The Wilson Journal of Ornithology 124(3):538-546, 2012 
BREEDING BIOLOGY OF THE RED-BELLIED GRACKLE 
(.HYPOPYRRHUS PYROHYPOGASTER ): A COOPERATIVE BREEDER OF 
THE COLOMBIAN ANDES 
DAVID OCAMPO. 1 M. CAMILA ESTRADA-F,' JENNY M. MUNOZ. 1 LAURA V. LONDONO. 1 
SANTIAGO DAVID. 1 GIOVANNY VALENCIA,' PAULA A. MORALES, 1 
JAIME A. GARIZABAL.' AND ANDRES M. CUERVO 2,3 
ABSTRACT.—We document the breeding behav ior of the Red-bellied Crackle i Hypopyrrhus pyrohypogasler. Icterid-ie 
from monitoring seven breeding groups during 4 consecutive years (2006-2009) in the central cordillera of the Colomfwn 
Andes. All nests were attended by three to seven individuals, representing family groups composed of adult males and 
females, as well as immatures from previous generations. Clutch size ranged from two to four eggs and was positively 
correlated with family group size. The incubation period was 15-17 days and nestlings left the nest when 16-18days cf 
age. Nestling success was relatively low (0.39). and mortality was caused by predation and harsh environmental events 
however, groups attempted to breed after nest failures. The Red-bellied Crackle has a cooperative breeding system and 
individuals delay dispersal by remaining in natal territories. Received 15 July 2011. Accepted 14 Aprd 2012. 
About 9% of bird species scattered across the 
avian evolutionary tree, from rheas ( Rhea spp.) to 
passerines (Skutch 1987. Hatchwell 2009, Corn¬ 
wallis et al. 2010), are now thought to exhibit 
cooperative breeding (Cockburn 2006). This 
behavior has been reported in Icteridae for no 
fewer than 14 species (Fraga 2008), including 13 
members of the South American quiscaline clade 
(i.e., grackles and allies sensit Johnson and 
Lanyon 1999. Lanyon and Omland 1999). Rcd- 
bellied Grackles (Hypopyrrhus pyrohypogaster ) 
are a member of this assemblage (Cadena et al. 
2004, Eaton 2006) and have recently been 
observed breeding in groups of three or more 
individuals (Betaneur 1994. Ochoa and Cuervo 
1998). These observations suggest Red-bellied 
Grackles have a cooperative breeding system, 
contrary to historical accounts reporting breeding 
by solitary individuals (Sclater and Salvin 1879^, 
Hilty and Brown 1986). 
Hypopyrrhus is a monotypic genus endemic to 
the humid montane forests of the Colombian 
Andes. Its restricted, disjunct distribution spans 
the northern sections of the western and central 
Andes, as well as the base of the eastern Andes in 
southern Colombia (Hilty and Brown 1986. 
Cuervo 2002, Cuervo et al. 2008). Red-bellied 
Grackles are currently categorized as endangered 
Institute de Biologia. Universidad de Antioquia 
Apartado A6reo 1226. Medellin. Colombia. 
Department ot Biological Sciences and Museum of 
Natural Science, 119 Foster Hall. Louisiana Slate Univer¬ 
sity. Baton Rouge. LA 70803, USA. 
Corresponding author; e-mail: acuervl@tigers.lsu.edu 
using 1UCN criteria (Cuervo 2002. BirdLife 
International 2011), mainly due to habitat loss 
(Renjifo 1999). However, Red-bellied Grackles 
are known to thrive in fragmented and disturbed 
habitats (Ochoa and Cuervo 1998. Cuervo 2003. 
Cuervo and Restrepo 2007). Red-bellied Grackles 
arc highly mobile, gregarious birds that form 
flocks of up to 30 individuals when not nesting 
(AMC, pers. obs.). similar to other cooperative¬ 
breeding icterids (R. M. Fraga, pers. comm.). 
Large non-breeding flocks in the non-breeding 
season imply the small reproductive flocks (3-7 
have great potential for fusion and rearrangement 
and suggest complex social and behavioral 
interactions are important in the cohesiveness ol 
breeding groups, hierarchical dominance, and 
kinship. 
The nests and eggs of Red-bellied Grackle> 
w'ere described >130 years ago (Sclater and 
Salvin 1879). However, little is known about 
other aspects of their breeding biology (Webster 
1992, Ochoa and Cuervo 1998. Jaramillo and 
Burke 1999). This information should serve as a 
basis for understanding the intrinsic biologic d 
traits involved in differential fates of populations 
to disturbance (i.e., to thrive or decline to local 
extinctions), and for informing conservation 
strategies. Our objective was to examine the 
breeding biology and behavior of Red-bellied 
Grackles in a suburban landscape in northwestern 
Colombia. 
METHODS 
Breeding groups of Red-bellied Grackles were 
observed at Alto San Miguel, along the upper 
538 
