Long distance movements by Caiman crocodilus yacare: Implications for management of the species in the Brazilian Pantanal

Abstract

Movement patterns of caimans were studied over a 16-year period in two areas of the Brazilian Pantanal, one dominated by intermittent rivers and another, adjacent region of many isolated lakes. We marked caimans in 100 lakes (1986-2001) and two rivers (1987-1999). We recaptured 163 adult males, 132 adult females and 237 juveniles. In a two-year interval, hatchlings moved only within the lake area or within the river area and the maximum distance moved was 6.0 km (mean=0.5 km, SD=1.0) in the lake area, and 1.25 km (mean=0.6 km, SD=0.3) in the river area. In a period of one year, females and males larger than 40 cm snout-vent length moved similar distances in both areas (max.=9.8 km). We monitored 47 adult caimans by radio-telemetry in the river area for about a year. The size of the area used by telemetered individuals over periods of 30 to 436 days varied from two to 1649 ha. The areas used by five males in sites subjected to experimental hunting were similar to those used by five other males in areas not subjected to hunting. In periods of 1-5 years, females and males larger than 40 cm SVL moved maximum distances of 16 and 18 km, respectively. Five individuals marked as hatchlings in the lake area were recaptured as adults after intervals of 5-15 years. The extensive long-term and short-term movements by caimans mean that individual ranches should not be considered independent management units for sustained use of caimans in the Pantanal.