Areta • SONG AND MIGRATION IN SEEDEATERS 
689 
At least two species have migratory and resident 
populations: the population of S. hypoxantha of 
eastern Formosa is resident with birds gathering in 
wintering flocks and wandering over local grass¬ 
lands (Di Giacomo 2005 k and a presumably 
resident population of S. ruficollis inhabits the 
Alto Madidi Savannas (Areta et al. 2011). These 
data show the existence of complex spatial and 
temporal associations of several species. For 
example, some species migrate together in 
mixed-species flocks, but later breed in close 
proximity but in different habitats, and finally 
take divergent migration routes to their non¬ 
breeding areas. The mechanisms and patterns 
behind this bewildering complexity have yet to be 
unraveled. 
Three main reasons account for the scant 
knowledge of migration of capuchinos. First, 
sampling effort has been low in the relevant areas 
(Silva 1999). Second, it can be difficult to reliably 
identify capuchinos to species based on plumages 
during winter (Pcarce-Higgins 1996, Sick 1997. 
Areta 2009. Kirwan and Areta 2009). Third, the 
birds are too small to follow with tracking devices. 
Movements between breeding and non-breed¬ 
ing areas are unknown for any individual of the 
migrant populations of capuchinos. Use of 
vocalizations seems a potentially powerful way 
to uncover the details of their migration patterns 
given the lack of genetic differentiation reported 
to date (Lijtmaer et al. 2004, Campagna el al. 
2011). and the diagnostic differences in their 
voices (Areta 2008, Areta and Repenning 2011, 
Areta el al. 2011). 
Vocalizations have been used successfully to 
reconstruct the migratory trajectory of some birds, 
but this approach has seldom been used in the 
Neotropics (Dowsett-Lemaire 1979; see Chu 
2001. Marler and Slabbekoorn 2004: 129). 
Schwartz (1975), in a unique study of the 
Sporophila, demonstrated the existence of two 
divergent migratory routes and breeding areas ol 
Lined Seedealers (.S', lineula) based on their 
vocalizations. This method allowed for a more 
precise delineation of the migration routes of 5. 
lineola (Silva 1994. Neto and Vasconcelos 2007); 
it was later proposed that further work with 
vocalizations of .S', lineola might show the 
existence of other geographical variants (Areta 
and Almiron 2009). 
My objectives are to: (1) present data that 
demonstrates that non-breeding male S. ruficollis, 
S. hypochroma , and S. hypoxantha in wintering 
areas can be assigned to a particular distant 
breeding population based on their vocalizations, 
(2) evaluate the potential contribution of vocal 
variation in other capuchinos to understand their 
migratory movements, and (3) use vocalizations 
to unravel migration patterns in capuchinos. 
METHODS 
I recorded vocalizations of all species using 
different microphones (audioTechnica 815b. 
Sennheiser ME-67 protected with a Rycote 6 Kit 
|shock-mount, windshield, and windjammer], 
Sennheiser ME-62 mounted on a Telinga Univer¬ 
sal Parabola or on a 60-cm parabola), and tape 
recorders (Marantz PMD-222. PMD-661, and 
Sony TC-D5M). Spectrograms were prepared 
using Syrinx 2.1 (John Burt, www.syrinxpc. 
com). Additional recordings were provided by 
other investigators (Appendices 1. 2). All record¬ 
ings by JIA are archived at the Macaulay Library 
of Natural Sounds (MLNS, Cornell Laboratory of 
Ornithology. Ithaca. NY. USA). The comparative 
data set for this study consists of recordings of the 
vocalizations of 348 individuals of all species of 
capuchinos from 49 localities (Fig. 1; Appendices 
I. 2; Areta 2008, 2010; Areta and Repenning 
2011; Areta et al. 2011). 
Songs of capuchinos include many different, 
non-repetitive, and morphologically complex 
notes. 1 characterized notes which, based on shape 
(including duration and frequency distribution) 
and relative position in the songs, could be 
identified unambiguously despite variation among 
individuals. The frequency of occurrence of these 
notes in individuals was compared within and 
among populations. The analysis was limited to 
sexually mature males, identified based on the 
possession of fully adult plumages. Only male 
capuchinos arc known to sing regularly, while the 
repertoire of females usually consists of high- 
pitched notes (Areta 2008; JIA, unpubl. data). 
Males of three species of capuchinos. S. ruficollis , 
5. hypochroma, and S. hypoxantha sing different 
songs depending on where they breed, and 
different macrogeographic song variants or re- 
giolects ("song variants encompassing extensive 
subpopulations of a species and all individuals 
within this large range’' Martens 11996:2211) 
have been defined based on the presence of 
diagnostic notes in their vocalizations. The known 
song types of 5. ruficollis have been separated 
into; (1) Mesopotamia (Argentina), and (2) Apolo 
Madidi Savannas (Bolivia) regiolects (Fig. I A; 
