Birds of Lake McLarty Nature Reserve, Western Australia: an internationally important wetland facing an uncertain future

WA Museum Records and Supplements | Updated 5 years ago

ABSTRACT – Freshwater wetlands are the most threatened major habitat type globally and freshwater birds are consequently disproportionately threatened among birds worldwide. These facts emphasise the need for obtaining detailed data on the occurrence and abundance of waterbirds against which to compare population trends and management actions designed to maintain populations. In response to this need we present information on the occurrence, seasonality and abundance of waterbirds and landbirds at Lake McLarty Nature Reserve, located approximately 85 km SSW of Perth, Western Australia. Most of the reserve consists of Lake McLarty, a shallow freshwater lake, with a narrow (~40 m wide) fringe of riparian paperbarks (Melaleuca spp.) and Flooded Gums (Eucalyptus rudis) along ~90% of the lake’s margin. A total of 100 species of waterbird and 78 species of landbird have been recorded at the reserve. Of the landbirds, the reserve provides habitat for one globally threatened species and one globally threatened subspecies as well as a range of species declining regionally. On the basis of its waterbird populations, Lake McLarty qualifies as a wetland of international importance in its own right. Over 20,000 waterbirds have been recorded on the reserve on 19 separate dates between 1996 and 2008. The reserve has also supported >1% of the global population of six species and >1% of the flyway population of one additional species. Furthermore, the lake has supported numbers exceeding these thresholds on as many as 50 dates, depending on the species, indicating that the reserve consistently supports globally significant populations of most of these species. Despite the importance of the reserve for waterbird populations, it faces serious threats from a variety of factors of which our data indicate that the changed hydroperiod resulting from reduced rainfall and, likely, groundwater extraction from an adjacent residential development, is the most significant. This changed hydroperiod, which means the lake is now normally dry for four to seven months annually, has also resulted in the increased expression of acid sulphate soils and colonisation of the lakebed by terrestrial plants. All of these threats combine to reduce the habitat quality that Lake McLarty provides for waterbirds. There are current plans to return the lake to an earlier hydroperiod, where it dries for between one and three months annually, and the data presented here should provide a robust baseline against which to assess the success of any future management actions.