A survey of a pampas deer, Ozotoceros bezoarticus leucogaster (Arctiodactyla, Cervidae), population in the Pantanal wetland, Brazil, using the distance sampling technique

The pampas deer is an endangered South American species which occurs in open grasslands and savannas. This aim of this survey was to evaluate the use of the distance sampling technique to estimate densities of the species in the Pantanal wetland, as well as to analyze the applicability of the method for a monitoring program. The surveys were conducted on roads from vehicles and also on foot along 26 parallel transects in November 1999 and 2000 at Campo Dora ranch, south-central Pantanal, Brazil. Deer densities were estimated using the program DISTANCE, and the program MONITOR was used to run a power analysis to estimate the probability of detection of a decline in the population. The deer density estimated from vehicles, with data from both years, was 9.81±3.8 individual/km2, and 5.53±0.68 individuals/km2 from transects sampled on foot. The power analysis of these data revealed a monitoring program would require at least two surveys per year over seven years to obtain a 90% chance of detecting a 5% decline in the population. Our results also indicate surveys from roads are not recommended for pampas deer counts as the animals appear to keep a relatively safe distance from cars.