Alien Birds in Sub-Saharan Africa: An Overview

Introduced species may pose one of the biggest threats to biodiversity conservation. Today, monitoring their status, distribution and abundance constitutes an important part of ecological and conservation studies throughout the world. In the Afrotropical Region (sub-Saharan Africa), avian introductions have attracted the attention of many researchers, but there is a lack of a comprehensive review of this subject on a continental scale. The presented paper constitutes an attempt to overview the status, distribution, threats and control measures of birds introduced to sub-Saharan Africa in the last 200 years. This review lists 146 bird species introduced to sub-Saharan Africa. Only 49 (33.6%) of them have developed viable populations and only 7 (4.8%) became invasive species, namely Passer domesticus, Sturnus vulgaris, Acridotheres tristis, Corvus splendens, Columba livia var. domestica, Psittacula krameri and Pycnonotus jocosus. Data on distribution of most introduced species are provided, together with information on the place and year of their first introductions. For Passer domesticus and Columba livia var. domestica, data on population densities are also provided from several southern African towns. The most speciose groups of introduced species were parrots (Psittaciformes), comprising 33.6% (including Psittacidae: 13.7%; and Psittaculidae: 15.1%); Anatidae: 12.3%; Phasianidae: 11.0%; and Passeriformes: 30.1%. Most avian introductions in sub-Saharan Africa took place in Southern Africa (mainly the Cape Town, Durban and Johannesburg areas) and in Madagascar and the surrounding islands (mostly Mauritius, Reunion and Seychelles). Most introduced species which have developed viable populations originate from the Afrotropical, Oriental and Palearctic regions (altogether 78%), with only 2% from the New World. The proportions among the introduced species which have not established viable populations are quite different: 29% from the New World and only 60% from the Afrotropical, Oriental and Palearctic regions. The main factors affecting successful avian introductions and introduction pathways have been identified. A review of the control measures undertaken in sub-Saharan Africa (mainly in small oceanic islands) is outlined for the following species: Passer domesticus, Acridotheres tristis, Corvus splendens, Pycnonotus jocosus, Foudia madagascariensis, Psittacula krameri and Agapornis roseicollis.