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THE WILSON JOURNAL OF ORNITHOLOGY • Vo/. 124. No. 1. March 2012 
et al. 2000, Marini and Duraes 2001). Yellowish 
Pipits had an earlier pattern (i.e., 89% of the 
clutch initiations occurred during the cold/dry 
season), concentrating its nesting activities in dry 
months (Aug-Sep), and ceasing in early rainy 
season (Oct). Nests of this species are poorly 
adapted to heavy rains. All nests that were 
abandoned (;i = 6) occurred after the loose nest 
walls became moist and collapsed (but we did not 
detect Hooding in nests in the river banks). Five 
abandonments occurred in 2009, an exceptionally 
rainy year with frequent storms even in July and 
September. Clutch initiation was also later in 
2009 with the number of clutch initiations smaller 
than in 2008 and 2010. 
Clutch initiation of Yellowish Pipit lasted 2 to 
3 months when each of the three study years was 
analyzed separately, but were highly concentrated 
in a single month. Our data reveal a short breeding 
season length when compared to congeners from 
the Northern Hemisphere, and suggests that if 
double-brooding occurs in this population, it must 
be rare. Laying periods lasted from April to July 
for central Europe Meadow Pipits (but middle Jun 
to Jul in northern Europe), from early May to late 
July in Sprague’s Pipits (Coulson 1956, Davies 
1958, Jones et al. 2010). but mid June to mid July 
for American Pipits in Wyoming alpine tundra 
(Verbeek 1970). The double-brooding rate seems 
low for Sprague’s Pipit (Sutter et al. 1996, Davis 
2009), but common in central Europe populations 
of Meadow Pipits (Davies 1958). 
Breeding season length has been often positively 
correlated with the number of broods per season 
and, consequently, to annual fecundity (Cooper et al. 
2005). It has been theorized that tropical and 
southern temperate birds produce fewer offspring 
than nonhem temperate species by having smaller 
dutch sizes (Lack 1947, Skutch 1949, Cieffen and 
Yom-Tov 2000, Ricklefs 2000. Auer et al. 2007). 
Recent reviews have shown that while clutch size 
tends to increase away from the tropics, nes 
attempts tend to decrease, resulting in similar ant 
fecundity across latitudes (Martin 1995, Boehn 
Gaese et al. 2000, Cooper et al, 2005). Tl 
reproductive investment would be better eslim; 
by the combination of dutch size and numbe: 
root s per season (Cooper et al. 2005). Our si 
clwchT mUS ' 1,0 single-brooded. 
Pipits; 
not only clutch siz2 the Imdings , 
representative (Ye llowish ^ 
total annual egg productivity. Thus, the hypothesis 
that annual fecundity can he similar across latitutb 
due to a negative correlation between clutch sue and 
number of renesting attempts was noi supported 
(Martin 1995, Boehning-Gaese et al. 2000,Coopei 
et al. 2005). Our data also contradicts the commonly 
claimed, but poorly tested hypothesis, that smaller 
clutch sizes in the tropics can be explained by i 
longer breeding season that permits more opportu¬ 
nities to renest within the same breeding season 
(Martin 1996), Skutch (1954) also found thai 
ground-nesting purulids were single-brooded in both 
Central and North America. Auer el al. (2007) found 
similar breeding season lengths of guilds of tunJids. 
emberizids. and flycatchers from subtropical Ar¬ 
gentina compared with their North .American 
counterparts. However, numbers of within-seasxi 
renesting attempts were not recorded and the annual 
fecundity comparisons between Central-South and 
North American birds remain poorly evaluated 
Jones et al. (2010) found much lower values of 
model-averaging nest success (27%) in a long-term 
study on Sprague’s Pipit than obtained for our 
study population of Yellowish Pipit. This refutes 
Skutch’s (1949) premise that higher nest predation 
in the tropics is a key factor explaining smaller 
clutch sizes in the Southern Hemisphere through 
constraining the rate at which parents can deliver 
food to the young. It supports the findings of 
Martin et al. (2000) that nest predation may not 
account for clutch size differences between eight 
pairs of phvlogenetically close and ecologically 
similar passerines from northern and southern 
temperate latitudes. However. DSR in our study 
area could be overestimated due to the presence o 
people visiting the park. Yellowish Pipits v;ere 
very tolerant of human presence, but park visitor 
may have repulsed potential nest predators 
Developmental rates are usually thought n 
be slower in the tropics and Southern Hemisphere 
habitats, causing longer incubation and nestlinc 
periods compared to north temperate popular 
(Skutch 1949. 1985; Ricklefs 1968. 1976; Mason 
1985; Martin 2002). Geffen and Yom-Tov (201X1' 
analyzed a large sample of tropical and northern 
temperate passerine species from the Old in “ 
New World; they concluded incubation and nestling 
periods actually tend to be similar, and the 
differences reported in previous studies could i* 
due to phylogenetic influence. These authors, 
control for phylogeny, analyzed the representum 
of different infra-orders and continents separan- 1 .' 
(New World Deutro-Oscines, New World Oscines. 
