Records ot the Western Australian ;\iluseum Supplement No. 75: 1~9 (2008).

Background information on Faure Island, Shark Bay, Western Australia

Barry Wilson

4 St Ives Loop, Kallaroo WA 6025, Australia; E.~mail: mureX(Ustarwon.com.au

Abstract Background information is given on a biological survey of Faun;Island, Shark Bay, conducted to provide a basis for a translocation programinvolving threatened mammal species presently surviving on outer islands ofthe bay. Tenure, climate, geology and land forms of the island arcsummarised. Late Pleistocene marine shell beds arc described that representtransgressive phases of the last interglacial. Above these arc dune depositscontaining fossil land snails deposited during the arid, low sea level period ofthe last glacial cycle prior to the post~glacial transgression that re~created thebay and isolated Faure as an island. This gcomorphic history is discussed inrelation to the extinction of the mammal species on the mainland of the regionand the suitabilitv of Faure Island as a translocation site.

Key words: Shark Bay World Heritage Property, tenure, climate, geology,land forms, threatened mammals, shell beds, transgression, translocation

INTRODUCTIONFaure Island is a small pastoral lease, of 5,816 ha,

in the Shire of Shark Bay, located within the SharkBay World Heritage Property. It was purchased bythe Australian Wildlife Conservancy (AWC; thenParuna Sanctuary L.td.) in 2000 for conservation andeducation. In particular, it was obtained as a site forthe translocation and establishment of securepopulations of threatened species of nativemammals.

As an island of modest size, Faure has specialconservation values. It offers suitable habitat forseveral of the native mammals once abundant in theregion but now extinct on the mainland. It is largeenough to offer sufficient area to support viablewild populations of the selected species withoutintrusive management. It is small enough for habitatrestoration and population monitoring to bemanageable. And, as an island, it is moderatelysecure from invasion of the exotic predators andherbivorous competitors that are believed to havebeen responsible, at least in part, for the extinctionof the selected species on the adjacent mainland.

The A WC principal management objectives forthe island were:• restoration and protection of natural habitats

and wildlife, principally through de-stocking(sheep, goa ts and horses) and erad ica lion ofexotic predators

• reintroduction of threatened mammals native tothe and the establishment of securepopulalions of the selected that mavbecome a supplenwntarv source of stock fortranslocalions to the mainland;

• research on the life histories and ecology of the

selected species that may inform conservationprograms elsewhere; and

• development of education and tralI1lI1gprograms that enhance understanding of thenatural history and major conservation issues ofthe region.

Although there has been intensive study of theflora and fauna of the Shark Bay region, bothmarine and terrestrial, Faure Island has been largelyoverlooked until now. There had been brief earliervisits by biologists but no comprehensive flora andfauna survey had been done. The only habitatinformation available had been the generalclassification of land systems of the island relatingto the nature and condition of its pasture. This didnot provide a sound basis upon which a threatenedspecies translocation program could be planned andimplemented.

Accordingly, AWC arranged a biological surveyof Faure Island between 22 May - 2 June 2000,conducted by experts with a range of naturalhistory expertise. The general aim of the survey wasto assess the current and recent habitats and speciesdiversity of native plants and animals on FaureIsland as a basis for the development of amanagement plan.

This publication reports the results of the 2000survev, supplemented by SOlI1e information tromearlier visits and some obtained AWC staffduring subsequent work on the islcllld. Lhesection on the of the island has drawn oninformation in an unpublished, preliminarv field

Dr I'hilip Playford and Dr I'atrick Berryto the A WC' (I'lavford and Berr\' IIw reportalso includes the results of ,1 SlIrVl'V of the

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abundance of feral cats on Faure Island prior tothe implementation of an eradication programthat followed after the 2000 survey wascompleted.

At the time this report was assembled forpublication (July 2007) all but one of the horses hadbeen removed from the island, sheep had eitherbeen removed or restricted to a single paddock, andferal goats (remnant from earlier pastoral practices)and cats had been successively eradicated. With thatbasis, and with the benefit of the habitat infor­mation provided by the survey, a mammaltranslocation program had been initiated(Burrowing Bettong Bettongia lesueur, Shark BayMouse Pseudomys fieldi, Banded Hare-wallabyLagostrophus fasciatus, Western Barred BandicootPerameles bougainville, Greater Stick-nest RatLeporillus conditor; Richards 2007). The progress ofthe translocation programs will be reportedelsewhere.

