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A Striking New Species of Barbet (Capitoninae: Capito) from the Eastern Andes of Peru

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Abstract

In 1996, an expedition of personnel from the Louisiana State University Museum of Natural Science and the Museo de Historia Natural de la Universidad Nacional Mayor de San Marcos made a trail from the east bank of the upper Río Cushabatay, departamento Ucayali, Peru, northeast to the top of a 1,538-m peak at 7°05′S, 75°39′W. The peak supports cloud forest from 1,200 m to the summit, and this “island” of habitat may be among the most isolated areas of cloud forest in South America. Among the depauperate cloud-forest avifauna we discovered a striking new species of Capito barbet, which apparently is the only member of the genus restricted to this habitat.
569
The Auk 117(3):569–577, 2000
A STRIKING NEW SPECIES OF BARBE T (CAPITONINAE: CAPITO)
FROM THE EASTERN ANDES OF PERU
J
OHN
P. O’N
EILL
,
1,5
D
ANIEL
F. L
ANE
,
1
A
NDREW
W. K
RATTER
,
2
A
NGELO
P. C
APPARELLA
,
3
AND
C
ECILIA
F
OX
J
OO
4
1
Museum of Natural Science, 1 19 Foster Hall, Louisiana State University, Baton Rouge, Louisiana 70803, USA;
2
Florida Museum of Natural History, University of Florida, Gainesville, Florida 32611, USA;
3
Department of Biological Sciences, Illinois State University, Normal, Illinois 61790, USA; and
4
Museo de Historia Natural de la Universidad Naci onal Mayor de San Marcos, Casilla 14-0434, Lima 14, Peru
A
BSTRACT
.—In 1996, an expedition of personnel from the Louisia na State Uni versity Mu-
seum of Natural Science and the Museo de Historia Natural de la Universidad Nacional May-
or de San Marcos made a trail from the east bank of the upper Rı´o Cushabatay, departamento
Ucayali, Peru, northeast to the top of a 1,538-m peak at 7 !05"S, 75!39"W. The peak supports
cloud forest from 1,200 m to the summit, and this ‘island’’ of habitat may be among the
most isolated areas of cloud forest in South Americ a. Among the depauperate cloud-forest
avifauna we disc overed a stri king new species of Capito barbet, which apparently is the only
member of the genus restricted to this habitat. Received 22 December 1999, accepted 17 March
2000.
B
ARBETS OF THE GENUS
Capito are widely dis-
tributed in the lowlands of northern South
America, reaching their greatest diversity in
the Choco´ rainforest of western Colombia and
Ecuador. Although they are colorful bird s of
the tropical forest canopy, most species remain
relatively poorly known, with two being de-
scribed in the early 20th century (Cherrie 1916
and Chapman 1921). We are exci ted, therefore,
to report the discovery of a previous ly undes-
cribed species that exhibits striking colors and
plumage pattern and ap parently is the only
member of the genus that is restricted to c loud
forest.
In July 1996, a Louisiana State University
Museum of Natural Science expedition l ed by
O’Neill camped at 300 m on the east bank of the
upper Rı´o Cushabatay, approximately 77 km
west-northwest of the town of Contamana, de-
partamento Loreto, Peru. On 7 July, field assis-
tants completed a trail to the top of a n un-
named, isolated peak that reaches 1,538 m at its
summit. Because of a lack of water, no perm a-
nent camp could be esta blished on the peak,
and most of the expediti on members had access
to the forest at the summit only during the day.
It took several days before the members of the
expedition began to become acquainted with
the avifauna of what must be some of the most
5
E-mail: par dusco@aol.com
isolated cloud forest in Peru, if not in all of
South America.
On 15 July, Lan e and Manuel Sa´nchez S. col-
lected four individuals of a spe cies of barbet
that they immediately suspected was new to
science. Its plumage, shape, and size clearly
seemed to place the bir d in the genus Capito
(see cover illustration). Within the next two
weeks, members of the party obtained nine
more specimens. Collecting of barbe ts ceased
on 26 July 1996, when members of the expedi-
tion concentrated more on obtaining informa-
tion on natural history. On a given day, we en-
countered up to eigh t individuals from the trail
through the cloud forest, which allowed us to
document their voice a nd habits with photo-
graphs, tape recordings, and behavioral notes
gathered during about 4 h of observation. We
are pleased to name this colorfu l new barbet:
Capito wallacei sp. nov.
Scarlet-banded Barbet
Holotype.Museo de Historia Natural de la
Universidad Nacional Mayor de San Marcos
(MUSM) No. 21269, fem ale, about 77 km WNW
of Contamana (ca. 7!05"S, 75!39"W), departa-
mento Loret o, Peru, elevation 1,450 m; collected
20 July 1996 by Orlando Riva P.; prepared by
Leticia A. Alamı´a, original catalog number
1045.
Diagnosis.—A capitonine, assignable to the
570 [Auk, Vol. 117O’N
EILL ET AL
.
genus Capito by the combination of a s tout bill,
circular nostrils separate d from each oth er by a
broad mesorhinum, a tail less than two-thirds
the length of the wing, outer rectrices more
than three-fourths as long as t he middle pair,
outermost primary ( P10) much less than half as
long as P9 and relatively narrow, back black
with some yellow and red coloration, and min-
imal sexu al dimorphism in p lumage pattern
(Ridgway 1914). Separable from all known s pe-
cies in the genus by the combination of scarlet
crown and nape (scarlet extending onto the
mid-back), white superciliary, b lack sides of
face, white throat separated from yellow breast
and belly by a broad scarlet band, a nd pale yel-
low li ne that extends mid-dorsally from the red
on the lower back to the uppertail coverts,
where it becomes a white rump patch that ex-
tends to the uppertail coverts (see cover).
