Field survey methods

1. Following the guidelines

2. Preliminary assessment

3. Habitat assessment

4. Obtaining a list of threatened species

5. Determining Biometric vegetation types

6. Survey methods and effort

7. Information to be included in the report

8. References

1. Following the guidelines

This section describes best practice survey methods for determining the presence of threatened species, populations, or ecological communities on sites proposed for development or other activities.

Where the level of survey effort or the methods outlined in these guidelines are not undertaken and threatened species are not detected, it cannot be assumed that the threatened species are not present. While the presence of a target species can often be confirmed at a location, it is generally impossible to confirm a species' absence (MacKenzie 2005). An observed absence may be the result of the survey method failing to detect a species that does reside at or use the location (MacKenzie 2005). For this reason, the effort and methods described below should be applied. The survey effort described is the minimum level that should be undertaken.

If you deviate from the survey effort or methods outlined in these guidelines, OEH strongly recommends that a scientifically valid justification that refers to scientific literature be provided. Use your professional judgement where appropriate, and always provide a justification for the course of action undertaken.

Habitat assessment is recommended, where possible, as a surrogate for intensive surveys. In this instance, threatened species should be assumed present if their habitat requirements are met.

Surveyor experience

You should have extensive experience in conducting field surveys and should be able to identify threatened species and their habitats relevant to the study area, as well as any similar species that may be confused with them. You should familiarise yourself with herbarium or museum specimens of any threatened species you are not already familiar with, before you conduct field surveys.

Guidelines for specific species

Specific survey methods and the effort recommended for each threatened species will be added to these guidelines as they become available. Currently, specific guidelines are available for amphibians (09213amphibians.pdf 177KB). Section 5 provides general information on survey methods and effort that are relevant for all threatened species.

These guidelines were developed using the best available information at the time of writing. However, for many threatened species, very little is known about their habitat needs or behaviour, making it difficult to determine adequate levels of survey effort. In addition, species' habitat needs may vary across NSW. Local information should always be sought, and you should use your professional judgement, backed up by sound reasoning and scientific information, where appropriate.

2. Preliminary assessment

The preliminary assessment includes a number of steps which need to be undertaken before the field assessment can be conducted.

Step 1: Defining the study area

You will need to accurately assess the potential impacts of the development proposal on the study area before commencing the field assessment. The study area will generally be larger than the development site as it includes any adjacent areas that will be directly or indirectly affected by the proposal. These may include adjacent parcels of land containing suitable habitat for threatened species. It is therefore important to recognise that these parcels may need to be investigated along with the development site.

The study area should be established before the list of threatened species potentially affected is determined so species that are less obviously affected are also included.

Direct impacts are those that directly affect individuals or their habitat. Examples of direct impacts include:

  • poisoning or removal of the organism itself
  • removal of habitat.

Indirect impacts occur when project-related activities affect species, populations or ecological communities in a manner other than direct loss. Examples of indirect impacts include:

  • sediment, pollutant or nutrient runoff into adjacent vegetation
  • habitat fragmentation or isolation
  • soil erosion
  • altered hydrology regimes
  • exposure to heat or predators, or loss of shade
  • inhibition of nitrogen fixation
  • weed invasion
  • fertilizer drift
  • increased human activity within or directly adjacent to sensitive habitat areas.

The study area must be:

  • clearly defined
  • marked on a map showing the development site boundary and any additional areas facing indirect impact
  • included in the final report.

Step 2: Obtaining licences

You will require a licence under section 132C of the National Parks and Wildlife Act 1974 to undertake an activity for scientific, educational or conservation purposes that is likely to result in one or more of the following:

  • harm to any protected fauna, or to an animal that is a threatened species or is part of an endangered population or an endangered ecological community
  • harm to any protected native plant, or any plant that is a threatened species or is part of an endangered population or an endangered ecological community. You will need a licence if you plan to collect voucher specimens for identification purposes, pick cuttings or whole plants, or collect seed
  • damage to critical habitat
  • damage to a habitat of a threatened species, an endangered population or an endangered ecological community.
    Section 132C came into effect in January 2003 and replaced the previous need for separate licences under other provisions of the National Parks and Wildlife Act 1974 and the Threatened Species Conservation Act 1995.

