Conservation implications of weed management of lake reservoirs on wildbirds

Abstract

Management of weeds around lake reservoirs is often implemented to reduce any possibility of siltation. However, machineries used in weed management have resulted in habitat degradation and geometrical multiplication of weeds by chopping rhizomes and scattering seeds. In general, the removal offers some feedbacks for wildlife around the lake which ought to be taken into account. We determined the effect of weed removal from a lake reservoir on wildbird activity and diversity using two transects 1.2 km each. Transects were subdivided into ‘twelve’ 200m sections using a GPS and variables taken into account were: wildbird species present; abundance; species activity; weed parameter (‘zero’ where cover was less than 10 percent of entire area, ‘one’ if extent of cover was less than 50 percent and ‘two’ if cover was greater than 50 percent). Complete removal of weeds significantly affected bird species abundance and richness. Comparison of this survey with previous data reveal that some species, such as Actophilornis africana African jacana have adapted to the removal of weeds while others such as the Gallinula chloropus Common moorhen, are now absent from the lake bank due to weed removal. Therefore, monitoring wildlife population to species holds great value for amplifying management decisions. 

Key Words: Wildbirds, Weed management, John Craig Lake, Transect, Conservation