Description of holotype.—Forehead, crown,
and nape brilliant scarlet red, nearest Spec-
trum Red (capitalized color names from Ridg-
way 1912), t his color extending posteriorly
onto the middle o f the back and ending in a
‘‘vee.’’ Supercilium white, extending from just
in front of the eye to the rear e dge of the ear
coverts, and broadening posteriorly. Lores, ar-
eas above and below eye, and ear coverts black
with the ventral-most row of subocula r feath-
ers tipped white, giving the appearance of tiny
white dots. Throat and upper breast white, bor-
dered below by a broad (13.5 mm at its center)
Scarlet-Red band. Lower breast and belly yel-
low, nearest Picric Yellow, fading into a yel low-
ish-white color between Sea-foam Yellow and
White on u ndertail coverts. Flanks washed
with yellow-orange, nea rest Light C admium,
with a few feathers bearing scattered red areas
and so me dark brownish-black feathe r bases
that show through the yell ow-orange. Scapu-
lars mostly black, outermost row of feathers
near Picric Yellow, forming a vee-shaped pat-
tern that joins at the posterior edge of the red
vee that exten ds onto the back; at this point th e
yellow extends medially a nd posterior ly ap-
proximately 10 mm in a narrow line that
abruptly changes to white and c ontinues pos-
teriorly down the otherwise black lower back
and rump to the uppertail coverts. Uppertail
coverts black, but with the in ner web of the cen-
tral covert fe athers mostly white, fo rming a
white rump patch. Wings black with P10
through P8 very dark brow n ( old and worn)
contrasting with blacker, new ly molted inner
primaries; outer ed ges of outer webs of second-
aries dull olive-green with pale buffy-white
spots along the shafts of the outer webs of the
innermost secondaries. All remiges but P10
edged buffy-yellowish white on inner webs;
rectrices plain black.
Irides blood red; maxilla light gray with dis-
tal half, including tomium, black; mandible
light gray with distal third and tomium black;
feet and tarsi greenish gray; sol es orange-yel-
low.
Measurements of holotype.Flattened wing
chord 90.0 mm, tail 55.0 mm, culmen (nares to
tip) 19.0 mm, culmen depth at nar es 9.5 mm,
tarsus 25.5 mm, ovary 9 # 5 mm, ova less than
1 # 1 mm, skull 75% ossified, no bursa, body
mass 78 g.
Specimens examined.—Lane (1999) scored
plumages of specimens of 36 o f the 39 named
taxa of Neotropical barbet genera (Capito and
Eubucco) and assembled tape recordings of as
many taxa as possible for vocal analyses. He ex-
amined approximately 500 s pecimens, at least
380 of which were in the genus Capit o (see Lane
1999). Below, we detail the specimens of the
new species examined in this study.
Thirteen specimens (holotype and 12 par a-
types), all from the type locality (ranging over
an elevational band from ca. 1,350 t o 1,500 m)
and prepared as conventional study skins un-
less otherwise noted in Table 1. Males: Louisi-
ana State Univer sity Museum of Zoology
(LSUMZ) 161645, 161648, 161649, and 161651;
MUSM 17573 and 17574. Fem ales: LSUMZ
161646 and 161650; MUSM 17570, 17571,
17572, and 21269 (holotype). Female (by plum-
age): LSUMZ 162073. The label information for
these specimens is presented in Table 1.
Etymology.—We name this species in honor of
Robert B. Wallace of Washin gton, D.C., in rec-
ognition of his intense interest in, and support
of, ornithological exploration by the Louisiana
State University Museum of Natural Science in
Peru. His understanding of the need to study
areas that a re biologically unknown, bef ore
they are forever changed by development, is
greatly appreciated. The English nam e draws
attention to the most distinctive marking of this
bird.
R
EMARKS
Variation wit hin the type ser ies.—In addition to
the holotype, we prepared 10 study skins, a
July 2000] 571New Peruvian Barbet
T
ABLE
1. Information f rom specimen labels of the ho lotype and par atypes of Capito wallacei.
Museum no. Elev. (m) Preparation Mass (g) Skull
a
Bursa
b
Gonads
c
Fat
Males
LSUMZ 16164 5
LSUMZ 16164 8
LSUMZ 16164 9
LSUMZ 16165 1
MUSM 17573
MUSM 17574
1,400
1,450
1,450
1,400
1,450
1,450
Skin
Skeleton, skin
d
Skin
Skin
Skin
Skin
65
65
75
69
78
63
5
10
10
100
10 # 4
9 # 6
3 # 3
2 # 2
4 # 2
3 # 2.5
2 # 2
2 # 2
Light
Light
Moderate
Light
Females
LSUMZ 16164 6
LSUMZ 16165 0
LSUMZ 16207 3
MUSM 17570
MUSM 17571
MUSM 17572
MUSM 21269
f
1,350
1,350
1,350
1,400
1,400
1,400
1,450
Skin
Skin
Alcoholic
Skin, s keleton
e
Skin
Skin
Skin
71
74
68
64
67
66
78
10
75
8 # 4
9 # 5
8 # 4
6 # 4
7 # 5
9 # 6
9 # 5
Light
a
Skull ossification (%).
b
Depth of bursa (mm).
c
Dimensi ons (mm) of left testis for males, ovary for females.
d
Complete skeleton, partial skin.
e
Complete skin, partial skeleton.
f
Holotype.
