SHORT COMMUNICATIONS 
619 
Brazil (Ridgely and Tudor 1994, Fitzpatrick et al. 
2004). The genus Rhynchocyclus is in the Flatbill 
clade, which includes the genus Tolrnomyias 
dan yon 1988. Tello and Bates 2007. Ohlson et 
al. 2008) as a sister taxon. The nests of both 
Tolrnomyias and Rynchocyclus have been de¬ 
scribed as pear-shaped structures with a tubular 
side entrance in the base made with sticks, libers, 
and dry leaves (Parker and Parker 1982. Hilty and 
Brown 1986. Fitzpatrick et al. 2004. Greeney et 
al. 2004, Brumfield and Mail lard 2007). 
The Fulvous-breasted Flatbill (Rhynchocyclus 
fulvipectus) is commonly found close to rivers and 
small creeks in secondary montane forest and 
shrubby edge vegetation between 750 and 2.300 m 
(Ridgely and Tudor 1994. Fitzpatrick et al. 2004, 
Schulenberg et al. 2007). It is known that clutch 
size varies from one to three eggs, which are 
white with reddish dots on the widest end (Sclater 
and Salvin 1879. Fitzpatrick et al. 2004. Greeney 
et al. 2004). The only information about the 
nestling period is from a nest found by Greeney et 
al. (2004) in Ecuador that had an incomplete 
incubation period of 18 days and a full length 
nestling period of 27 days. Despite the large 
distribution of this species in South America, it is 
uncommon throughout its range and its lethargic 
behavior may underlie the lack of nesting 
information for it (Hilly and Brown 1986). 
Detailed studies about the nesting biology ol any 
species of the genus Rhynchocyclus ure lacking 
(Fitzpatrick et al. 2004): our study was designed 
to provide the first complete description of the 
nesting biology of the Fulvous-breasted Flatbill. 
METHODS 
Study Area .—This study was conducted in the 
Kcosnipata Valley at Cock of the Rock Field 
Station in the buffer area of Manu National Park. 
Cusco. Peru (13 0.39' 19.40" S, 71 3.29' 48.50" 
W) from August through December 2009. The 
station is at 1,450 m in an Andean cloud forest 
with a canopy height of 25 m, average tempera¬ 
ture of 18.3 C (min-max = 12.1 to 26.6 C), and 
average precipitation of 521 mm with a rainy 
season from November through April and a dry 
season from May through August. 
Nest. Eggs, and Nestling Measurements.—We 
obtained measurements of the nests, eggs, and 
nestlings. We took internal and external measure¬ 
ments for five of seven nests, and described and 
weighed the different nest materials and layers. 
We measured the length, width, and mass of the 
eggs. We took daily morphological measurements 
of the nestlings that included wing and tarsus 
length, and body mass; wc also made qualitative 
descriptions every other day. We measured 
nestling body temperature using a thermocouple 
(Onset Computer Corporation, Pocasset, MA, 
USA) that we inserted into the cloaca. Body 
temperatures were taken to estimate when nest¬ 
lings were able to regulate their body tempera¬ 
tures (when they became endothermic). We 
measured body temperature as soon as we took 
each nestling from the nest after placing each 
nestling on a plastic lid for 3 min (to prevent 
variation in loss of body heat due to die ground 
being hot or cold). The thermocouple tip was 
cleaned with alcohol between measurements, and 
was coated with petroleum jelly to reduce stress 
created by insertion. We also conducted direct 
observations of provisioning for 1.5 hrs at one 
nest on 2 different days for a total of 3 hrs. All 
mass measurements had an accuracy of 0.05 g 
(FlipScale F2; My Weigh, Phoenix, AZ, USA) 
and measurements of length/width were taken 
with a caliper with an accuracy of 0.1 mm. 
Incubation Patterns.—We monitored incuba¬ 
tion behavior at three nests on ditferent days for a 
total of 21 days using two thermal sensors. One ot 
the sensors was placed under the eggs, providing 
incubation rhythm and nest microclimate infor¬ 
mation, and the second was attached to the 
external face of the nest wall, providing ambient 
temperature. Both sensors were connected to a U- 
12 HOBO data-logger (Onset Computer Corpora¬ 
tion, Pocasset, MA. USA) programmed to record 
temperatures every minute. 
Incubation Rhythm Analysis—We quantified 
the length and number of temperature fluctuation 
events produced by foraging trips (cooling 
periods) and returning to the nest to incubate 
(warming periods), following Cooper and Miles 
(2005). This procedure allowed us to estimate nest 
temperature fluctuations, number and length of 
foraging and incubating trips, and percentage ol 
time the adult was incubating the eggs (Londono 
2009). 
RESULTS 
We found seven nests of which six contained 
two eggs each and one had only one egg. Four 
nests were depredated and one nest was destroyed 
when the branch upon which it was built fell into 
the river. We found an empty nest on 20 October 
2009 and 7 days later (27 Oct) the nest contained 
