A young male koala from St Bees Island.

A young male was pursued to the outer branches of a 20 metre gum tree by a larger, mature male koala.

We watched the young male clinging to the outer-most branches until it was dark.

The mature male established itself in a way that blocked any escape by the younger male. It adopted an erect posture and fed actively.

At one stage the young male attempted to crawl along the underside of the branch but was driven back. Next morning both animals were gone and not seen again during the trip.

July 2007

St Bees Island field visit
Eleven volunteers joined me on St Bees Island this winter. They came from Australia, England and the United States of America. We arrived by boat in calm weather – thank goodness. Our routine task was to spend 12 days monitoring koala movements and tree use across the island. This adds to the nine years of accumulated data on this population. Mid trip we were joined by my partner Rhonda Melzer (in her capacity as Queensland Parks and Wildlife Service officer) and a member of her team, John Clarke. Some of us were to work with them for a week monitoring vegetation and installing environmental monitoring equipment to track climatic influences on plant growth. This is part of our collaborative study of the impact of goat browsing and climate change on island ecosystems and koala habitat. With them came colleague Dr William Ellis and Dr Sean Fitzgibbon. With the assistance of the volunteers they worked to catch selected koalas and remove and replace radio tracking collars.

The weather was fine and clear for the first week but a fog descended on the island for the last week providing a constant cool cloud cover with occasional light showers.

The trip ran smoothly and all our objectives were met. The team sighted 55 individual koalas, collected 128 day records of tree use and 32 night records. They measured 360 trees and collected six skeletons of koalas that had died since our last visit. Six koalas were caught and either recollared or had their collars removed.

Our observations of tree use showed that the koalas used a variety of tree species during the day but at night used predominantly their principal fodder species – Forest Redgum (Eucalyptus tereticornis).

The radio tracking data will take sometime to analyse.

The skeletons will be cleaned and used to study aspects of koala longevity and aspects of disease syndromes influencing survivorship. We don’t know how long koalas on the island live or what diseases are impacting on their lifespan.

Climate change and goats
Despite us having an enjoyable and productive field trip the island was in a poor state. Since October 2006 the island ground cover has collapsed. This was most evident on the exposed hill slopes. When we first visited the island in 1999 these slopes supported a dense cover of native grasses (mainly Imperata cylindrica and Aristida spp.). Commonly the grass was over a metre high or formed dense swards that covered rocks and concealed hollows, vertical drop-offs and loose rocks. Now these hillside grasslands have been replaced by sparse to dense shrublands and sparse herblands with extensive areas of bare earth. Previously almost impenetrable native shrublands had disappeared to be replaced by fields of dead timber and sparse herbs. Even the robust Xanthorrhoea latifolia was reduced to well prune remnants in many areas.

This ecological collapse was after record summer and winter rains. Goats are the main suspects. There are now hundreds if not thousands of goats across the island and we know that they will eat many species on the island. Over the last few years we have documented goats eating everything from rainforest trees and ferns, eucalypt woodland species, grassland species and mangroves. In the seasonally dry spring they are commonly seen searching for freshwater soaks along the high tide line. In particularly severely dry seasons they are seen to drink seawater. The impact of the goats has been exacerbated by an ongoing drought. This drought has affected most of eastern Australia including St Bee Island. We believe that the combination of the drought and the goat browsing has pushed the island vegetation over a threshold. The Queensland Parks and Wildlife Service is planning to cull the goats this year (October 2007). Has the cull been left too late? What will be the nature and direction of the post goat succession in the ground cover? We know that the main koala fodder tree species is not regenerating. Is this due to browsing by goats? We’ll be working with the Queensland Parks and Wildlife Service to monitor the recovery process.

Some trees are dieing on the island. These include the koala fodder species (E. tereticornis) and the non-fodder species (Corymbia intermedia). Because the Corymbia is dieing along with the E. tereticornis we are confident that the dieback is probably associated with the influence of long-term drought – not over browsing by koalas.

Like much of eastern Australia, the St Bees Island climate is slowly changing – increasingly less humid with more extended and more intense dry seasons. Plant communities are changing. After 10 years research we think we have some sense of the koalas strategies for dealing with a drying environment. If the drying trend continues we expect that the koala will disappear from many localities across its range in Queensland.

Drama in the tree tops
When you live in close proximity to your study animals occasionally the researcher gets an opportunity to observe the private life of the study animal.

