Geography, Flora, Fauna
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Geography – The Georges River National Park lies upon a thick bed of Hawkesbury sandstone. In other sections of the park at Sandy Point, Mittagong sandstone is more common. Mittagong sandstone is younger much finer grained sandstone compared to Hawkesbury sandstone. The 96 km long saltwater Georges River runs through the centre of the park, named and honoured after King George the III. The parks highest point of elevation is at Mill Creek, 100 metres above sea level, with an average elevation of 60 metres. Additionally, the national park receives an average annual rainfall of 850-900 millimetres (mm), 435 mm less than Sydney's annual rainfall of 1309 mm.
Flora – The river side predominantly consist of mangrove swamps, occupying 24 hectares on the national park, and salt marshes occupying 11 hectares of the national park. However, aerial photo analysis suggest between 1966 and 1998 unauthorised vehicles, BMX bikes, and motorised dirt bikes have reduced and declined these occupied areas of mangrove swamps and salt marches. The most common vegetation found throughout the park is Sydney Hinterland Exposed Sandstone Woodland, covering 293 hectares, characterised by eucalyptus trees 10–25 metres tall and small sclerophyll shrub. However, other floral habitats can be found in the national park as well, such as, Littoral Rainforests, Sydney Coastal Heaths, Coastal Freshwater Lagoons, and Coastal Floodplain Wetlands. Prioritised tree species that are under threat identified in the park are swamp mahogany and red gum. These are flowering tree species which nurture and feed animals species such as the grey-headed flying fox and little lorikeets. They are under-threat due to high public disturbance, and are not widely dispersed within the park. Moreover, there has been a reduction in the numbers of hollow-bearing trees with in the park, which shelter and allow for the breeding of Sittella bird species.
Fauna – Roughly 248 native vertebrate species have been recorded in the Georges River National Park compromising of animals ranging from amphibians, reptiles, birds, and mammals, both introduced and native. Out of the 248 species found in the park 20 of those species are threatened under the Threatened Species Conservation Act, 1995 and 8 species listed under the Environment Protection and Biodiversity Conservation Act, 1999, including animals such as the Green and Golden Bell frog and the blue billed duck. In total sixteen frog species have been recorded in the national park, the most common being the eastern dwarf tree frog and Tylers tree frog. Thirty two locally endemic reptile species can be found in the park, one freshwater turtle species, twenty two types of lizards (four geckoes, thirteen skinks, three dragons, two goannas), and nine snakes. The most abundant reptile species is the dark-flecked garden sunskink. Moreover, 180 species of native bird can be observed, 59 being waterbird species. Finally, twenty species of mammals are locally native to the park, the most frequently occurring being the common ringtail and brushtail possums, the swamp wallaby and the grey-headed flying-fox. A breeding population of Koalas live in the park, however are listed at as threatened. It is further noted that 59% of mammals are nocturnal microbats, such as the little forest bat, and the chocolate wattled bat. Eighteen invasive species threaten the parks native fauna, with the common fox being the most wide spread and devastating, impacting the long-nosed bandicoot population as well as the swamp wallaby.
Swamp Wallaby
