SHORT COMMUNICATIONS 
809 
set. MA. USA; http://www.onsetcomp.com). This 
allowed reconstruction of the temperatures expe¬ 
rienced by the embryo, the nest microclimate, and 
lime, at which the parent left or returned to the 
nest, the latter indicated by temperature shifts ot 
at least 1.5 C. The information contained in the 
data logger was downloaded every 10 days until 
the eggs hatched, or when the nest was no longer 
active due to predation or abandonment. 
Provisioning Behavior and Nestling Growth. 
The sensors were removed in the two nests where 
eggs hatched and the chicks were weighed daily to 
the nearest 0.05 g. Provisioning behavior was 
recorded by a motion sensor-triggered camera 
iPC85 Rapidfireprofessional: Reconyx Inc.. Hol- 
men, WI. USA) placed between 0.5 and 0.7 m 
from the nest entrance. We activated the camera 
to take 12 photographs with any movement 
between the nest entrance and the camera. 
Pectoral Sparrows are sexually dimorphic and it 
was possible to record differences in provisioning 
behavior by gender. 
Data Analysis .—Incubation rhythm was ana- 
lyzed following Londono (2009). The algorithm 
used detected all intervals when temperature 
changed monotonically and three values were 
retrieved for each interval: duration, total de¬ 
crease/increase in temperature, and initial rate ot 
temperature increase/decrease. The start of an in¬ 
bout or off-bout period was triggered when 
temperature increased or decreased, respectively, 
utan initial rate of at least 0.5 C/rnin (Cooper and 
Mills 2005). 
RESULTS 
We found four nests in 2008 and 11 in 2009; 
most were found when one of the parents flushed. 
Incubation patterns were obtained in six nests tor 
ume spans that ranged from I to 15 days 
•Spending on how long the nest was active, for 
a total across all nests of 28 incubation days. Only 
'wo nests produced nestlings and were monitored 
fer 2 and 9 days, respectively before all young 
"ere predated. 
Nest and Eggs .—Nests had a bulky roofed cup 
with a side entrance and a spherical interior 
chamber. Fourteen nests were found <0.2 m 
above ground level on gentle slopes with poor 
drainage. Nest sites were usually within the 
vicinity of a stream, where the soil was saturated 
with water. The entrance of the nest faced down 
Mope with the back of the nest against a live tree, 
a fallen log, or the slope. The only nest not found 
in these conditions was on a shallow shelf formed 
naturally in the bark of a live tree, ~1 m above 
ground level. 
Average (± SD) external nest dimensions were 
121 1 ± 27.3 X 132.8 ± 19.6 mm in length and 
width, and 124.8 ± 32.2 mm in height (n = 10). 
The nest entrance averaged 56.5 ± 25.8 mm in 
width X 75.7 ±11.9 mm in height (n = 10). 
Internal distance from the entrance to the back 
wall of the chamber averaged 72.8 ± 14.0 mm (n 
= 10) with an average inner cup depth (where 
eggs were deposited) of 56.5 — 25.8 mm (n — 
10). We collected and weighed nests atter they 
were no longer active; the average fresh nest mass 
was 48.0 ± 26.2 g (» = 5). All nests consisted of 
two layers, which were weighed separately. The 
outer layer was composed of dry bamboo 
(Gnculiui spp.) and dicotyledonous tree leaves, 
small roots, twigs, and fresh leaves of fern, and 
weighed 34.8 ± 25.3 g (n = 5). The proportion ot 
materials used varied among nests with some 
having almost exclusively dry material (85%) in 
the outer layer while others had an equal 
proportion of dry and green materials (50%). 
The inner layer was mainly small pale brown 
rootlets (80%). and dry and fresh leaves (20%); it 
weighed 12.9 ± 3.2 g (n = 5). 
The earliest nest was found on 28 August and 
the latest on 7 December, both with recently laid 
eggs; no developed embryo was visible when eggs 
were viewed against a bright flashlight. All nests 
had a clutch size of two. Egg color was highly 
variable among nests; four nests contained 
immaculate white eggs, while seven contained 
white eggs with brown speckles that ranged from 
sparsely to heavily speckled (Fig. 1). The eggs 
weighed an average (± SD) of 3.50 ± 0.33 g 
(range = 2.85—4.10 g, n = 23); and had an 
average length of 23.6 mm (range - 21.8- 
24.9 mm, n = 23) and a width ot 17.4 mm (range 
= 16.1-17.9 mm. n = 23). 
Provisioning Behavior and Nestling Growth.— 
E^gs in only two nests hatched due to predation 
and abandonment. The first hatched on 25 
September and. although the chick was not 
measured until 28 September, it was possible to 
delineate hatching day by changes in incubation 
patterns recorded by the temperature sensors. The 
chick weighed 8.14 g on day 3 after hatching, had 
closed eyes, fine black down on the back, and 
small pin feathers covering the wings. The eyes 
were open on day 9 and the feathers had started to 
emerge, revealing an olive-gray color on the 