During this trip we had a young male koala calling from a large eucalypt behind one of the houses. This male territorial call is a deep throated staccato grunting and low frequency bellowing. Late one afternoon we were attracted to a high pitched chattering. On investigation we observed a large mature male in the same tree as the young male. The young male moved to the outermost branches and assumed what appeared to be a supplicant position clinging almost upside down to the fine branches and foliage. The older male initially followed the younger male to the outer canopy but then retreated to the point where the young male’s branch joined the trunk of the tree. At this point the older males sat upright and commenced feeding in a very overt manner. The next morning both males had departed. The older male had a large and obviously active sternal gland. The younger male had a sternal gland that was just discernable. We assume that we chanced on the exclusion of a young male from the range of a larger mature male. Based on our radio tracking records the young male will be driven across the island as it tries to find some empty habitat within which to establish a range and continue to develop.

Our next field trip is in October – late spring and the peak season for male territorial activity.

Who are we and why are we here?
Hello, I’m Dr Alistair Melzer and together with my colleagues, community volunteers and Earthwatch I have been studying koalas since 1988. My early studies were funded by the Australian Koala Foundation. Most recently I’ve been working with Dr William (Bill) Ellis on the problem with koalas on St Bees Island. The problem is that there is no problem. Koalas were introduced to St Bees in the 1930s and an apparently stable and healthy population has been established. Elsewhere in Australia introduced populations and isolated mainland populations have grown rapidly and outstripped their habitat. A small team of researchers (Dr Frank Carrick and Dr Ellis from the University of Queensland and me from Central Queensland University) supported by the Central Queensland Koala Volunteers established the study in 1998. Subsequently, Bill and I went on to establish a long term study supported by the Earthwatch Institute. We visit the island at least four times a year with a team of five or more Earthwatch volunteers. Now, in 2007, we are in our seventh season with Earthwatch support. Bill now works with the Associate Director of Conservation and Research for Endangered Species, Dr Fred Bercovitch, at the Zoological Society of San Diego. Together we established a new collaborative team in 2006.

The problem is that there is no problem.
A small number of koalas were introduced to St Bees Island from the adjacent mainland in the 1930s. Later koalas were taken from St Bees Island to nearby Brampton and possibly Newry Islands. On St Bees Island, at least, the koala population has persisted and it is currently estimated that the island supports a population of between 200 and 300 animals.

Koalas are also found on other Queensland islands – Magnetic, Rabbit, Newry, Brampton and Stradbroke islands. On all these islands, animals persist in low and apparently stable numbers. The Queensland experience contrasts sharply with that of Victoria and South Australia. As in Queensland, the southern island populations were established early in the 20th C. from very few animals. In contrast to the Queensland experience, the koala populations on these islands increased - rapidly outstripping their habitat. Public concern for these island populations has resulted in decades of human intervention to preserve these populations and the eucalypt communities within which they live. Animals have been transferred to the mainland to reduce pressures on the islands as well as reintroduce koalas to habitat within their former range in Victoria and South Australia. In South Australia the available mainland habitat is limited. Public opposition to a cull of the Kangaroo Island koala population resulted in the development of an extensive and expensive programme of sterilisation and translocation. On the Victorian mainland koala populations established in habitat fragments have increased and overexploited these habitats.

In Queensland introduced island populations show no similar tendency for explosive population growth or overexploitation of island resources and there is no management of the populations.

St Bees Island provides an opportunity to explore the dynamics of an island koala population as there is a written history of koalas on the island, the tenure as national park ensures that competing land uses will not compromise any studies or impact on the koalas, and there are facilities on the island to support field studies. It is also a very scenic and fun place to work.

What is St Bees Island like?
St Bees Island, a continental island within the Cumberland archipelago, lies about 30 km east north east of Cape Hillsborough on the Central Queensland coast. The island is largely composed of steep, volcanic hills reaching 370m above sea level.

A former island resident Lionelle Berck has given an account of recent historical land use on St Bees Island that provides some context to the understanding of koalas and their habitat on the island.

Goats were introduced to the island prior to 1905 (and are still present on the island in large numbers in 2007 A.M.). Grazing by sheep, cattle and horses started in the 1907 and declined during the 1950’s. A few abandoned sheep, horses and cattle survived to the 1970s. (We’ve found fresh signs of cattle as recently as January 2006 A. M.).

