The Wilson Journal of Ornithology 123(2):251-258, 2011 
BIPARENTAL CARE AND NESTING SUCCESS OF THE SWALLOW¬ 
TAILED COTINGA IN NORTHWESTERN BOLIVIA 
VERONICA DEL ROSARIO AVALOS 12 
ABSTRACT.—I studied the breeding biology, parental care, and nesting success of the Bolivian Swallow-tailed Cotinga 
{Phihalura flavirostris boliviano) in Aten, northwestern Bolivia, from October 2005 to February 2006. The incubation 
period ranged from 17 to 19 days and the nestling period was 25 to 30 days. Swallow-tailed Cotingas appeared to be 
monogamous during the entire nesting stage, from nest construction to fledging of nestlings, based on 10 nests with focal 
observations. Each parent took care of the nest every hour during the incubation period, but males spent more time at this 
activity than females. Both parents spent equal time taking care of the young during the nestling period. Nest care decreased 
as nestlings developed, the provisioning rate of parents increased, and length of foraging trips increased. The probability of 
daily survival between the nestling (0.9773) and incubation periods (0.9455) was not statistically significant; overall nesting 
success was low (20%). This work is the first detailed report of the nesting of this species in Bolivia. Received 5 November 
2009. Accepted 6 November 2010. 
Breeding biology has been a principal concern 
in ecological studies of birds because this 
information is important to understanding life 
histories, including social and reproductive sys¬ 
tems. population dynamics, and biological con¬ 
servation (Stutchbury and Morton 2001. Green 
2004). Among mating systems, monogamy is 
most common in birds, even in the tropics (Gill 
1995. Stutchbury and Morton 2001). In this 
system, birds form a prolonged and essentially 
exclusive pair bond for purposes of raising young 
(Gill 1995, Cockbum 2006). Both parents con¬ 
struct the nest, incubate the eggs, and feed the 
nestlings. The extent of parental participation in 
each activity varies by species and length of the 
nesting period, which reflects growth of nestlings 
(Gill 1995). 
hi contrast, lek displays of polygynous birds are 
more characteristic of cotingas. Females visit 
males only for purposes of fertilization and care 
for their young by themselves (Snow 2004). For 
*ome cotingas, such as fruiteaters (Pipreola spp.). 
purpleiufts ( lodepleura spp.), and the Black-faced 
(otinga ( Conioptilon mcilhennyi), monogamy and 
biparental care prevail (Snow 2004). However, 
few quantitative studies of parental care by 
cotingas exist (but see Amaya-Espinel 1997, 
Karubian et al. 2003). Nesting success of most 
c °tingas is unknown because their nests are 
Cr yptic and difficult to locate and observe (Snow 
Carrera de Biologi'a, Universidad Mayor de San Andrds, 
^Paz, Bolivia. 
Currrent address: Colcccidn Boliviana de Fauna. 
Insiituto de Ecologia. Campus Universitario: Calle 27 
*-°ta-Cota, La Paz. Casilla de Correo Central 100777, La 
Paz - Bolivia; e-mail: veronikavalos@gmail.com 
2004). Studies have shown that nesting success of 
the Guianan Cock-of-the-rock (Rupicnla rupicola) 
and Bearded Bellbird ( Procnias averano) are low 
because of unfavorable climatic factors and 
predation (Snow 2004). It is also low for the 
Andean Cock-of-the-rock (/?. peruvianas) because 
of habitat modification and human activities 
(Sarria-Salas 2005). Nesting success is reportedly 
low in neotropical birds in general (Skutch 1985, 
Martin 1996), but more research is needed. 
The near-threatened (1UCN 2008) Swallow¬ 
tailed Cotinga ( Phihalura flavirostris) is also a 
poorly known species, and observations of its 
nesting behavior are limited (Snow 2004) despite 
nesting in open areas. The nests and eggs of 
Phihalura f flavirostris (Fraga and Narosky 1985) 
and Phihalura f. boliviana (Bromfield et al, 2004) 
have been described, but little is known about 
incubation of this species. Both males and females 
appear to care for nestlings although quantitative 
information on parental care is lacking (Snow 
1982, Ridgely and Tudor 1994. Snow 2004). Only 
a single population of Phihalura f boliviano is 
known from Bolivia, and it may be specifically 
distinct from the Brazilian populations. Informa¬ 
tion on the breeding biology of Lhis species could 
contribute to its conservation and to our ability to 
manage it. I present basic data on incubation and 
nestling care of the Bolivian Swallow-tailed 
Cotinga ( Phihalura f boliviana). I also report 
parental investment in both activities, and nesting 
success. 
METHODS 
Study Area. —I conducted this study in the 
locality of Aten (68 : 19' W, 14° 55' S; 1,400- 
251 
