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Oreomanes fraseri

Giant Conebill

  • Order: Passeriformes
  • Family: Thraupidae
  • Monotypic

Authors: Mason, Nicholas A. and Kevin J. Burns

Identification

Summary

The Giant Conebill is a stout passerine with a long pointed bill. Back and wings are blue-gray, with chestnut throat, belly and underparts. Forecrown whitish; the nominate subspecies has a chestnut eyestripe and black malar, but there is significant variation in the facial pattern.

Similar Species

Nearly unmistakable plumage and distinctive behavior. Similar in color and pattern to the White-browed Conebill (Conirostrum ferrugineiventre); C. ferrugineiventre is smaller, lacks the distinctive white cheek-patch, and generally occupies lower elevations, although the two do occasionally overlap and have been known to hybridize (Schulenberg 1985). Oreomanes also bears a behavioral resemblance to Sitta nuthatches, sometimes hanging upside down while foraging (George 1964). Chestnut underparts and dark mantle might suggest Black-throated Flowerpiercer (Diglossa brunneiventris), however the Giant Conebill’s chunkier stature and association with Polylepis woodland serve to distinguish the two (Jaramillo 2003).

Vocalizations

Generally quiet and unobtrusive while foraging. Calls include a moderate-pitched keek! or eek!, a seep in flight (Parker 1976) and a high-pitched plaintive whistle ssit ssit ssit or sseet sseet (George 1964, Isler and Isler 1999). Song includes a rapidly delivered series of whispy whistles, squeaky cheeps and sharp chip notes: whip-whee-which-chit, ti-chip ti-whit-ti, whip-whee-wit etc. Song sounds similar to closely related Conirostrum species.

Nonvocal Sounds

Can sometimes be detected by the sound of peeling bark off of Polylepis trees while foraging (Parker and O’Neill 1980).

Detailed Description (appearance)

Adults: Monochromatic species, male and female plumages indistinguishable. Adults have plumbeous backs and wings, with a chestnut throat, belly and crissum. Face has a large white cheek patch, generally with a dark chestnut eyeline and patch around eye, defining a thin white supercilium (Jaramillo 2003). Rounder body than other passerines, and a long, sharply pointed bill.


Immature: Crown mostly dusky; lower cheek, throat and supercilium white, throat mottled with blue-gray spots, and underparts slightly lighter russet than adult plumage (Fjeldså and Krabbe 1990).


Juvenile: Similar to immature, but browner on back and wings with a whiter throat (Fjeldså and Krabbe 1990).

Bare Parts

Iris: Brown (Schulenberg 1985)


Bill: Dark slate to black, mandible sometime described as paler than maxilla (Schulenberg 1985)


Tarsi: Gray-brown, dark gray, black (Schulenberg 1985)
 

Measurements

Total length: 15 cm (6 in.) (Isler and Isler 1999).

Mass: mean 25 g (range 22.0–27.0 g, n=25) (Vuilleumier 1984, Isler and Isler 1999).
 

Table taken from Vuilleumier (1984).

Molts

Little is known regarding the timing and sequence of molts in the Giant Conebill, but juveniles are distinguishable from parents for at least five weeks after hatching (Cahill et al 2008).

Geographic Variation

Minor geographic variation in some morphological and plumage features has been reported, and up to three subspecies have been recognized (Storer 1970; see also Systematics). Vuilleumier (1984), however, demonstrated that most of this variation is clinal and that the species is best considered to be monotypic. Oremanes fraseri from Colombia and Ecuador have a darker crown and back, while more southern populations in Peru and Bolivia tend to have lighter plumage. Following Gloger’s rule this clinal variation in plumage is correlated with the precipitation of each respective habitat, such that darker morphs appear in areas with more rainfall (e.g. Ecuador), and lighter morphs in drier areas (e.g. Bolivia), along with intermediate morphs (e.g. Peru) (Vuilleumier 1984, Fjeldså and Krabbe 1990). However, there appears to be discontinuities in the plumage patterns of certain features (i.e. underparts, superciliary stripe), so that the geographical variation in plumage appears to be more checkerboard than clinal (Vuilleumier 1984). Vuilleumier (1984) noted some indications of clinal variation in culmen length, such that the southernmost Giant Conebills were larger than northern populations, but did not have enough specimens to test the gradation statistically.

Systematics

Oreomanes is a currently recognized as a monotypic genus with O. fraseri as the sole representative. The taxonomy of Oreomanes was a topic of much debate during the 20th century. Oreomanes fraseri was described by Sclater (1860: 75), and currently is recognized as a monotypic genus. A second species, O. binghami, was described by Chapman (1919, locality 20, table 1, fig. 1), but was later identified as an immature O. fraseri specimen by Hellmayr (1919: 11-12). The third and last taxon to be described in Oreomanes was the subspecies O. fraseri sturninus by Bond and Meyer de Schauensee (1939), which corresponded to the lighter plumage morphs of Bolivia. Zimmer (1942) recognized three subspecies to account for geographic variation in plumage: O. f. fraseri (Ecuador and southern Colombia); O. f. binghami (Peru); and O. f. sturninus (Bolivia). Vuilleumier (1984) showed that the geographical variation corresponding to these subspecies is minor and clinal or checkerboard in nature, however, suggesting that the disjunct populations do not appear to represent incipient speciation, and should thus be considered under the same taxon.

Various sources have placed O. fraseri in different families including Coerebidae (e.g. Sclater 1986), however, most identify O. fraseri as belonging to Thraupinae or Thraupini (Sibley and Monroe 1990, Dickinson et al. 2003, Clements et al. 2010). Ridgway (1902: 376) was the first to note similarities between Oreomanes and the Conirostrum conebills. This relation has been supported by the discovery of a intergeneric hybrid between O. fraseri and C. ferrugineiventre (Schulenberg 1985), while generic level molecular work has demonstrated that Oreomanes forms a strongly supported monophyletic group with Conirostrum (Burns et al. 2003). Ongoing phylogenetic work has shown that Oreomanes is actually nested within Conirostrum, rendering Conirostrum paraphyletic (K. J. Burns and W. M. Mauck unpublished data).

Recommended Citation

Mason, Nicholas A. and Kevin J. Burns. 2010. Giant Conebill (Oreomanes fraseri), Neotropical Birds Online (T. S. Schulenberg, Editor). Ithaca: Cornell Lab of Ornithology; retrieved from Neotropical Birds Online: http://neotropical.birds.cornell.edu/portal/species/overview?p_p_spp=589196