The pastoral activities affected the island vegetation. Photos published by Lionelle Berck provide selected views of some hills on the island in 1926, 1930 and the late 1930s revealing a pattern of forest cover reminiscent of that seen today. In 1936 the island was described as “…a large forest island…timbered with ironbark, bloodwood, gum and Moreton Bay ash, all of small size; grassed with kangaroo grass….” (extract of Ranger McKeown’s report in Lionelle Berck’s account ). In this account the lessee in 1941 obtained the highest wool yield per acre in coastal Queensland. He records 200 sheep per square mile and between 320 and 580 head of sheep, seven to 17 horses and 25 to 86 head of cattle being grazed on St Bees and neighbouring Keswick Island from 1941 to 1947. Lionelle`Berck’s extract from the Lands Inspector’s report for that period talks of spear grass, lantana and prickly pear. By the late 1950’s lantana occurred throughout the island and required intensive management to control (Land Commissioner’s account).

Pastoral activities had ceased by 1968 and active land management was restricted to occasional culling of goats up to the island being gazetted as national park in 2000. There are no accounts of the use of fire apart from “burning with a flame thrower” to manage lantana “during the dryer months” (Land Commissioner’s account in Berck’s text). Diligent searching, however, reveals very old signs of fire (charred stumps and tree scars) across the island. The weathered state of these scars and the occurrence of some within rainforest communities suggest an absence of fire for some decades.

Today intertidal wetlands, eucalypt forest and woodland, casuarina woodland, rainforest and grassland form a mosaic of contrasting ecosystems across the island. Kangaroo grass (Themeda triandra) rarely occurs and grass communities are dominated by white speargrass (Aristida spp.), black speargrass (Heteropogon contortus) and blady grass (Imperata cylindrica). Lantana is widespread and thick in places. “Ironbark” and “Moreton Bay ash” are not found on the island. Steep gullies form drainage lines that discharge into bays around the island. On the northern and western aspects of the island the intertidal zone in these bays is an extensive, shallow, muddy or sandy coral rubble shelf behind a fringing coral reef. Here the drainage lines discharge to the bay through a barrier ridge of “coral rock”. Behind this barrier a saline/brackish tidal estuary supports low closed forest or low woodland of mangrove species including Avicennia marina, Rhizophora stylosa, Ceriops tagal, Excoecaria agallocha, Bruguiera gymnorrhiza, Xylocarpus granatum, Lumnitzera racemosa, Hibiscus tiliaceus and Crinum pedunculatum. Species are distributed along a gradient of increasing salinity and frequency of tidal inundation. Sand dunes or coral rubble banks occur on the coral rock barrier but on opposite sides of each bay. Casuarina equisetifolia woodlands dominate the sands. Low microphyll vine thickets (a type of rainforest) dominate the coral rubble banks. On the exposed eastern and southern aspects of the island the bays are subject to strong wave action and characteristically contain rubble and coarse sandy substrates. Notophyll/microphyll rainforests occur in drainage lines and on slopes in relatively sheltered aspects around the island. On drier slopes and ridges and more open aspects woodlands of gum trees and bloodwoods (Eucalyptus tereticornis, Eucalyptus platyphylla and Corymbia intermedia) dominate. Sheoaks (Allocasuarina littoralis) and a shrubby understorey of rainforest species are important components of this community. In places extensive stands of sheoak and bloodwood (Allocasuarina littoralis and Corymbia intermedia) form dense, low (often wind-sheared) shrublands. Grass trees (Xanthorrhoea sp.) can be a major element in these communities. On the most exposed aspects dense Imperata/Aristida grasslands occur frequently with scattered Xanthorrhoea sp. and rainforest species. Stands of hoop pine (Araucaria cunninghamii) occur on exposed, rocky headlands or rock outcrops adjacent to the high tide line.

Our research objectives.
We see the island as a living laboratory in which to study what keeps an isolated population in balance and look for answers to managing overpopulated habitats elsewhere in Australia. So, this study aims to:
1. understand the ecology of the island population,
2. use this understanding to assist in the management of population isolates in Victoria and South Australia, and
3. apply this knowledge in the management of increasingly fragmented koala habitat in Queensland.

The research objectives being pursued to achieve these aims are:
Aim 1 (on St Bees Island)
• Accurately describe the koala population on St Bees Island (number and demographic profile),
• Investigate the prevalence of chlamydial infection within the population,
• Describe the genetic diversity of the population and consider any difference from the parent mainland population,
• Understand the way the koalas use their habitat and distribute themselves across the island (tree use, fodder selection, tree and habitat preferences and avoidances, home ranges and movement patterns), and
• Describe the plant community composition, structure and dynamics to understand the resource foundation for the koala population.
Aims 2 & 3 (Nationally)
• Develop associations with koala researchers and managers in Queensland, Victoria and South Australia to facilitate transfer of knowledge, and
• Facilitate comparable studies in southern island koala populations.

