Range Expansion and Breeding of White-Cheeked Pintail (Anas bahamensis) in the High Andes

Abstract

We review the distribution of White-cheeked Pintail (Anas bahamensis rubrirostris) in mainland Ecuador and show that the species has expanded its range significantly. Contrary to published records, A. b. rubrirostris has been present in mainland Ecuador at least since the early 20th century, although probably in low numbers. During the 20th century, the species increased its range along the entire coastlands of Ecuador and has reached the coasts of Colombia. The species has also extended its presence along the Andes, and we report the first breeding records of A. b. rubrirostris in the Andes at altitudes between 23602440 m, the highest across the entire range of the species. Additionally, we describe the transitioning plumage between ducklings and juveniles, which has not been portrayed in detail before.

Full text

Range Expansion and Breeding of White-Cheeked Pintail
(Anas bahamensis) in the High Andes
Authors: Cisneros-Heredia, Diego F., Izurieta, Mirjaya, Peñaherrera,
Emilia, and Musschenga, Maartje
Source: Waterbirds, 45(2) : 218-224
Published By: The Waterbird Society
URL: https://doi.org/10.1675/063.045.0213
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218
Range Expansion and Breeding of White-cheeked Pintail
(Anas bahamensis) in the High Andes
Diego F. Cisneros-HereDia1,2,3,4*, Mirjaya izurieta1, eMilia PeñaHerrera,1,2
anD Maartje MussCHenga4,5
1Universidad San Francisco de Quito USFQ, Colegio de Ciencias Biológicas y Ambientales, Quito 170901, Ecuador
2Universidad San Francisco de Quito USFQ, Instituto de Biodiversidad Tropical iBIOTROP, Museo de Zoología &
Laboratorio de Zoología Terrestre, Quito, Ecuador
3Instituto Nacional de Biodiversidad INABIO, Quito, Ecuador
4Colectivo ciudadano AvesQuito, Quito, Ecuador
5Universidad Central de Ecuador, Facultad de Filosofía, Carrera de Pedagogía de las Ciencias Experimentales
Química y Biología, Quito, Ecuador
*Corresponding author; E-mail: diego.cisnerosheredia@gmail.com
Abstract.—We review the distribution of White-cheeked Pintail (Anas bahamensis rubrirostris) in mainland Ecua-
dor and show that the species has expanded its range significantly. Contrary to published records, A. b. rubrirostris
has been present in mainland Ecuador at least since the early 20th century, although probably in low numbers. Dur-
ing the 20th century, the species increased its range along the entire coastlands of Ecuador and has reached the
coasts of Colombia. The species has also extended its presence along the Andes, and we report the first breeding
records of A. b. rubrirostris in the Andes at altitudes between 2360–2440 m, the highest across the entire range of the
species. Additionally, we describe the transitioning plumage between ducklings and juveniles, which has not been
portrayed in detail before. Received 27 Nov 2021, accepted 18 Jul 2022.
Key words.—Anatidae, Anseriformes, distribution, Ecuador, nesting, plumage, urban water reservoirs.
Waterbirds 45(2): 218-224, 2022
The White-cheeked Pintail (Anas baha-
mensis) is widespread but spottily distributed
across the Caribbean and South America,
where it mainly inhabits brackish waters,
mangrove swamps, tidal creeks, estuaries,
coastal lagoons, and inland freshwater wet-
lands, including reservoirs and sewage ponds
(Kear 2005; Erize et al. 2006; Johnsgard 2010;
Carboneras and Kirwan 2020). Until the 20th
century, highland regular records of this spe-
cies were only known at Lake Alalay, Bolivia
(2550 m), and accidental reports at 3700 m at
Lake Poopó, Bolivia, and at 4080 m in Junín,
Peru (Bond and Meyer de Schauensee 1943;
Fjeldså 1985; Fjeldså and Krabbe 1990). Since
the late 20th century, the species has started
to disperse into the Andean highlands of
Colombia, Ecuador, and Peru (Schulenberg
et al. 2007; Freile et al. 2013; Astudillo et al.
2015; Freile et al. 2019a; Rodrıguez-Villamil
and Álvarez-Moya 2020).
Three subspecies of Anas bahamensis are
currently recognized: A. b. bahamensis, inhab-
iting the Caribbean and northern Atlantic
coasts of South America, south to Brazil; A. b.
galapagensis, endemic to the Galapagos Archi-
pelago; and A. b. rubrirostris, from the Pacific
coasts and Southern Cone of South America
(Kear 2005; Johnsgard 2010; Carboneras
and Kirwan 2020). Most information on the
breeding biology of A. bahamensis is based on
data from A. b. bahamensis (Sorenson 1992;
Sorenson et al. 1992; Kear 2005; Johnsgard
2010; Davis et al. 2017). Accounts about the
southern A. b. rubrirostris report that nest-
ing occurs from April–September along the
coasts of Ecuador (Marchant 1958, 1960;
RSOLAB7 2020), October–November in Ar-
gentina (Kear 2005), and November–Febru-
ary in Chile (Saratscheff et al. 1991; Tala and
Gabella 1991; Vilina 1995; Rubio 1998).
