A preliminary survey of bobolinks (Dolichonyx oryziborus) in rice fields and natural grasslands in Argentina.

DI GIACOMO, ADRIÁN S.; LOPEZ LANÚS, BERNABE M.; DI GIACOMO, ALEJANDRO G.; BLANCO, DANIEL

Veracruz, México

Conferencia; VI North American Ornithology Conference.; 2006

American Ornithologist Union

During the summers of 2004/05 and 2005/06 we searched for concentrations of bobolinks (Dolichonyx oryziborus) in Argentina. We carried out surveys ad libidum and point counts in rice fields when the rice was at the milky stage, in the provinces of Formosa, Corrientes, Chaco and Santa Fe. In Formosa bobolinks are seen frequently, although flocks seen in grasslands close to the rice fields were no larger than 2,500 individuals. We failed to find bobolinks around Mercedes, Corrientes, where they are unknown and no conflicts between birds and rice production here either. In San Javier, Santa Fe, bobolinks use rice fields as roosting and feeding sites. We counted more than 100,000 individuals in sections of some roosts. In this rice-growing area bobolinks were more often found in rice crops of a ‘Long grain’ variety. During the day they use Paraná river grasslands too. In San Javier the bobolinks and Agelaius ruficapillus are combated often with pesticides that are not authorised for this use and which could lead to undesired effects on other animals. The bobolink concentrations in only one type of rice crop makes them more vulnerable to intoxication, although they could be advantageous as ‘habitat refuges’ for conservation purposes.