ORIGINAL ARTICLE / ARTÍCULO ORIGINAL
ECCENTRIC PREFORMATIVE MOLT IN A MUSEUM SPECIMEN OF THE BLUE-AND-YELLOW
TANAGER (PIPRAEIDEA BONARIENSIS DARWINII BONAPARTE, 1983) (AVES: THRAUPIDAE)
MUDA PREFORMATIVA EXCÉNTRICA EN UN ESPÉCIMEN DE COLECCIÓN DE LA TANGARA
AZUL Y AMARILLA (PIPRAEIDEA BONARIENSIS DARWINII BONAPARTE, 1983) (AVES:
THRAUPIDAE)
1Estación Biológica Río Santa Eulalia, Centro de Ornitología y Biodiversidad (CORBIDI),
Calle Sta. Rita 105 Ocina 202, Urb. Huertos de San Antonio, Surco, Lima, Perú
2Department of Biology, University of Miami, Coral Gables, FL 33146, USA
3Department of Biological Sciences, University of Texas El Paso, El Paso, TX 79968, USA
*Corresponding author: alexis.diaz@corbidi.org
ABSTRACT
We document a unusual variation in the extent of preformative molt across 20 formative-plumaged Blue-
and-yellow Tanager (Pipraeidea bonariensis darwinii Bonaparte, 1838) museum specimens from Peru.
Our finding represents the first evidence of eccentric replacement of primaries and primary coverts during
the preformative molt for this species.
ISSN Versión Impresa 1816-0719
ISSN Versión en linea 1994-9073 ISSN Versión CD ROM 1994-9081
273
Keywords: eccentric – museum specimen – preformative – Peru – Pipraeidea bonariensis darwinii
The Biologist (Lima)
The Biologist
(Lima)
The Biologist (Lima), 201 , 1 (2), jul-dic: 8 6 273-279
1,2* 1,3
Alexis Díaz & Flor Hernández
RESUMEN
Documentamos una variacion inusual en la extension de la muda preformativa en un espécimen de
colección entre un total de 20 especímenes en plumaje formativo de la Tangara Azul y Amarilla
(Pipraeidea bonariensis darwinii Bonaparte, 1838) colectados en Perú. Esto representa la primera
evidencia de reemplazo excéntrico de primarias y cobertoras primarias durante la muda preformativa para
esta especie.
Palabras clave: excéntrico – espécimen de museo – preformativa – Peru – Pipraeidea bonariensis darwinii
274
The partial to incomplete nature of the extent of the
preformative molt in most Neotropical resident
landbird species can be used to facilitate an
accurate and rapid technique for ageing birds in the
hand (Pyle, 1997b; Pyle et al., 2004; Hernández,
2012). To date, the preformative molt of species in
the family Thraupidae in the Neotropics has been
documented as partial, incomplete or complete
(Ryder & Wolfe, 2009; Gómez et al., 2012;
Hernández, 2012; Pyle et al., 2015; Johnson &
Wolfe, 2018; Díaz et al., 2018) with possible
variations among these molt extents within the
same genera and even individuals of the same
species (Ryder & Wolfe, 2009; Johnson & Wolfe,
2018). Evidence of eccentric flight feather
replacement during the preformative have been
documented in 20 species among 13 genera within
the family (e.g. Chlorophanes, Sicalis, Phrygilus,
Diglossa, Volatinia, Eucometis, Ramphocelus,
Cyanerpes, Sporophila, Saltator, Tiaris, Diuca,
and Tangara) (Pyle et al., 2004; Ryder & Wolfe,
2009; Wolfe et al., 2009; Gómez et al., 2012; Pyle
et al., 2015; Johnson & Wolfe, 2018, Díaz et al.,
2018); but has not yet been reported for the Blue-
and-yellow Tanager (Díaz et al., 2018). To survey
how regular incomplete molts (sensu Pyle, 1997b)
might be in the Blue-and-yellow Tanager
(Pipraeidea bonariensis darwinii Bonaparte,
1838), we examined specimens collected in Peru
from several national and international
ornithological museums.
Bird specimens of the Blue-and-yellow Tanager
from Peru were examined at the “John O'Neill”
Ornithological Collection at the Centro de
Ornitología y Biodiversidad (CORBIDI), Museo
de Historia Natural Javier Prado (MHNJP), Museo
de Historia Natural de la Universidad Nacional de
San Agustín de Arequipa (MUSA), Florida
Museum of Natural History (FLMNH), and the
Louisiana State University Museum of Natural
Science (LSUMNS). Plumage terminology is
based on Howell et al. (2003), and feather-tract
terminology and abbreviations follow those of Pyle
(1997b). Wing coverts and flight feathers of each
specimen were carefully examined in both wings in
order to avoid cases of adventitious replacement
(Mulvihill, 1993; Pyle, 1997a; Burton, 2002;
Wolfe & Frey, 2011). Moreover, since no
individuals with unossified skulls were found
undergoing the typical molt sequence (sensu Ginn
& Melville, 1983) or having a definitive-basic
plumage aspect, we discarded the presence of
complete preformative molts among examined
specimens and focus our attention on individuals
possesing formative plumages as consequence of
partial or incomplete molts. Age determination was
based on the molt cycle-based aging system
proposed by Wolfe et al. (2010) and refined by
Johnson et al. (2011). Data of skull ossification
gathered from specimen labels were also used to
confirm age (Díaz et al., 2018), and sex of birds
were established from museum labels and plumage
differences. Ethical approval: The conducted
research is not related with live animals use.
