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Evidence of large‐scale range shift in the distribution of a Palaearctic migrant in Africa

Howes, Caroline, Symes, Craig T., Byholm, Patrik
Diversity & distributions 2019 v.25 no.7 pp. 1142-1155
Palearctic region, Pernis apivorus, anthropogenic activities, birdwatching, databases, forests, global change, habitats, migratory behavior, migratory birds, population growth, rolling, trees, urban areas, Southern Africa, Tanzania
AIM: Long‐distance Palaearctic migrant birds are declining at a faster rate than short‐distance migrant or resident species. This is often attributed to changes on their non‐breeding grounds and along their migratory routes. The European honey buzzard (Pernis apivorus) is a scarce migrant in southern Africa that is declining globally. This study assessed the distribution and abundance of honey buzzards in southern Africa over the past four decades and compared it to trends in the East African population to examine possible drivers of population expansion in southern Africa. LOCATION: Southern and East Africa. METHODS: European honey buzzard reporting data were collected from a variety of sources including citizen science databases (1983–2017). In addition, records of all other southern African vagrants (including ten other regularly occurring species) were gathered to account for changes in birdwatching effort in the subregion. To assess the effect of forest loss on honey buzzard abundance, rolling correlations were performed using forest cover in East Africa and number of honey buzzard records in both subregions. RESULTS: European honey buzzard records in southern Africa have increased over five times more than other regularly occurring vagrant species and almost 40 times more than honey buzzard in Tanzania, where the population has remained stable. Loss of forested area in East Africa was correlated with an increase in European honey buzzard records in southern Africa. MAIN CONCLUSIONS: We suggest that the European honey buzzard shift in wintering range may be driven by a decline in suitable habitat further north in Africa amongst other possible reasons. This effect may have been amplified by an increase in appropriate habitat across southern Africa brought about by anthropogenic changes to vegetation such as increased tree cover in urban areas. This study further highlights the importance of using African distributional data banks to understand the effects of global change on Palaearctic migrant bird species.