GENETIC VARIABILITY BETWEEN BREEDING AND NON-BREEDING POPULATIONS OF THE BLACK SKIMMER (Rynchops niger intercedens) IN SOUTHERN SOUTH AMERICA: FIRST INSIGHTS ON POPULATION CONNECTIVITY

ROCIO MARIANO Y JELICICH; ENRIQUE MADRID; PAMELA S. DEL FRESNO; MARCO FAVERO

Cusco

Congreso; IX Congreso de Ornitologia Neotropical, VII Congreso Peruano de Ornitologia. Cusco, Peru 2011; 2011

The Black Skimmer (Rynchops niger) is a neotropical bird widely distributed in South America. In Argentina, anecdotal reports from small colonies of R. niger intercedens on the breeding grounds next to rivers, contrasts with the high numbers registered in nonbreeding grounds on the southeastern coast of Argentina (up to 10,000 non-breeders in Mar Chiquita Coastal Lagoon). Even though differences in breeding phenologies occur between colonies in Brasil and Argentina, the observed contrast in bird abundances raises the question of the existence of a non-breeding mixture of birds proceeding from colonies distributed throughout major South American hydrological basins. In this study we analyzed the molecular polymorphisms between skimmers’ populations from Brasil and Argentina. Significant genetic differentiation was detected between sampling sites providing evidence that South American populations of the black skimmer are not completely panmictic. Moreover, results suggest the existence of two genetic groups, one formed by the Brasilian population and another including Argentinean sites. Higher genetic diversity was observed in Mar Chiquita population, which is consistent with the hypothesis that this site is a converging wintering area for multiple skimmers groups. Based on the molecular analysis presented here, we suggest that populations from Brasil and Argentina should be managed separately until further information about the connectivity between these areas is found. Ongoing studies including additional colonies will reinforce these results. Mar Chiquita should be consider a key wintering /stopover area where several populations of skimmers seems to be converging, being a critical and important site for the conservation and management of this species.