Chapter 5 Feeding Ecology of the Australian Raven on Rottnest Island

present (Storr, Green and Churchill 1959). Of <strong>the</strong>se species, <strong>the</strong> Tuart Eucalyptus
gomphocephala has been introduced deliberately, being trialed successfully as a timber
crop and stands are still evident near <strong>the</strong> cemetery and Pinky Beach. The vegetation
inventory lists 246 plants (vascular flora) <strong>of</strong> which 42% are exotic species, and are obvious
around <strong>the</strong> urban areas (Rippey, Hislop and Dodd 2003). Moreten Bay fig Ficus macrophylla
and Norfolk Island pine Araucaria heterophylla, as well as marlock Eucalyptus platypus, E.
utilis and Casuarina glauca, have been deliberately established for aes<strong>the</strong>tic purposes, with
<strong>the</strong> two former species visually dominating <strong>the</strong> settlement. West <strong>of</strong> <strong>the</strong> settlement, <strong>the</strong>
island vegetation has been shaped drastically over <strong>the</strong> last two centuries by three major
processes: <strong>the</strong> clearing <strong>of</strong> land by European settlers, changes in fire regimes and changes in
Quokka Setonix brachyurus abundance. These processes appear to have subsequently
modified <strong>the</strong> distribution and abundance <strong>of</strong> <strong>the</strong> bush bird species on Rottnest Island.
Early European visitors described <strong>the</strong> island vegetation as a dense forest <strong>of</strong> cypress Callitris
preissii interspersed with Melaleuca lanceolata and Pittosporum phylliraeoides, with Acacia
rostellifera ‘relatively uncommon’ (Seddon 1983). Following settlement <strong>the</strong> eastern
vegetation was rapidly cleared for <strong>the</strong> development <strong>of</strong> agriculture and establishment <strong>of</strong>
dwellings. The western woodlands were cleared for firewood collection, with impacts
intensified by grazing stock and an increase in <strong>the</strong> frequency <strong>of</strong> fires. Evidence from charcoal
deposits found in <strong>the</strong> sediments <strong>of</strong> Barker Swamp (Backhouse 1993) suggest that prior to
European settlement, major fires occurred on Rottnest only once every two centuries
(Rippey and Hobbs 2003) most likely caused by lightning strike. Following settlement, fire
frequency escalated to a weekly event with fire being used as a tool by Aboriginal prisoners
to flush Quokka from vegetation during weekend hunts that occurred until <strong>the</strong> late 1800s
(Somerville 1976). The last major fire in 1955 burnt two-thirds (1800 acres) <strong>of</strong> <strong>the</strong> island
(Storr 1963; Pen and Green 1983), with a smaller fire in 1997 burning ninety hectares <strong>of</strong>
heath between <strong>the</strong> centre and nor<strong>the</strong>rn coastline (Rippey and Hobbs 2003). The vegetation
on Rottnest has not had sufficient time to adapt to <strong>the</strong> rapid increase in fire events. Two
species in particular, Callitris preissii and Melaleuca lanceolata, are extremely sensitive to
fire and have been greatly reduced (Baird 1958; Rippey and Hobbs 2003), while Acacia
rostellifera has thrived (Storr 1963) although inhibited by Quokka grazing.
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