SHORT COMMUNICATIONS 
383 
The last trip before continuous incubation during 
night occurred in early afternoon between 1301 
and 1501 brs and lasted on average 31.75 ± 
19.4 min. The adult spent on average 58.9 ±8.1% 
of the time incubating the egg during these 5 days. 
The bird made an average of 7.8 foraging trips/ 
day (min-max = 6 to 9) that lasted on average 
36.1 min (min-max = 11.3 to 66). Nest temper¬ 
ature fluctuated between 30.1 and 15.1 1 C. and the 
average nest temperature during incubation was 
26 2 C (min-max = 22.3 to 31.4) decreasing to 
23.5 C (min-max = 20.7 to 26.7) when the adult 
was absent. We could not confirm directly how 
many individuals incubated, but we only saw the 
female entering or leaving the nest. The low nest 
attentiveness (58.9%; Deeming 2002) and data 
from other tanager species (Isler and lsler 1999) 
suggest that only the females incubate. 
Nestling Description.— Two of five nests had 
nestlings. One nest was found with an egg on 11 
October 2009 which hatched in the afternoon on 
12 October. We monitored the nest until 2 
November when the nestling successfully left 
(he nest; thus, the nestling period was 21 days. 
The first day the nestling had black down on the 
head, back, rump, shoulder, and Hanks, the skin 
color was a pale yellow, the eyes were closed, the 
commissures were yellow, and the tip of the bill 
was black. The eyes began to open on day 7 and 
by day 9, the eyes were completely open. The 
leather sheath breaking through the skin was a 
green color on the head, wings, back, flanks, 
rump, and abdomen, but the nestling still had 
down, and the bill was totally black. The bill was 
completely black on day 14; the nestling had a 
yellow eve ring, green feathers all over the body, 
and blue feathers on the abdomen. The nestling 
was fully feathered on day 20 and the tail feathers 
were almost completely emerged from the 
sheaths. The next day the nestling left the nest. 
It weighed 4.15 g on hatching, and gained mass at 
a rate of 0.8 g/day during the first 14 days, 
reaching a mass of 15.35 g. The mass ranged 
between 14.60 and 15.15 g on following days, 
finally reaching 16.95 g on day 21. The calculated 
'Pecific rate of growth (A'l was 0.26. Recently 
hatched nestlings (day 2) had a tarsus length of 
8 mm and a wing length of 8 mm. and grew at a 
rate of 1.1 mm/day and 2.6 inm/day, respectively, 
reaching a length of 23 and 54 mm on day 20 
(Fig. 2B). The second nest with a fully feathered 
nestling was empty (he following day. The 
nestling weight was 16.3 g when found on 13 
October and the tarsus and wing measured 22 and 
53 mm. respectively. 
DISCUSSION 
Hilly and Brown (1986) published the only nest 
information known for the genus Chlorochrysa-, a 
brief description of the nest of the Glistening-green 
Tanager. Our study provides the first detailed 
description of the nests, eggs, and nesting biology 
of a member of the genus Chlorochrysa. The cup 
nest of the Orange-cared Tanager is similar to that 
of most tanagers (lsler and Isler 1999). but the nest 
location in hanging mossy clumps from horizontal 
branches seems to be unique to this genus (Hilty 
and Brown 1986) and different from other tanagers 
(Isler and lsler 1999). The dutch size is one egg 
(Stiles and Skuteh 1989, Isler and Isler 1999, 
Martin et al. 2006, our study). One-egg clutches are 
not common among neotropical passerines but 
members of the mountain tanager clade. which is 
sister to the Chlorochrysa and Stephanophorus— 
l’a maria clade (Sedano and Bums 2010). also have 
a clutch size of one egg (G. A. Londono, unpubl. 
data). Thus, it is possible this trail is present in 
other neotropical passerines. The concentration of 
brown spots at the large end of the egg in C. 
calliparea differs from other members of the 
subfamily Thaupinae that commonly have white 
eggs covered with dense spots or lines all over the 
egg surfaces (Greeney et al. 1998. Isler and Isler 
1999). We are not aware of any other tanager using 
a nest-like structure as a dormitory. The growth 
rate of C. calliparea nestling when contrasted with 
other passerine species was slower than temperate 
passerine birds (Remes and Martin 2002). and was 
also slow compared with tropical passerines 
(Greeney 2008). 
We believe the unique location of a cup nest 
inside dense clumps of moss on horizontal 
branches has made it difficult to locate Chlor¬ 
ochrysa nests. We hope this paper will encourage 
researchers to look for these nests and investigate 
if the unusual nesting habits described for C. 
calliparea apply to other species of this genus. 
ACKNOWLEDGMENTS 
We thank Adam Carter and Jamie Miller for finding and 
monitoring some of ihe nests. We thank David Ocampo 
Rincon. Rachel Hanauer. and Julio Cesar Bermudez, for 
help during the 2009 field season. Comments by two 
anonymous reviewers, S. K. Robinson, D. W. Steadman, 
and C. E. Braun improved the manuscript. Our study was 
possible thanks to the logistical support of tiie NGO Peru 
Verde that allowed use of the Cock-of-the-Rock Reserve 
