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Dr. Desley Whisson
Deakin University, Victoria, Australia
Landscape modification through urbanisation, agriculture, and associated human activities is a leading driver of biodiversity decline worldwide. These changes reduce native vegetation to fragmented and isolated patches, often degrading habitat quality and increasing stressors such as noise and light pollution. Many wildlife species respond by contracting their ranges or altering behaviours—responses that have profound effects on health, reproduction, and survival.
Koalas (Phascolarctos cinereus), due to their specialised diet, limited mobility, and low reproductive rates, are especially susceptible to these impacts. While populations in parts of Queensland and New South Wales are listed as endangered, populations in Victoria and South Australia are believed to be stable, though few long-term studies have confirmed this.
The Mornington Peninsula in Victoria is a highly modified landscape with a mosaic of urban, rural, and remnant bushland areas. This case study explores the current distribution of koalas in this landscape, identifies key environmental and anthropogenic factors influencing their presence, and suggests targeted conservation strategies using passive acoustic monitoring techniques.
Study Region and Context
Location: Mornington Peninsula, Victoria (~73,000 ha)
Land Use: Mix of urban development, agriculture, bushland reserves, and coastal habitat
Native Vegetation: ~30% remains, 10% of which is within reserves
Koala History: Low-density population, likely reintroduced from French Island in the mid-20th century
Passive Acoustic Monitoring: 123 sites monitored using autonomous recording units (ARUs) during the 2019 breeding season
Sampling Period: 7 nights per site, from 20:00–02:00 h
Detection Metric: Presence of male koala bellows
Spatial Scale Analysis:
Site scale (100 m radius): Local tree cover, land use disturbance, anthropogenic sound (NDSI)
Landscape scale (1 km radius): Tree cover, road density, fragmentation indices (CAI_MN, ENN)
Occupancy Modelling: Single-season models accounting for imperfect detection
Variable Assessment: Weather (affecting detection), tree cover, road density, fragmentation
Predictive Mapping: Based on strongest predictors, mapped at 1 ha resolution
Detection Rate: Koalas detected at 31% of sites; nightly detection probability = 0.363
Influencing Factors:
Detection: Negatively affected by inclement weather
Occupancy:
Positively associated with landscape-scale tree cover
Negatively associated with road density
High Probability Habitat:
7.08% (51 km²) of the Peninsula has ≥75% probability of koala presence
Most high-probability areas are in or near public reserves or HMAS Cerberus military land
Public vs. Private Land:
Public land: 17.38% supports high-probability koala habitat
Private land: Only 4.75%, mostly grazing or rural residential
Conservation Opportunity Zones:
~85 km² identified where increasing tree cover could significantly enhance koala presence
87% of this land is under private tenure
Koala presence is strongly influenced by landscape tree cover and road density. Site-scale factors (e.g., presence of food trees, sound levels) had minimal explanatory power, likely due to the consistent availability of koala food species and high overall habitat fragmentation.
Protected reserves serve as important habitat and potential source populations. However, these cover a limited area, and long-term conservation requires enhancing connectivity and habitat availability on private land.
High road density is correlated with lower koala occupancy and higher mortality risks (e.g., vehicle collisions, dog attacks). Wildlife shelter records support these findings, with vehicle collisions accounting for ~70% of koala admissions on the Peninsula between 1987 and 2006.
Habitat Restoration:
Target tree planting in areas with 30–68% existing tree cover and road density <1 m/ha
Focus on rural private land to build habitat corridors
Connectivity Enhancement:
Link isolated patches using road verges, riparian zones, and paddock trees
Prioritise zones adjacent to major reserves
Threat Mitigation:
Install fencing and wildlife crossings along major roads (e.g., near Arthur’s Seat)
Implement dog control measures in koala-prone areas
Further Research:
Examine influence of anthropogenic noise on koala communication
Use bioacoustic indices (e.g., NDSI) in behavioural studies
Monitoring and Policy:
Regular acoustic surveys to track population changes
Incentives for private landholders to engage in habitat creation
Koalas on the Mornington Peninsula are present but likely at low densities due to habitat fragmentation and urban pressures. Despite challenges, there is significant potential to improve their conservation status through targeted reforestation, road safety measures, and collaboration with private landholders. The use of passive acoustic monitoring has proven to be a cost-effective and scalable method for guiding such efforts and should be adopted more widely in koala conservation programs.
In the spirit of reconciliation, Faunatech acknowledges the Traditional Custodians of Country throughout Australia and their connections to land, sea and community. We pay our respect to Elders past and present and extend that respect to all Aboriginal and Torres Strait Islander peoples today.