Habitat degradation threatens the survival of the Ethiopian bush crow Zavattariornis stresemanni

Abstract

The Ethiopian bush crow Zavattariornis stresemanni is one of the most remarkable ornithological discoveries of the 20th century. It is restricted to an area of c. 5,000 km² in southern Ethiopia, and a large part of its range is protected inside Yabello Wildlife Sanctuary. We report on the results of roadside counts carried out in 1989, 1995 and 2003 showing that the population of the species has decreased by 80% during this time. By comparing two Landsat satellite images from 1986 and 2002, we highlight land cover trends within the range of the species. These include a general increase in bush density, probably related to increasing grazing pressure by domestic animals, fire suppression (only in the Sanctuary) and the disappearance of wild herbivores. Land cover trends differed between the Sanctuary and the area outside, where open areas expanded, apparently indicating an increase in agricultural exploitation. Satellite images also showed that, within its range, the bush crow selects areas having relatively open terrain. Our data suggest that the population decrease within the Sanctuary could be due to the encroachment of open savannah by dense bush and that, therefore, the Sanctuary has failed to protect the bush crow. More research is urgently needed to evaluate its conservation status outside the Sanctuary and the impact of human activities on the species.