Abstract:
Previous studies demonstrate that old-growth forest remnants and vegetation regenerating after anthropogenic
disturbance provide habitat for birds in a human modified coastal dune forest landscape in northern KwaZulu-Natal,
South Africa. However, occurrence does not ensure persistence. Based on a 13-year monitoring database we calculated
population trends for 37 bird species and general trends in overall bird density in different vegetation types. We evaluated
species’ characteristics as covariates of population trend and assessed changes in rainfall and proportional area and survey
coverage per vegetation type. 76% of species assessed have declined, 57% significantly so at an average rate of 13.9% per
year. Overall, bird density has fallen at 12.2% per year across old-growth forest and woody regenerating vegetation types.
Changes in proportional area and coverage per vegetation type may partly explain trends for a few species but are unlikely
to account for most. Below average rainfall may have contributed to bird declines. However, other possibilities warrant
further investigation. Species with larger range extents tended to decline more sharply than did others, and these species
may be responding to environmental changes on a broader geographical scale. Our results cast doubt on the future
persistence of birds in this human modified landscape. More research is needed to elucidate the mechanisms driving
population decline in the study area and to investigate whether the declines identified here are more widespread across the
region and perhaps the continent.