T
ABLE
2. Selected measurements (mm) of Capito wallacei.
Museum no. Culmen Wing Tail Tarsus Bill depth
Males
LSUMZ 16164 5
LSUMZ 16164 9
LSUMZ 16165 1
MUSM 17573
MUSM 17574
x¯ $ SD
16.5
16.5
17.0
16.0
18.0
16.8 $ 0.76
91
93
95
86
88
90.6 $ 3.65
56.0
53.0
54.0
53.5
51.0
53.5 $ 1.80
25.0
25.5
25.5
24.0
23.0
24.6 $ 1.08
9.0
9.0
9.0
10.0
9.5
9.3 $ 0.45
Females
LSUMZ 16164 6
LSUMZ 16165 0
MUSM 17570
MUSM 17571
MUSM 17572
MUSM 21269
x¯ $ SD
18.0
17.5
17.0
17.0
16.0
19.0
17.4 $ 1.02
91
93
92
91
90
90
91.2 $ 1.17
51.0
54.0
54.5
55.0
55.0
53.9 $ 1.67
26.0
25.0
23.5
24.5
25.0
25.5
24.9 $ 0.86
9.5
9.0
9.0
9.5
9.0
9.5
9.3 $ 0.27
complete skeleton with skin, and p reserved a
specimen in formalin for dissection. Aside
from bein g slightly smaller (Ta ble 2), males dif-
fer from females only in lacking the golden-yel-
low edges to the feathers of the scapu lars, by
having no white dots in the black plumage be-
low the eyes, and by lacking pale spots on the
inner portion of the outer webs of the inner-
most secondaries (see cover). The size of these
pale spots varies among females. In addition,
the anks of males tend to be washed more
strongly with oran ge than a re those of fem ales.
The skulls of three individuals that retained the
bursa of Fabricius were not fully o ssified (see
McNeil and Burton [1972] and Harrison [1964]
for discussion of the u se of skull pneumatiza-
tion and bursa of Fabricius in aging birds). As
with other membe rs of the genus, it appears
that Capito wallacei molts quickly into adult-like
plumage; thus, young of t he previous breedin g
season may be sexually immature, but look like
adults (D. F. Lane pers. obs.).
Distribution.—The species is presently known
only from an unnamed peak labeled on topo-
graphic maps as ‘‘Peak 1538’ (ca. 7!05"S
75!39"W) and so referred to by us. This peak is
572 [Auk, Vol. 117O’N
EILL ET AL
.
F
IG
. 1. Headwaters of the Rı´o Cushab atay. Montane areas above 1,000 m are shown in black, with ele-
vations of major peaks noted in meters. Solid arrow points to peak where Capito wallacei was discover ed.
Cloud fore st in this area seems to develop only above 1,200 m.
approximately 15 km NNE of the upper Rı´o
Cushabatay, between the east bank of that river
and the west bank of the ´o Ucayali, of which
the Cushabatay is a tributary, approximately 77
km WNW of Contamana, departamento Lore -
to, Peru (see Fig. 1). A long (%50 km), narrow
ridge at more than 1,000 m elevation that ex-
tends to the north of Peak 153 8 has two addi-
tional high peaks, one of 1,688 m and anot her
of 1,610 m. In the main ridge of the Cordillera
Azul, appr oximately 30 km to the west, a larger
area above 1,000 m contains several peaks that
range from 1,372 to 1,687 m. We predict that the
new ba rbet will be found in the ridge s ystem to
the north of Peak 1538 and that it probably oc-
curs to the west as well. Except for Peak 1538,
the system of low mountains stretching north
to the ´o Huallaga and some of it to the south
July 2000] 573New Peruvian Barbet
remains unexplored. Any areas above 1,250 m
are likely to provide cloud-for est habitat for
Capito wallacei. Presently, threats to C. wallacei
are few because little human habitation occurs
in the Cushabatay watershed, and none above
300 m. Only a small amount of hunting is done
by the infrequent visitors, and a recent ban on
harvesting of mahogany (Swietania sp.) will
probably result in even fewer visitors. Howev-
er, deforestation is extensive and increasing on
the west slope of the Co rdillera Azul, especial-
ly i n the drainage of the ´o Biabo, which flows
into the valley of the ´o Huallaga.
Habitat.—We found Capito wallacei only on
and near the summit of Peak 1538 on a rela-
tively at plateau cloaked in cloud forest. Dur-
ing our dry-season visit, the summit plateau of-
ten was covered in clouds, even when adjacent
areas were clear. Epiphytes, especially bryo-
phytes, bromeliads, and orchids, covered most
of the trunks and large br anches of the short
trees (generally 10 to 20 m tall) in the fore st.
