. Bonn zoological bulletin. Zoology. 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 cumulative nunihei of search days Fig. 4. Reptile species sample-based rarefaction curve with fitted 4-parameter Weibull function. ~^ji~> "1 9 11 13 15 17. ^^T^*— negative exponential 3-parameter Weibull - - - 4-parameter Weibull Chapman-Richards search days Fig. 3. Deviations of the fitted models from the sample-based rarefaction curve (residuals). has reached a more or less stable level. A similar result (unpublished) was obtained on the basis of a dataset that underlies a study of Bornea
. Bonn zoological bulletin. Zoology. 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 cumulative nunihei of search days Fig. 4. Reptile species sample-based rarefaction curve with fitted 4-parameter Weibull function. ~^ji~> "1 9 11 13 15 17. ^^T^*— negative exponential 3-parameter Weibull - - - 4-parameter Weibull Chapman-Richards search days Fig. 3. Deviations of the fitted models from the sample-based rarefaction curve (residuals). has reached a more or less stable level. A similar result (unpublished) was obtained on the basis of a dataset that underlies a study of Bornean snakes (Van Rooijen 2009): the 4pW-based estimate reached an approximately stable plateau rather early with the CR- and 3pW-based estimates approaching the 4pW-based estimate with increasing search days. On the basis of these results, the 4pW-based estimate, 69, is assumed to be the least biased. Finally, the estimate based on the nonparametric Chao I estimator, 62, agrees reasonably well with the 4pW-based estimate. Taking the average, 65 reptile species are expected to inhabit Pangkor Island. As for amphibians species richness, the fitted 4pW and Chao I estimator both resulted in an esti- mate of 17 species. Figure 4 depicts the sample-based rarefaction curve as well as the fitted 4pW. The only noticeable deviation of the fit- ted 4pW from the rarefaction curve lies in the fact that it passes through (p,0) instead of the origin (0,0). The close fit of the 4pW is in agreement with results obtained in studies of avian diversity (Flather 1996), snake diversity (Van Rooijen 2009) and diversity of small reptiles (Thompson et al. 2003). The progression of the rarefac- tion curve clearly indicates that an asymptote has not yet been reached, thus the surveys have not been exhaustive. Figure 5 shows how the richness estimates (as opposed to observed richness or fitted model-values) develop with increasing search days during the second half of the sur- vey. The NE is neglected due
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