From a total of 178 examined Blue-and-yellow
Tanagers, we focused on 20 formative-plumaged
specimens (Table 1). These specimens were
collected in Cajamarca, Cuzco Junin, La Libertad
and Lima, between March to December since 1941
until 2012 (Table 2). Eighteen specimens exhibited
INTRODUCTION
MATERIAL AND METHODS
RESULTS
Museum
CORBIDIa
MHNJPb MUSAc LSUMNSd FLMNHe
Sample Size
12
85
49 33 1
a b c
Centro de Ornitología y Biodiversidad. Museo de Historia Natural Javier Prado. Museo de Historia Natural de la Universidad
d e
Nacional de San Agustín de Arequipa. Florida Museum of Natural History. Louisiana State University Museum of Natural Science .
Table 1. Sample size of museum specimens of the Blue-and-yellow Tanager (Pipraeidea bonariensis darwinii)
collected in Peru and deposited in ve ornithological collections.
Díaz & Hernández
The Biologist (Lima). Vol. 16, Nº2, jul - dic 2018
275
a formative plumage as consequence of a partial
replacement, and only one specimen (MUSM
4066) showed evidenced of a more extensive molt
pattern. This last specimen showed a simetrically
wing molt replacement that involved all secondary
coverts (lesser, median and greater), carpal and
alula coverts, lesser and greater alula, tertials (s7-
9), and all rectrices. In addition, the specimen had
replaced p9, s6 and two outer primary coverts.
These replaced formative flight feathers contrasted
with their retained juvenal ones, by being more
lustrous, less worn, and evidencing a bluish
coloration at the leading edge of each feather
(Figure 1).
Table 2. List of Blue-and-yellow Tanager (Pipraeidea bonariensis darwinii) museum specimens in formative
plumage. Date, location, sex, and specimen number associated with each specimen is provided.
Specimen Numbera
Month
Year
Department
District
Altitude
Sex
MUSM 7190
November
1941
Junín
Huasahuasi
800
Male
MUSM 7193
December
1942
Junín
Palca
2700
Female
MUSM 7198
December
1953
Lima
San Bartolomé
2850
Unknown
MUSM 7201
October
1955
Lima
San Batolomé
2840
Female
MUSM 4066
October
1964
Lima
Chosica
700
Male
LSUMNS 34729
November
1964
Lima
San Bartolome
3050
Male
LSUMNS 93344
August
1971
La Libertad
Cochorco
1050
Male
LSUMNS 80859
August
1975
Cajamarca
Balsas
2011
Male
LSUMNS 85536
September
1977
Cajamarca
Cutervo
2545
Female
MUSM 7328
March
1980
Lima
San Bartolomé
2850
Female
MUSM 7324
April
1980
Lima
San Bartolomé
2850
Female
LSUMNS 127917
October
1984
Junin
Santo Domingo de Acobamba
3300
Male
MUSA 1222
December
2003
Arequipa
Yarabamba
2650
Female
MUSA 1260
October
2004
Arequipa
Quequeña
2600
Unknown
CORBIDI AV 011705
December
2006
Cuzco
Urubamba
3380
Male
CORBIDI AV 001426
September
2008
Junín
Satipo
3350
Male
CORBIDI AV 003040
November
2009
Cuzco
Marcapata
2240
Male
LSUMNS 190403
July
2010
La Libertad
Cospan
2700
Male
MUSA 4635
April
2011
Apurímac
Chalhuanca
3263
Female
MUSA 4513
March
2012
Junín
Chanchamayo
3284
Unknown
aLabel Codes: Centro de Ornitología y Biodiversidad = CORBIDI AV, Museo de Historia Natural Javier Prado = MUSM, Museo de Historia
Natural de la Universidad Nacional de San Agustín de Arequipa = MUSA, and the Louisiana State University Museum of Natural Science=
LSUMNS.
Eccentric preformative molt in Pipraeidea bonariensis darwinii
The Biologist (Lima). Vol. 16, Nº2, jul - dic 2018
276
F
F
Figure 1. Museum specimen of the Blue-and-yellow Tanager (Pipraeidea bonariensis), collected at Chosica, dpto. Lima, Peru,
October 1964 (MUSM 4066), showing formative (“F”) outer primary (p9), inner secondaries (s6-s9) and two outer primary
coverts as evidence of an eccentric incomplete molt (Photo: Alexis Díaz).
