Movement of Captive-Released Orinoco Crocodiles (Crocodylus intermedius) in the Capanaparo River, Venezuela

Abstract

To test the feasibility of using captive-reared Orinoco crocodiles to restock depleted wild populations we used radio-telemetry to monitor eight crocodiles (103.3-139.3 cm total length) released in the Capanaparo River in southwestern Venezuela. Crocodiles were located every 1-2 d from April 1991 to March 1992 to determine movement patterns, survivorship, and growth rates. The crocodiles moved consid- erably during the first month following release, and the maximum distance moved was 11.6 km upstream by one crocodile four months after release. However, following an initial period of movement, crocodiles became more sedentary and by the end of the study the maximum distance from the point of release was less than 8 km. Six of the eight crocodiles moved upstream while two moved up to 3.3 km downstream. Crocodiles remained principally along the main course of the river in areas with mixed shallow and deep water habitats and abundant sand beaches. As the river rose during the wet season, crocodiles remained in the same areas, but moved into shallow-water areas among flooded riparian vegetation. The mean growth rate of released crocodiles (0.079 cm TL/day) was similar to that of smaller wild-born juvenile crocodiles. One animal was accidentally killed by a local resident who was hunting spectacled caiman. Based on the results of this study, we feel that a carefully designed program of releases of captive-reared crocodiles can be an effective conservation tool to speed the recovery of depleted populations of Orinoco crocodiles. How- ever, care must be taken to insure that the release program is designed as one component of an overall crocodile strategy and not an excuse to avoid the onerous issues of the protection of wild crocodile popu- lations and their habitat