Knowledge on the distribution and
breeding of many Ecuadorian waterbird spe-
cies is scarce, and breeding data has usually
been inferred from studies from other areas.
Here, we review the distribution range of
Anas bahamensis rubrirostris in Ecuador, re-
port the first breeding records in the high
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AnAs BAhAmensis in tHe HigH anDes 219
Andes of South America, and describe the
transitioning plumage between duckling
and juveniles.
MetHoDs
We made field observations during citizen science
activities run by AvesQuito, a citizen collective that pro-
motes bird watching, and urban bird ecology studies
and research projects of Universidad San Francisco de
Quito USFQ. We have periodically birdwatched since
2010 at the Cumbayá Reservoir, Quito Metropolitan
District, province of Pichincha, Ecuador (0° 11ʹ 41ʺ S,
78° 25ʹ 45ʺ W, 2360 m) and since 2014 at the Guango-
polo Reservoir, Quito Metropolitan District, province of
Pichincha, Ecuador (0° 16ʹ 09ʺ S, 78° 27ʹ 13ʺ, 2440 m),
especially for Quito’s Christmas Bird Count (Cisneros-
Heredia et al. 2015). Intensive bird censuses were car-
ried out every two weeks between April and September
2015 at the Cumbayá Reservoir and between 2019 and
2020 at the Guangopolo Reservoir. Cumbayá and Guan-
gopolo are about 9 km apart in straight-line and have
similar climatic patterns, with two annual well-marked
wet seasons (March to May and October to December),
but precipitation is higher in the south at Guangopolo
(ca. 1360 mm/year) and lower in the north at Cumbayá
(ca. 1160 mm/year) (López and Echeverría 2013; Ca-
zorla 2021; Manciati et al. 2021).
We obtained occurrence data from mainland Ec-
uador from different sources. Published records were
synthesized based on a literature review, not limited
by study type, study design, or language, conducted
in Google Scholar™ scholarly text search (https://
scholar.google.com) by online searches. We gathered
relevant references using the search term ‘Anas baha-
mensis’. Open metadata for all occurrences from main-
land Ecuador were downloaded from eBird (https://
ebird.org) by Cornell Lab of Ornithology (eBird 2020)
and iNaturalist (https://www.inaturalist.org) by Cali-
fornia Academy of Science and National Geographic
through datasets available in the Global Biodiversity
Information Facility (GBIF 2021). Data search and ex-
traction from all sources were conducted in March 2020
and updated in April 2021. For each occurrence point,
we compiled geographic data and all other associated
information. Protocol for data curation and mining in-
cluded validation of localities and duplicate detection.
All localities were reviewed and validated individually,
and coordinates were amended when incorrectly geo-
referenced in the source. Geographic records of A. b.
rubrirostris from mainland Ecuador used for this paper
are available in Figshare: http://doi.org710.6084/
m9.figshare.14776242
results
Marchant (1958, 1960) recorded several
A. b. rubrirostris between 1954–1957 in the
Santa Elena Peninsula, southwestern Ecua-
dor, the first published record in the coun-
try (Ridgely and Greenfield 2001). However,
an adult male A. b. rubrirostris collected at
the Santa Elena Peninsula on 22 December
1933 (by Philip Hershkovitz and deposited
at the bird collection of Museum of Zoology,
University of Michigan; UMMZ 91899, GBIF
2021) provides evidence that the species has
been present on the coast of Ecuador at least
since the early 20th century—though prob-
ably rare based on the lack of specimens col-
lected by expeditions visiting the area dur-
ing the late 19th century (Chapman 1926).
During the 20th century, A. b. rubrirostris
increased its range along the Pacific coast-
lands of Ecuador, becoming locally common
below 50 m and evaluated as a non-threat-
ened subspecies in the country (Ridgely
and Greenfield 2001; Santander et al. 2013;
Freile and Restall 2018; Freile et al. 2019b;
eBird 2020; GBIF 2021). There are few in-
land records on the western lowlands of Ec-
uador, mainly on the floodplains and rice
paddies between Quevedo and Guayaquil
(Fig 1) (eBird 2020; GBIF 2021). Ridgely
and Greenfield (2001) reported the north-
ernmost Ecuadorian locality of the species in
Atacames, province of Esmeraldas, where it
has been observed since the 1990s. Solano-
Ugalde et al. (2009) evidenced that the spe-
cies kept advancing north, observing it just
40 km S from the Colombian border (Fig.
