of the gigantic and ridiculously ornate wigs. Among the exotic paraphernalia Madame de Pompadour incorporated into her stupendous wigs were whole birds, and the first described specimen of the red lavender-coloured pompadour cotinga was described from a shipment of bird skins captured by the British on its way to the Madame.

The two groups of pihas are quite dull-coloured birds, though the screaming piha (Lipaugus vociferans) makes up in volume what it lacks in colour. All pihas were once included in a single genus Lipaugus, but Prum (2001) showed that the two species of Snowornis were not closely related to the other pihas.

Finally, the fruitcrows include the largest of the cotingas. Many of the fruitcrows and the Lipaugus pihas are lek breeders (the fruitcrow genus Querula are monogamous with nest helpers, while the breeding habits of Snowornis pihas are largely unknown but have not been observed to include lekking). The best-known of the fruitcrows are undoubtedly the spectacular umbrellabirds of the genus Cephalopterus with their bouffant hair-dos and long, hanging throat sacs (shown at the top of this post in a photo from BirdQuest). But just as notable is the calfbird (Perissocephalus tricolor), whose cow-like call is accompanied by a strange movement of stretching the neck, puffing the feathers around the head and tottering precariously on the legs. See for yourself!



REFERENCES

Austin, O. L., Jr. 1961. Birds of the World: A survey of the twenty-seven orders and one hundred and fifty-five families. Paul Hamlyn: London.

Ohlson, J. I., R. O. Prum & P. G. P. Ericson. 2007. A molecular phylogeny of the cotingas (Aves: Cotingidae). Molecular Phylogenetics and Evolution 42 (1): 25-37.

Prum, R. O. 2001. A new genus for the Andean green pihas (Cotingidae). Ibis 143: 307-309.

Prum, R. O., N. H. Rice, J. A. Mobley & W. W. Dimmick. 2000. A preliminary phylogenetic hypothesis for the cotingas (Cotingidae) based on mitochondrial DNA. Auk 117 (1): 236-241.