AVIAN RARITY IN 10 CLOUD-FOREST COMMUNITIES IN THE ANDES OF ECUADOR -IMPLICATIONS FOR CONSERVATION

Avian rarity was investigated in ten high-altitude cloud forests in th e Andes of Ecuador. Data on species compositions and abundances were o btained by a fully standardized method (standardization for area, alti tude, habitat, effort and seasonality). The rare species were isolated from rank-abundance plots on the basis of the quartile definition of rarity. A positive correlation between mean abundances of species and number of sites occupied suggests that high-altitude bird species clas sified rare by abundance generally can also be classified rare by rang e. However, it is necessary to be cautious using this result in rankin g conservation priorities since the generality is not obeyed by all sp ecies. Within the two abundance classes (contains one and two individu als, respectively) represented among the rare species, the one-individ ual class had significantly more species than the two-individual class . The quantitative rarity of taxa and ecological groupings produced si milar results for all sites, while pairwise similarity of rare species between sites was very low. Together with the difficulty of identifyi ng species that are truly rare by abundance, these results imply that sites selected for conservation preferably should be based upon a qual itative evaluation of lists of species referred to vulnerability categ ories such as endemic, restricted-range, CITES or IUCN threatened/near -threatened species. However, it is necessary also to incorporate othe r aspects of biodiversity to cover a full range of biotic diversity.