Habitat alterations that often accompany land-use change are one of the
major drivers of global biodiversity losses. In Africa, these threats
are especially severe, as this continent has the most rapidly growing of
all human populations. Inevitably, increasing areas of land are being
transformed for agriculture, including drought-prone drylands in
southern and central Africa, despite often having poor soils. In
Zimbabwe, a land reform programme provided a unique opportunity to study
the biodiversity response to abrupt habitat modification in an extensive
dryland area of mixed grassland and woodland savannah. Small-scale
subsistence farms were created rapidly during 2001-2002 in formerly
semi-natural savannah. We measured the changing compositions of bird
communities in transformed and untransformed land over an 8-year period,
commencing one decade after subsistence farms were established. Over the
study period, repeated counts were made along identical transects in
order to assess species' population changes that may have resulted from
trait-filtering responses to habitat disturbance. We recorded
significantly increased abundances in both land-use areas, accompanied
by increases in species diversity and functional redundancy. Temporal
trends showed increased abundances across all feeding guilds, and in
species of virtually all sizes. Influxes of new species did not increase
functional traits' diversity, and no species with distinctive traits
appear to have been lost as a result of land-use change. Nearly two
decades after habitat transformation, the bird communities in the
transformed and untransformed areas had become more similar in
composition. The broadly benign impact on birds of land conversion into
subsistence farms is attributed to the relatively low-level of human
activities and disturbance in the transformed land, and the large
regional pool of non-specialist bird species.