Rodrigue: et al. • VENEZUELAN BIRD SURVEYS 
239 
TABLE 3. Continued. 
Observed 
Family 
Surveys 
Checklists 
Expected 
% Observed 
Rhinocryptidae 
2 
2 
3 
67 
Tvrannidae 
80 
86 
138 
58 
Pipridae 
II 
11 
16 
69 
Cotingidac 
9 
11 
22 
41 
Vireonidae 
9 
9 
13 
69 
Corvidae 
4 
4 
5 
80 
Hirundinidae 
10 
1) 
II 
91 
Troglodytidae 
14 
15 
19 
74 
Cinclidae 
0 
0 
1 
0 
Polioptilidae 
2 
2 
2 
100 
Turdidae 
12 
14 
20 
60 
Mimidae 
1 
1 
1 
100 
Motacillidae 
1 
1 
2 
50 
Parulidae 
15 
17 
29 
52 
Emberizidae 
21 
23 
38 
55 
Thraupidae 
53 
60 
84 
63 
Cardinalidae 
11 
11 
13 
85 
Icteridae 
17 
18 
23 
74 
Fringillidae 
4 
4 
4 
100 
Mean 
65 
typical pattern of high Andean locations (Fjeldsa 
and Krabbe 1990, Stotz et al. 1996). 
A reassuring finding was that species compo¬ 
sition by families did not differ significantly from 
that expected (Table 3). There were several 
families that diverged considerably from the mean 
proportion of species per family. Nocturnal 
families such as nightjars (Caprimulgidae), potoos 
(Nyctibiidae). and owls (Strigidae); some water- 
birds including ducks (Analidae). plovers and 
lapwings (C'haradriidae). and shorebirds (Scolo- 
pacidae): and hummingbirds (Trochilidae) had 
proportions lower than expected (Table 3). We 
believe the lower proportion of these families in 
the surveys was for two different reasons. (I) 
Roadside surveys, as has been proposed for the 
BBS (Robbins et al. 1986, Robbins 2000). tend to 
be adequate for most common and diurnal species, 
but inadequate for rare, nocturnal or colonial 
species. Our surveys began around dawn and most 
nocturnal species were not detected: no nightjars 
and only one owl (Ferruginous Pygmy Owl 
[Glauiidiwn brasiliiuwrn \, which is also partly 
diurnal) were observed. (2) The low number of 
waterbird and hummingbird species was probably 
not due to the survey method, but reflected their 
actual low abundance. The period between May 
2009 and April 2010 corresponded to one of the 
‘El Nino-Southern Oscillation’ (ENSO) episodes, 
whose most obvious effect was severe drought, 
diminished water bodies, and overall dry vegeta¬ 
tion throughout the country (Ropelweski and 
TABLE 4. Number of species, individuals, records, and proportion of 'common' species for the four ecoregions in 
Venezuela and all 27 study locations combined. 
Ecoregion 
Species* 
Species 1, 
Individuals 1 
Records 1 
% 'common'* 
NonhCoast 
199 
227 
3.488 
2.347 
56 
N'WCordilleras 
302 
351 
2.506 
1.197 
41 
Llanos 
238 
271 
5.560 
2.673 
53 
Guayana 
339 
375 
3.560 
2.356 
37 
All combined 
593 
676 
15.114 
8.573 
27 
Based on daia from Survey I and Survey 2 combined. 
’ Raced on data from Ihe checklists. 
c Based on data from Survey I. 