The predominant trees near the summit were
melastomes (Melastomaceae) and clusias ( Clu-
sia sp.). T he forest floor ha d a deep (up to 1 m),
spongy cover of mosses intermixed w ith leaf
litter and soil. The wet, epiphyte-covered mon-
tane forest of the summit changed abruptly to
taller and drier subtropical forest below 1,250
m. Epiphyte cover in the forest below 1,250 m
was greatly redu ced compared with the wetter,
higher-elevation forest, and th e soil surface was
much firmer, with little or no moss. We found
C. wallacei on all parts of the plateau that we
visited but never saw it below the transition to
drier forest at 1,250 m. Several species charac-
teristic of the higher montane forest (e.g . Ver-
sicolored Barbet [Eubucco versicolor], Blue-
winged Mountain-Tanager [Anisognathus somp-
tuosus], White-winged Tanager [Piranga leucop-
tera], and Hepatic Tanager [P. ava]) were seen
repeatedly below the transition zone. Perhaps
the presence of a congener, the Gilded Bar bet
(C. [nige r] auratus), just below the transition
zone restricts C. wallacei to cloud forest above
1,250 m.
Peak 1538 occurs at the southern end of a
north-south spur off the main axis of th e Cor-
dillera Azul, which trends southwest to north-
east (Fig. 1). Although similar wet montane for-
ests undoubtedly occur on adjacent peaks to
the west and north in the Cordillera Azu l, we
were able to v isit only this one area. Assuming
that 1,25 0 m is the lower elevational limit of the
distribution of C. wallacei, Peak 1538 provides a
small island of habitat isolated by 30 km from
another larger island of habitat farther north on
the same spur. T hese two habitat islands are
about 35 km east of the main axis of the Cor-
dillera Azul, which has an exten sive area (ca.
1,200 km
2
) of terrain above 1,250 m and peaks
to 1,700 m or more in elevation. Cloud cover on
the main axis of the Cordi llera often matched
that on Peak 1538, suggesting similar climates
and fo rest types. Capito wal lacei was common in
the wet forests on Peak 1538.
Behavior.In general, the barbets moved
through the tree canopy unobtrusively and
were rather quiet or gave only soft calls. They
foraged with the characteristic sluggish move-
ments of other species of Capito, at least when
in fruiting trees, and seldom changed perches.
Despite their sluggishness, they were rather
easy to nd because of the distinctive whirring
noise produced by the wings during ight
(louder than other Capito; D. F. Lane pers. ob s.).
They stayed near the crowns of the t rees in
loose groups even when traveling with other
species. Attesting to their predilection for the
tree canopy was our failure to capture any in
mist nets, even though we intensively sampled
birds in the u nderstory of these fore sts (ca.
4,800 net h).
On 5 August 1996 (nearly two weeks after we
ceased collecting C. wallacei), from approxi-
mately 1400 to 1500 EST, Kratter and Lane
watched a group of six birds that stayed in the
vicinity of a non-melastome fruiting tree that
contained reddish berries that were 1 cm in di-
ameter. Often, one bird of this group stayed on
the same perch for more than 5 min at a time.
The birds foraged quietly in the shad ed interior
of the tree crowns, about 15 m above the
ground and 5 m below the to p of the canopy,
although one bird sat motio nless in the sun ,
with its body plumage fluffed out, for more
than 5 min. Foraging birds used small (&1 cm
in diameter) horizontal perches in fairly dense-
ly leafed portions of the tree crown. Foraging
maneuvers (n ' 10) consisted of ‘gleans’’ or
‘‘reach outs’’ (see Remsen and Robinson 1990)
for fruits. The birds generally kept a diagonal
posture on their perches, with the tail he ld at
about 30! below the horizontal. One p air flew
into the area together and perched within 5 cm
of one another on a small horizontal stem. They
574 [Auk, Vol. 117O’N
EILL ET AL
.
faced each other and tapped their bills togeth-
er, perhaps allofeeding. Krat ter then watched a
group of three disappear into the dense leaves
at the base of a large bromeliad, where they
may have been drinking water. Lane later ob-
served one bird in the group drinking from a
bromeliad.
During another foraging observation, Kratter
noted a bird about 10 m up (ca. 5 m below the
canopy top) ‘hang down from a horizontal
perch and glean a fruit, probably a mistletoe
berry. This bird kept i ts tail horizontal as i t
reached its head below the branch vertically.
Although so me barbets (especially Eubucco
spp., but also Capito) r egularly forag e for in-
sects in clusters of dead leaves trapped above
ground (Remsen and Parker 1984, Ro senberg
1997, A.W. Kratter and D. F. Lane pers. obs.), we
did not see C . wallacei foraging in this manner
during our relatively brief observations.
We found C. wallacei in monospecific groups
in 50% of our observations (4 of 8). Group size
ranged from two to seven whether barbets
traveled in single-specie s or in mixed-species
flocks. All of the barbets in one mixed-species
flock appeared to be foraging for insects in the
outer crowns of trees in the canopy, and the
barbets moved more actively in these mixed-
species flocks than when they foraged in fruit-
ing trees. Other species in mixe d flocks includ-
ed Chestnut-tipped Toucanet (Aulacorhynchus
derbianus),Versicolored Barbet, Mottle-cheeked
Tyrannulet (Phyllo scartes ventralis), Slaty-
capped Flycatcher (Lepto pogon superciliaris ),
Masked Tityra (Tityra semifasciata), Th ree-
striped Warbler (Basileuterus tristriatus), Slate-
throated Redstart (Myioborus miniatus), Blue-
naped Chlorophonia (Chlorophonia cyanea),
Bronze-green Euphonia (Euphonia mesochrysa),
Orange-bellied Euphonia (E. xanthogaster),
White-winged Tanager, Hepat ic Tanager, and
Blue-winged Mountain-Tanager.
