Trends in populations of Blue Crane Anthropoides paradiseus in agricultural landscapes of Western Cape, South Africa, as measured by road counts

Abstract

Population trends of the Blue Crane Anthropoides paradiseus were monitored by volunteers participating in Coordinated Avifaunal Roadcounts (CAR) in the Overberg and Swartland agricultural regions of the Western Cape province from 1993 and 1996, respectively, until 2019 in the Overberg and 2017 in the Swartland. The number of Blue Cranes in the Overberg increased from mean density of 47.3 to 204.7 birds 100 km−1 in the summer breeding season, and in the Swartland from 7.5 to 34.2 birds 100 km−1. In both regions, agriculture has resulted in extensive transformation of the original Renosterveld and Fynbos vegetation (Shaw 2003). Results show dramatic population increases in these two regions, following a major decline in populations in the Grassland biome (McCann 2000) where there has also been land transformation. Roadcounts conducted during the breeding season proved more effective in indicating population trends than those during the non-breeding season when birds aggregate in flocks. The survey results show what can be achieved by citizen scientists using a standardised method of monitoring.