Occurrence of Caiman latirostris and Caiman yacare in the Middle Delta of the Paraná River, Argentina

Abstract

In Argentina, there are two species of the Crocodylia group, both belonging to the Alligatoridae family. The black caiman (Caiman yacare) is found in the provinces of Chaco, Corrientes, Formosa, Misiones, Salta, and Entre Ríos. The other species, the broad-snouted caiman or flat-faced caiman (Caiman latirostris) inhabits Chaco, Corrientes, Entre Ríos, Formosa, Jujuy, Misiones, Salta, Santa Fe, and Santiago del Estero (Prado et al., 2012). Both species were listed as Least concern in the IUCN Red List (Siroski et al., 2020, Campos et al., 2020). Historically, there have been anecdotal records of both species in various localities of the Middle Delta of the Paraná River in the north of Buenos Aires (Chebez, 2008). Restivo et al. (2011) mention that caimans occasionally use rivers for dispersal, thus reaching more southern latitudes than usual for them. They add that these are generally adult individuals, often males that move south in the summer, but it is unknown if they manage to survive the winter. The objective of this work was 1) record alligator occurrences in the Middle Delta of the Paraná River during the extraordinary downturn of the Paraná River that occurred between 2020 and 2022 and 2) confirm the winter survival of alligators in this area.