It is a condition of all licences that you submit a report of the work carried out under the licence, including any results, to OEH within two months of the expiry of the licence.

For more information regarding licences, email the Wildlife Licensing and Management Unit of OEH or phone (02) 9585 6540.

Also, be aware of the requirements relating to animal care and ethics when conducting wildlife surveys. The handling and capture of animals is regulated by the NSW Animal Research Act 1985 and the NSW Animal Research Regulation 1995, which are administered by NSW Department of Primary Industries. The Act requires that every person undertaking animal research must hold an Animal Research Authority. Under the Act, animal research includes the use of animals in field surveys.

All surveys must be carried out in accordance with the NSW Department of Primary Industry's Guidelines for wildlife surveys.

Step 3: Stratifying the site

When designing a field survey, firstly stratify the study area (i.e. divide the area into relatively homogenous units - often referred to as 'environmental sampling units' or 'stratification units'). Stratified sampling provides a logical, objective and efficient method of undertaking surveys and ensures that the full range of potential habitats and vegetation types will be systematically sampled.

Initial stratification can be done using recent aerial photography or Spot 5 imagery but should be confirmed during the preliminary site visit.

The study site should be stratified by OEH BioMetric vegetation type (see section 4). If the site supports only one vegetation type, or a very large area of one vegetation type, the site can be further stratified by vegetation condition or disturbance history. Once the stratification units have been identified, they should be recorded on a survey map.

Step 4: Visiting the site

Conduct a preliminary site visit to refine the initial stratification units, determine the OEH Biometric vegetation types present at the site, assess the vegetation condition and conduct a habitat assessment. You should take a description of the Biometric vegetation types for the relevant catchment management authority into the field during the preliminary site visit.

3. Habitat assessment

Habitat assessment is recommended, where possible, as a surrogate for intensive surveys and threatened species should be assumed present if their habitat requirements are met. Ensure all impact assessments include a thorough habitat assessment.

Section 110 of the Threatened Species Conservation Act 1995 requires a species impact statement to include a full description of the type, location, size and condition of the habitat (including critical habitat) of all threatened species and populations assumed to be present on the site.

Undertaking a habitat assessment of the study area will assist with predicting the occurrence of threatened species in the study area and will guide the location for targeted surveys. A comprehensive habitat assessment should be conducted across the whole site, identifying key habitat features for both flora and fauna.

You should be familiar with the habitat requirements of each threatened species identified as possibly occurring in the study area. This information can be obtained from recovery plans, threatened species profiles and scientific literature.

The habitat assessment should include information on:

  • landscape features in the study area (e.g. river banks, rocky outcrops, dry slopes, wetlands, undulating terrain)
  • any other features that could provide habitat such as hollow-bearing trees or culverts
  • the BioMetric vegetation types (see section 5 for more information).

It is important to record all areas of native and introduced vegetation, as even weeds can potentially provide habitat for threatened fauna.

As part of the habitat assessment, you should look for:

  • hollow-bearing trees, including dead stags
  • bush rock and rocky outcrops
  • natural burrows, such as those of the Hastings River mouse
  • large trees with basal cavities
  • logs
  • wetlands, streams, rivers, dams and other water bodies
  • nests and roosts
  • wombat burrows
  • dens used by yellow-bellied gliders, squirrel gliders and brush-tailed phascogales
  • yellow-bellied glider and squirrel glider sap feed trees
  • distinctive scats (e.g. those of the spotted-tailed quoll or koala)
  • latrine and den sites of the spotted-tailed quoll
  • Allocasuarina spp.
  • flying-fox camps
  • Microchiropteran bat tree roosts
  • Microchiropteran bat subterranean roosts (caves, culverts, tunnels and disused mineshafts)
  • swift parrot and regent honeyeater feed or nest trees
  • winter-flowering eucalypts
  • permanent soaks and seepages in potential habitat for Philoria spp.
  • areas that can act as corridors for plant or animal species.

