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.