Oxpeckers in north-eastern Namibia: recent population trends and the possible negative impacts of drought and fire

Abstract

Both redbilled oxpeckers ( Buphagus erythrorhynchus) and yellowbilled oxpeckers ( Buphagus africanus) have experienced recent population decreases in southern Africa largely as a result of cattle dipping against ticks, their primary source of food. In Namibia, oxpeckers are confined largely to the Caprivi region in the north-east and the yellowbilled oxpecker is classified as a Namibian Red Data species. Counts in 1983–1984 estimated populations of 2285–3780 redbilled oxpeckers and 2062–2613 yellowbilled oxpeckers on cattle in East Caprivi. In this study, three counts of oxpeckers were made in 1997–1998. Bird numbers had not increased in proportion with cattle numbers, the primary host which had increased three-fold in the last 15 years. Current redbilled oxpecker numbers (3627–4902) were similar to those in the 1980s. Too few yellowbilled oxpeckers were observed to derive robust population estimates, but our counts suggest a decline to about 330 birds. There have been no official cattle dipping programmes in Caprivi, and private tick control is virtually non-existent. We suggest that the current dry conditions, in combination with the increasingly widespread and more frequent practice of veld burning are having a substantial, differential effect on some of the tick species favoured by the two species of oxpeckers. We hypothesise that these two factors act as a control mechanism on ticks favoured by yellowbilled oxpeckers, so precipitating the dramatic decline of this species. If current trends continue, yellowbilled oxpecker will soon disappear from Caprivi.