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THE WILSON JOURNAL OF ORNITHOLOGY • Vol. 123, No. 3. September 2011 
TABLE 1. Sociality of parrot species on the clay lick at Tambopata Research Center, Peru during 20 mornings ftom 
December 2002 to January 2003. The species are arranged by body mass. ‘Green macaws' were recorded when observers 
could not distinguish between Chestnut-fronted and Red-bellied Macaws. Monospecific = percent of counts for which the 
species Was recorded on the lick in a monospecific group. Large Parrot = percent of counts when the species was pan of lb: 
large parrot aggregation. Parakeet and Large Macaw = percent of counts for which species were pan of the parakeet and 
large macaw aggregations. Total = number of bird minutes recorded for the species. Body masses are from Dunntn -1 l99*i 
and Terborgh et al. (1990). 
Species 
Mass (g) 
Large parrot 
Red-and-green Macaw 
1,250 
40 
Blue-and-yellow Macaw 
1,125 
49 
Scarlet Macaw 
1,015 
56 
Mealy Amazon 
610 
96 
Yellow-crowned Amazon 
510 
79 
Chestnut-fronted Macaw 
430 
95 
‘Green Macaw' 
100 
Red-bellied Macaw 
370 
96 
Blue-headed Macaw 
250 
72 
Blue-headed Parrot 
247 
83 
White-eyed Parakeet 
157 
68 
White-bellied Parrot 
155 
0 
Orange-cheeked Parrot 
140 
69 
Dusky-headed Parakeet 
108 
1 
Totals (bird minutes) 
25,400 
Large macaw 
Parakeet 
Mono-specific 
Other 
52 
2 
7 
0 
45 
1 
6 
0 
42 
0 
2 
0 
1 
0 
4 
0 
3 
2 
9 
6 
3 
0 
2 
0 
0 
0 
0 
0 
0 
4 
0 
0 
0 
28 
0 
0 
13 
2 
0 
2 
5 
8 
17 
2 
0 
43 
58 
0 
I 
22 
I 
7 
0 
92 
7 
0 
1,727 
1,555 
2.580 
280 
Tout 
124 
1,137 
574 
12,471 
130 
2,267 
336 
1,076 
18 
1,210 
11.363 
40 
259 
537 
31.542 
(Gilardi et al. 1999, Brightsmith et al. 2008). The 
slope of the lick face ranges from moderate (—30°) 
to nearly vertical (80°). 
Lick Counts .—Data were collected during 
December 2001 and 2002, and January 2000 and 
2003 from a point ~200 m from the clay lick. 
Observers arrived before sunrise and stayed until 
the end of the early morning activity (0700 to 
0730 hrs). Observers watched the staging birds 
and recorded when the first group of birds began 
to fly in slow circles in front of the lick in 
anticipation of landing. Observers counted all 
birds perched on each section of the clay lick 
every 5 min (Brightsmith 2004). More detailed 
location data were collected in December 2002 
and January 2003 (n = 20 mornings) for each bird 
on the lick to quantify the social group member¬ 
ship of each species using the lick. 
Arrivals ami Disturbance .—Observers recorde 
die numbers and species of parrots as they arrive 
in the area Irom a point on the opposite river ban 
~400 m to the east of the clay lick. It was nc 
possible to record the birds that arrived fror 
forests behind the lick (to the west). 
Observers recorded the cause of the disturbanc 
whenever >25% of the birds simultaneously fle\ 
from the clay lick or surrounding trees. 
Data Analyses.-The clay lick use by eael 
species was calculated as the total number of ‘bin 
minutes’ on the lick (Brightsmith 2004). Bird 
minutes were defined as the number of birds on 
the lick multiplied by the number of minutes they 
stayed on the lick (i.e.. 4 birds for 15 min each = 
60 bird min). We conducted principal componenl 
analysis of the data for birds which simultaneous¬ 
ly shared each section of the lick to identify the 
groups of species which used the lick together. 
Only principal components with eigenvalues ^1 
are reported. We tested differences among species 
for group sizes arriving at the lick using Kruskal- 
Wallace and Mood’s median test with 95% 
confidence intervals around the medians using 
StatGraphics Centurion XV. Normal variables are 
presented as mean ± SD, while those that failed 
Shapiro-Wilks’ test for normality are presented as 
medians with 95% confidence intervals. Alpha = 
0.05 for all statistical tests. 
RESULTS 
Thirteen species of psittacines used the clay 
lick in the early morning period (before 0730 hrs- 
Table 1). Over 99% of all lick use was in groups 
Mixed species aggregations accounted for 92% of 
the total lick use, monospecific groups 8%. and 
single individuals <1% (Table I). 
Five principal components (eigenvalue > D 
together explained 58% of the variance in group 
composition on the clay lick (Table 2). These 