SURVEY PARTICIPANTS

Australian Wildlife ConservancyMartin Copley Founder and ChairmanBarry Wilson Director, zoologistTim Flannery Director, zoologistAndre Schmitz Sanctuaries Manager, zoologistleon Pericles ArtistDaniel Bowles AssistantDick Hoult (sen.) AssistantRichard Hoult AssistantElvie Cook

Western Australian Department ofEnvironment and ConservationGreg Keighery Botanist

Western Australian MuseumPatrick Berry Marine zoologistAlexander Baynes MammalogistJulianne Waldock Invertebrate zoologistJohn Dell Ornithologist

South Australian MuseumSteve Donnellan Vertebrate zoologistTerry Reardon MammalogistJan Forrest Invertebrate zoologist

COLLECTION AND LODGEMENT OFSPECIMENS

For the most part, protected species wereidentified and recorded in the field without theneed for collection of specimens. Where voucherspecimens were taken for further study, this wasdone under licence issued by the WesternAustralian Department of Conservation andL.and Management (now Department ofEnvironment and Conservation; DEC), with the

B. Wilson

vertebrate and invertebrate specimens lodged inthe collections of either the Western AustralianMuseum or the South Australian Museum. Plantspecimens were lodged at the WesternAustralian Herbarium.

LOCATION AND TENURE

Faure Island is located in Disappointment Reach,the eastern gulf of Shark Bay (Figure 1). It is centredon 25°50'S, 113°53'E and lies within the Shark BayWorld Heritage Property.

The island is Crown land, comprising a pastorallease, a narrow coastal reserve on the eastern sideand a narrow strip of Unassigned Crown land(UCl) on the western side. It is entirely surroundedby the Shark Bay Marine Park (Reserve 7).

The eastern reserve (Crown Reserve 30885) isvested with the Conservation Commission (DEC)with the 40 m strip above High Tide level reservedfor "Preservation of Sedimentary Deposits". Thecorresponding 40 m strip of UCl along the westernside is intended for reservation in the near future aspart of the Marine Park.

The pastoral lease has an area of 5,816 hacomprising the whole of that part of the islandenclosed within the boundary set at 40 m above thehigh water mark. The lease is numbered 3114/922,issued to the Australian Wildlife Conservancy(AWC) by the Pastoral lands Board (PLB) underthe authority of the land Administration Act 1997.The lease expires in the year 2015 but will berenewed beyond that date subject to certainconditions.

The Shark Bay Regional Strategy (WesternAustralian Planning Commission 1997) indicatesthat Faure Island should remain under pastoraltenure. Management of the pastoral lease by AWCwill include operations to promote conservation ofthe island's natural environment and wildlife undera Division 5 permit.

Under the provisions of the World HeritageProperties Conservation Act 1983, Shark Bay wasentered on the World Heritage List in 1991following nomination by the AustralianGovernment with the agreement of the WesternAustralian Government. The Shark Bay WorldHeritage Property encompasses Faure Island. Thenomination document identifies scenic qualitiesthat include those of Faure Island, and key seabirdbreeding sites on the island as among the WorldHeritage values. Management of Faure Island willtake World Heritage status and the specifieduniversal values into account.

The Shark Bay Marine Park, established under theConservation and land Management Act in 1990,surrounds Faure Island and extends up to the hightide mark. The plan designates the waters aroundFaure Island as a General Purpose Zone.

Background information

N

Figure 1 I.ocation of Faure Island in Shark

~ FAURE"(j ISLAND

Western Australia.

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CLIMATEShark Bav has a semi-arid to arid climate with hot

summers and mild winters. Summer minimumand maximum temperatures average between about20 C and 35c C respectively and winter temperatures

between about IOU and 2()uC. Rainfall is erratic withannual totals ranging from 200 to 400 mm at theDenharn weather station. Most rain falls in thewinter months but cyclones bring sumrner rain insome Years. r;'aure Station records collected between

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1991 and 2005 show that rainfall on the island fallspredominantly between March and August with anaverage of 185 mm per annum (AWc, unpublisheddata).

