Common TRUTHS

Birders love to find rare birds; few things match the excitement of coming across something completely unexpected. But the obsession with rarities can result in population changes in more common birds being overlooked. Breeding bird surveys in Europe, Asia and North America show that many bird populations are in flux, but what do we know about the status of common birds in South Africa?

- PETER RYAN

the best way to tell how birds are faring is through standardised counts of birds at the same sites year after year. In South Africa, Coordinated Avifaunal Road (CAR) counts have shown steady decreases in some large terrestrial species such as Southern Black Korhaan, whereas others exhibit regionally distinct responses. For example, Blue Cranes have decreased in the grassland biome, increased in agricultural areas of the Western Cape and remained more or less constant in the eastern Karoo.

Counts of breeding seabirds and coastal birds also show substantial changes in many species’ numbers. The recent decreases in African Penguin, Cape Gannet and Cape and Bank cormorants have attracted widespread attention, with all four species now listed as Endangered. Numbers of coastal birds have remained relatively constant overall, but there has been a marked shift from migrant shorebirds to resident species such as ibises, Egyptian Goose, Blacksmith Lapwing and Cape Wagtail. 

Inland, the numbers of waterbirds at wetlands are captured through Coordinated Waterbird Counts (CWAC), but they vary greatly in relation to site-specific changes in water quantity and quality, obscuring broader-scale patterns. The BIRDIE Project (birdie. sanbi.org.za) is developing indices of change across all wetlands, but this is a work in progress.