We did not observe breeding behavior, but
three individuals retained the bursas o f Fabri-
cius, suggesting that they h ad fledged within
the past six months. Thus, it is likely that the
groups we observed were composed of one or
more families.
Voice.We obtained three sound recordings
of Capito wallacei, all of which are archived at
Cornell Laboratory of Ornithology’s Library of
Natural Sounds. Capito wallacei was obs erved
giving two distinct vocalizations: a s ong (Fig.
2A) and a t ityra-like grunt ing call (Fig. 2C).
The latter was the most frequent vocalization
given by the barbets and was frequently given
by individual s in mixed-speci es foraging
flocks, between members of presumed pairs,
and among members of the evening congrega-
tion observed by Kratter and Lane. Grunt calls
varied in harshness and dur ation depend ing on
the circumstances but were similar to those
given by other members of Capito. In addition,
grunt calls were reminiscent of certain vocali-
zations given by Aulacorhynchus derbianus and
Eubucco versicolor at the same s ite and in th e
same elevational range occupied by C. wallacei.
The long (ca. 50 to120 notes), even-frequency
purring song was given infrequently and ap-
parently only by one member of a presumed
pair (Fig. 2A). A de tailed look at individual
notes of the song shows what appears to be a
pattern of a more heavi ly stressed note fol-
lowed by a mo re lightly stressed note followed
by a heavily stressed note, etc. (Fig. 2B). Owing
to the small sample size of individuals and
number of songs recorded, it is unclear wheth-
er this pattern is real. To the human ear, how-
ever, the song of C. wallacei strongly rese mbles
the distant drumming of a medium-sized
woodpecker and is quite unlike the slower,
hooted songs of most other Capito. Songs of
Orange-fronted (C. squamatus) and Spot-
crowned (C. maculicoronatus) barbets are nearly
identical to that of C. wallacei (Figs. 2D, E), dif-
fering in having slightly higher frequencies and
fewer numbers of notes (n ' 12 for C. squ ama-
tus, n ' 2 for C. maculicoronatus, n ' 13 for
C. wallacei) and lackin g the couplet pattern
of notes present in C. wallacei. The voice of
the Brown- breasted Barbet (C. brunneipectus)
shows some similarities to that of C. wallacei as
well (Fig. 2G) but accelerates from hooted notes
into a purr that drops in pitch at the same time.
Nearly all other members of the genus Capito,
such as the closely related White-mantled Bar-
bet (C. hypoleucus; Fig. 2F), have hooted songs
with fewer, more easily defined notes. Purred
songs are also present in two species in the sis-
ter genus Eubucc o (Lane 1999).
On 4 August 1996, Kratter watched a single
bird in a monospecific group of ve or six bar-
bets giving the very soft purring song. The bird
was pe rched more horizontally than usual,
with its tail parallel to the ground and its head
thrust forward and pointed downward. Its
July 2000] 575New Peruvian Barbet
F
IG
. 2 . Sono grams of Capito wallacei and four other me mbers of the genus Capito. Names of recordists are
in parentheses. (A) ‘‘Purring’’ song of C. wallacei (D. F. Lane); (B) section of song in A enlarged 10 # to show
the apparent couplet structure of notes within song; (C) tityra-like ‘‘grunt’’ call of C. wallacei (D. F. Lane);
(D) ‘‘purring’ song of C. squamatus (P. Coopmans); (E) ‘‘purring’ song of C. maculicoro natus (L. Macaulay);
(F) ‘hooting’ song of C. hypoleucus (B. W. Whitn ey); and (G) ‘hoot-to-purr’’ song of C. brunneipectus (M.
Cohn-Haft).
back feathers were fluffed out, and its tail quiv-
ered laterally as it sang.
Phylogenetic relationships.— Based on a cladis-
tic analysis of plumage and vocalizations in the
Capitoninae, C. wallacei bel ongs to a group with
largely black-and-white plumage: C . squam a-
tus, C. maculicoronatus, and C. hypoleucus (Lane
1999). Ea ch of these species has a relatively
small geographic range, and with the exception
of C. wallacei, t hey are found on the western
(Choco´) or northern (Nechı´) anks of the An-
des. The discovery of C. wallacei suggests that
the ancestor of this clade was widespread as a
lower-elevation and/or submontane compo-
576 [Auk, Vol. 117O’N
EILL ET AL
.
nent of the northern Andean avifauna (at least
as far south as northern Peru) that was frag-
mented into sibling populations that became
separate species, a scenario previously sug-
gested by Chapman (1928).
