Species Turnover Rates on Islands: Dependence on Census Interval

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Science  15 Jul 1977:
Vol. 197, Issue 4300, pp. 266-270
DOI: 10.1126/science.197.4300.266


Measurements of species turnover in island bird communities demonstrate two trends with increasing census interval t: (i) Apparent turnover rates T decrease greatly with t, and (ii) the coefficient of variation of T decreases asymptotically to a constant value. These effects are predicted by a statistical model whose parameters are the immigration and extinction probabilities of each species. Available bird censuses at intervals of decades underestimate turnover rates by about an order of magnitude.