Nestedness of insular avifaunas: simple summary statistics masking complex species patterns

Abstract

Nestedness patterns have been recommended as a guide in designing refuges . The birds of three island archipelagoes and one set of mainland quadrats display strongly nested patterns, exactly as do most systems studied in this way. Nestedness maybe expressed by several statistics, which are likely to be highly correlated, and may be viewed from either the community-wide or individual species vantagepoint . The latter is more informative. Individual species' nestedness scores can be similar even though the ecological forces generating them differ greatly. Nestedness scores based on island or site area are not directly comparable to those based on species richness . It is neither intuitively apparent nor empirically demonstrated that extinction would produce characteristically different nestedness scores than would colonization . Nestedness statistics are closely related to incidence functions in the ecological literature and to SLOSS comparisons in the conservation literature . None of these statistics is likely to provide much insight into refuge design .