Temporal Fluctuations in Raptor Abundances in Grasslands of Southeastern South America

Abstract

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Variable Seasonal Movement Dynamics among Individual Snail Kites (Rostrhamus sociabilis) in South America

“…These results provide the first evidence that individual Snail Kites undertake both short-and long-distance movements in South America, with some utilizing major wetland areas such as the Pantanal, and multiple river basins such as the Amazon, Araguaia-Tocantins, Paraná-Paraguay, and Mamoré, within the same year. The differences in the extent of individual movements within and between years agree with the highly variable seasonal and yearly abundance of Snail Kites observed in the southern portions of their range (i.e., Uruguay, Argentina and Rio Grande do Sul, Brazil; Arballo and Cravino 1999, Bencke 2001, Juhant 2010, Zilio et al 2014.…”

“…Lees and Martin (2015) found that the Rufous-thighed Kite (Harpagus diodon) is migratory within Brazil, and Olivo (2003) reported that the White-tailed Hawk (Geranoaetus albicaudatus) migrates through the center of the continent. Additionally, Zilio et al (2014) reported that the White-tailed Hawk, previously thought to be resident in southeastern South America, is actually partially migratory.…”

“…In northern Argentina, Snail Kites are seen migrating in large numbers in May and June (Capllonch 2004), and are observed arriving in Uruguay in September then departing in April (Arballo and Cravino 1999). It is thought to be a partial migrant in southern Brazil (Albuquerque et al 1986, Belton 1994, Bencke 2001, Zilio et al 2014) and the Chaco ecoregion of Argentina and Paraguay (Short 1975, Hayes 1991. Nevertheless, its movements are unpredictable, as the species may be abundant in a given region in one year, but scarce in other years (L. Bugoni unpubl.…”

Geographical variation and current knowledge on breeding traits of vultures in the neotropics

“…This might relate to the larger sizes attained by adults of wholly Nearctic subspecies (Wetmore 1964;Ferguson-Lees and Christie 2001), therefore agreeing with Bergman's body mass rule, as stated by Campbell (2015). Overall, our analysis does not seem to support Jaramillo's (2003) proposal of a split in Cathartes aura, even though this would require elucidation of other aspects of its biology as well, such as migratory behavior (Olmos et al 2006;Zilio et al 2014).…”

Variable Seasonal Movement Dynamics among Individual Snail Kites (Rostrhamus sociabilis) in South America

“…These results provide the first evidence that individual Snail Kites undertake both short-and long-distance movements in South America, with some utilizing major wetland areas such as the Pantanal, and multiple river basins such as the Amazon, Araguaia-Tocantins, Parana ´-Paraguay, and Mamore ´, within the same year. The differences in the extent of individual movements within and between years agree with the highly variable seasonal and yearly abundance of Snail Kites observed in the southern portions of their range (i.e., Uruguay, Argentina and Rio Grande do Sul, Brazil; Arballo and Cravino 1999, Bencke 2001, Juhant 2010, Zilio et al 2014.…”