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THE WILSON JOURNAL OF ORNITHOLOGY • Vol 124. No. 3. September 2012 
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FIG. 2. Nesting activity ot Yellow-olive Fluthills, and average monthly precipitation and 
1995 and January 2000 in the Barreiro Reserve, Belo Horizonte, Brazil. 
photoperiod between July 
after the first rains in 4 of the 5 years but, first 
clutches in 1997 coincided with the onset of the 
seasonal rains. Dry seasons varied in length from 
2 to 3.5 months, but this variation did not seem to 
aflect the start of reproduction. Reproduction in 
2 years (1996 and 1997) was more synchronous 
among individuals (Fig. 3). 
Clutches and Eggs.— The Yellow-olive Flatbill 
laid three (« - 27. 47%) or four (/? = 28. 48%) 
eggs, more rarely two (n = 3. 5%) (mean ± SE = 
3.4 ± 0.1. n = 58). Eggs were apparently laid 
every other day. as laying of a four-egg clutch 
took 7-8 days. Most eggs were immaculate, but 
one clutch of three had brown spots on the larger 
end. Eggs weighed 2.57 ± 0.05 g (n = 28j and 
were 21.9 ± 0.4 mm [n = 30) long by 15.2 ± 
0.2 mm (// = 30) wide with a mean volume of 
2.57 ± 0.06 cm’ (n = 30). 
Incubation Period. —Incubation presented ir¬ 
regular rhythm delay, starling before ihe clutch 
was complete, and hatching was asynchronous. 
We observed only one individual incubating the 
eggs. The attending adult would leave the nest 
when we approached and perch silently at least 
10 m from the nest. Incubation lasted 20.1 ± 
0.4 days (n =11) and ihe hatching rale was 0.81. 
Both parents cared for the nestlings. 
Brood Size and Nestling Growth .—Most suc¬ 
cessful nests produced two fledglings (17 of 29 
nests that produced fledglings) with total fledgling 
productivity of 0.8 fledglings per nest (consider¬ 
ing all breeding attempts by a breeding pair) and 
one fledgling per breeding pair (considering only 
successful attempts). Nestlings reached 50% of 
their Hedging size in -5 days (tarsus) and 14 days 
(tail); chicks Hedged at an average of 107% (Cl = 
106-108%) of mean adult body mass (Table 2. 
Fig- 4). 
Nestling Period .—The nestling phase was 23.4 
— 0.7 days (n = 7). We observed one adult during 
nest monitoring performing alarm calls while 
perched 30 m from an active nest in the nestling 
phase. This individual flew into the nest carry ing 
an insect larva and. shortly thereafter, two adult 
individuals left the nest. 
Reproductive Success .—Overall raw nest suc¬ 
cess for the 5 years was 29% (mean among years = 
31%. Cl - 25-37%). Nest predation was the main 
cause of nest failure (49%). 7% of the nests were 
abandoned, and 15% failed due to other causes. 