Díaz et al. (2018) described the preformative molt
in Blue-and-yellow Tanagers as partial in a tropical
montane desert scrub intermixed with a mosaic of
agroscapes (MINAM, 2012) in the highlands of
Lima, Peru. Specifically, they reported the
replacement of the body feathers (including all
lesser and median coverts, and at least one to all
greater coverts), and a variable number of tertials
and rectrices, but not flight feathers (as
secondaries, primaries, or primary coverts). Our
closer examination of museum specimens
corroborated these findings in relation to the extent
and timing of molt (Table 3). However, we report
evidence of an unusual eccentric (i.e., incomplete)
molt pattern in a formative-plumaged bird
specimen of this species. So far, we are aware of
incomplete eccentric preformative molts reported
in some species of thraupids (Pyle et al., 2004;
Ryder & Wolfe, 2009; Wolfe et al., 2009; Gómez et
al., 2012; Pyle et al., 2015; Johnson & Wolfe, 2018;
Díaz et al., 2018); hence, it should not be
unexpected to find eccentric molt limits in other
species within this extensive family (Johnson,
2013). In addition, records of primary covert
replacement during preformative molts has also
been evidenced in other neotropical passerine taxa,
as Elaenia parvirostris von Pelzeln 1868,
DISCUSSION
The Biologist (Lima). Vol. 16, Nº2, jul - dic 2018
Díaz & Hernández
277
Tyrannus melancholicus melancholicus Vieillot
1819, and some others species which records
remain unpublished (Johnson & Wolfe, 2018).
Because of our unique formative-plumage bird
specimen exhibiting this unusual feather
replacement pattern, it is difficult to hypothesize
why this variation exists. Moreover, we cannot
eliminate the possibility of this molt pattern being
prevalent for other subspecies. Previous studies
reporting more extensive molt patterns for other
taxa suggest possible associations with age-sex
groups (Pyle, 1997a, 1997b, 1998; Guallar et al.,
2016; Díaz et al., 2018), fledge date (Elrod et al.,
2011; Crates et al., 2015), latitude and migration
(Pyle, 1997a, 1997b; Howell, 2010; Johnson,
2013; Morganti et al., 2013), and occupancy of
open habitats and high levels of solar exposure for
long-distance migrants (Pyle, 2008; Pyle &
Kayhart, 2010). Molt patterns are among the most
important tools used by bird banders to determinate
the age of birds (Pyle 1997a, 1997b).
Consequently, it is essential to continue to carefully
document unusual molt patterns in any living bird
or museum specimens to ensure that species are
correctly identified in future work.
Table 3. Variation in the extent of the preformative molt by feather tract among 20 formative-plumaged Blue-and-
yellow Tanager (Pipraeidea bonariensis darwinii) specimens collected in Peru and deposited in different
ornithological collections. Carpal covert and alula tracts were not included in our analysis since they were difcult to
examine for most specimens (Johnson et al., 2013).
aGreater
coverts aSecondaries aRectrices aPrimaries aPrimary
coverts
aNumber of
individuals
none none none none none 2
none none r1 (R) (asymmetrical) none none 1
2 none r1-6 none none 1
2 s9 none none none 1
3 none none none none 2
3 none r1 none none 1
3 none r1-6 none none 1
4 none none none none 1
4 none r1-4 none none 1
4 none r1-6 none none 1
4 s8-9 r3-4 none none 1
5 none r2-6 none none 1
5 s8-s9 none none none 1
6 s9 none none none 1
6 s9 r1 none none 1
8 s8-9 none none none 1
8 s7-9 none none none 1
all s6-9 all p9 2 outermost 1
aData shows symmetrical replacements across the different tracts unless it expresses another replacement mode.
Cardiff for the permission and access to specimens
housed at Centro de Ornitología y Biodiversidad,
Museo de Historia Natural Javier Prado, Museo de
Historia Natural de la Universidad Nacional de San
Agustín de Arequipa, Florida Museum of Natural
History, and Louisiana State University Museum
Special thanks to Thomas Valqui, Letty Salinas,
Mauricio Ugarte, Andrew Kratter, Thomas
Webber, Van Remsen, Robb Brumfield, and Steven
ACKNOWLEDGMENTS
Eccentric preformative molt in Pipraeidea bonariensis darwinii
The Biologist (Lima). Vol. 16, Nº2, jul - dic 2018
278
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Received March 28, 2018.
Accepted May 20, 2018.
Eccentric preformative molt in Pipraeidea bonariensis darwinii
The Biologist (Lima). Vol. 16, Nº2, jul - dic 2018
