摘要：Indicator species may provide useful substitute for large scale surveys to monitor biodiversity. Weconducted surveys in the Afro-alpine habitats of the Bale Mountains National Park (BMNP) with theobjective of identifying indicators for the species richness of the raptor guild. Raptors were countedby scan sampling technique from a suitable vintage point. Three classes of 18 sample units groupedaccording to the variability of the moorland ecosystem in the magnitude of process variables importantfor raptor species richness were used in determining the indicator value of species as a function oftheir abundance concentration and the percentage of species occurrence per sample group. Thisprocedure determined indicator values for all species in the resident raptor community. Comparisonwith randomly expected values demonstrated that only Aquila verreauxii and A. chrysaetos haveindicator values that were significantly larger than the randomly expected values. The species richnessestimated using the abundances of these two species predicted the observed species richness of thewhole community in a linear regression model that explained 66% of the deviance in the data set.Furthermore, the species richness of the community predicted by process variables had correlation ofvery high significance with that predicted by the indicator species. We have thus identified twoindicator species to a raptor guild of the BMNP and demonstrated that these two species encapsulatedmost of the information regarding the species richness response of the guild to key process variablesin the Afro-alpine moorland ecosystem. Our findings contribute significantly to current and futureefforts of monitoring the biodiversity of the park providing a cheap and quick means of data generationrelevant for making management decisions.
