Zoogeography and geographic variation of Atlapetes rufinucha (Aves: Emberizinae), including a distinctive new subspecies, in southern Peru and Bolivia

7 Pages·1993·3.2 MB·

by  J V Remsen

PROC. BIOL. SOC. WASH.
106(3), 1993, pp. 429^35
ZOOGEOGRAPHY AND GEOGRAPHIC VARIATION OF
ATLAPETES RUFINUCHA (AVES: EMBERIZINAE),
INCLUDING A DISTINCTIVE NEW
SOUTHERN
SUBSPECIES, IN
PERU AND BOLIVIA
J. V. Remsen, Jr.
Abstract.—K distinctive new subspecies, Atlapetes rufinucha terborghi (Em-
berizinae), is described from the isolated Cordillera Vilcabamba, a spur range
ofthe Andes in Dpto. Cuzco, Peru. This population is isolated from the nearest
populations of^. rufinucha by more than 200 km, and intervening areas with
suitable habitat are inhabited by another species, A. schistaceus. The new taxon
is greener breasted than any other subspecies of^. rufinucha. The four sub-
species found in southern Peru and Bolivia represent four discrete phenotypes
with respect to plumage. Geographic variation in size in the southern Andes
does not support Bergmann's Rule.
The Cordillera Vilcabamba, Dpto. Cuz- Atlapetes rufinucha terborghi,
co, Peru, is a mountain range isolated from new subspecies
the main chain ofthe Andes by deep river
Holotype. —American Museum of Natu-
valleys with tropical, non-montane habitats
(AMNH)
ral History #820436; mist-netted
(Terborgh 1971, Haffer 1974). Although
by John S. Weske and John W. Terborgh
specimens ofbirds collected there in the late
on 22 Jul 1967 in the Cordillera Vilcabam-
1960's by John Weske and John Terborgh
ba, 2630 m, Departamento Cuzco, Peru,
haveyettobe analyzedin a systematic man-
12°37'S, 73°33'W. The specimen, prepared
ner, some endemic taxa have been or are
being described: Schizoeaca vilcabambae by Weske (#1334), is a female in breeding
(Vaurie et al. 1972, Remsen 1981), Crani- condition (ovary and oviduct much en-
oleuca marcapatae weskei (Remsen 1984), larged, largest ovum 8 mm; brood patch
Ochthoecaflimicolor subsp. nov. (P. Hosey, present) with a completely pneumatized
in litt.), and Coeligena violifer subsp. nov. skull and little fat.
(J. Weske and J. P. O'Neill, pers. comm.). Description. —Capitalized color names are
While examining specimens of Andean from Ridgway (1912). Crown closest to Ha-
Atlapetes for a project on their patterns of zel, becoming slightly paler (Cinnamon-Ru-
distribution (Remsen & W. S. Graves 1994), fous) on hind-crown and nape, with some
I found five specimens of^. rufinucha col- Cinnamon Rufous feathers extending to ex-
lected by Weske and Terborgh in the Vil- treme upper back. Rest ofback, upper sides
cabamba that represent an important range ofwings, and tail black, obscurely suffused
extension for this species. Furthermore, with olivaceous tones on back and on outer
these specimens differ distinctly from any webs ofsecondaries. Upper tail coverts Ol-
other population oiA. rufinucha, so much ivaceous Black. Lores, broad superciliary,
so that even with just five specimens, it is face, and auriculars black, contiguous with
clear that they represent a new taxon, which black of dorsum at neck, but contrasting
may be known as: with the darker back. Chin and throat Light
.
430 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
Greenish Yellow. Faint, broken malar stripe imens of^. r. terborghi, the yellow is paler
dark olive. Breast closest to Javel Green. and more washed out than in the nominate
Centerofbellylikethroat, blendingto broad, subspecies. The back and uppertail coverts
darker, Olive Green flanks andslightlypaler of^. r. terborghiare slightlypalerthan those
undertail coverts. Rather than uniformly ofA. r. melanolaemus or the nominate sub-
colored, the underparts have faint hints of species; the black of the face of A. r. ter-
obscure streaks throughout; the breastis not borghicontrasts with the paler back, where-
sharply demarcated from the paler throat as there is little or no contrast between the
and belly. Undersides of remiges and rec- face and back of^. r. melanolaemus or the
trices Fuscous. Soft part colors recorded by nominate subspecies. In these respects, A.
