Data about sightings of native fish, amphibians, reptiles, birds and mammals has been collected over many decades.

By analysing these records, we can:

• determine the number of species that are known to have existed in the region
• calculate the probability that each species still exists.

The specific method used here was developed by Fiona Caryl, Rodney van der Ree and Kelly Holland at the Australian Research Centre for Urban Ecology. Records were used from the Atlas of Victorian Wildlife, Melbourne Water Frog Census, Melbourne Water Fish Census and the Atlas of Australian Birds (co-ordinated by Birds Australia).

The method analyses the number, regularity and date of sightings for each record.  The analysis produces, for each species, a probability of persistence (a ‘p’ value) expressed as a number between 0 and 1.   The ‘p’ value for a species will decline as time elapses since the species was last observed.  The higher the ‘p’ value, the greater the probability that the species still exists.   A score close to 1 indicates the species is almost certain to still exist, while a score close to 0 means it is very likely to be extinct.  The use of the method in this strategy assumes that a species probably continues to persist if it has a ‘p’ score >0.5.

It is important to note that this method is designed only to answer the question, how likely is it that a species persists?  The method does not measure rarity or conservation status.  Helmeted Honeyeaters have very small, isolated populations but a ‘p’ score of 1.0 as they are regularly monitored and observed.  The Growling Grass Frog is in small numbers and listed as ‘endangered’ in Victoria but regular monitoring ensures it is consistently observed and it has a high ‘p’ value.  Conversely, there may be species that have stable populations, but low ‘p’ values because it is difficult to find and/or there have been limited monitoring efforts and infrequent recordings.   Common species may also have low ‘p’ scores.  The 2008 analysis linked to this strategy produced a low rating for Australian Pelicans in Western Port.  Perhaps they are so common there that no-one has thought to submit Atlas entries for them for the last decade!  These anomalies show the need for more consistent monitoring across the region, especially for species that are not thought to be threatened.

The landscapes, habitats and pressures on native animals are highly diverse across the Port Phillip and Western Port region.  Few species assessments would give results that are valid for all parts of the region. To monitor and report native animal diversity, the region has been divided into seven sub-regional areas. These seven areas are clusters of municipalities that share relatively similar landscapes.  These areas acknowledge the important role of local governments in conserving environments for locally-valued native animals and make it easier for people to identify environmental conditions where they live.

The seven sub-regional areas in which native animal diversity is to be monitored in this Strategy are:

• Mornington Peninsula
• Moorabool, Melton, Wyndham, Greater Geelong
• Macedon Ranges, Hume, Mitchell, Whittlesea
• Yarra Ranges, Nillumbik
• Casey, Cardinia, Baw Baw
• Bass Coast, South Gippsland  & Islands
• Urban Melbourne; inner and middle metropolitan council areas.

The results for each species for each area are presented in tables such as the one below.

Summary of native animal diversity in the Mornington Peninsula

Method for assessing native animal diversity

Report – Probability of persistence of native species in the Port Phillip and Western Port region
This report  provides the method for assessing native animal diversity as developed by the Australian Research Centre for Urban Ecology in 2008.  This report includes the ‘p’ scores for each species in each of the 7 sub-region areas.

The species diversity method described above only tells us if a species is likely to exist. It does not tell us if its populations are healthy and likely to survive into the future. Monitoring and assessing every population of every species across the region would solve this problem but is an impossible task.  Instead, this strategy proposes to assess the population health of a selection of Indicator Species.

Assessing the population health of indicator species is proposed as a way to:

• Measure the health of a wider range of animals sharing similar landscapes and threats
• Pose questions about the condition of land and water environments as habitats for native animals.

Indicator species are listed in the table below.  They have been selected under six criteria:

1. They include animals from various taxonomic groups
2. They are relatively widespread and inhabit many of the region’s environments
3. They share habitat, breeding and food requirements with other species in the same environments
4. They share, with other species, sensitivity to extent and/or quality losses in their habitats
5. They are sensitive to other common threats such as introduced predators
6. They are (as far as possible) easy to identify so monitoring can be done by landholders and community groups

The health of indicator species populations will be assessed by using, where feasible and appropriate, Bayesian Belief Network models. These models are tailored to each species and its habitat and involve assessment of interconnected factors such as habitat conditions, existing populations, food and predator pressures.

The end result is a rating of whether the health of an animal population in a particular area is most likely ‘improving’, ‘stable’ or ‘declining’.

Most of these indicator species live in many parts of the region.  The location of on-going population health monitoring will be determined in the monitoring program design.

Indicator species, their habitats and pressures

* Probability of Persistence (POP) is explained in the ‘Diversity’ section above.
^ IR = Insufficient records to make an assessment.

Indicator species mostly exclude species listed as threatened under the Victorian Fauna and Flora Guarantee.  Active management directed to threatened species reduces their value as indicators.  Threatened species are often scarce, difficult to monitor and have unique and particular habitat needs.  Exceptions are marked in the list below where (regretably) it is difficult to find non-threatened species that meet the indicator criteria for some of the region’s major landscape types.

Threatened species conservation programs will continue.  Their success in halting the slide of threatened species towards extinction will be monitored by the species diversity method described above.

Targets have been set to improve or maintain the population health of Indicator Species.  The first aim of these targets is to drive monitoring.  In the longer term, they should also direct actions for habitat conservation.  Measured improvements in the population health of Indicator Species should create measurable habitat improvements for other species.