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BirdLife International's Important Bird Areas (IBA) program is the most developed global system for identifying sites of conservation priority There have been few assessments, however, of the conservation value of IBAs for nonavian taxa. We combined past data with extensive new survey results for Uganda's IBAs in the most comprehensive assessment to date of the wider biodiversity value of a tropical country's IBA network. The combined data set included more than 35,000 site x species records for birds, butterflies, and woody plants at 86 Ugandan sites (23,400 km2), including 29 of the country's 30 IBAs, with data on additional taxa for many sites. Uganda's IBAs contained at least 70% of the country's butterfly and woody plant species, 86% of its dragonflies and 97% of its birds. They also included 21 of Uganda's 22 major vegetation types. For butterflies, dragonflies, and some families of plants assessed, species of high conservation concern were w'ell represented (less so for the latter). The IBAs successfully represented wider biodiversity largely because many have distinctive avifaunas and, as shown by high cross-taxon congruence in complementarity, such sites tended to be distinctive for other groups too. Cross-taxon congruence in overall species richness was weaker and mainly associated with differences in site size. When compared with alternative sets of sites selected using complementarity-based, area-based, or random site-selection algorithms, the IBA network was efficient in terms of the number of sites required to represent species but inefficient in terms of total area. This was mainly because IBA selection considers factors other than area, however which probably improves both the cost-effectiveness of the network and the persistence of represented species.

Complementarity analysis based on overlaying large numbers of species distribution maps is increasingly being employed by conservationists to determine conservation priorities. This method is used because of its efficiency in representing selected species in a minimal number of areas, thus maximizing the number of conserved species in relation to area. As such analyses are mostly based on coarse spatial scales, it is essential to test the efficiency and accuracy of these methods, and to develop supplementary analyses that allow us to translate the result into identification of conservation sites of a manageable size. Here we test the effectiveness of a coarse-scale (continent-wide) analysis using a more detailed (nation-wide) logical inductive model based on point records. We find that, although there are differences in the effectiveness at these scales, most of the areas identified by the fine-scale data are nested within those identified by the coarse approach. We also find that areas identified as important for birds fit well within the current national focal areas for conservation in Uganda. [ABSTRACT FROM AUTHOR]

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