Terrestrial activity of Caiman in the Pantanal, Brazil

Abstract

Coordinated terrestrial movement has not previously been reported in crocodilians. However, between 1989 and 1999, 94% of 525 Caiman crocodilus yacare found on land in the Pantanal were in coordinated groups (n = 73) walking head to tail and forming nearly straight lines. Caimans left pools and initiated terrestrial movements spontaneously and in response to disturbance by researchers and hunters. The sex ratio of the groups was biased toward males (0.8 ± 0.24) and was similar to that found in aquatic habitats in the study area. However, two groups consisted only of females. When caimans left pools subjected to disturbances, such as hunting and capture for research, they walked head to tail in lines. Caimans that left pools in response to disturbance buried in mud near pools or in leaf litter in forest.