Buteo swainsoni (MGT):breeds in central and western North America and migrates to South America in boreal winter, especially to northern Argentina, southern Brazil and Paraguay (White et al., 1994). It apparently moves through the inland of the continent heading to the Pampas in Argentina, Uruguay and Brazil and it overwinters on the Atlantic coast in southern Brazil (Antas, 1987; Sick, 1997). It is suspected that age separation exists since there is a great concentration of juveniles in Argentina (White et al., 1994) and of immature individuals in Brazil (Sick, 1997) during boreal winter. Studies with satellite transmitters showed that this species gathers on the eastern coast of Mexico and flies from there mainly along the Pacific coast and eastern Andes until it reaches central Argentina, and there are some localized records for instance for RR (Stotz et al., 1992; White et al., 1994). Radio-satellite data showed that the northbound and southbound migration routes use similar paths comprised almost entirely of continental stretches, except in Central America, where some coastal stretches are used (Fuller et al., 1998). One individual banded in Oklahoma (USA) was recovered in AC in February and one chick banded in Alberta (Canada) in August was recovered in November of the same year in RS (Belton, 1984; Sick, 1997). This species can be observed in Tocantins (TO) in March and August (Dornas & Pinheiro, 2011) and in RJ, SP, PR, SC and RS between November and January, and a flock of over 100 individuals has also been reported in AM in November (WikiAves, 2016). Additionally, there is one collected specimen from SC in October (MZUSP 92336).