Month: July 2020

Introduction

The observations were made in the Eastern part of Bunyip State Park in an area of regrowth Mountain Ash (Eucalyptus regnans) that burnt in Black Saturday in 2009. The site is about 250m above sea level and in the Lawson Creek catchment which eventually flows into Westernport Bay via the Bunyip River.

Bunyip State Park covers 16,600 hectares of various types of wet forest and heathland in the southern fall of the Great Dividing Range about 65km east of Melbourne. It contains a variety of forest types with the Mountain Ash forest largely confined to slopes in the north of the Park. Large parts of the east of the park burnt extensively in 2009 with much of the remainder burning in 2019. The burnt Mountain Ash habitat in the eastern of the park is similar to habitat where Leadbeater’s possum (Gymnobelideus leadbeateri) occurs elsewhere with dead trees and an understory containing various wattle species. While not specifically targeting Leadbeater’s Possum at this site in May 2020 a brief stop did result in a good sighting with Scott Baker and Jim Wright.

Observations

On the 15th of May 2020 Scott Baker, Jim Wright and myself (Tim Bawden) headed into the southern part of Tarago State Forest near Jindivick spotlighting in particular targeting Leadbeater’s Possum and large forest owls. The night was particularly successful with Leadbeater’s Possum found in the very south of Tarago State Forest (these records are some of the southernmost since rediscovery in 1961) and Sooty Owls observed along the Tarago River. Later in the evening the group decided to head home through the eastern edge of Bunyip State Park down Forest Road and stopped to check out the range-limited locally endemic Gully Grevillea (Grevillea barklyana). To our surprise we spotted a Leadbeater’s Possum in the very tree we were looking at. Upon leaving the car we pished and were able to call the animal back close enough for photos – another animal was observed close by and was heard drumming. The diagnostic shape and behaviour on both animals leaping through the understory was very evident. There was significant movement on the other side of the road which may have indicated a third animal but this was not confirmed. After a couple of minutes of spotlit observation we left the animals alone and tried two more sites further down with out success. Conditions were a very crisp, still and clear night with no risen moon and a temperature around 3 degrees C. Needless to say I was a little excited as I had tried for a while for this species in Bunyip SP.

I was keen to return so a week later I headed back with Rohan Clarke and Scott Baker on the 23rd of May 2020. Unfortunately this night conditions were not ideal with constant drizzle and a SE-E wind and ~20kph winds with a temperature around 8 degrees C – there was no risen moon but would have been irrelevant with total cloud cover and fog throughout. Still we persisted and with a combination of pishing and Rohan’s thermal scope were able to locate a Leadbeater’s Possum approximately 200 meters south of the last sighting in Acacia dealbata. The animal was skittish perhaps due to the conditions but Scott was able to secure a diagnostic photograph. Other sites above and below this one were unsuccessful but conditions were definitely not conducive. Eventually we had to admit defeat and move to more sheltered areas.

On the 13th of June 2020 I returned with my son Lucas and we managed an hour of spotlighting in the area without success before gale-force winds moved us on. On the 19th of June 2020 Isaac Clarey and I had completed a loop through Tarago State Forest (LBP at 2 sites in State Forest) and spent 2 hours working Forest Road inside Bunyip State Park after midnight without success. Unfortunately Covid-19 has at this stage prevented further visits to the area.

Over the past 5 years I have driven this road many times at night and have stopped regularly to play owl calls without observing anything unusual.

