Research ecologist Dr Adrian Wayne’s discussion could have been titled ‘The ups and downs of Woylie populations in WA’ , for that is what has happened in recent years to these endearing little macropods, with several serious crashes that sent researchers scrambling for answers before it was too late. Adrian brought his large audience up to date with the encouraging progress that has been made with the in-depth research up to now.
As a very fitting introduction to the subject June Butcher screened a mother woylie with joey in pouch during one evening. Yes, in pouch but not for long for out of pouch it scrambled, found its feet with a couple of tentative little hops and then off it shot around the enclosure streaking here and there leaping over obstacles including mum and when finally exhausted, diving head first into mum’s pouch with her assistance. Quite hilarious!
Brush-tailed Bettongs were once found throughout Australia with Bettongia penicillata ogilbyi in all states except Queensland, which has Bettongia penicillata tropica; until the introduction of foxes to Victoria where many small mammal species such as the chudich, woylie and numbat disappeared. Foxes spread rapidly across to WA and by the 1960s woylies were reduced to three small populations amounting to around 100 animals! Fox control was introduced and by 1980 numbers were up in the thousands, but in 1992 numbers were fewer than 5000. However, by 1996 numbers were back to around the 20,000 mark and woylies were delisted from the Endangered List. Come the period between 2001 and 2006 and crash! – a huge decline. So, back on the E. List again with populations such as at Dryandra, Kingston etc falling dramatically one after another. Kanyana has the remnant ‘clean’ population of one special group and there remain healthy populations on some coastal islands as with Venus Bay in S. Australia.
With the Woylie now in great danger of extinction on mainland WA, serious research into the causes of these fluctuations of woylie populations began in earnest. Most of the focus for this research was in the upper Warren area alongside Karakamia and Kanyana sanctuaries.
Research started with demographics: the careful monitoring of population rises and declines in the study areas, decline characteristics, conservation and management response experiments with long-term data to prove that there is a real problem, with trapping, radio trapping and sensor cameras employed. Sand pad strips were laid out to check for the tracks of foxes and cats along with those of target marsupials.
The diet of woylies is made up largely of hypogeal fungi (truffles), bulbs, seeds and insects but no greens or water. The ecological benefits of their foraging include the cultivating and aerating of soil, spreading fungi which are mycorrhizal (a huge benefit to eucalypts and other vegetation = 2x growth/strength stimulation).
Woylies are very prolific breeders, for every 100 days a joey leaves the pouch and another in diapause takes its place; and maybe a good thing as declines in populations can be massive being from 25 to 95% per annum. In 2005 this was a drastic 80 – 100% in some areas of WA and SA. Health checks are carried out for viruses, bacteria etc via universities i.e., clinical examinations. Haematology studies look for viral infections which may lower the immunity of woylies to disease, and are vital indicators forewarning of trouble ahead and quick action can be taken. Shaky evidence points to such factors as toxoplasma, which must go through a cat and theilera, a blood toxin, as culprits in the battle.
Predators: Cats feature as the largest killer, bringing numbers down initially, with foxes then keeping them down. Crashes affect many other precious native animals such as the quenda, dunnart, wambenger and ringtail possum. Predators alone do not explain the sudden declines that occur in these animals and other factors such as disease, fire, body mass and even weather conditions must be considered. The amazing recovery of the woylie population in the Perup sanctuary is a hopeful indicator for the future of our wonderful little marsupial, and future emergencies must benefit from the above intensive research. Apart from June’s captivating pictures, that was all we actually saw of the animals for Adrian’s presentation was largely facts, diagrams and figures; but his total enthusiasm and dedication to his beloved woylies was really infectious and kept us all on the hop. A great evening.
Kevn Griffiths