Bird Species Distribution and Habitat Diversity in an Exotic Forest in South Australia

SUMMARY

Pine plantations can be described in terms of four successive age-management classes, i.e. growth stages. The distribution and abundance of these growth stages (young, unthinned, middle-aged, old), and areas of native forest and grassland have been described for one Forest Reserve in the Adelaide Hills and show that exotic forests of a commercial undertaking form a mosaic of different vegetation structures.

The different growth stages of the exotic forests have been compared as habitats for birds using (1) the total numbers of bird species, (2) the number of species at the edge and interior of the habitats and (3) the number of species grouped according to their foraging sites. The latter, in particular, indicates the diversity of foraging sites within the different growth stages. Similar comparisons have also been made between the exotic forest and the native vegetation.

Fewer species of birds were seen in the individual growth stages than in the native vegetation. The least number of species occurred in the interior of the unthinned compartments which is the most uniform vegetation structure. However, the total number of species of birds was almost the same as that in native vegetation when the different growth stages were considered altogether. The largest number of species in either exotic or native habitats occurred in areas which exhibit the greatest vegetation diversity.

The mosaic of planted pines, grazing land and native vegetation provide sufficient habitat diversity to provide niches for most of the birds known to occur in the vicinity of the Forest Reserve.