1). Anas b. rubrirostris was unknown from the
Pacific coasts of Colombia until 2013, when
Calderón et al. (2013) reported it from the
Mar Agrícola farm, in the department of
Nariño, ca. 27 km from the Ecuadorian bor-
der. Subsequently, there are records of the
species up to Buenaventura, department
of Valle del Cauca, Colombia, since 2015
(eBird 2020).
The first high altitude reports of A. b. ru-
brirostris in Ecuador was at La Mica Lagoon
(3900 m) in 2002 (Lock et al. 2003), where it
was recorded again in 2005 and 2006 (eBird
2020, GBIF 2021). Subsequently, it has been
recorded at several highland wetlands, in-
cluding (only first record cited, details of all
records in the Andes of Ecuador are avail-
able in Figshare): Cumbaya reservoir (2360
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220 WaterbirDs 45(2) – june 2022
m elevation) in 2009 (Freile et al. 2013);
Llaviucu lagoon, Cajas National Park (3160
m) in 2009 (Astudillo et al. 2015); El Para-
iso park (2490 m) in 2009 and Ucubamba
reservoir (2415 m) in 2012 (Astudillo Web-
ster and Siddons 2013); Quito Airport pond
(2350 m) in 2015 (Boyla and Sanchez 2015);
Guangopolo reservoir (2440m) in 2017
(Bedoya 2017); Colta lagoon (3310) in 2017
(Morocho 2017); El Salado lagoon (2780 m)
in 2017 and Yaguarcocha lagoon (2200 m)
in 2018 (Loaiza Bosmediano 2017; Freile
et al. 2019a), Jipiro park (2030 m) in 2018
(Hefty 2018), and Yambo lagoon (2600 m)
in 2020 (Fattorelli 2020). Records of A. b.
rubrirostris across the Andean highlands of
Ecuador are becoming more recurrent. The
species is present year-round in low numbers
at the Cumbaya, Guangopolo and Ucubam-
ba reservoirs and the artificial ponds of El
Paraíso Park and Museo Pumapungo (pers.
obs.; eBird 2020; GBIF 2021).
On 26 June 2015, a female A. b. rubrirostris
was observed with eight ducklings swimming
in the southern pool of the Cumbaya reser-
voir (Fig. 2). Ducklings were still covered
by down but transitioning to juvenile plum-
age: face grayish-cream, superciliary band
grayish-cream and faint, dark line from eye
to nape diffuse, foreneck dark gray, cheeks
whitish, lines on sides of back whitish and
soft, ventral surfaces whitish with faint lat-
eral stripes, bill bluish gray with light pink
wash at the base, eyes brown (Fig. 2). Ten A.
b. rubrirostris were either preening or swim-
ming between the northern and southern
pools until 06 August 2015. All birds had
adult size, but plumage was not as bright
in eight of them, suggesting they were juve-
niles, thus probably corresponding to the fe-
male and her offspring. During mid-August,
the northern pools were cleaned for sedi-
ment removal, and no juveniles were seen
subsequently, but three adults were observed
regularly.
Between 13–16 November 2019, a fe-
male A. b. rubrirostris with two ducklings was
Figure 1. Map of Ecuador showing the distribution
range of White-cheeked Pintail Anas bahamensis rubriros-
tris. White dots: Records until the late 1990s. Black dots:
Records since the early 2000’s, showing the range ex-
pansion towards the northern coast, inland western low-
lands, and Andean highlands. Yellow dots: New highest
breeding records.
Figure 2. Adult female and eight ducklings of White-
cheeked Pintail Anas bahamensis rubrirostris at the Cum-
baya reservoir, Quito Metropolitan District, province of
Pichincha, Ecuador, on 26 June 2015.
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AnAs BAhAmensis in tHe HigH anDes 221
observed swimming in a narrow channel,
part of the Guangopolo reservoir. On 17
November 2019, two adults were sitting on
the channel wall, but there was no trace of
the ducklings, and they were not seen sub-
sequently. On 15 July 2020, an adult female
with eight ducklings covered by down were
swimming in the same channel of the Guan-
gopolo reservoir as in November 2019 (Fig.
3). Duckling plumage is overall the same as
described in the literature (Kear 2005; John-
sgard 2010; Carboneras and Kirwan 2020).