Annual evaporation rates within the area are veryhigh ranging from 2000 to 3000 mm. Rainfall isgreater and evaporation rates lower on the westernside of Shark Bay than on the eastern side (includingFaure Island), which tends to be more arid.

In summer winds are predominantly southerlyand may blow for long periods at over 25 km perhour. Winds tend to be lighter in winter althoughlow pressure system winter storms occuroccasionally. Faure Island is protected from severewesterly and southerly storms by the mainland butis exposed to heavy weather from the north early inthe life of both summer cyclones and winter storms.

GEOLOGY

Shark Bay lies within the Carnarvon Basin. Thesurface geology consists of Pleistocene andHolocene limestone and sandstone, overlaying theLate Cretaceous Toolonga Calcarenite (Hocking etal. 1987) and largely covered by superficial sand(Playford 1990).

Faure Island is built of Peron Sandstone, aPleistocene unit of soft, poorly consolidated,orange-red, eolian sandstone which formed as dunesystems over anticlinal ridges developed in theunderlying formations. The Peron Sandstone isexposed around much of the periphery of theisland, forming "rocky" headlands where it iseroded by the sea and scree slopes where it isexposed below calcrete-topped cliffs. It gives rise tothe orange-red sand that forms the contemporarydunes covering much of the surface of the island. Instark colour contrast, in many places there arecoastal foredunes and plains comprising whiteHolocene sand derived from the contemporaryintertidal flats that surround the island.

An undulating subsurface layer of calcrete formedwithin the Peron Sandstone below the present landsurface. It is exposed at several localities, includingsurface outcrops in low swales in the centre of theisland and as hard crusts on cliff tops producingbreakaway topography along both the west and eastcoasts. On the west coast there are also blown outdunes where the calcrete surface is exposed.

There are two units of Late Pleistocene marinelimestones outcropping around the shores of SharkBay (Logan et al. 1970; Hocking et al. 1987;Kendrick 1990; Playford 1990) including FaureIsland. They are thought to represent transgressivemarine episodes of the last interglacial in the LatePleistocene, the former relating to substage Se(Shackelton and Opdyke 1973) and the latterpossibly to a subsequent transgressive period(Kendrick 1990).

B. Wilson

The older of these two marine deposits, theDampier Limestone, contains a rich fauna ofintertidal marine molluscs broadly like the fauna ofcontemporary sandflats in Shark Bay but includingseveral species not now living in the region(Kendrick 1990). For example, the cardiid bivalvesAcrosterigrna dupuchense and Fragurn carinaturnare very common in these fossil deposits but theirliving Australian distributions are now confined tothe Pilbara and Kimberley coasts north-east ofNorth West Cape. Also present among these fossilsis the arcid bivalve Anadara trapezia, which ischaracteristic of hyposaline estuarine environmentsand is thought to indicate a period of relativelymoist climate and possibly associated with theWooramel River when the river flowed morestrongly (Kendrick 1990; Kendrick et al. 1991;Murray-Wallace et al. 2000). This species alsobecame extinct on the west coast after the lastinterglacial.

At Faure Island there are Late Pleistocene shelldeposits that are of clearly two different fadesrepresenting very different depositional envi­ronments. They may represent the Dampier andBibra Limestones but their relationship is not clearand requires detailed study.

In the north of the island, along the southernshore of an ephemeral salt lake opening into theeastern side of Tadpole Lagoon (Figure 2), there isan exposure of limestone at water level containingfossil bivalves in a fairly well consolidated matrix.A hand-held GPS unit gave an elevation at the topof this exposure of about three metres above meansea level. The bivalves include both Acrosterigrnadupuchense and Anadara trapezia and it seemslikely that this is an exposure of the DampierLimestone. The presence of Anadara trapeziasuggests deposition in an estuarine environment(see above).

Adjacent to this exposure, and apparentlyoverlying it, there is a shell bed of a very differentfacies. It occurs at the break of slope between thesurrounding dunes and the water level of the saltlake and extends around the southern shore of thelake and lagoon for a distance of several hundredmetres. This deposit, 1-1.5 m thick, is notconsolidated but comprises a rich assemblage ofbivalves (many of them articulated) and somegastropods in a loose matrix of quartz sand. The topof this deposit is not level and GPS readings gaveelevations ranging from 5-9 m above mean sealevel. Acrosterigma dupul-nense is common amongthe many species of bivalves present but Anadaratrapezia is not. The facies and molluscanassemblage appear to represent a marine intertidalsand flat that was not estuarine, while the presenceof Acrosterigrna dupuchense indicates that it is ofLate Pleistocene age and not Holocene. The contactbetween this deposit and the slightly lower one has

Background information

[:=J Acacia

EJ:J Beach~ Dunes~ Birridas[IT] SamphireI: :: :1 Eucalypts.. Mangroves~ Scattered Mangroves

Figure 2 Vegetation of Faun' Island,

5

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Kilometres

····•···Middle •Tank '.

