A review of the impacts of control operations against the red-billed quelea (Quelea quelea) on non-target organisms

Abstract

Spraying with the organophosphate fenthion has been the predominant means to control the red-billed quelea (Quelea quelea), a major bird pest throughout semi-arid regions of sub-Saharan Africa, for more than forty years. A review of known effects of fenthion and other control measures used against Q. quelea on non-target organisms, provides a basis for comparisons with any alternative chemical control agents. Birds of prey, owls and passerines have been commonly reported casualties of spraying with fenthion over land. Moreover, fenthion is known to have negative effects on aquatic invertebrates, in particular on populations of crustacea, which predicates against its use near water bodies. Non-target species may be affected directly by spraying, but predatory birds, scavenging birds and even mammals can be contaminated by secondary poisoning when they eat Quelea carcasses found up to 20 km or more from the primary control site. To avoid secondary poisoning, where possible quelea carcasses should be removed from a site after spraying. The use of explosions to kill roosting quelea birds has similar effects to those of fenthion in terrestrial habitats, killing non-target species including birds of prey and owls. Another control method, harvesting quelea as a source of protein, is benign and could contribute to local nutritional and economic needs. However harvesting is unlikely to reduce quelea populations substantially. Integrated pest management (IPM) approaches are recommended to minimize environmental damage, but until these are successfully adopted, standardized procedures for comparative assessments of the effects of quelea control are required.