Weske: iris rich brown; bill black; legs dark r. terborghi resembles distant A. r. carrikeri
brown. Measurements: wingchord 70.2 mm; (but A. r. carrikeri is much paler-backed,
exposed culmen 18.5 mm; tail 74.2 mm; paler-breasted, and smaller in size); such
and tarsus 23.9 mm. mosaic distribution ofcharactersis a prom-
Diagnosis. —Atlapetes r. terborghi is inent feature of geographic variation in A.
greener and darker ventrally over-all than rufinucha (Paynter 1978).
any other subspecies of^. rufinucha. It can Distribution. —Cordillera Vilcabamba,
be distinguished from the nearest popula- Dpto. Cuzco, Peru.
tion of A. rufinucha, A. r. melanolaemus Paratypes.—Four other specimens were
(which A. r. terborghi resembles in lacking also mist-netted in the Cordillera Vilca-
a loral spot and black feathers on fore- bamba by Weske and Terborgh and pre-
AMNH
crown), byitsyellow-greenthroatand malar pared by Weske: (1) 820438, 2620
area, which is variably clouded with black m, 12°37'S, 73°33'W, male, 18 Jul 1967; (2)
AMNH
in A. r. melanolaemus. In A. r. terborghi, 820437, 2620 m, 12°37'S, 73°33'W,
AMNH
thebreast, althoughgreenishanddarkerthan male, 30Jul 1967; (3) 820609, 3300
the throat orbelly, lacks the variable amount m, 12°36'S, 73°30'W, female, 17 Jul 1968;
AMNH
of irregular blackish scalloping that char- and (4) 820633, 3500 m, 12°36'S,
acterizes melanolaemus. The nominate 73029'w, female, 31 Jul 1968. Thetwomales
subspecies ofA. rufinucha, from dptos. La are darker below than the holotype, with
Paz and Cochabamba, Bolivia, (which is the underparts more heavily suffused with
more similarinplumage to othersubspecies green; the two females are paler than the
of^. rufinucha throughout the Andes than holotype, with brighter yellow throats and
either^, r. terborghi orA. r. melanolaemus) bellies. The holotype, a female, was selected
differs from A. r. terborghi in the following partly because it is intermediate in ventral
ways: (1) ^. r. terborghi lacks the yellowish coloration, although closertothetwo males.
loral spot of the nominate subspecies; this One female paratype (820609) has a trace
area is black in ^. r. terborghi; (2) in ^. r. of the yellow loral spot and a few black
terborghi, the chestnut ofthe crown extends feathers on the forecrown, characters more
to the bill, whereas in the nominate sub- fully developed in other subspecies. Softpart
species the feathers closest to the bill on the colors were not recorded on any ofthe para-
forehead are black; (3) the nominate form types, but in the dried study skins, the bills,
has a conspicuous black malar stripe, tarsi, and toes appeared identical in color
whereasA. r. terborghi has only a faint trace to those of the holotype. Measurements of
ofa darker malar stripe; (4) the underparts the paratypes and holotype are in Table 1
ofthe nominate subspecies are a bright yel- Etymology. —It is a pleasure to name this
low, whereas those of ^. r. terborghi are distinctive taxon endemic to the Cordillera
greener; even in the two most yellow spec- Vilcabamba for the person who engineered
VOLUME 106, NUMBER 3 431
and conducted its ornithological explora- Table 1.—Measurements (in mm) ofholotype and
tion, Dr. John W. Terborgh. The survey of paratypes ofAtlapetes rufinucha terborghi.
the Vilcabamba by Terborgh and John
Weskerepresentsthemostrigorousandwell- Wing Tail Tarsus Ecxuplomseend
executedinventoryofanyareaoftheAndes. Specimen (AMNH #; sex) chord length length length
The name is particularly appropriate be- 820436; 2 (holotype) 70.2 74.2 23.9 18.5
cause patterns of distribution of brush- 820609; 2 71.5 79.1 25.1 17.9
finches in the Andes provide evidence for 820633; 2 72.6 74.2 24.7 18.4
820437; 6 71.6 76.3 25.0 18.6
the influence ofinterspecific competition on
820438; S 75.3 77.7 25.0 19.4
their zoogeography (Remsen & Graves
1994), a major theme ofTerborgh's (1971)
research in the Vilcabamba.