~_. __ .-\.d \

Ceo!",1 Ra:'_ - - ...

'-"\"'~'\\• \ j:.

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, .. ~........... \~...... ....... \t.

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Homestead+

not been observed but it seems reasonable tointerpret the higher shell bed as the result of a latertransgressive event, possibly equivalent to the BibraLimestone that occurred after the termination ofestuarine cond itions,

At the southern end of the in the vicinit\'of the boat land there is a shelldeposit with a facies and molIuscan assemblagevery similar to the higher one at Tadpole Lagoon, Itis eroded the sea and forms a low, undercutbench along several hundred metres of the shore.The top of this shell bed has an undulating surfacebut is generally 1~2 m above high tide level. It

lenses out at the eastern and western ends but at thecentre it is about 1.5 m thick. Below it isconsolidated orange-red quartz sand. Above it is athickness of poorly consolidated orange-red[)leistocene sand the coastal dunes of thatpart of the island. Like the d t atradpole andFragul11 carinatul11 are common among the man\'species of bivalves present but Anadara IS

not I !owever, two very worn valves of the latkr"Ut:lllt·" were picked up at the water's in thevicinity.rhey do not appear to have come from thesupra-tidal shell bed. Further searches may reveal

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an exposure of Dampier Limestone in the intertidalzone below the supratidal shell bed.

The semi-consolidated dunes above the southernshell bed are eroding rapidly, forming an irregularshore "cliff" with blown out dunes above.Embedded within these sands are fossils of the landsnail Bothriembryon onslowi. Specimens may beobserved embedded in the exposed face of the cliffwithin centimeters of the top of the underlyingmarine shell bed. These deposits may be interpretedas representing a terrestrial depositional phaseimmediately following the final Late Pleistocene searegression. It is noteworthy that a sample of thesefossil snails were significantly larger than theirdescendants living on the island at the present time(Wilson 2008). It is suggested that this species mayhave existed continuously in that area throughoutthe terrestrial period of the last Pleistocene glacialuntil the present but became smaller.

LAND FORMS

There are three distinct landform types in SharkBay. Faure Island belongs to the Peron Provincewhich comprises undulating sandy plains anddunes with interdunal birridas. The Peron Provinceincludes two of the peninsula-island ridges thatcontain and divide Shark Bay, that is, the NangalPeron Peninsula unit and the Petit Point/FaureIsland unit. Faure Island represents a seawardextension of the latter.

In a 1986 submission to the Shark Bay RegionalPlan the Western Australian Department ofAgriculture (AgWest) referred to the Peronlandform as the Victoria Sand Plain geomorphicregion and described it as an "extensive flat toundulating plain of sand". Within this geomorphicregion AgWest identified several land systems,three of them represented on Faure Island - Birrida,Littoral and Sandplain (Figure 2; Keighery andMuir 2008).

The Faure Sill, a bank of Holocene sand formingvast areas of sandy shallows, crosses the eastern gulfof Shark Bay (Disappointment Reach) from the PeronPeninsula to the mainland on the eastern shore.Apart from a series of deep channels it bars themouths of Hamelin Pool and Lharidon Bight. FaureIsland is an emergent portion of the Sill and isentirely surrounded by sandy flats, much of whichare exposed during periods of low spring tide.

The general topography of the island comprisestwo roughly north-south dune ridges forming thewestern and eastern margins of the island withlower dunes and swales in between. The highestpoint on the island is a dune on the north easternside whose summit is 26 m above sea level.

