598 
THE WILSON JOURNAL OF ORNITHOLOGY • Vol 123, No. 3, September 2011 
TABLE 3. Group size for arriving birds at the Tambopata Research Center clay lick based on six mornings of 
observations. Birds were not detected arriving in mixed species groups. Species which share superscript letters do not differ 
(Mood's median test, P > 0.05) in median group size. 
Species 
Median 
95% Cl 
Group sizes (% of total) 
Lower 
Upper 
1 
2 
3 or 4 
£5 
a 
Red-and-green Macaw’ 
2 
1 
2 
36 
64 
0 
0 
22 
Scarlet Macaw 3 
2 
2 
2 
34 
57 
9 
0 
127 
Chestnut-fronted Macaw 3 
2 
2 
2 
31 
54 
11 
4 
455 
Blue-and-yellow Macaw 3 
2 
2 
2 
21 
62 
13 
4 
142 
Mealy Amazon 3 
2 
2 
2 
25 
46 
21 
8 
550 
Blue-headed Parrot 3 
2 
2 
3 
22 
29 
29 
21 
125 
Red-bellied Parrot 3 
3 
2 
4 
8 
37 
27 
27 
51 
Dusky-headed Parrot b 
10 
6 
14 
0 
0 
21 
79 
34 
White-eyed Parakeet 1 
22 
12 
28 
2 
9 
3 
86 
65 
could not usually detect arrivals of White-bellied 
Parrots or Orange-cheeked Parrots as they flew 
lower than other species and arrived quietly. 
However, all other species regularly arrived flying 
high above the canopy and were readily detected. 
The members of the large parrot aggregation 
began to arrive 8.4 ± 5.8 min before sunrise (n = 
70 mornings) and usually perched in trees 
immediately above and behind the clay lick. The 
median arriving group size was two except for 
Red-bellied Macaws which was three (Table 3). 
The first large macaws began arriving at about 
the same time as members of the large parrot 
aggregation (9.3 ±11.7 min before sunrise, n = 
70 mornings). The large macaws continued to 
arrive throughout the morning at a slow steady 
rate (1.1 ± 0.3 individuals/min. n = 577 birds 
over 6 days). Macaws arrived in pairs (61%), 
singles (30%). and rarely groups of three or four 
(7%, n = 291 groups; Table 3). 
The members ol the parakeet aggregation began 
to arrive 21.7 ± 15.6 min after sunrise (n = 68 
mornings) and staged in short trees at the lick’s left 
edge. Both common parakeets arrived in large 
groups: Dusky-headed Parakeet median = 10, n = 
34 groups. White-eyed Parakeet median = 22, n = 
65 (Table 3). The arriving groups of parakeets 
were relatively large, but waited and joined with 
other conspecifics before moving to the lick. 
Our observations suggest many birds spend hours 
socializing in the trees around clay licks without 
descending to eat soil. We focus in this paper on 
birds that consumed soil and do not address the 
social aspects of gathering near clay licks. 
Descent to the Lick .—Most species were able to 
join more than one type of aggregation, but the 
tnree aggregations commonly approached the lick 
independently and in stereotypical patterns. The 
members of the large parrot aggregation began to 
move towards the clay lick by 15.7 ± 11.5 min in 
~ 66 mornings) after sunrise. There were at least 
424 ± 152 birds in the area (n — 6 mornings) at this 
lime. One or more small groups of birds (usually < 
20) led the descent by flying in large circles in front 
of the lick. Birds from the trees joined these groups 
until there were up to 100 birds in flight. These 
flights lasted 3.4 ± 4.3 min (// - 62 mornings). The 
birds flew in slow circles in front of the lick, 
apparently choosing where to land. Detections of 
predators or landslides during these flights often 
caused the birds to choose an alternative section of 
the lick or break off approach completely. 
The large macaw aggregations often formed as 
groups of 6-29 birds flew to the lick to join the 
tail end of the large parrot aggregation (19% ol 69 
mornings). Groups of up to 30 large macaws also 
initiated lick use on unoccupied sections ot the 
clay lick (29% of 69 mornings). The latter 
occurred —50 ± 23 min after sunrise (n “ 26" 
mornings) when they staged and flew to the lick in 
a manner similar to that described for the large 
parrot aggregation. 
Members ol the parakeet aggregation descend¬ 
ed to the left edge of the lick starting -101 - 
21 min (n = 34 mornings) after sunrise. These 
groups did not engage in exploratory flights like 
the large parrot aggregation or large macaw 
aggregation, and instead moved deliberately 
through the trees progressively closer to the lick 
and then flew directly from the trees to the lick 
(usually a distance of <20 m). There were at leas 1 
217 ± 120 parakeets in the area (n = 5 mornings) 
by the time the first parakeet flocks descended w 
the lick. 
