Changes in the Avifauna of a region, district and remnant as a result of fragmentation of native vegetation: the wheatbelt of western Australia. A case study

The wheatbelt of Western Australia is an area of about 140 000 km² which has undergone massive changes since European settlement in 1827. Clearing of native vegetation for agricultural development has removed up to 93% of the original vegetation in some areas and replaced it with exotic grasses, cereal crops and frequent watering points. The remaining vegetation is made up of thousands of remnants of various sizes, shapes and degreees of isolation scattered across the landscape.

The avifauna of the wheatbelt is examined at the regional level, the district level and at the level of the individual remnant and changes over the last 80 years or so are described. Two species of bird have gone extinct in the wheatbelt out of 148 species of land birds recorded in the region over the last 80–90 years. At the district level, more species have become extinct, the numbers depending on the extent of the removal of native vegetation and length of time since clearing took place. There is demonstrable loss of bird species at the level of the individual remnant; in the example cited (81 ha) three species have gone extinct over the last 10 years.

This rapid loss of species from district avifaunas means that remnant vegetation needs to be retained intact and conservation agencies should develop assessment techniques to identify reserve networks which include the species that have declined so that management can concentrate on them. Priorities for management should then be developed and local communities involved in the management of their local conservation systems or networks.