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POSSUM in by GordonFri,end Tiny boneyposswnts a.re still ctn n on in heothl.and.sof the soath-west...bat for howmach longer? They rely on o ronge of flowering plants for a yoar-rownd. sttp?ly\fnecta.r and pollen - tbe very sen aplents tha,tore threatened.by the hiller d.ieb a chfung us. he species-richheathlands and shrublandsof the south-westof WesternAustralia are home to one of Australia'smost unusual mammals, the honeypossum, or noolbmger, as itw:r knownto the Aborigines.In fact,it is no morea possumthan it is a bandicootor a dunnart,being so distinct that it is ina categoryall of its own: the superfamily Tarsipedoidea. This tiny marsupial is highly specialisedfor feedingon nectarand pollen.Itslong, pointed snout and brush- tippedtongue are perfectlysuited for probingthe flowersofbanksias and otner plants.Apart from somebats, the honey possumis the only mammal in theworld PreuiousPage: I that feedsexclusively on nectar and greatscientific interest, Thehoney possum, seen here feeding therewas little, I pollen. This amazingspecies has the ifany, a on a Banksiacoccinea, Dollinates ecologicalresearch on thespecies severalheathland banksia species. smallestnewbornyoungofany mammal, until the late 1970s.This was mainly - Photo Bertand Babs Wells but the largestsperm. Reflecting the becauseno-one knew how to catchthe latter'ssize, the testesare suspended rn animals,as they would not I Aboae: enter the a large scrotum which representsa usualmetal a Bankia grcndis andBankia caleyi or wire-cagetrap. In 1926a I are importantfood sources for honey significant proportion of the animal's teamof MurdochUniversity researchers possums. bodyweight(the testes alone being more (Ron Wooller, Marilyn Renfreeand Photos- Jiri Lochman than four per cent).Its breedingis not EleanorRussell) working in the Albany relatedto seasons,but is closelytied to I Eelow: areaheard that locallarmers often found I Thehoney possum is sodistinct it is the floweringpatterns of the nectar- honeypossums in newlydug post holes, producing I in a categoryall of its own. plantson whichit relies, particularlyin sandyareas near remnant Photo - Jiri Lochrnan Althoughthe honeypossum is of bush.These scientists establisheda oitfall 24 unasco* -i e: trappingtechniqu€ which readilycaught I Aboae left: the possums,and over the next 15 years I Youngpossums accompany their the Murdoch team, together with I mothersfor the last threeto four week of a l2-week researchersfrom other organisations, sucklingperiod. Photo- Bert andBabs Wells assembledavastamountof information on the population dynamics, habitat nsht: preferences, lTop breeding and diet of the f Honeypossums probe banksia flowers species.Ken Richardsonand RonWooller I with their long point€dsnouts and gatheredmuch of the recent data from brush-tippedtongues for nectarand pollen. the FitzgeraldRiver park, National rn a Photo- liri Lochman project supported by the World Wde Fund for Nature Australia (WWF). I Aboaeright: Honeypossumsarefoundonly in the I Honeypossums sometimes shelter in south-westof WesternAustralia, where f abandonedbird nests. they occur in heathlandson sandysoils Photo- Bertand BabsWells which supportarich assemblageofplant species of the families Proteaceae lRisht: They have (banksias,dryandras, grevilleas I the smallestnewborn young and so I OIany mammal, on) and Myrtaceae(such as eucalypts Photo- Bertand Babs Wells and bottlebrushes).This habitat restriction reflects the animal's banksia (Banfrsliz nutans), which was bottlebrush(Ca1otft amnus quadrifidus) specialised pollen diet of and nectar. important from autumn to spring, and and gracefulhoneymyrtle (Melaleuca Studiesofpollen samplesfrom the head scarlet banksia (&n trsia coccinea), wed radula).Similarly ,near Mt Lesueurnorth fur of honey possumshave shown that, throughout spring and early summer. ofPerth,Steve van Leeuwen from CALM although the plant speciesused differ Morerecentwork by Ken Richardson foundthe possums relied on a numberof betweenareas in accordancewith species' and Ron Wooller in the western half of Proteaceousand ^4yrtaceous species, in distributions, the possums consistently Fitzgerald River National Park showed particufarpine banksia relied on proteaceous lBanksia species, that noddingbanksiais the mainsummer tricuspis), Banksia micrantha, couch particularlybanksias. For example, in foodthere. with woollybanksia (Ban,trsriz honeypotand silky-leaved blood flower the heathlands along the south coasr baueri) and four speciesof Drgandra (Calot hamnus sanguineusl. near Albany, Ron Wooller and hrs rmportantover winter. Scarlet banksia, Thiswork on thefood preferences of colleagues from Murdoch, and Steve however,was relativelyunimportant. honeypossums showed that, in some Hopper from the Department of Further north, in