Although a ll other members of th e clade that
contains C. wallacei appear to be quite distinct
from it in lacking the red breast band an d the
white superciliary, and in t he extent of streak-
ing on the dorsum, they share several charac-
ters (Lane 1999). All have some suggestion of a
breast band—yellow in C. macu licoronatus,
brownish in C. squamatus and C. hypoleucus
a character lacking in the rest of the genus with
the e xception of C. brunneipectus. All clade
members have a yellowish wash on the anks,
which is concentrated into a localized patch of
yellow-orange or red in C. macul icoronatus. Fi-
nally, all show sexual dichromatism, but the de-
gree varies among members of the clade. Capito
maculicoronatus and C . squamatus share white
throats in males and black hoods in females,
whereas this difference is reduced to the fe-
males acquisition of a black malar spot in C . hy-
poleucus. By comparison, sexual dichromatism
in C. wallacei is more similar to that of members
of the Black-spotted Barbet (C. niger) clade
(sensu Lane 1999) in that it is limited to the fe-
males acqui sition of pale streaks on the scap-
ulars, pale spots on the innermost secondaries,
and pale-freckled lower auricular patches. Cap-
ito br unneipectus, a member of the C. niger clade,
shares these sexually dimorphic characters
with C. wallacei. However, these characters are
only part of a larger suite of plumage charac-
ters exhibited by females of the C. niger clade,
such as heavy spotting on the underparts, ex-
tensive pale marki ngs on the wings, and exten-
sive pale streaking on the head and back.
The song of C. wallacei is a ho llow purr that
is nearly identical to those of C. maculicoron atus
and C. squamatus (Fig. 2). The song of C. hypo -
leucus is a slower series of hooted notes and is
quite distinct from other members of the clade
(Fig. 2) but more similar to other members of
the genus Capito. Because C. hyp oleucus is l ocal-
ly sympatric with C. maculicoronatus, it is con-
ceivable that their different songs evolved to
maintain reproductive isolation (Lane 1999).
Sympatry, bu t with spatial separation by e le-
vation, exists between C. wallacei and C. [niger]
auratus. Interestingly, th ese two species also
differ strongly in their voices, the latte r having
a h ooting song and the former a pur ring song.
Whether this is coincidental, or is a case of ‘vo-
cal niche partitioning’ that reinforces repro-
ductive isolation, is not clear. Owing to its dis-
tinctiveness in plumage pattern and sexual di-
chromatism compared with other mem bers of
its clade (much less the rest of the genus), we
believe it is safe to say that Capito wallacei is a
valid species by any species concept.
With the description of this barbet, we look
forward to retur ning t o the northern portion of
the Cordillera Azul to see what other hidden
treasures it holds and to look in other montane
islands for additional populations of Capito wal-
lacei. The members of the 1996 expedition en-
countered several other ‘mystery’ birds that
were not collected and likely are unde scribed
taxa. The headwater regions of the ´o Cusha-
batay, ´o Pisqui, and ´o Biabo encompass one
of Perus largest pristine and biologically un-
known areas. The region has been propo sed as
a protected area, and no matte r what level of
protection it receives, the cloud forests, includ-
ing the entire known range of the new barbet,
will receive legal protection as waters hed for-
ests.
A
CKNOWLEDGMENTS
We are grateful for the assistance of t he following
people during the 1996 expedition: Leticia A. Ala-
´a, Julio Figueroa, Thomas Hurd, Antonio Ramirez,
Orlando Riva P., Carlos R´z, Manuel Sa´ nchez S .,
Marta Chavez de Sa´nchez, and Huguer Sa´nchez C.
We are grateful to the officials of the Instituto Na-
cional de Recursos Naturales (INRENA) for the is-
suance of permits for our work. In addition, t he cu-
rators and staff of the following museums allowed
Dan Lane access to their collections and graciously
allowed for the loan of a large number of specimens:
David Agro, Academy of Natural Sciences of Phila-
delphia; Franc¸ois Vuilleum ier, Lester L. Short, and
Paul Sweet, American Museum of Natural History;
Shannon J. Hackett and David E. Willard, Field Mu-
seum of Natural History; Raymond A. Paynter, Jr.,
Museum of Comparative Zoology; Irma Franke J.,
Museo de Historia Natural de la Universidad Na-
cional Mayor de San Marcos; and Gary R. Graves,
National Museum of Natural History, Smithsonian
Institution. Th e fo llowing recordists kindly lent tape
recordings (these recordings are, or will be, archived
in various sound archives such as Cornell Laboratory
of Ornithologys Library of Natural Sounds): Mario
Cohn-Haft, Paul Coopm ans, Linda Macaulay, and
Bret M. Whitney. Phyllis R. and Morton L. Isle r freely
gave of t heir time to produce the sonograms repro-
July 2000] 577New Peruvian Barbet
duced herei n. The 1996 expedition was mainly fund-
ed by a grant to JPO from the National Geographic
Society’s Fund for Research and Exploration (grant
no. 5678–96). We also grateful ly acknowledge the
continued inte rest and support o f Robert De-
Bellevue, A nne W. Geier, George Mitchell, H. Irving
Schweppe, James R. Stewart, and Robert B. Wallace.
This manuscript bene fited from reviews by Scott M.
Lanyon, Pamela C. Rasmussen, James V. Remsen, and
Lester L. Short.
L
ITERATURE
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OSENBERG
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No. 48.
