In Victoria, much of the existing site data for fauna has come from individual records from a range of sources supplemented by information from systematic surveys. A lack of species records in certain strata does not necessarily mean that the strata have not been sampled; it simply means that the information was not appropriate for use in this analysis. All biological records over an area as large and diverse as the Central Highlands are to some extent artefacts of differential collecting effort and subject to the sampling bias arising from the relative ease with which the occurrence of certain groups (such as birds) can be scored. A lack of systematic survey for specific faunal groups weakens the power of the audit tool to expose under-sampled environmental strata for those groups, but it is not without value.
The site-based biological data sets used in the fauna assessment were drawn from the Atlas of Victorian Wildlife and the Victorian Freshwater and Estuarine Fish Database. A description of these data sets is given in a separate metadata report.
The fauna core data fields extracted were: reference number, date, latitude, longitude, survey method, survey effort and species code.
The Atlas of Victorian Wildlife covers birds, mammals, reptiles, amphibians, threatened invertebrates and threatened fish. Of these, the following groups were excluded from the study: marine birds, waders (except Latham’s Snipe), marine mammals and marine reptiles. Records with less geographic precision (i.e. greater than two minutes of latitude or longitude), were also excluded. Invertebrate fauna were also not included in the review.
In preparation for further analysis, the data were collated into discrete data sets to cover the following species groups:
* Arboreal mammals
* Large mammals
* Small ground mammals
* Diurnal birds
* Nocturnal birds
* Large forest owls
As was done for flora information, the distribution and density of survey site records were used to evaluate the adequacy of sampling of the environmental variation in the region. Strata and large polygons with low densities of sites were identified. The probability of the next species recorded for a particular stratum being new (i.e. not previously recorded in surveys for that fauna group in that stratum) was used as an indication of the adequacy of sampling effort. The analysis was confined to the 20 most extensive strata which range from 15% to 0.8% of the area (totalling 93% of the area).
3.3.2 Results and discussion
The results of the survey site analysis for each fauna functional group are shown in Table 3.4b, Maps 2 to 10 and in Appendix B. Incidental records were not included in the analysis but are shown on the maps referred to above.
Arboreal Mammal Surveys
A total of 1,371 sites has been surveyed, including 212 in stratum 20, 155 in stratum 29 and 133 in stratum 1. Stratum 27 has not been surveyed and is the only one of the 20 largest stratum with the probability of detecting a new species being greater than 20%. Large unsurveyed areas occur in strata 26 and 27 on Mt Baw Baw.
Large Mammal Surveys
A total of 251 sites have been surveyed. Of the 20 most extensive strata, numbers 44 and 53 have not been survey and only strata 10, 15, 25, and 45 have sufficient samples to reduce the probability of new species in the next survey to 5%. Survey effort is concentrated with strata 29, 10, 25 and 39 having 18%, 10%, 10% and 9% respectively of the samples. Poorly sampled strata include 44 and 53 (both with no survey sites), as well as 1, 8, 11, 20, 42 and 43. There have been very few sites surveyed west of Toolangi.
A total of 1,995 sites have been surveyed for small ground mammals in the Central Highlands. Only one of the 20 most extensive strata (strata 53) has not been surveyed. Of the other strata with sufficient survey sites to make a calculation, strata 2 and 8 have probabilities >5% of a new species being detected. Surveyed sites are generally well distributed across the area although large areas of stratum 10 in the north-east, strata 9, 10 and 15 near Mount Gordon, stratum 10 south east of Glenburn, strata 1 and 56 on the western slopes of Mt Disappointment, strata 36, 43, 45, 53 and 70 south of Mt Baw Baw and strata 27 on Mt Baw Baw remain unsurveyed.
A total of 738 sites have been surveyed for forest bats. Of the 20 most extensive strata, strata 2, 27 and 53 have not been surveyed and of the others, only stratum 42 has a probability >5% of a new species being detected. Areas with low survey effort occur in strata 27, 29 and 56 on Mt Baw Baw, 10 in the north-east, 10, 11 and 20 in the Toolangi area, various strata in the Cathedral Range, stratum 1 in the far west and various strata in the Noojee Sate Forest.
Diurnal Bird Surveys
A total of 933 sites have been surveyed for diurnal birds. Two strata have been intensively surveyed, stratum 20 with 248 survey sites and stratum 36 with 166 survey sites. Surveys have been conducted in 17 of the 20 most extensive strata, with strata 2, 27 and 53 having no survey sites. Strata 8, 9 and 59 have probabilities >5% of a new species being detected in the next site surveyed. Areas with low survey site intensity include strata 26 and 27 on Mt Baw Baw.
Nocturnal Bird Surveys
A total of 1,119 sites have been surveyed, generally being well distributed across the region. The main exception is stratum 27 which has no surveyed sites. There are however several strata which still have high probabilities of a new species being detected in the next site survey - these are 2, 8, 10, 11, 24, 42, and 59.
Large Forest Owl Surveys
A total of 733 sites have been surveyed for large forest owls, representing all but one of the 20 most extensive strata (stratum 27 has no surveyed sites). However, several of these strata had only low numbers of surveyed sites which prevented any meaningful analyses for these. Stratum 11 still has a high probability of new species being detected.
A total of 943 sites have been surveyed for reptiles. Of the 20 most extensive strata, 17 have been surveyed and of these six (9, 11, 20, 39, 45 and 59) having low probabilities (5%) of new species being detected. Strata 42, 44 and 53 have not been surveyed. Surveys have been concentrated in the south-east. Large areas with low survey intensity include stratum 10 in the east, the area between Alexandra and Eildon, east of Mt. Disappointment (stratum 56), Acheron Valley (strata 43 and 50), south of Mt Baw Baw (strata 6, 8, 36, 53 and 70), north and west of Mt Baw Baw (strata 10, 25, 26, 27 and 29) and the Dandenongs.
A total of 957 sites have been surveyed, including 17 of the 20 most extensive strata. However, only strata 9, 20, 39 and 45 have been surveyed intensively enough to reduce the probability of a new species in the next site surveyed to below 5%. Strata 1, 44 and 53 have not been surveyed. Despite several of the strata having 50 or more surveyed sites, many of these still have high probabilities of new species being detected Areas with low survey intensity include strata 26, 27 and 29 in the north-west and Mt Baw Baw, strata 10 in the north-east, 15, 43 and 44 in the Acheron Valley, 36 in the west and all strata in the Dandenongs.
Table 3.2: Terrestrial vertebrate fauna survey data, by species group.
Number of the 20 largest strata with low probability (5%) of new species in next survey
Of the 20 largest strata generated by the stratification of the Central Highlands region, between 17 and 19 were surveyed for each of the fauna groups considered. Bats and small ground mammals are the groups most comprehensively surveyed across the region, based on them having the most large strata with low probabilities of new species being detected. Future surveys for reptiles, amphibians and large mammals are most likely to detect species not previously recorded in formal surveys - this is so for the majority of largest strata. Site survey intensities appear adequate for many of the strata and fauna groups. However, a number of survey gaps have been identified at substrata level in different parts of the region.