The density and stability of birds in shrubland and drainage line woodlandin the southern Karoo, South Africa

Comparative surveys of bird species richness and abundance showed that a to tal of 69 bird species was recorded on 1 km transects (n = 996) through shr ubland, with a total estimated density of birds of 32.7 +/- 32.8 (S.D.) bir ds/km(2), of which resident birds made up 24.4 +/- 21.0 birds/km(2), nomads made up 1.9 +/- 11.7 birds/km(2) and local nomads made up 6.3 +/- 20.1 bir ds/km(2). There was no correlation in general between total bird numbers or total bird biomass and rain, but numbers and biomass of nomads showed the strongest correlations with rainfall two months previously. total of 86 spe cies was recorded on 276 surveys along a 1 km stretch of drainage line wood land. Species richness varied from an average of about nine species to 24 s pecies each month, and only showed a marked change during the 'dry' period of 1990 to early 1991. Density of birds in this woodland was 59.2 +/- 20.8 birds/km. Biomass of birds was relatively constant throughout the study per iod, with marked increases in certain months when large species were presen t.