The importance of berries of some invasive shrub species in the diet of birds in an urbanised habitat in South African grasslands

Abstract

Fruits play an important role as a source of diet for many bird species in southern Africa. In some areas, e.g., in the Highveld, planting of fruit trees and berries in urbanised areas may cause expansion of the population and the range of some frugivore birds. A study on birds feeding on fruits was carried out in an urbanised habitat in the Highveld. Out of 51 bird species recorded in the study area, four were found to feed regularly on berries of exotic tree/shrub species, namely Onychognathus morio, Pycnonotus nigricans, Zosterops pallidus, and Colius striatus. In the dry season, Pyracantha angustifolia was by far the most important in that regard (62.5%), followed by Melia azedarach (21.1%). Other exotic berry species were picked much less often. Birds fed on berries mostly in June, July and August, i.e., in the dry season (85% of recorded birds). Although berries were still available later, they were taken by birds only sporadically. This study suggests that, at least in grasslands and semideserts of southern Africa, planting fruit trees and shrubs in urbanised areas may contribute to the expansion of the range and/or the population increase of some frugivorous species.