Regnet, R. A., F. M. Quintela, O. M. Entiauspe-Neto, V. H. Teixeira, F. L. Silveira & D. Loebmann

Remarkable aggregation of squamates and caecilians associated with flood events during El Niño in southern Brazil. pp. 537-540.

Abstract. The effects of the El Niño Southern Oscillation (ENSO) on biota remain poorly understood, despite the fact that this atmospheric-oceanic phenomenon influences both aquatic and terrestrial life forms worldwide. Herein, we report on a massive aggregation of thousands of squamate reptiles and caecilians that were drifted after a period of heavy rainfall. We surveyed a linear transect of 1,000 metres in length and 25 metres in width on a tourist beach in the Patos Lagoon in southern Brazil during five consecutive days. A total of 2,152 amphibians and reptiles were registered, with the majority of 2002 (99.5%) belonging to the Pampean water snake species, Helicops infrataeniatus. Similar events of inundation with subsequent massive drifts of herpetofaunal elements have occurred in this region at least four times in the past decades, all associated with strong El Niño years.

Key words. El Niño Southern Oscillation (ENSO), aggregation, squamate reptiles, caecilians, drift, Pampean water snake, Helicops infrataeniatus.