Areta • SONG AND MIGRATION IN SEEDEATERS 
693 
Areta et al. 2011). Songs of S. hypochroma have 
been separated into: (1) Corrientes (eastern popu¬ 
lations. Argentina), and (2) Bolivia (western 
populations. Bolivia) regiolects (Fig. IB; Areta 
2010). Songs of S. hypoxantha have been separated 
into: (1) Entre Rios (Argentina). (2) Corrientes 
(Argentina), (3) Formosa (Argentina). (4) south¬ 
east Brazil (Brazil), and (5) Bolivia (Bolivia) 
regiolects (Fig. 1C: Areta and Repenning 2011). 
Vocalizations display a geographic signature 
(i.e.. diagnostic acoustic features that are found in 
a limited area during the breeding period) and 
could be useful as indicators of a specific 
geographic origin. I investigated the correspon¬ 
dence between songs recorded during the breed¬ 
ing season in known breeding areas and songs 
recorded outside the breeding season in presumed 
wintering areas of S. nificollis. S. hypochroma, 
and S. hypoxantha. 
RESULTS 
Dark-throated Seedeater (.S', nificollis ).—I tape 
recorded a mixed-species Hock in the Beni 
savannas on 26 October 2006, close to the city 
of Trinidad (64 54' W. 14 50' S). Beni, Bolivia. 
1 visually identified adult males of .S', nificollis , S. 
hypoxantha. and S. hypochroma as part of the 
flock which had —200 Spomphila individuals. I 
found songs identical to that of 5. nificollis. 
belonging to an undetermined number of birds. I 
tape recorded a male on 16 June 2008 in the 
seasonally inundated cerrado of the Campos do 
Encanto (59 48' W. 15 03' S), close to Vila Bela 
da Santissima Trindade, Mato Grosso, Brazil. The 
bird was heard singing and was immediately 
identified as S. nificollis. I observed the singing 
male after the tape-recording. It had a yellow base 
to the lower mandible, light brownish-gray back, 
gray cap. light creamy-rufous belly, and had a few 
dark-brown feathers in the throat, making it 
identifiable to species based on plumage. The 
voice-type of both recordings is known to exist in 
males breeding in Entre Rios. Santa Fe. Buenos 
Aires (Argentina), Paysandu (Uruguay), and Rio 
Grande do Sul (Brazil). The minimum distances 
between wintering localities and the breeding area 
is — 1.800 km (Vila Bela-Paysandu) or 2,300 km 
(Vila Bela-Saladillo) (Fig. I A). 
Rufous-rumped Seedeater (S. hypochroma ).—I 
tape recorded a male on 16 June 2008 in the 
seasonally inundated cerrado of the Campos do 
Encanto, close to Vila Bela da Santissima 
Trindade, Mato Grosso, Brazil. The bird was 
heard singing and was immediately identified as 
S. hypochroma. 1 observed the singing male after 
tape-recording and it only displayed a few 
somewhat lighl-orangish feathers on the otherwise 
creamy throat. The belly had a few light-orangish 
feathers, and the back and cap were light-brown. 
This male was not possible to identify to species 
based on plumage features. This voice-type is 
known from males breeding in Corrientes and 
Santa Fe (Argentina). The minimum distances 
between the wintering locality and the breeding 
area is —1,500 km (Vila Bela-Esteros del Ibera) 
or 1.700 km (Vila Bela-Campo del Medio) 
(Fig. IB). 
Tawny-bellied Seedeater (S. hypoxantha ).—I 
tape recorded a male in the Beni savannas on 26 
October 2007. close to the city of Trinidad (64 
54' W. 14 50' S). Beni. Bolivia. The bird was 
heard singing and was immediately identified as 
.S', hypoxantha. The bird could not be seen while 
singing as it was hidden amid vegetation. Three 
birds were Hushed from the precise spot where the 
bird appeared to be singing. At least one was S. 
hypoxantha, but it did not show any diagnostic 
plumage feature. This voice-type is known 
exclusively from Entre Rios (Argentina), although 
presumably transient individuals were also re¬ 
corded at a locality in Santa Fe (Argentina). The 
minimum distance between the wintering locality 
and the breeding area is —2,150 km (Trinidad- 
Gualeguaychu) (Fig. 1C). 
DISCUSSION 
The large geographic area over which capuchi- 
nos are distributed during the non-breeding 
season, acquisition of confusing ‘eclipse’ plum¬ 
ages, sharing of habitats among species during 
w inter, and lack of, or scant genetic differentiation 
of several forms pose difficulties to understanding 
their migration patterns within South America. 
Vocalizations can partly overcome these difficul¬ 
ties, and reveal important biogeographic and 
ecological relationships between distant breeding 
and non-breeding areas for S. nificollis , S. 
hypochroma . and 5. hypoxantha (Fig. 1). Sample 
sizes of recordings of wintering birds are small, 
but geographic coverage and sample sizes of 
breeding birds are satisfactory: thus, the migration 
patterns uncovered are unequivocally supported 
by my data. 
The Cerrado region and the upland Amazonian 
savanas ot Humaita (Brazil) were recognized as 
two important wintering areas for S. nificollis 