Geographic Variation
Natural History Atlapetes r. terborghi is the northernmost
The only information available comes of four distinctive subspecies distributed
from the specimen labels. Four specimens from about 18°S in northern Dpto. Santa
were mist-netted in humid, montane cloud- Cruz, Bolivia, north to ca. 12°S in Dpto.
forest and elfin forest, from 2620 to 3300 Cuzco, Peru. Paynter (1978) summarized
m, andthe fifth was mist-netted in "mixture plumage features ofthe three previously de-
oftall grassland and dfin forest on crest of scribed subspecies (the nominate subspe-
mountain range" at 3500 m; Weske (1972) cies, A. r. carrikeri, and A. r. melanolae-
gave the elevational limits as 2520 to 3520 mus), each of which represents a discrete,
m. All five specimens are adults: for four of strongly marked unit (Graves 1985). The
the five, skull pneumatization was recorded only signs ofintergradation between any of
A
as "complete," and forthe one with no skull the subspecies are as follows. specimen
notation, the testes were highly enlarged (Louisiana State University Museum of
(largest 1 1 mm). Both males had enlarged Natural Science, hereafter LSUMZ, 96808)
testes and cloacal protuberances. The ho- in a series of55 ofthe nominate subspecies
lotype female was also in breeding condi- from Cotapata, Chuspipata, and Sacramen-
tion, with the largest ovum 8 mm, but for to Alto, Dpto. La Paz, has black scalloping
the other two females, gonad information on the breast and an enlarged black malar
5x4 mm
was recorded as "ovary (not area, thereby approaching melanolaemus;
mm
enlarged)" and "ovary 6 (not en- whetherthis represents intergradation orin-
larged)." Thus, at least some individuals dividual variation within the nominate form
seemed to be breeding in July, which is dur- cannot be determined.
ingthe driest part ofthe yearin the southern Specimens from the El Choro area, Prov.
Andes (Weske 1972, Fjeldsa & Krabbe Ayopaya, northern Dpto. Cochabamba, are
1990). anomalous in their variable crown color.
IfA. r. terborghi is like other subspecies Most show the nearly typical cinnamon-ru-
ofA. rufinucha, then it shouldbe a common, fous crown ofthe nominate subspecies, but
conspicuous species that favors forest edge several are paler to varying degrees. For ex-
rather than interior; and it should forage ample, some (e.g., LSUMZ 36861) are no-
actively, often in mixed-species flocks, from tably but not greatly paler, some are paler
near ground to the subcanopy while search- still (e.g.. Academy of Natural Sciences,
ing foliage of trees and shrubs, and epi- Philadelphia 134927; Field Museum of
phyte-covered as well as bare branches Natural History 217844), and two (ANSP
(Remsen 1985, Fjeldsa & Krabbe 1990). 134928, FMNH 217837) are very pale, al-
432 PROCEEDINGS OF THE BIOLOGIC.-VL SOCIETY OF WASHINGTON
most as pale as A. r. baroni ofthe Rio Ma- for males. -0.062 for females, P = 0.84,
rafion valley of Peru. 0.46. respectively).
Atlapetes rufimicha is one of many (but Interpretation of latitudinal gradients in
not all; see Graves 1991. Kratter 1993) An- body size is complex when the populations
dean bird species and superspecies that show are not in genetic contact (Graves 1991). as
geographic variation in body size that con- is the case in the four taxa ofA. rufimicha.