During the Holocene the seaward sides of thedune ridges of Faure Island were severely erodedby the sea following the last post-glacial rise of sea

B. Wilson

level, forming steeply sloping, breakaway cliffswith calcrete rims, especially along the western andeastern shores. The process of erosion and shoreregression is continuing on the western shore, theloose sand from the cliff faces slipping down to theshore and being spread by wave action across theflats. There is evidence that the western shore mayhave been subject to Late Pleistocene or Holoceneuplifting (Playford and Berry 2002). But along thenorthern, southern and eastern sides of the islandthe shore is prograding with accumulation of whiteHolocene sand to form sandy beaches, narrowcoastal plains and foredune systems.

Along the western and southern shores there areseveral blow-outs in both the orange-redPleistocene and white Holocene dunes. In the caseof the Pleistocene dunes the sand above the calcretelayer has blown off, accumulating as mobile dunesbehind the cliffs. The calcrete surface is exposed insuch places. In situ it has an undulating surfacewith laminated convex structures that, whenexposed, appear as dome-shaped protrusions,creating a very unusual landscape. Fossil bones ofcormorants have been found in one such blow-out,interpreted by Playford and Berry (2002) asevidence that the site may once have been acormorant rookery like the contemporary ones atthe northern end of the island.

Playa lakes, known locally as birridas, occur inthe interdunal swales and contain evaporitedeposits consisting largely of gypsum, believed tobe of Pleistocene age.

In three areas, the southwestern corner, thenorthwestern corner and the eastern side, tidalflows and wind driven waves have formed series ofchernier sand spits enclosing shallow lagoons thatsupport mangrove vegetation (mangals) andassociated supra-tidal samphire flats.

SHORE HABITATS

Faure Island is located within the FaureSalinocline of the eastern gulf (Logan and Cebulski1970). It is within that part of the gulf where there israpid change from the metahaline condition of thenorthern part of the gulf, to the hypersaline watermasses of semi-enclosed Lharidon Bight andHamelin Pool in the south. The range of salinity islikely to be much lower at the southern end of theisland than at the northern end, with correspondingchange in marine communities.

The three most important shore habitats aroundFaure Island are i) intertidal flats, ii) shallowlagoons and iii) mangals. At some locations on thewestern side of the island there are "rocky" shores,composed of semi-consolidated Peron Sandstone.However, these rocks are soft and friable and donot provide suitable habitats for rocky shorecommunities.

Background information

Sand flats'The island is surrounded by wide intertidal sand

flats and the shore comprises mostly sandy beaches,with either reworked sands derived from thePleistocene Peron Sandstone or Holocene marinecarbonate sands derived from the contemporary flats.At low spring-tide the flats are exposed. Beyond lowspring-tide level, the sand flat habitat passes to denseseagrass beds which form one of the dominant marinehabitats in Shark Bay (Walker 1990).

The sand flats support a very rich burrowinginvertebrate fauna, especially small polychaetes andbivalved molluscs (Slack-Smith 1990). The biomassof these organisms provides a food resource forlarge numbers of shore birds. The flats on theeastern end of the island are more muddy than onthe windward eastern side and appear to have anexceptionally rich biomass. It is this habitat thatsupports extremely large numbers of shore birdsthrough the summer months.

Shallow lagoonsAt the south western corner and along the eastern

side of the island, tidal flows and wind drivenwaves have formed chernier sand spits enclosingshallow lagoons that are open to the north. Thelagoons are fringed with mangroves and associatedsupratidal mud flats vegetated with halophyticsucculent shrubs.

The largest and deepest of the lagoons is locatedat the southwest corner of the island. It has a depthof more than one metre and is used as a safeanchorage for small vessels.

At several locations on the east coast, series ofsand spits of different age have produced lagoonsat different stages of development. The older onesclosest to shore are filled with sediment and areinundated only by extreme high tides. The youngerones (seaward) retain water even at low tide. Theyare developing mangals and are in early stages ofsiltation. In this way the east coast is prograding.

At the northern end of the island the sea hasflooded via a narrow, shallow channel, into ameandering, multi-lobed birrida forming an inlandlake. It was dubbed 'Tadpole Lagoon' by surveyparticipants because of its shape.

The shallow lagoons appear to be places ofexceptionally high primary production and play asignificant role in the ecology of the surroundingshallows. A large Pied Cormorant rookery inmangrove trees at or near the entrance of TadpoleLagoon is particularly interesting in this regard(Dell and Cherriman 2008). The shallow channelsand tidal pools in that area are nutrified during thecormorant breeding season. Mangrove trees areseriously damaged by the birds and their excrementwhile they are breeding, but regrowth of youngmangroves at these places during the followingyear is particularly vigorous.

