The Wilson Journal of Ornithology 124( 1): 133-138, 201 2 
reproductive success of the creamy-bellied thrush in a 
SOUTHERN TEMPERATE ZONE 
ANDREA ASTIE 1-2 AND NATALIA LUCHESI 1 
ABSTRACT—We describe ihe breeding biology and reproductive success of a Creamy-bellied Thrush (TWio 
i wmrochalinus) population from a southern temperate zone in western Argentina. We tound 236 Creamy-bellied Thrush 
nests of which most were predated (67T). The breeding season was from late October to late December and clutch size was 
three eggs. Egg survival, hatching success, and fledgling survival of non-depredated nests were quite high <0.6/ - U.U3. 
074 ± 0.03. and 0.87 ± 0.04. respectively). The number of eggs in the nest did not affect egg survival or hatching success, 
bu! number of nestlings in the nest affected fledgling success. Daily nest mortality was higher during the early and late 
nestling period than durina laving, and early and late incubation periods. Highest nest mortality coincided with periods 
when activity of parents at'the nest was highest The clutch size was similar to data reported lor thrushes Irom the tropics 
and south temperate areas, and lower than reported for thrushes from north temperate areas. This latitu ina P attem ,s 
similar to the general pattem described for passerines in the tropics and southern temperate areas. Recei\e( < e ruary 
1011. Accepted 14 September 2011. 
The study of avian breeding ecology in the 
Americas has mostly concerned tropical and 
northern temperate species. New data from the 
Southern Hemisphere suggest life history traits 
and behavior of southern temperate species are 
more similar to tropical than to northern temperate 
species (Martin 1996, Martin et al. 2000, 
Robinson et al. 2010). This conclusion is based 
on a limned number of southern temperate 
locations and species, and more information is 
needed on avian life history traits in southern 
temperate areas (Robinson et al. 2010). 
The Turdidae (true thrushes, Turdus spp.) is a 
cosmopolitan group in the tropics, and northern 
and southern temperate areas around Ihe world. 
Tints, they are an excellent model for study of life 
history evolution, breeding biology, and latitudi¬ 
nal variation among related species occupying 
different ecosystems. However, there are only a 
comparative studies (Martin et al. 2000, 
berretti et al. 2005) and the available information 
ls biased to north temperate species. Most 
information on breeding biology for species ol 
T'irdiis in Argentina comes from studies in the 
Eintpas and Yungas (e.g„ Martin et al. 2000, 
Suckmann and Reboreda 2003, Ferretti ct al. 
2005). There are no studies available tor popula- 
lions Irom semi-arid areas of western Argentina 
(but see Mezquida and Marone 2001 for other 
Passerine species). 
The Creamy-bellied Thrush (Turdus amauro- 
' Institute Argcntino de Investigaciones de Zonas Aridas. 
•ADIZA-CONICF.T, Mendoza. Argentina. 
Corresponding author; 
e -mai|; aastie @ mendoza-conicet. gob .ar 
chalinus) is widespread in South America, but its 
breeding biology has only been recently studied 
(Astie and Reboreda 2005, 2006). The objectives 
of our study were to obtain information on 
breeding biology and reproductive success of a 
Creamy-bellied Thrush population from a south¬ 
ern temperate zone in western Argentina. Specif¬ 
ically, we examined if number of eggs and 
nestlings present in the nest affect reproductive 
success during different stages of the nestling 
cycle. 
METHODS 
Study Species.—The Creamy-bellied Thrush is 
a monomorphic and monotypic passerine ot the 
genus Turdus. This species is widely distributed 
from southern Brazil to southern Argentina (Ridge- 
|y and Tudor 1989), but little is known about its 
breeding biology. Creamy-bellied Thrushes build 
open cup nests composed of grasses cemented with 
mud and lined with grasses and hairs. They lay 
three esgs with a pale greenish background and 
spots and blotches of reddish-brown concentrated 
at the larger pole (Astie and Reboreda 2005). The 
incubation period is 11.5 days and the nestling 
period is 12 days (Astie and Reboreda 2005, 
2009a). Average adult mass is 55 g (Astie and 
Reboreda 2005). This species is heavily parasitized 
by the Shiny Cowbird (Molothms bonariensis) in 
the study area (Astie and Reboreda 2005, 2006, 
2009a, b). 
Study Site .—The study was conducted at Guay- 
mallen. Mendoza Province. Argentina (32 51' S, 
68 42' W) during the 1999-2002 breeding seasons 
(Oct-Dec). Mendoza is in the Monte Desert region 
of Argentina. The Creamy-bellied Thrush only 
133 