tradicts Bergmann's "Rule" (Remsen 1984: In two of the four taxa. sample sizes and
Remsen et al. 1991: R. Brumfield. pers. latitudinal ranges are large enough to ana-
comm; D. Wiedenfeld. pers. comm.). Over lyze trends withinataxon. In.4. r. rufimicha,
the limited latitudinal range ofthe southern both males and females show a "Bergman-
populations of A. rufi?mcha a non-Berg- nian" trend, but the relationship is not sta-
mannian pattern is evident. To illustrate tistically significant (Kendall's Tau correct-
geographic variation in size. I used wing ed for ties = —0.1 15 for males, —0.155 for
length as an index ofbody size. For 30 male females. P = 0.15. both sexes). In A. r. me-
A. rufimicha specimens \^ithbodymass data lanolaeinus, both males and females show
from Dpto. Puno. Peru, to Dpto. Santa Cruz, a "non-Bergmannian" trend, but the rela-
Bolivia, wing length is significantly corre- tionship is statistically significant only for
=
latedwith cube root ofbodymass (Kendall's females (Kendall's Tau corrected for ties
Tau corrected for ties = 0.27, P = 0.04), in 0.085 for males, 0.50 for females, P = 0.63,
spite ofthe large potential measurement er- 0.007, respectively).
rorassociatedwith bodymass causedby use
of different scales by different workers at
Zoogeography
different localities on birds that had often
been in mist nets for varying periods. How- Recent fieldworkinPerub>'the FieldMu-
ever, for 24 females from the same area, seum of Natural Histor\- has extended the
wing length is not significantly correlated distribution of-4. r. melanolaemus north in
with cube root ofbody mass (Kendall's Tau Dpto. Cuzco to 13°13'S. where John W.
corrected for ties = 0.07. P = 0.66). For Fitzpatrick and David Willard collected
males, wing length decreases significantly specimens at Pillahuata. 25 10 m. in the Rio
with increasing latitude (Kendall's Tau cor- Cosfiipata valley, near the northern limit of
rected for ties = 0. 14; P = 0.03; Fig. 1). For the Cordillera de Carabaya. This locality is
km
females, wing length also decreases \^dth in- about 75 north ofthe Marcapata region
creasing latitude, but the relationship is not of southeastern Dpto. Cuzco. the previous
statistically significant (Kendall's Tau cor- northern limit for.4. r. melanolaemus. Oth-
rected for ties = 0.14. P= 0.10; Fig. 1). For er areas of humid montane forest in Dpto.
both males and females, the relationship of Cuzco between the Cosfiipata valley andthe
wing length to latitude may not be linear: Cordillera Vilcabamba are inhabited by a
only increased sample sizes from southern different species, Atlapetes schistaceus.
Peru and northern Bolivia will determine Remsen & Graves (1994) found that A. ru-
whetherthe apparent trough at 14-15°S and fijiucha and^. schistaceus replace each oth-
consequent bimodal distribution is real or er throughout their extensive .Ajidean dis-
an artifact of low sample size. Elevation is tributions: they proposed that these two
not significantly correlated with wing length species were either close relatives and com-
in either sex (Kendall's Tau corrected for petitors or, conversely, that they were yel-
ties = 0.075 for males. 0.14 for females. P low and gray representatives of the same
= 0.21, 0.09. respectively) or with latitude lineage. In either case. A. r. terborghi and.4.
(Kendall's Tau corrected for ties = 0.013 r. melanolaemus are separated from each
VOLUME NUMBER
106, 3 433
80n
S. LATITUDE
Fig. 1. Relationship ofwing length and latitude (degrees S Lat.) for four subspecies ofAtlapetes rufinucha in
southern Peru and northern Bolivia. Latitudes, and elevations forlocalities notrecorded on the specimen labels,
were taken from Stephens & Traylor (1983) and Paynter (1992). Vertical dashed lines represent approximate
boundariesbetween foursubspecies ofregion. Diagonal linesrepresentregressionlinesofwinglength on latitude
for males (upper line; y = 82.1 + 0.72x, r- = 0.1 1) and females (lower line; y = 76.2 + 0.60x, r^ = 0.13); lines
presented only to illustrate general trends, not formal statistical analyses, because data are largely inappropriate
for parametric statistics.
Other by more than 200 km, and so ^. r. border, where L. C. Binford and T. S. Schu-
terborghi is yet another isolated population lenberg collected specimens in Dpto. Puno
of v4. rufinucha (Paynter 1978). The gap, at Valcon, 3000 m, 14°26'S, and Abra de
between the Urubamba-Concebidayoc val- Marucunca, 2000 m, 14°14'S. The southern
ley east to at least the Rio Vilcanota valley, limit oiA. r. melanolaemus is unknown but
is inhabited by A. schistaceus canigenis. is probably somewhere in northern Dpto.
