An evaluation of bird presence and breeding activity in regenerating coastal dune forests, Maputaland, South Africa

Abstract

Researchers use changes in bird community composition to illustrate ecological succession in restoration studies. These studies utilise a variety of methods, some of which may bias their outcomes. Here I used the point and line transect methods to obtain community compositions as well as to estimate total density, species richness and species diversity for bird communities living in a successional sere of coastal dune habitats. The two methods yielded similar estimates of community variables in the younger regenerating sites with the point transect method giving higher estimates in the older regenerating sites. The line transect method provided higher density estimates than the point transect method across all sites but there was no significant difference between variance estimates for the two methods. The point transect method reached the maximum number of detectable species in half the time that it took the line transect method. In contrast to my expectations, the point transect method proved to be superior in terms of efficiency. Past research suggests that bird presence itself does not reflect on colonisation success. I compared the community composition, variables and age related trends of point transect and breeding assemblages within the study area. The breeding assemblages represented a subset of the point transect assemblage. Age related trends were significantly similar with both assemblages approaching the variables noted on an undisturbed reference site with an increase in regeneration site age. I concluded that presence based surveys of bird communities adequately captured age related trends to make valid conclusions about patterns of succession.