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THE WILSON JOURNAL OF ORNITHOLOGY • Vol. 124. No. 3. September 2012 
TABLE 2. Matrix of interspecific associations of species observed in >10% of the mixed-species bird flocks in a mon 
tane zone of Salerno. Quindio, central Andes of Colombia. The number of co-ocurrences and P value (among brackets) is 
indicated for each species pair. Significant associations {P < 0.05) are in bold type. 
M. squarniger M. leucophrys \l ornatus 
A. lacrynutsus 
C siltieolor 
1 rufivertex 
T. vassori 
II eximia 
T. uSitihatU 
A. igniventris 
16 (0.346) 13 (0.587) 2 (0,993) 
7 (0.063) 
7 (0.002) 
3 (0.246) 
2 (0.542) 
1 (0.17) 
6 (0.703) 
M. squarniger 
9(0.871) 6 (0.352) 
6 (0.468) 
13 (0.009) 
11 (0.084) 
5 (0.281) 
8 (0.321) 
5 (0.788) 
M. leucophrys 
7 (0.824) 
5 (0.541) 
9 (0.265) 
6 (0.876) 
I (0.002) 
4 (0.403) 
1 (0.027) 
M. ornatus 
7 (0.971) 
7 (0.971) 
4 (0.156) 
6 (0.876) 
6 (0.716) 
7(0.139) 
A. 1 aery mo sits 
5 (0.662) 
3 (0.072) 
7 (0.739) 
3 (0.228) 
5 (0.769) 
C. sitticolor 
6 (0.796) 
6 (0.797) 
7 (0.248) 
3 (0.362) 
1. rufivertex 
0 (0.0) 
5 (0.97) 
5 (0.663) 
T. vassori 
5 (0.975) 
5 (0.663) 
B. eximia 
5 (0.286) 
T. solstitialis 
B.. niontana 
H. superciliaris 
H. verticalis 
M. stictopterus 
P. boissoneauti 
D. cyanea 
(Atlapetes schistaceus ). and Golden-fronted 
Whitestart, participated in mixed-species bird 
flocks at different elevations suggesting this 
behavior is important in their biology as well as 
for the nine species observed more often within 
mixed-species bird Hocks than apart from them 
(Table 1). Most of these species are known to be 
usually present in mixed-species bird flocks along 
the Andes (Hilly and Brown 1986. Fjeldsa and 
Krabbe 1990). 
Several tanager species participated in mixed- 
species bird flocks in our study zone. A similar 
pattern has been documented for other sites along 
the Andes where tanagers seem to be involved in 
cohesion of mixed-species bird Hocks (Moynihan 
1979. Bohorquez 2003. Arbelaez-Cortes et al. 
201 la). Three of the five potential nuclear species 
belong to the Thraupidae. Species contributing 
significantly to cohesion of mixed-species bird 
Hocks share attributes including: contrasting or 
conspicuous plumages, high occurrence, large 
intraspecific groups, conspicuous maneuvers, 
regular calls, and a tendency to be followed more 
than they follow others (Moynihan 1979. Powell 
1985. Hutto 1994. Sridhar et al. 2009, Goodale 
and Beauchamp 2010, Harrison and Whitehouse 
2011). Some of these attributes could be used as 
signals by other species that follow them or could 
be related to enhancing the sensitivity of those 
species to predators. The five potential nuclear 
species in the Alto Quindio (Table 3) exhibit 
some of these attributes, but only share one ot 
TABLE 3. Potential nuclear species of mixed-species bird flocks in a high montane zone of Quindio. central Andes of 
Colombia. Their proportions of occurrence in the three elevation bands evaluated are indicated. Five attributes related with 
cohesive roles in mixed-species bird flocks arc depicted for each species (X = present). 
Occurrence in mixed-species bird flocks Attributes related with a nuclear role in mixed-species bird flocks 
Elevation Elevation Elevation 
_ . band A band B band C 
Speoes (3,000-3.150 m) (3,150-3.300 ml (3.300-3.450 
M squarniger 
14.3% 
37.5% 
45.5% 
1. rufivertex 
0.0% 
8.3% 
51.5% 
C. sitticolor 
0.0% 
33.3% 
36.4% 
M. stictopterus 
14.3% 
16.7% 
15.2% 
D. cyanea 
57.1% 
4.2% 
9.1% 
Large 
intraspecific 
groups 
Conspicuous 
maneuvers 
Regular 
calls 
Contrasting 
or conspicuous 
plumages 
Tendency w be 
followed by other 
species 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