However, lines on the back were yellow, not
whitish, especially in the younger ducklings,
and there was a brown spot under the eye
line, also more visible in the younger duck-
lings. By 30 July 2020, ducklings were tran-
sitioning to juvenile plumage, but the face,
cheeks and neck were still yellow, although
drabber than in ducklings (Fig. 3). On 04
August 2020, the reservoir was cleaned for
sediment removal, and the ducklings were
not seen anywhere. On 23 August 2020, the
reservoir’s water level was average again,
and nine A. b. rubrirostris were observed. All
ducks had adult size, but bill and plumage
were not as bright as in adults suggesting
they were juveniles. Their head was smaller
and less round, head plumage looked a bit
fluffy or downy, and the base of the bill was
narrow and ended wider, whereas, in adults,
the width of the bill seemed more constant.
On 04 September 2020, two juveniles (bill
and plumage less bright than adult) were
swimming next to each other in the chan-
nel. In October 2020, two or three adults
and up to five juveniles were in the reservoir
(Fig. 3). Subsequently, 8–15 A. b. rubrirostris
were regular at the Guangopolo reservoir
until December 2020, suggesting that the ju-
veniles stayed.
DisCussion
An extensive revision of the distribution
of A. b. rubrirostris in mainland Ecuador
shows that the species has been present in
mainland Ecuador at least since the early
20th century, although probably in low num-
bers, and has increased its range significant-
ly in the last decades. Further data is needed
to understand the causes behind this recent
range expansion that could be related with
multiple factors including increase of hu-
man-made wetlands, decrease of hunting ac-
tivities due to conservation actions and law
Figure 3. Adult female and eight ducklings of White-
cheeked Pintail Anas bahamensis rubrirostris at the Guan-
gopolo reservoir, Quito Metropolitan District, province
of Pichincha, Ecuador, 15 July 2020 (upper) and 30 July
2020 (lower)
Figure 4. Juvenile of White-cheeked Pintail Anas baha-
mensis rubrirostris at the Guangopolo reservoir, Quito
Metropolitan District, province of Pichincha, Ecuador,
01 October 2020.
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222 WaterbirDs 45(2) – june 2022
enforcement, and local and global climate
changes. Interestingly, A. bahamensis was the
most abundant fossil duck at La Carolina, a
late Pleistocene site in the Santa Elena Pen-
insula, south-western Ecuador (Campbell,
1976), suggesting that the species’ abun-
dance has fluctuated in the region over the
last millennia, most probably due to climate
and environmental changes (Grootes et al.
2001; Scott et al. 2002).
We present the highest breeding records
of A. bahamensis across its distribution and
evidence that the species may be starting to
establish self-sustaining populations in the
Andean highlands. Reproductive biology was
within the reported ranges for brood size,
parental care, and fledging time (Kear 2005;
Carboneras and Kirwan 2020). Breeding
seasonality in the Andes of Ecuador mostly
coincides with that reported along the coast-
lands (April-September), although we also
recorded a breeding event in November.
All breeding records or long-standing pop-
ulations in the Andes are in human-made
wetlands, probably due to lower impacts by
human disturbances, lower predation by
domestic and feral dogs and cats (since ac-
cess to all reservoirs and artificial ponds is
controlled), and relatively constant water
levels. To the best of our knowledge, we pres-
ent the first description of the transitioning
plumage between duckling–juveniles for A.
b. rubrirostris (Kear 2005; Johnsgard 2010;
Carboneras and Kirwan 2020). Information
on plumage transitions is important to en-
sure proper identification and improve our
knowledge on the species’ biology (Carney
1992, Hawkins 2011).
aCknoWleDgeMents
We would like to thank Empresa Eléctrica Quito
EEQ for the permission to access Cumbaya and Guan-
gopolo reservoirs; all members and citizen scientists of
AvesQuito for their enthusiastic and constant support;
Universidad San Francisco de Quito USFQ, Instituto
iBIOTROP, Museo de Zoología and Laboratorio de
Zoología Terrestre for logistical and financial support;
and two anonymous reviewers for their comments on
the manuscript. This paper was possible thanks to the
contribution of a wealth of naturalists continuously
contributing to eBird and iNaturalist; to scientific col-
lections publishing their curated catalogues in GBIF,
and to the Biodiversity Heritage Library for making
important literature freely available. This work was sup-
ported by Universidad San Francisco de Quito USFQ
through research projects (HUBI ID 33 “Diversidad,
historia natural, biogeografía y conservación de las aves
del Ecuador”, 35 “Estudio de la biodiversidad en áreas
urbanas y rurales”, 1057 “Impact of habitat changes
on the biological diversity of the northern tropical An-
des”, 5452 “Estrés en aves en matrices urbano-rurales
en los Andes tropicales”); outreach projects (HUBI ID
278, 292, 483, 607 “Celebrando la Naturaleza: Ciencia
ciudadana y educación Ambiental para valorar la bio-
diversidad”), and operative funds assigned to Instituto
iBIOTROP, Museo de Zoología and Laboratorio de Zo-
ología Terrestre.
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