Which taxon of Atlapetes, if any, inhabits La Paz, possibly the north side of the Rio
the region from there east to the Rio Yan- Mapiri canyon, another region virtually
atili valley and Rio Yavero valley, the unexplored by ornithologists.
northwestern limit of^. r. melanolaemus, Weske (1972) listed one locality record
is unknown. for Atlapetes tricolor in the Vilcabamba, at
Recent fieldwork in Peru by the Museum 2100 m, below the lower limit of^. r. ter-
of Natural Science, Louisiana State Uni- borghi. \fA. tricolor occurs at lower eleva-
versity, has extended the distribution of^. tions than A. rufinucha in the Vilcabamba,
r. melanolaemus south to near the Bolivian then this would represent a similar pattern
434 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
in elevational distribution to that in the Paynter, Jr., and DavidA. Wiedenfeld made
Western Andes of Colombia and Ecuador, many helpful comments on the manuscript.
where the two species replace each other at
m &
about 2000 (Remsen Graves 1994). In Literature Cited
central Peru, from central Dpto. Cuzco north
&
to Dpto. Huanuco, A. tricolor is replaced at Fjelda,dJe.s,. ZoNo.loKgriacbableM.us1e9u90m., UBniirvdesrosfittyheofhiCgohpAenn--
higher elevations by A. schistaceus. hagen, Denmark, 876 pp.
Additionalrecentfieldworkin Perubythe Graves, G. R. 1985. Elevational correlates ofspeci-
Museum ofNatural Science, Louisiana State ation and intraspecific geographic variation in
University, has extended the distribution of plumageofAndean forestbirds.—Auk 102:556-
579.
A. r. ruflnucha southeastward from its pre- . 1991. Bergmann's rule near the equator: lat-
vious southern limitin Prov. Chapare, Dpto. itudinal clines in body size ofan Andean pas-
Cochabamba, Bolivia, into Prov. Carrasco, serinebird.—ProceedingsoftheNationalAcad-
where C. Gregory Schmitt and Donna C. emy ofSciences 88:2322-2325.
Schmitt collected a specimen at Quebrada Haffer, J. 1974. Avian speciation in tropical South
Majon, 6.6 km northwest of Lopez Men- America.—Nuttall Ornithological Club Publi-
m cation no. 14, 390 pp.
doza, 3150 (17°32'S, 65°22'W). This Kratter, A. W. 1993. Geographic variation in the
specimen is indistinguishable from speci- Yellow-billed Cacique (Amblycercus holoseri-
mens from Prov. Chapare. ceus), a partial bamboo specialist.—Condor (in
A specimen (LSUMZ 38472) collected by press).
Paynter, R. A., Jr. 1978. Biology and evolution of
F. Steinbach at San Mateo, extreme eastern
the avian genusAtlapetes (Emberizinae).—Bul-
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the Dpto. Santa Cruz border, represents A. 148:323-369.
r. carrikeri, formerlyknown onlyfrom Dpto. . 1992. Ornithological gazetteer of Bolivia.
Santa Cruz. The specimen matches the type Second edition. Museum of Comparative Zo-
ANSP ology, Cambridge, Massachusetts, 185 pp.
specimen of^. r. carrikeri at (M. B. Remsen, J. V., Jr. 1981. A new subspecies ofSchi-
Robbins, in litt.). zoeaca harterti (Aves: Fumariidae), with com-
ments on the taxonomy of Schizoeaca.—Pro-
ceedingsoftheBiologicalSocietyofWashington
Acknowledgments
94:1068-1075.
I thank Frangios Vuilleumier and his cu- . 1984. Geographic variation, zoogeography,
and possible rapid evolution in some Crani-
ratorial staff(American Museum ofNatural oleuca spinetails.—Wilson Bulletin 96:515-523.
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.
new taxon. I am grateful to the staffs ofthe ofbirds of high elevation humid forest ofthe
Academy of Natural Sciences at Philadel- Bolivian Andes. Pp. 733-756 in P. A. Buckley
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