The Wilson Journal of Ornithology 124(3):506-512, 2012 
MICROHABITAT NEST COVER EFFECT ON NEST SURVIVAL OF THE 
RED-CRESTED CARDINAL 
LUCIANO N. SEGURA. 1 ’ 3 DIEGO A. MASSON, 2 AND MARIELA G. GANTCHOFF 1 
ABSTRACT.—We evaluated the influence of microhabitat vegetation cover on Red-crested Cardinal (Panaris 
coronata) nest survival in natural forests in central eastern Argentina by monitoring 106 nests for 1,262 exposure day 
Daily nest survival rates increased with vegetation cover above the nest and decreased linearly as the breeding sea'on 
progressed. Increased concealment above the nest helped hide and protect nests from predators (mainly aerial predator-. 
Earlier nesting attempts in the breeding season were more successful than those later in the season. This is the first study to 
evaluate the effect of microhabitat vegetation cover on daily nest survival rates of a south temperate passerine. We highlight 
the importance of microhabitat nest concealment on nest success of the Red-crested Cardinal. Received 23 October 2011 
Accepted 23 March 2012. 
Predation is a major ecological force influenc¬ 
ing biological systems al a multitude of levels 
(Fontaine et al. 2007). Nest predation has been an 
important factor in the evolution of avian life 
histories (Skutch 1985, Ricklefs 2000) and nest 
site selection (Lima 2009, Martin and Briskie 
2009) as egg and chick predation are the main 
causes of nest failure in birds (Ricklefs 1969, 
Martin 1993b, Lima 2009). 
Nest predation rates of numerous bird species 
are affected by the physical features of a nesting 
site (Martin 1993b, Liebezeit and George 2002, 
Gjerdrum et al. 2005, Eggers et al. 2006, Fontaine 
and Martin 2006). Many studies have reported 
vegetation cover in the immediate vicinity of a 
nest provides greater concealment and lower 
accessibility to predators, which results in higher 
survival rates (Kelly 1993. Martin 1995, Hewlett 
and Stutchbury 1996, Flaspohlcr et al. 2000 
Liebezeit and George 2002, Weidineer 20(P 
Wmter et al. 2005. Kdleher and O’Halloran 
-007. Rangel-Salazar et al. 2008, Kerns et al. 
2010; but see Vergara and Simonetti 2004). 
Nest site selection likely affects nesting success 
(Eggers et al. 2006). Many bird species do not 
choose nest sites randomly with respect to 
; e Q ~, characteri - s,ic * s (Martin and Roper 
988 Holway 199!. Knopf and Sedgwick 
cant vegeU,lon cover frequently has a signifi- 
‘ T™, 0n /'! dll0r foraging success (Stinson 
nlsfj Ir ' 982) - SmM bi| -‘ ls choose 
nest sues offertng more protective cover given a 
y Evolueidn, 
Buenos Aires. CM’SFOA ft. -n ^'a U " lversidlui * 
’Bacullad de OcfciS ^ Al * e " ,in “' 
"S«- * fa Pb,a. ^\ Un,V ?*“ W 
C °™" 8 .- a. 
506 
simulated increase of predation risk (Eggers et al 
2006). Birds have been observed to change nest 
microhabitat following predation to more con- 
eealed locations (Lima 2009). The type of nesi is 
also important, as cavity and closed nests are 
likely to be more protected from both enviwit- 
mental conditions and nest predators than open 
nests (Ricklefs 1969, Martin and Li 1991 
Robinson ct al. 2000). 
Most studies of nesting success have been 
conducted in cither north temperate or tropical 
areas (Martin 1996). Some authors have inferred 
that birds in the Southern Hemisphere have higher 
nest predation rales than in north temperate areas 
based on the presence of certain life-history traits 
(reviewed in Martin 1996). The contrasts between 
tropical and temperate birds still remain large!) 
unresolved (Martin 1996. Ricklefs 2000. Farcin 
et al. 2005). Vegetation cover has been identified 
as an important influence on predation risk in bird 
species of north temperate and tropical areas. M 
little is known about how these factors ntf) 
influence reproductive biology and nesting sue 
cess ol birds in south temperate regions 
Mezquida and Marone 2002. Vergara and Sinn- 
netti 2004). 
The Red-erestcd Cardinal (Parociria coronal - 
is (he basal species of the Thraupidae (Davalo) 
and Porzecanski 2009), an emblematic group “ 
neotropical birds. It is distributed from centra, 
eastern Argentina to southern Brazil. Parage 
eastern Bolivia, and Uruguay (Ridgely and Tuck 
2009). Cardinals inhabit semi-open forests iS'A 
1997), and build open-cup nests (~13 cm widen" 
ihe tree canopy in small forks or thorny branch 
between 2 and 6 m height (Segura 2011). The; 
breed from early October to late February. nesting 
"i three different tree species: primarily in Tala 
