Abstract

From July 1993 until November 1998 the authors studied the distribution, abundance and habitat association patterns of four grebes species, White-tufted Grebe (Rollandia rolland); the Silver Grebe (Podiceps occipitalis), the Great Grebe, (Podiceps major), and the Pied-billed Grebe (Podilymbus podiceps), in a wetland of the Mediterranean zone of Chile. Possible relationships between these patterns and increased precipitation associated with El Nino-Southern Oscillation (ENSO) were also studied. The study was carried out in four wetland habitats over the 47 months. The results showed a positive correlation between the spring average abundance of these species and total rainfall in the previous year. Grebe populations increased in the summer of the year of the ENSO evens and peaked in the spring of the post-ENSO year. The patterns of habitat association did not change with the quantity of rainfall. In general, the four species were associated mostly with seasonal habitats, which are deep and hold abundant emergent vegetation. The Silver Grebe uses this kind of habitat to establish breeding colonies only during ENSO and post-ENSO years.