PRELIMINARY EVALUATION OF SAMPLING STRATEGIES TO ESTIMATE THE SPECIESRICHNESS OF DIURNAL, TERRESTRIAL BIRDS USING MONTE-CARLO SIMULATION

Various environmental stratifications for estimating the total bird sp ecies richness across the south east region of Australia were evaluate d using Monte Carlo simulation techniques. This was possible because o f the availability of gee-referenced point data for the birds observed in the region that could be generally associated with a set of primar y environmental attribute data. The bird data set consisted of a total of 173 species recorded from 1,075 sites. Several stratification opti ons were assessed including: random sampling; sampling within gradsect s positioned to span some of the region's major environmental gradient s; sampling within stratifications based on climate attributes; and sa mpling within a stratification based on climate and substrate variable s. Variation in Sample size was the most important factor affecting es timates of bird species richness. Several limitations associated with the origins of the bird data set and the distribution of the bird site s across the region dictated what could be achieved by the simulation study. We discuss some of the problems and limitations associated with the use of existing data sets to investigate biological issues at a r egional scale. (C) 1997 Elsevier Science B.V.