Associate Editor: J. S. Marks
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Article
One reason suggested for the high avian species diversity in tropical forests is increased specialization on resources that are absent in temperate habitats. This study investigates in detail one such specialization, namely foraging for arthropods in suspended aerial leaf-litter in lowland tropical rainforest. Up to 16 species at two southwestern Amazonian sites constitute a guild of specialized dead-leaf foragers that make up roughly 11% of the region's insectivorous bird species. Most dead-leaf specialists are ovenbirds (Furnariidae) or antbirds (Formicariidae) that are characteristic members of mixed-species foraging flocks in the understory or canopy. These specialists, compared with other insectivores, tended to use more acrobatic postures and manipulated foraging substrates with the bill or feet. These species segregated to some extent by habitat, including several congeneric replacements. The guild reaches its highest diversity in a belt across southwestern Amazonia and along the base of the Andes, where bamboo and other disturbance-related microhabitats add to forest heterogeneity. Individual dead leaves, as resources for birds, were abundant in all forest types and supported higher prey densities (number per leaf) than adjacent live foliage. Prey density was highest in larger leaves, especially in large, crumpled Cecropia leaves. The arthropod fauna of aerial leaf-litter was similar among seasons, habitats, and sites, being dominated by spiders, roaches, other orthopterans, and small beetles. This contrasts greatly with arthropods available on live foliage. Guild members differed significantly from each other in either foraging height, size or type of leaves searched, diet composition, or prey size, although overlaps between species pairs were usually high (≥0.900). Although twice as many species were supported in low-lying forest than in upland forest, ecological overlaps among species in each habitat were usually similar. Behavioral similarity among species was not related to dietary overlap. Size of prey taken, however, was correlated with bill size, except that the largest species, Xiphorhynchus guttatus, ate surprisingly small prey. Diet composition of all species differed significantly from prey availability in dead leaves, with orthopterans selected by all species and small roaches and spiders often avoided. Censuses of 92 mixed-species flocks revealed no negative and only two positive associations between species, suggesting that birds join flocks independent of other species present. Co-occurring Myrmotherula leucophthalma and M. ornata in the same flocks were not aggressive and converged in foraging height and substrate use. In contrast, co-occurring Automolus foliage-gleaners tended to diverge in foraging height and exhibited overt aggression. Niche segregation among dead-leaf foragers therefore represents a balance between benefits and constraints imposed by feeding in a mixedspecies flock; that is, increased vigilence and group defense of territories versus feeding close to potential competitors. Dead-leaf specialization evolved independently in several bird families but shows strong phylogenetic constraints among genera. Phylogenetic study of Myrmotherula antwrens revealed that all specialist species were related and that they have been evolving separately from other antwrens perhaps for as long as nine million years. Foraging specialization is therefore a primitive trait within this group (and probably others), appearing before the radiation of modern species. Study of present-day ecology may not elucidate factors leading to the evolution of such specialization, especially without concurrent phylogenetic analyses. /// Una de las razones sugeridas para la gran diversidad de aves en los bosques tropicales es el aumento en la especialización sobre recursos que están ausentes en hábitats templados. Este estudio investiga en detalle una de tales especializaciones, esto es, el forrajeo para artrópodos en hojarasca suspendida en bosques tropicales de tierras bajas. Hasta 16 especies de aves en dos sitios en el suroeste de Amazonia consituyen un tipo de forrajeadores especializados en la hojarasca, los cuales forman aproximadamente el 11% de las especies de pájaros insectívoros de la región. La mayoría de los especialistas en hojarasca son pizpitas (Furnariidae) o pájaros comehormigas (Formicariidae), que son miembros característicos de bandadas mixtas de forrajeo en el sotobosque o el dosel. Estos especialistas, comparados con otros insectívoros, tendieron a colocarse en posturas más acrobáticas y a manipular el sustrato de forrajeo con las patas o el pico. Estas especies se segregaban por hábitat, hasta cierto punto, incluyendo varios congéneres que les reemplazaban. Esta asociación alimentaria alcanzó su mayor diversidad en la faja a través del suroeste de Amazonia y a lo largo de la base de los Andes, donde las bambúas y otros microhábitats de áreas perturbadas le añaden heterogeneidad al bosque. Hojas muertas individuales, como recurso para los pájaros, eran abundantes en todos los tipos de bosque y sostuvieron una mayor densidad de presas (número por hoja) que el follaje vivo adyacente. La densidad de presas fue mayor en hojas más grandes, especialmente en las hojas arrugadas grandes de Cecropia. La fauna artrópoda de la hojarasca suspendida fue similar a través de las estaciones del año, hábitats, y sitios, siendo dominada por arañas, cucarachas, otros ortópteros y escarabajos pequeños. Esto contrasta grandemente con los artrópodos disponibles en el follaje vivo. Miembros de las distintas asociaciones alimentarias difirieron significativamente uno del otro en altura de forrajeo, tamaño o tipo de hojas forrajeadas, composición de la dieta, o el tamaño de la presa, aunque los solapamientos ecológicos entre parejas de especies fueron usualmente altos (≥0.900). Aunque se encontró el doble de especies en terrenos bajos comparados con bosques en terrenos altos, el solapamiento ecológico entre las especies en cada hábitat fue usualmente similar. La similaridad en el comportamiento entre especies no estuvo relacionada con el solapamiento dietético. El tamaño de las presas cazadas, sin embargo, estuvo correlacionado con el tamaño del pico, excepto que la especie más grande Xiphorhynchus guttatus, consumió presas sorpresivamente pequeñas. La composición dietética de todas las especies difirió significativamente de la disponibilidad de presas en hojas muertas, siendo los ortópteros seleccionados por todas las especies, mientras que cucarachas y arañas pequeñas fueron evitadas. Censos de 92 bandadas de especies mixtas no revelaron asociaciones negativas y solamente dos asociaciones positivas entre especies, lo que sugiere que las aves se asocian con bandadas independientemente de qué otras especies estén presentes. Individuos de Myrmotherula leucophthalma y M. ornata que se encontraban en las mismas bandadas no eran agresivos y convergían en la altura y substrato utilizado. En contraste, Automolus tendió a divergir en la altura de forrajeo y exhibió agresión abiertamente. La segregación de nichos entre forrajeros de hojas muertas, por lo tanto, representa un balance entre beneficios y costos impuestos por alimentarse en bandadas de especies mixtas; esto es, aumento en la vigilancia y la defensa grupal de territorios versus la alimentación cerca de competidores potenciales. La especialización en hojas muertas evolucionó independientemente en varias Familias de aves, pero muestra fuertes restricciones filogenéticas entre Géneros. El estudio filogenético de Myrmotherula reveló que todas las especies especialistas estaban relacionadas y han estado evolucionando separadamente de otros del mismo Género, quizás por tanto como nueve millones de años. La especialización en el forrajeo, por lo tanto, es un rasgo primitivo dentro de este grupo (y probablemente otros), que aparece antes de la radiación evolutiva de especies modernas. El estudio de la ecología actual puede no elucidar factores que conlleven a la evolución de tal especialización, especialmente sin los análisis filogenéticos correspondientes.