We are also looking at some other projects. These are:
• Describing adult home-ranges and resource partitioning,
• Understanding seasonal and environmental influences on activity, fodder selection and habitat utilisation,
• Identifying patterns of maternity and paternity amongst the koalas,
• Developing mechanisms for aging the koalas,
• Identifying the causes of mortality,
• Mapping the extent, composition and structure of the plant communities on the island,
• Studying the role of fire and browsing by goats on the maintenance of koala habitat on the island.

How do the Volunteers help?
Wherever it is considered safe to do so Earthwatch volunteers are involved in most aspects of the studies especially (a) searching for koalas, (b) catching koalas when necessary, (c) assisting in the weighing and measuring of koalas (d) radio tracking the koalas, (e) studying the rainforests and woodlands, (f) assisting with data collection and (g) supporting the field team. This is a “hands on” project and volunteers are often asked to handle koalas while assisting us measure the animals.

Depending on the size of the team a roster will be established to ensure that all volunteers have opportunities to experience all aspects of the project – including the cooking cleaning and fishing and have some time off to rest and recreate.

(a) searching for koalas.
This activity involves groups of volunteers systematically “sweeping” the bush searching each tree and bush for koalas. The search requires a keen eye and closely coordinated teamwork.
(b) catching koalas
It is not always necessary to catch the koalas we encounter. Once a decision is made to catch a koala, however, a catching team is formed. This team consists of a tree climber (the researcher) and a ground team. The volunteers form the ground team after proper training. The tree is climbed and the koala is encouraged down the tree by means of waving a flag in the face of the koala. Meanwhile the ground team has quietly positioned its members behind cover around the base of the tree. Once the koala is on the ground the ground team secures the koala and places it into a hessian (burlap) bag for delivery to the processing site.
(c) processing the koalas
At the processing site we will weigh and measure and may take tissue samples from the koala before fitting ear tags and a radio transmitter. The koala is then released to the tree from which it was taken. Some volunteers may be asked to assist us with this process.
(d) radio tracking koalas
Once fitted with a radio collar the koala is tracked once per day and once per night (at a random time) by a team of two or three people. Once the koala is located the tree is marked, the species of tree identified and the plant community the tree is within is classified and the location of the tree is established by GPS. Data are collected by the volunteers in field note books for entry into a data base on return to base camp.
(e) studying the rainforests and woodlands
The structure and composition of the plant communities within the koala’s environment will be described using plotless sampling techniques. Volunteers will assist the researchers through providing field assistance in collecting specimens and processing plant specimens, measuring physical aspects of the forests and recording field data.
(f) data collection
Throughout volunteers will be asked to assist in the collection of field data and the entry of that data into data bases at base camp.
(f) supporting the field team.
On a roster basis volunteers assist in the maintenance of the base camp, the preparation of meals and the maintenance of supplies and equipment.

Here are some general reading options if you are interested in knowing more about St Bees Island or koalas.

Berck L. (1995) St Bees Island: its history, life-style and tales. Boolarong Press, Mackay, Queensland. A colloquial history of St Bees Island by the current lessees – an essential part of understanding the current state of St Bees Island. It can be purchased on the island from the son of the Author – island resident and owner of the base camp cottages.
Martin R, and Handasyde K. (1999) The koala – Natural history, conservation and management. Australian Natural History Series. UNSW Press, Sydney. A good introduction to our understanding of koala ecology but biased towards southern studies.
Melzer A., Carrick F., Menkhorst P., Lunney D. and St John B. (2000) Overview, critical assessment and conservation implications of koala distribution and abundance. Conservation Biology 14 (3) 619-628.
Phillips B. (1990) Koalas – The little Australians we’d all hate to lose. Australian National Parks and Wildlife Service, Australian Government Publishing Service, Canberra. Provides a good perspective on European Australian cultural involvement in koalas.

So, if you’re interested, revisit this site every few weeks. I’ll be providing summaries of our research to date as well as giving accounts of our most recent field investigations. I’ll also build a picture gallery of koalas, people and landscapes so you can get some sense of the research community and the environment.

Alistair Melzer May 2007