Habitat

The area the Bunyip SP sightings occurred in was a small tongue of Mountain Ash in the Lawson Creek catchment that had burnt heavily in Black Saturday in 2009. It appears that this gully may have been logged before declaration of Bunyip State Park with none of the fire killed trees particularly large. No real evidence of large stags visible from the road during daylight visits. The fire appears to be have burnt hot enough to induce stand replacement in the Mountain Ash with many young ~10 year old trees coming through. Interestingly above the road line in the sighting location the forest changes to more stringybark types including Eucalyptus obliqua and Eucalyptus sieberi typical of many other slopes in Bunyip SP. There is a thick understory with abundant Acacia dealbata and Acacia obliquinervia with the odd Acacia melanoxylon and of course the Grevillea barklyana in which the first animal was spotted. The makeup of the understory is very similar to many other locations where I have observed Leadbeater’s Possum previously. Daylight observations of the forest area did not find any obvious denning locations with no large stags located – it is possible that the fire killed trees from 2009 are now cracking enough to provide some cover or there were other undiscovered options.

Other nocturnal mammals seen in the immediate area during recent observations include Sugar Glider (Petaurus breviceps), Bobuck (Trichosurus cunninghami), Feather-tailed Glider (Acrobates sp) and Common Ring-tailed Possum (Pseudocheirus peregrinus). Nocturnal birds noted were Australian Owlet-nightjar (Aegotheles cristatus) and Australian Boobook (Ninox boobook)- it is noteworthy that in ~10+ nocturnal visits to this area over the past 5 years I have not not located any large forest owls with playback in this area of burnt forest despite them being relatively common nearby. Diurnal birds in the area are typical of similar wet forest areas in the region with notable species including Pilotbird (Pycnoptilus floccosus), Superb Lyrebird (Menura novaehollandiae), Brown Gerygone (Gerygone mouki), Rose Robin (Petroica rosea) and Lewin’s Honeyeater (Meliphaga lewinii).

Significance

The Leadbeater’s Possum is a Critically Endangered possum species restricted to the Central Highlands around Melbourne and is Victoria’s fauna state emblem. It was discovered in 1867 and was only known from five specimens with the last one collected in 1909 and was considered likely extinct as most of the original lowland swamp habitat was drained and cleared for agriculture. In 1961 it was rediscovered by Eric Wilkinson in Ash forests near Cambarville. It has since been found to inhabit an area of perhaps 70 by 80 km from Toolangi in the west, Rubicon in the north, Baw Baw in the east and Tarago in the south – see interactive map. The majority of these records are in ash or snow gum forest with only one small isolated lowland population known at Yellingbo. There are few records in the Westernport Bay catchment since 1961.

In Bunyip State Park itself there are perhaps two previous records of Leadbeater’s Possum. The first by Richard Loyn and Ed McNabb occurred in 1981 on the southern slopes of Mount Beenak in an area on the very edge of the current day park in what was then Gembrook State Forest at an altitude of about 600m. I have searched this area over past few years without result. There is a second record from the 1990’s in the Blue Range on the very northern edge of Bunyip SP (ALA) but it is unclear if this was inside the park boundary – this area contains a lot of regrowth Ash forest and would be worth further investigation. The current observations are approximately 8km ESE of these and are well with the current park boundaries. Probably the closest sightings are the recent ones in the southern portion of Tarago State Forest – before these the species was not well known south of the Tarago River. It is interesting to consider if these recent sightings have moved in following regrowth and opportunity following the Black Saturday fires or have always been in the area. Further searching in the immediate catchment area and other parts of the Bunyip catchment would be worthwhile, particularly in lowland areas which are not dissimilar to the Yellingbo habitat. At this stage Covid restrictions prevent further investigation.

References

“Atlas of Living Australia – Open Access to Australia’s Biodiversity Data.” Atlas of Living Australia, http://ala.org.au.
“Leadbeater’s Possum Interactive Map.” Leadbeater’s Possum Interactive Map, http://lbp.cerdi.edu.au/possum_map.php.
Lindenmayer, David, et al. Mountain Ash. CSIRO PUBLISHING, 2015.
Loyn, Richard, and E. G. McNabb. “Discovery of Leadbeater’s Possum in Gembrook State Forest.” Victorian Naturalist Vol 99, 1982.
Menkhorst, Peter, and Frank Knight. Field Guide to Mammals of Australia. OUP Australia & New Zealand, 2010.