Cestari et al • COMMON POTOO NESTLING BEHAVIOR 
105 
TABLE 2. Frequency per hour (total recording time = 9 hrs and 6 min) of behavioral activities by Common Potoo 
nestling when alone at the nest and when accompanied by an adult. 
Feeding on passing flies 
Defecation 
Brief movements 
Wing flapping 
Plumage maintenance 
Vocalization (calls) 
Alone 
1.87 
0.31 
6.25 
4.06 
4.37 
4.37 
Accompanied 
0 
0.34 
2.38 
0 
1.70 
647.1 
was alone. The nestling vocalized much more 
frequently while accompanied by one of the 
parents than when alone (Table 2). 
Adults A and B stayed in the nest for 1 hr and 
59 min (17.5% of total recording time), and 4 hrs 
and 17 min (47.2% of total recording time), 
respectively. A change-over between adults at the 
nest was recorded four times: day 1 at 2028 hrs; 
day 2 at 2135 hrs; and day 3 at 1919, and 2115 
hrs. Both adults left the nest six and 13 times 
during the sampled period: adult A (day 1 at 2030 
hrs; day 2 at 1957 and 2056 hrs; day 3 at 1919 and 
2115 hrs; and day 4 at 1927 hrs), and adult B (day 
1 at 1931, 1935, 2008, and 2209 hrs; day 2 at 
1905, 1940, and 2137 hrs; day 3 at 1909, 1919, 
1942, and 2131 hrs; and day 4 at 1904 and 1923 
hrs). Adults also fed on passing insects while 
perched in the nest, but only adult B called once. 
The frequency of food regurgitation to the 
nestling was similar between adults (Table 3). 
The nestling, adult A, and adult B adopted the 
alert posture during nearly 5 min and 24 sec 
(1.0% of total sampled time), 2 min and 24 sec 
(0-4%), and 1 hr and 48 min (19.8%) of video 
recording, respectively. 
DISCUSSION 
The infrared recording sessions enabled us to 
analyze and quantify behaviors of nestling and 
adult Common Potoos during the darkest nights. 
Parental attendance at the nest decreased as the 
nestling grew. Skutch (1970) and Tate (1994) 
reported that 25 days after hatching, adults were 
no longer staying with the nestling at the nest. 
They also reported that until nearly 50 days of 
a ge, the fledgling moved frequently with short 
flights, and the adults fed it in surrounding areas. 
Some behaviors of Common Potoo recorded in 
our study were also reported elsewhere, but rarely 
quantified, including: brief movements of the 
nestling in the nest (Tate 1994); wing exercising 
(Skutch 1970); alert posture (Muir and Butler 
1925, Skutch 1970, Tate 1994); calling of the 
nestling and adults at the nest (Muir and Butler 
1925, Skutch 1970, Corbo and Macarrao 2010); 
adults feeding the nestling by regurgitation 
(Skutch 1970, Corbo and Macarrao 2010); and 
alternation of adults at the nest (Lopes and Anjos 
2005). Other behaviors of the potoos we observed 
are described for the first time, including: feeding 
bouts on passing insects by both the nestling and 
adults while sitting in the nest; defecation, and 
plumage maintenance by the nestling. 
Brief movements on the nest by the nestling 
were performed when it was alone. Tate (1994) 
also observed nestling movements on a nest in 
Venezuela. We observed the nestling moved 
mainly to empty space left by the adult when it 
flew from the nest. One explanation for brief 
movements might be the improvement of blood 
circulation considering the great motionless 
period of the nestling during the day (Cohn-Haft 
1999). The nestling flapped its wings at times for 
a few seconds after or before moving, probably as 
a way to exercise its pectoral muscles. This wing 
exercising started when the nestling was 14 days 
of age, 2 days earlier than mentioned by Skutch 
(1970) in Costa Rica. 
The adults and nestling relied on the motionless 
alert posture during most of the day and in threatening 
situations during the night (Skutch 1970). We noted 
that a noise caused by a person near the nest site 
immediately modified the relaxed posture to an alert 
posture. We also observed the adult slowly turning its 
head to keep the intruder in focus in agreement with 
Muir and Butler (1925), Skutch (1970), and Tate 
TABLE 3. Frequency per hour (total recording time = 9 hrs and 6 min) of behavioral activities by adult Common 
p °toos (A and B) at the nest. 
Feeding on passing insects Callin g _ Feeding of nestling 
Adult A 
Adult B 
3.77 
1.86 
8.18 
0.70 
0 
0.93 
2.52 
2.10 
