The only previous density estimate made in Cat Tien National Park was that by Robson et al. (1991), who recorded 17 calling birds in approximately View the MathML source in the center, southeast and northeast part, giving a density estimate of about 1.31 calling birds/km2. The density estimation from our survey in 2012 was 3.03 and 4.69 calling birds per square kilometer in the southeast and center part respectively. In contrast to Yok Don National Park, the density estimates in these two areas of Cat Tien National Park were higher in 2012 than in 1991.