Table 1. Estimates of orangutan density and population size in different vegetation types, kilometric indices for areas where no density estimate could be obtained, and total population estimate for the two concession areas.
| Type of habitat | Number of nests | Survey effort (km) | Kilometric index (nests/km) | Mean nest decay rate (lower– upper estimate) | Mean density of orangutans (ind/km2) (lower– upper estimate) | Area (km2) | Mean number of orangutans (lower– upper estimate) |
| SRH planted areas | 167 | 31.5 | 5.3 | 123 (102–144) | 1.45 (1.24–1.75) | 314.2 | 456 (390–550) |
| SRH buffer zone | 272 | 22.65 | 12.0 | 21.7 | |||
| SRH conservation areas | 92 | 10.03 | 9.2 | 153 (60–243) | 1.76 (1.11–4.5) | 68.0 | 120 (75–306) |
| SRH unplanted areas | 84 | 10.64 | 7.8 | 222 (119–323) | 1.34 (0.92–2.5) | 585.6 | 785 (539–1464) |
| SHJ planted areas | 101 | 7.32 | 13.8 | 72.3 | |||
| SHJ conservation areas | 38 | 1.48 | 25.7 | 4.45 | |||
| SHJ unplanted areas | 183 | 6 | 30.5 | 118.5 | |||
| POPULATION ESTIMATE | 1361 (1004–2320) | ||||||