the heathlands areas,the possums reliance on certain Conservation and Land Management within thejarrah forestnear Dwellingup plant speciesdiffered somewhat from (CALM), found that honey possums and Pinjarra, consultants surueying that of the honeyeaters.In the jarrah collectedfood from at least13 speciesof mammals for the Worsley Alumina heaths,for example,the honeypossum plants, ll from the Proteaceaeand two project found that the possumsrelied appearedto be a major pollinatorof from the Myrtaceae (see Table). mainly on variousspecies of Dryandra, ground-hugging species with Particularly important were a particularly couch honeypot(Dryandra inconspicuousflowers, plants that are bottlebrush (Beaufortia anisandrol, niueo), as well as woollybush seldomvisited by honeyeaters.This whichwasused during summer,nodding (Adenant hos cggnorum), one-sided researchalso showedthat in any uuosmpr:25 heathlandarea there are always several plantspecies in flower, providingasource of pollenand nectarfor the possums throughoutthe year. Thehoney possum and the Plants on whichit liveshavethus evolvedtogether, with the possumrelying on the plants for food,and the plantsbeing pollinated by the possum.The honeYPossum's highlyspecialised adaptations enable it to respondin averyfine-tunedway to the seasonaland annual changes in its habitat anditsfood.This maybecomethespecies' downfall,however, in an environment increasinglysubject to disturbance. UNDERTHREAT Apart from direct destructionof heathlandsthrough clearing, two kinds of disturbancethreaten the honeY possum.The first, fire, is likely to be a problemmainly on a local scale,and then only if largetncts of habitatare burnt by high intensitywildfire at frequentintervals leaving few unburnt patches.Research being carried out by CALMonthe south coast isshowingthat honeypossums can use areas burnt at lowto moderateintensity, provid€d there arenearby patches of unburntvegetation fromwhich the animals can recolonise. Managementstrategies that Yeducethe intensity,frequencY and extent of wildfiresare therefore likely to enhance thesurvival of local populations of honey possums. Theother threat to thefuture ofthis speciesleaves no roomfor complacency. Soilandairborne fungiwhich attack and kill plantsthrough either their aerial shootsor rootsystems are an enormous This diminutivecreature (males of Governor George GreY, but threat to south-westecosystems (see weigh only about nine gramsand missDeltit. Therewere thus three LANDSCOPE,Spring 1991). There is' as - females11 grams) came to the specificnames in commonusage yet,no practicalcure for thesediseases' attention of the scientificworld in rostrotus,spenserae and spenceroe, The best-knownand most widelY the 1840s, when sPecimensfrom and this causedturmoil in the researchedof thesepathogens is the the King Ceorge Soundarea were scientificliterature. In the earlyI 980s dieback fungus, PhAtoqhthora sent to England.lt was given the somecareful detective work by lack cinnamomi (seeZANDSCOPE, Spring generic name fors,Pesbecause lts Mahoneyfrom the Universityof 1989and 1991).Since the soil-borne long, slenderfoot (pes)was similar Sydney established that a funguswas shown to be the causeof the to that of the smallprimate forsius communicationby Gervaisand mysteriousdeath of patchesof jarrah from Indonesiaand the Philippines. Verreaux,in which they describe forest in 1965,scientists have learnt However, there was considerable Torsipesrostrotus, was published on muchof the dynamicsof the organism, confusionover the specificname; it 3 March1842, onlyfive daYs before the conditionsunder which it rapidly was calledrostrotus by Gervaisand Gray's descriptionwas Publisheo. spreads,and the quarantinetechniques Verreauxand sPenseroebY GraY, Bythe law of taxonomicpriority the neededto limit its sprend.Most of this both in early1842. GraY named the honey possum is therefore called research,however, has concentrated on speciesafterEliza Lucy Spencer, wife Torsipesrostrutus. thejarrah forest, and only in thelast few years did work commenceon the 26 ,nnosa"" :.:.d;-.aj--. r. heathland and shrubland ecosystems which arejust assusceptible to dieback. Furthermore, a poorly known group of aerially dispersedcanker fungi was recently identified as the causeof the crown-induced dieback of many south coast heathlandspecies, particularly in the FitzgeraldRiver National Park. Many of the plants most susc€ptible to diebackand the canker fungi belong tothe Proteaceaeand Myrtaceae families that dominatethe heathlands.These are the sameplants upon which the honey possumis dependent.Of the l3 major food plants used by honey possumson the south coast near Albany, five are highly susceptibleto dieback(80 per cent killed at any site), sevenare of variable susceptibility (20-80 per

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