Species richness estimation of bird communities: how to control for sampling effort?

Since estimates of total species richness increase with sampling effort, me thods to control for this sampling effect need to be tested and used. We pr esent seven non-parametric and 12 accumulation curve methods that have been used recently in the ecological literature. To test their performance, we used data from bird communities in the Queen Charlotte Islands, Canada. The performance of each method was evaluated by calculating the bias and preci sion of its estimates against the known total species richness. For our dat a set, the two Chao estimators were the overall least biased and most preci se estimation methods, followed by the two jackknife estimators, thus suppo rting results of previous studies. Nonparametric estimators tended to perfo rm better than accumulation curve models. Most estimation methods had the p roblem that they tended to underestimate species richness for early samples , but slightly overestimated it for late samples. We briefly discuss the pr actical use of these methods which may greatly increase our ability to answ er ecological questions and to guide conservation decisions, especially for species-rich tropical bird communities.