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THE WILSON JOURNAL OF ORNITHOLOGY • Vol. 124, No. 1. March 2012 
occupies areas irrigated for agriculture. The study 
area was a 1.OOO-ha cultivated field with vineyards, 
olives (Olea europaea), and poplar (Papains nigra ) 
groves. 
Data Collection .—We followed the fates of 236 
thrush nests which were found by observing adult 
behavior and systematic search. Nests were 
visited every 1-2 days until nestlings Hedged or 
the nest (ailed. We recorded the numbers of eggs 
and nestlings during visits. We considered a nest 
to have been predated when the complete clutch 
disappeared between two subsequent visits. 
Data Analyses .—We divided the reproductive 
season into groups of 10 days starting with the 
first egg laid until the last nest in laying stage was 
found. We recorded the frequency of nests that 
started in each period and estimated the survival 
ol nests (0-1) throughout the season with logistic 
regression including a subset of nests found 
during building and laying periods (n = 08 nests). 
We calculated (mean ± SE) success of eggs 
and nestlings in nests in each nesting cycle period 
(egg laying, incubation, and nestling) that were 
not predated, deserted, or parasitized by the Shiny 
Cowbird. Egg survival was calculated as the 
proportion of eggs present in the nest at the end of 
incubation divided by the number of eggs in the 
nest at the start of incubation. Wc only considered 
nests found in building and laying stages that 
survived until the hatch of the first egg („ = 48 
nests). We calculated hatching success as the 
proportion of eggs that hatched divided by the 
number of eggs in the nest at the end of 
incubation. We only considered nests found in 
building, laying, or incubation stages where at 
least one egg hatched (n = 109 nests). Fledglim- 
survival was calculated as the proportion of 
fledglings divided by the number of eggs that 
hatched. We considered only nests found during 
building, laying, or incubation stages that fledged 
at least one nestling (n = 44 nests). We used a 
Chi-square test to analyze if number of eggs in the 
nest affected egg survival (all eggs survived or at 
least one disappeared) or hatching success (all 
eggs hatched or at least 1 failed), and if fledgling 
survival was associated with number of nestlings 
(all nestlings survived or at least I died). 
We evaluated if nest survival was associated 
with adult activity in the nest by subdividing the 
the f 8 Cyt ? ,mo tivc P eri °ds: laying (laying of 
stacelTavin^ .T"? ^ -VincSon 
. Ce me laying of the third egg until d .v 7 > , 
incubation ,da y S u nti , the h « 
early nestlings (from the day the first egg hatches 
until day 6). and late nestlings (from day 7 unit 
the first fledgling left the nest). 
Nest mortality risk (m) was calculated for each 
period following Mayfield (1975). and the 
standard error was calculated as suggested b; 
Johnson (1979). Wc compared mortality rates 
with a Fisher test of contingence. We compared 
each nest mortality period versus every other 
period and applied a Bonferroni correction (or 
multiplc comparisons (Abdi 2007). 
Adult activity in the nest was recorded h 
videotaping 20 nests with Hi8 Sony vide, 
cameras. Nests were recorded during 4 hr- 
beginning at 0700. Cameras were placed 2 m 
from the nest and camouflaged with leaves We 
recorded two nests during the laying stage, >u 
nests during early incubation, two during late 
incubation, four with early nestlings, and six w-ith 
late nestlings. We obtained latencies (time elapsed 
since placement of the camera and the moment m 
adult returned to the nest ), frequency of visits per 
hour (average number of times an adult entered 
the nest in I hr), and nest attentiveness (average 
proportion of time an adult stayed in the nest 
during I hr) for each video. All statistical tests 
were conducted with StatView 5.0 (SAS 1998). 
RESULTS 
We found 236 nests of Creamy-bellied Thrush¬ 
es. 42% during the building and laying period. 
51 % during the incubation period, and l a c during 
the nestling period; 18 were found in 1999. 87 in 
2000. 91 in 2001. and 40 in 2002. Sixty-seven 
percent of the nests were predated. 8 C 7 were 
deserted, and 2.5% were destroyed by strong 
winds or rain. Only 22.5% of the nests produced 
at least one fledgling. The majority of the nests 
(62%) were parasitized by the Shiny Cowbird and 
at least one egg in 68% of the nests was 
punctured. 
Most of the nests (70%, n = 236) found were in 
vineyards and in olive trees, and the rest in popL' 
and fruit trees. Nest dimensions (mean - SC 1 
were; 10.5 ± 0.5 cm in external height. 6.1 - 
0.3 cm in depth, and 12.3 ± 0.2 cm in externa! 
width with an internal diameter of 7.9 ± 03 cm 
(n = 20 nests). 
The first nest was found on 21 October and the 
number of nests in the laying stage increased to a 
maximum between 23 and 25 November: the las' 
nest in the laying stage was found on -- 
December (Fig. I). Nest survival was not associ- 
