The use of wetland bird species as indicators of land cover change within the Mgeni Estuary and Beachwood Mangrove swamps.

Abstract

Because of the variety of ecological and economic functions they perform, estuaries and mangrove swamps are recognised as amongst the most valuable habitats on earth. However, estuaries and related mangrove swamps are threatened by human expansion and exploitation which leads to changes in land cover change within and surrounding these sensitive ecosystems. Such land cover changes can either have desirable or undesirable effects on natural ecosystems. Examples of undesirable impacts of land cover change include soil erosion and degradation, the removal of indigenous vegetation for human development, and the pollution of water. Without an effective means of identifying, monitoring and managing land cover changes over time, these sensitive ecosystems face a bleak and uncertain future. The researcher sought to determine whether wetland bird species could be used as an effective method of monitoring the environmental health of estuaries and mangrove swamps. In particular, the research sought to determine whether analysing fluctuations in the populations of wetland bird indicator species, as evident in the CWAC Bird Census data, could assist in monitoring and assessing undesirable and desirable land cover changes within the Mgeni Estuary and Beachwood Mangrove Swamps. An examination of the archival aerial imagery of the study area for the years 1991, 1997, 2003 and 2008 provided by the University and private companies, revealed significant changes in land cover over the last two decades. The land cover changes identified represent an actual decline or increase in the suitable foraging, roosting or reproductive habitats of wetland bird indicator species within the study area. The research focused on investigating whether fluctuations in wetland bird populations can be correlated with the recorded changes in land cover over the last two decades. The research discovered a direct and comprehensive link between fluctuations in specific populations of wetland bird indicator species and the land cover changes identified within the study area over a 20 year period.