BOBOLINK (DOLICHONYX ORYZIVORUS) NUMBERS AND NON BREEDING ECOLOGY IN THE RICE FIELDS OF SAN JAVIER, SANTA FE PROVINCE, ARGENTINA

摘要: – The Bobolink (Dolichonyx oryzivorus) breeds in temperate North America and migrates winter to southern South America. During the non-breeding season, this species occupies grasslands, marshes, rice fields Paraguay, Bolivia, Brazil Argentina. Since 1960 s, a population decrease has been noted, largely due modification of breeding habitat. It is thought that these changes habitat Bobolink’s association with crops could be related their decline, although information concerning distribution ecology during season scarce. objective study was asses value near San Javier (Santa Fe Province) as nonbreeding area for migratory Bobolinks. We present data on abundance use. Fields surveys were carried out November 2004 March 2005. used circular plot sampling incidental observations count Bobolinks fields. Besides, we made interviews farmers assess knowledge about species. While no observed, recorded pairs, small groups (20-100 ind.), large flocks (1000 10,000 ind.) fields, when “milky stage”. observed maximum approximately individuals ~50 ha field. These results demonstrate species’ strong crop, which it finds food shelter, especially comes into milky stage. Interviews confirmed considered pest by farmers, who apply various control methods area. recommend further studies conducted region Javier, well other areas throughout its range, order investigate potential threats populations. Accepted 28 April 2007.