Accipitridae Vigors 1824

Accipitridae

Harpagus diodon (MGT): breeds from August to April in the Atlantic Forest and in forest fragments in the Cerrado, and overwinters mainly in the equatorial forests of the Amazon Basin with some individuals staying further north in the Guiana Shield (Cabanne & Seipke,2005; Lees & Martin, 2014). The species needs to be better studied in the Atlantic Forest in the northeastern region of Brazil to determine if records in austral winter are of a resident population, vagrant individuals (Lees & Martin, 2014) or overwintering individuals from the south (B. Whitney, pers. obs.). In RS, where it is considered rare, there are records in October, November and May (Belton, 1994).

Ictinia mississippiensis (MGT): occurs in southern central USA from Kansas, Arizona and New Mexico south to Florida (White & Marks, 2016).It breeds in North America and overwinters in South America (Ferguson-Lees & Christie, 2001), especially in Paraguay, southeastern Bolivia, southwestern Brazil and northeastern Argentina (White & Marks, 2016). It breeds in North America between May and July and pre-migration flocks gather in early August in groups of 200-300 birds that move south in early September (Thiollay, 1994). The migration south between September and November seems to be through the foothills of the Andes as far as the Amazonian lowlands (Stotz et al., 1992). From December to February, the species is found in central South America, where the Chaco forest is its main wintering site (Juhant & Areta, 2013). The migration north occurs from late February to April departing from central and northern Argentina, over the Colombian Andes (Juhant & Areta, 2013). In Brazil, this pattern is supported by records from RO, MT, MS, PR and RS (WikiAves, 2016) and by data from AM, PA and MG (Stotz et al., 1992; Vasconcelos et al., 2008 a, 2011) that are restricted to the period between September and March. The scarce records of this species for South America during austral winter are of juvenile individuals (Juhant & Areta, 2013) that probably got lost during migration (Bildstein, 2004).

Buteo platypterus (MGT): breeds from central Canada to southern USA and virtually its entire population (except birds from southern Florida) migrates to South America during boreal winter and reaches northwestern Brazil, with some of the birds covering up to 8,800 km (White et al., 1994) in very large flocks (Bildstein, 2004). In Brazil, it occurs mainly in the Amazon Basin, but there are some records in the Cerrado and the Atlantic Forest, with no apparent flocks forming. It can be observed from October to March in the Amazon region and in the Pantanal (in spite of one record for MT in June), and in the southeastern and southern Atlantic Forest – in RJ, MG, PR, SC and RS – from November to January (WikiAves, 2016; MNRJ; MZUSP, MPEG).

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).