Hennessey • SPECIES RANK OF PHIBALURA (FLA VIROSTRIS) BOLIVIAN A 
455 
breast) or pale yellow (lower breast). The lower 
underparts are variable yellow, pale yellow 
(including vent) with slight black streaking on 
belly becoming denser on flanks; the feathers of 
the back and rump are brownish-olive with black 
subterminal bar and contrasting broad yellow tips. 
The tail is strongly forked, outer feathers rather 
pointed, outer rectrices black with dusky-brown 
base, remaining rectrices black with mostly olive- 
yellow outer and dusky-brown inner webs at base. 
The wing has blue-black coverts, primaries, and 
secondaries with the outer webs edged greenish- 
to yellow-olive. The female plumage has more 
variable streaking, possibly related to age. This 
similar, but slightly duller overall to the male 
plumage, dull brown-gray shadow of the male's 
black mask with black appearing on ear coverts, 
underparts more extensively barred black (vari¬ 
able), tail notably shorter, outer rectrices dusky- 
brown with blackish-brown lip, remaining rectri¬ 
ces with mostly olive-yellow outer webs, blackish 
tips and dusky-brown inner webs; marginal wing 
coverts at wing bend blackish, remaining lesser 
and median coverts appear variable from black to 
dark olive-green tipped black, greater secondary 
coverts and tertials gray-brown broadly edged 
greenish-olive on outer webs, and black greater 
primary coverts. 
The most quantifiable characteristic distin¬ 
guishing the two taxa is the tail length of the 
males. The only male boliviano specimen has a 
tail length of 131 mm (Chapman 1930; Peter 
Capainolo, pers. comm.), which is 24.8 mm 
longer than the mean 106.2 mm (range = 99 
to 125.8 mm) tail length of male flavirostris 
specimens (n ^ 23) (AMNH: Peter Capainolo, 
unpubl. data; Alex Jahn, pers. comm.. Goeldi 
Musuem). There was no overlap in tail length 
with the longest flavirostris tail 5.2 mm shorter 
than the only adult male tail of boliviano. Field 
observations and photographic comparisons (n = 
7) confirm that male boliviano consistently have a 
long tail similar in length to that of the male 
specimen tpers. obs.; J. C. Atienza, pers. comm.; 
Geoff Bromfield. pers. comm.; Mileniusz Spano- 
wicz, pers. comm.) 
The extent of barring on female Phihalura is 
variable among individuals, but flavirostris is 
more extensively barred than boliviano. The chin 
and underbelly barring of flavirostris is variable in 
intensity but no individuals show a complete lack 
of barring (AMNH; n ~ 21), in contrast with 
boliviano where most females show no barring on 
the chin or underbelly (n = 32; pers. obs.; J. C. 
Atienza, pers. comm.; Geoff Bromfield. pers. 
comm.; Mileniusz Spanowicz, pers. comm.). 
Female flavirostris have dull green upperwing 
coverts in contrast with the black male upperwing 
coverts. This feature does not appear to be 
constant in boliviano where, in some breeding 
pairs, the female has black upperwing coverts. 
Other than the shorter tail, some female individ¬ 
uals of boliviano have plumage features similar to 
the male, whereas the sexually dimorphic body 
plumage of flavirostris is clearly demarcated in all 
specimens (/? = 12). 
The marked differences in female plumage 
between the two taxa are important in considering 
why boliviano was initially considered only a 
subspecies. Chapman (1930) in identifying the 
subspecies status of boliviano (based on a single 
female specimen) did not indicate the boliviano 
female was substantially different from the female 
flavirostris. Chapman (1930) noted there were 
‘marked differences' but concluded this called into 
question the correctness of the identification of 
gender. Chapman speculated that it was possible 
the female boliviano used to base his subspecies 
conclusion ‘may be a young male’. Snow (1982) 
agreed the 1902 AMNH female boliviano speci¬ 
men was probably incorrectly assigned to gender. 
Krabbe (1984) examined all three boliviano 
specimens and compared them with flavirostris 
specimens, and also concluded, based on its 
distinctively different markings, die single female 
boliviano specimen was incorrectly assigned to a 
gender. These authorities believed it better resem¬ 
bled a mal e flavirostris, as they were not aware of 
the different female boliviano plumage. 
Soft Part Colors .—The iris color of boliviano 
and flavirostris is distinctly different with no 
observed variation in color (boliviano n = 17, 
flavirostris n = 10, pers. obs.; J. C. Atienza, pers. 
comm.; Geoff Bromfield, pers. comm.; Mileniusz 
Spanowicz. pers. comm.). The iris of boliviano is 
mustard yellow, whereas the flavirostris iris is 
blood red. The iris in both taxa is semi-concealed 
suggesting the color may be involved in signaling. 
Foot coloration also differs markedly between 
the two taxa. Feet of boliviano are dull to bright 
orange-yellow, whereas flavirostris feet are dull to 
bright pink. No overlap has been recorded. Soft 
part colors were not known for boliviano or noted 
in Chapman’s (1930) classification. 
Vocalizations.—No vocalizations offlavirostris 
were recorded before this study. I obtained 34 
