Cape sugarbird & orange-breasted sunbird population and visitation on Protea species, Western Cape, Fynbos, 04-09 2012

We estimated the population size of Cape sugarbirds and orange-breasted sunbirds in 26 study plots (200x200m, 110x110m core zone) and visitation rates of birds of the two species (number of bird visit during 45 minutes) on 1333 focal plants of 17 Protea species (Protea burchellii, P. coronata, P. compacta, P. cynaroides, P. eximia, P. laurifolia, P. lepidocarpodendron, P. longifolia, P. lorifolia, P. mundii, P. nana, P. neriifolia, P. nitida, P. obtusifolia, P. punctata, P. repens, P. susannae). We investigated the effects of resources (standing crop of nectar sugar) provided by the Protea plants in the study sites on the avian population sizes (max. number of simoultaneous birds observed in 10min point count surveys within 30m distance from the observer) and per-plant visitation rates. We mapped all overstorey Protea plants (19 species) and estimated the temporal variation in standing crop of nectar sugar for each mapped plant.