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MangrovesShark Bay is' the most southerly area where

complex mangrove (mangal) systems occur on thewest coast (Johnstone 1990). Within the bay themost dense and structurally developed mangalsoccur at Guichenault Point on the eastern side ofPeron Peninsula, the mainland coast on the easternside of the eastern gulf, and on the shores of FaureIsland.

The largest of the Faure mangals is in the widelagoon at the windward south-western corner of theisland. Lesser examples occur as fringes along thechannels of Tadpole Lagoon and the muddynorthern shore and in the lagoons on the easternside of the island.

On the tropical Pilbara and Kimberley coasts,mangals comprise many kinds of mangrove treeand have a species-rich associated fauna ofmolluscs, crustaceans and other invertebrates. TheFaure Island mangals comprise a single mangrovespecies, A vicennia marina, with a zone of succulentshrublands around their shoreward margins whichare inundated at high tide (Keighery and Muir2008). They support a restricted fauna, with verypoor representation of the suite of obligatemangrove associates that are characteristic of thishabitat further north. This is a manifestation of thenorth-south attenuation in tropical marine plantand animal species on the west coast (Wilson andAllen 1987).

No study of the Faure Island mangrove fauna hasbeen attempted but it seems that only two of themollusc species characteristic of this habitat innorthern Western Australia occur on the island. Thepotamidid mud-creeper Terebralia semistriatuslives in dense colonies on the mud flats in andaround the mangrove trees. The littorinid Littorariacingulata (endemic Shark Bay subspecies L. c.pristissini) lives on the mangrove trunks and in vastnumbers in the adjacent zone of succulent shrubs.There is only one species of fiddler crab, Ucaelegans, which lives in colonies in burrows on mudflats high in the intertidal zone behind themangrove trees. There is only one otherconspicuous crab in the mangals, Neosarmatiumtrispinosum, which lives in turreted burrowsamong the pneumatophores of the mangroves andthe stems of the succulent shrub Halosarcia indica.

LATE PLEISTOCENE-HOLOCENE HISTORY OFFAURE AND ITS RELEVANCE TO THE

TRANSLOCATION PROJECT

Shark Bay has had a very unstable history throughthe Quaternary as a consequence of change in bothclimate and sea level. Throughout this period sealevel fluctuated significantly.

A major transgressive, warming event initiatedthe last interglacial phase of the Late Pleistocene

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about 128,000 years ago. Sea level rose to a fewmetres above that of the present time and oscillatedaround that level for several thousand years[corresponding to substage 5e of the deep-seaisotopic chronology of Shackelton and Opdyke(1973)]. Shark Bay was formed at this time. FaureIsland may then have existed as an island but morelikely as a set of sandy cays with some emergentparts. This period is recorded in the sediments ofthe island by the Late Pleistocene shell bedsdescribed above. There is evidence that during thistime the climate was wetter than it is at present(WyroIl1993).

Around 115,000 years ago a period of globalcooling began and sea level fell dramatically,fluctuating between about 20 m and 130 m belowits present level until about 18,000 years ago. This isthe normal state of the region with the continentalshelf much narrower than it is today. During thisrelatively long period, the broad gulfs of Shark Baydid not exist and sand dunes accumulated on top ofthe Late Pleistocene marine deposits. Faure Islandwas not then an island but a series of dunes on asandy plain. Terrestrial plants and animalscolonised the new dunes, including the snailBothriembryon onslowi whose fossil remains maybe found in the semi-consolidated sandimmediately above the marine deposits (see aboveand Wilson 2008).

At around 18,000 years ago, global coolingpeaked and the sea suddenly fell to at least 130 mbelow its present level. This was a time of greateraridity and cooler conditions (Kendrick 1978;Wyroll 1993). In the latitude of the present SharkBay, the shore was then located west of the linefrom Cape Farquar to Point Quobba and thencedown the western sides of Bernier, Dorre and DirkHartog Islands. The dunes of Faure Island weremerely high points on the Petit Point/Faure dunalridge nearly 100 km from the sea.