Article
study of age criteria in some species of North American shorebirds brought us to consider two of the best known techniques of age deter- mination in birds, the size of the bursa of Fabricius and the degrees and pat- terns of skull pneumatization. The only attempt, known to us, to correlate bursa of Fabricius and gonadal development with the ossification of the skull is that of Davis (1947). The bursa of Fabricius is a lympho-epithelial organ lying dorsally above the cloaca. At least in some species it has an opening in the cloaca. It reaches its maximum size at 4-6 months and then begins involution (Davis, 1947). By cloaca1 examination of the bursal pouch, it is possible to distinguish juvenile from adult individuals of some taxa of birds especially Anseriformes and Galliformes (Gower, 1939; Hochbaum, 1942; Linduska, 1943; Kirkpatrick, 1944). Unfortunately, in shorebird species, the bursa of Fabricius has no cloaca1 opening and thus cannot be used as an age criterion of living birds. The pneumatization of the skull has been used as a criterion for estimating the age of birds by C. L. Brehm as far back as 1822 (Niethammer, 1968)) but it was not generally used until the turn of the century (Serventy et al., 1967). Miller (1946) describes the skull ossification process as follows: "The skull of a passerine bird when it leaves the nest is made of a single layer of bone in the area overlaying the brain; at least, the covering appears single when viewed mac- roscopically. Later the brain case becomes double-layered, the outer layer being separated from the inner layer by an air space across which extend numerous small columns of bone. . . . Externally the skull of an immature bird appears uniform and pinkish in live or freshly killed specimens. The skull of the adult is whitish, due to the air space, and also it is finely speckled as a result of the dense white bony columns between the layers." Nero (1951) and Serventy et al. (1967)) in their respective studies of Passer domesticus and Taeniopygia castanotis, give examples of the pattern and rate of cranial ossification, from the juvenile to the adult; through a series of stadia ending with the complete pneumatization of the cranial roof in the adult before it is one year of age. Th is general rule, applied to the Passerines, ad- mits some exceptions as mentioned by White (194S), Chapin (1949)) Grant (1966)) McNeil and Martinez (1967)) and Payne (1969). Chapin (1949) also reported that "swifts and small sandpipers retained a condition through- out life that suggested immaturity. In some other larger birds the pneumatiza- tion of the cranial vault seemed to proceed very rapidly." Other workers like Chapin (1949)) V er e h y en (1953), Harrison (1958, 1964) were interested in 329
Pnematization of bone. FPAGE. 649-650. in. A new dictionary of birds A.L. Thomson Ed
  • J G Harrison
Harrison, J. G. 1964. Pnematization of bone. FPAGE. 649-650. in. A new dictionary of birds A.L. Thomson Ed. McGraw-Hill, New York.
A phylogenetic analysis of the American barbets using plumage and vocal characters (Aves; family Ramphastidae; subfamily Capitoninae)
  • D F Lane
LANE, D. F. 1999. A phylogenetic analysis of the American barbets using plumage and vocal characters (Aves; family Ramphastidae; subfamily Capitoninae). M.S. thesis, Louisiana State University, Baton Rouge.
Color standards and color nomenclature
  • R Ridgway
RIDGWAY, R. 1912. Color standards and color nomenclature. Published by the author, Washington, D.C.
New birds from the Collins-Day expedition to South America
  • G Cherrie
CHERRIE, G. 1916. New birds from the Collins-Day expedition to South America. Bulletin of the American Museum of Natural History 35:394-395.
Ecology of dead-leaf foraging specialists and their contribution to Amazonian bird diversity. Pages 673–699 in Studies in Neotropical ornithology honoring
ROSENBERG, K. V. 1997. Ecology of dead-leaf foraging specialists and their contribution to Amazonian bird diversity. Pages 673–699 in Studies in Neotropical ornithology honoring Ted Parker (J. V. Remsen, Jr., Ed.). Ornithological Monographs No. 48.