Sea level rose abruptly during the FlandrianTransgression immediately after the glacialmaximum 18,000 years ago, reaching its presentlevel about 6,000 years ago and creating Shark Bay.What had been high parts of the coastal plainbecame peninsulas such as Peron and Petit Point, orislands such as Faure, surrounded by the shallowwaters of the bay. The contemporary peninsula andisland floras and faunas are relics of those that hadpersisted on the coastal plain through the arid LatePleistocene and survived the subsequent warmingevent.

Isolation on islands may have significantconsequences on flora and fauna. Reduced area andisolation from other breeding populations, coupledwith climatic change, increase the risk of localextinction in some species. Conversely, isolation onislands may bring protection from threateningprocesses such as predation and fire that prevail

B. Wilson

regionally. The survival of certain native mammalson the outer islands (Bernier and Dorre Islands) ofShark Bay, and their extinction on the mainland isan example.

In the present context, that is, management ofFaure Island as a wildlife sanctuary and a site forthe reintroduction of threatened mammals, this isan important consideration. We need to considerthe possibility that native species that colonisedthese arid sand plains after retreat of the sea 110,000years or so ago may have faced local extinctionpressure when the sea rose again, the area ofterrestrial habitat became drastically reduced andthe island populations became isolated frommainland populations.

Baynes (2008) has shown that several nativemammals once present on the island are nowextinct there. Whether they became extinct becauseof climate change, isolation and reduced habitat,that is, from "natural causes", is a key question inrelation to the AWC translocation project. In theabsence of information that these animals wereextant on the island until the time of humanoccupation, it cannot be assumed that theextinctions are a consequence of goat and sheepgrazing or cat predation brought by humans in the19th and 20 th centuries. Nevertheless, while grazingand feral predation may not be the cause ofextinction, they would surely be unhelpful to areintroduction program in circumstances wherethere are natural stresses. Eradication of feral cats(Algar and Angus 2008) and removal of sheep andgoats is critical to the success of the reintroductionproject.

ACKNOWLEDGEMENTS

The author thanks all the members of the surveyteam for their assistance in the field and their livelycontributions to discussions of the objectives andresults. Dr Philip Playford and Dr Patrick Berrymade helpful suggestions in regard to the sectionon geology. Most of all, the author acknowledgesthe input of AWC founder and Chairman, MartinCopley, whose enthusiasm and support werefundamental to the success of the project.

REFERENCESAlgar, D. and Angus, G.J. (2008). Feasibility study for the

eradication of feral cats from Faure Island, Shark Bay,Western Australia. Records of the Western AustralianMuseum Supplement 75: 71-75.

Baynes, A. (2008). The original non-volant mammalfauna of Fame Island, Shark Bay, Western Australia.Records of the Western Australian MuseumSupplement 75: 25-31.

Dell, J. and Cherriman, S. (2008). The birds of FameIsland, Shark Bay, Western Australia. Records of

Background information

the Western Australian Museum Supplement 75:55-70.

Hocking, RM., WiIliams, S.J., Moor, H.T. and Van DeGraff, W.J.E. (1987). Geology of the Carnarvon Basin,Western Australia. Western Australia GeologicalSurvey Bulletin 133: 289 pp.

Johnstone, RE. (1990). Mangroves and Mangrove Birdsof Western Australia. Records of the WesternAustralian Museum Supplement 32: 120 pp.

Keighery, G. and Muir, W. (2008). Vegetation andvascular flora of Faure Island, Shark Bay, WesternAustralia. Records of the Western AustralianMuseum Supplement 75: 11-19.

Kendrick, G.W. (1978). New species of fossil nonmarinemolluscs from Western Australia and evidence of lateQuaternary climate change in the Shark Bay district.Royal Society of Western Australia 60: 49-60.

Kendrick, G.W. (1990). A Pleistocene molluscan faunawith Anadara trapezia (Deshayes) (Bivalvia: Arcoida)from the Dampier Limestone of Shark Bay, WesternAustralia (pp. 33-48). In: Berry, P.F., Bradshaw, S.D.and Wilson, B.R (eds), Research in Shark Bay, Reportof the France-Australe Bicentenary ExpeditionCommittee. Western Australian Museum, Perth, WA.

Kendrick, G.W., Wyroll, K-H. and Szabo, B.J. (1991).Pliocene-Pleistocene coastal events and history alongthe western margin of Australia. Quaternary ScienceReviews 10: 419-439.

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