Another important factor to consider is the connectivity value of the site. If the proposal site forms an important corridor in the area, the development is likely to have an effect on threatened species in the region.

A map of the study area detailing key habitat features, including the BioMetric vegetation types, must be included in the report (see section 7).

4. Obtaining a list of threatened species*

OEH recommends using the BioBanking Credit Calculator to obtain a list of threatened species possibly occurring on the site. Although only consultants accredited to use the credit calculator can submit a BioBanking Statement under the BioBanking Scheme, anyone can download and use the credit calculator.

The BioBanking Credit Calculator uses five criteria to determine which species are likely to be present on a site:

  • the catchment management authority subregion the proposed site is in
  • the Biometric vegetation types present on the site (see section 4)
  • the vegetation condition, which will be either 'low' or 'not low', that is, vegetation in medium or high condition (see the BioBanking assessment methodology and credit calculator operational manual)
  • the surrounding vegetation cover class (determined by aerial photography - see the BioBanking assessment methodology and credit calculator operational manual)
  • the adjacent remnant area or patch size (determined by aerial photography - see the BioBanking assessment methodology and credit calculator operational manual).

Once you have downloaded the credit calculator, select the 'development sites' button and complete steps 1 to 4 to obtain a list of threatened species potentially occurring on the site. Steps 5 and 6 are not necessary for generating a threatened species list. Make sure you select both the 'Print list of threatened species requiring field survey or checking for known populations' AND the 'Print list of threatened species predicted on site' buttons in step 4. The credit calculator produces the list of those species requiring species credits separate to the list of species requiring ecosystem credits under the BioBanking Scheme. For Environmental Planning and Assessment Act assessments all species potentially occurring on site (i.e. both lists) need to be considered during the field survey. 

If you do not wish to use the BioBanking Credit Calculator to compile a list of threatened species, you will need to provide a justification for how this list was determined. Other resources you could use include:

Consultants should note it is important to obtain a full Atlas report by contacting the OEH Wildlife Data Unit gis@environment.nsw.gov.au. Full reports contain more detailed information about individual sightings than that available from the above website. OEH can only provide information for the records which OEH is the custodian of, and consultants should also seek information held by other organisations such as CSIRO, Australian Museum, Department of Primary Industries and local councils.

Any 'final determination' to list a species, population or ecological community as 'critically endangered' or 'endangered' made after lodgement of a development application or activity proposal needs to be included in the consideration of impacts and the application of the assessment of significance. Vulnerable species listed after lodgement are not subject to impact assessment as long as the application is determined within 12 months of lodgement.

* Consultants should note that where Director-General's Requirements (DGRs) have been issued for Species Impact Statements, or Director-General's Environmental Assessment Requirements (DGEARs) have been issued for projects assessed under Part 3A of the Environmental Planning and Assessment Act 1979, proponents must address everything contained in the DGRs or DGEARs.

5. Determining Biometric vegetation types

The classification of native vegetation in NSW follows the system described by Dr David Keith in Ocean shores to desert dunes: the native vegetation of New South Wales and the ACT (Keith D 2004). This classification scheme divides native vegetation into 17 broad vegetation formations. Each formation consists of a number of vegetation classes. There are 99 vegetation classes.
These classes are further divided into vegetation types (referred to here as 'BioMetric vegetation types'), which are the finest scale of vegetation classification used in NSW.

Find out more about native vegetation

OEH has developed a NSW Vegetation Types Database for use with the BioMetric tool, which is designed to assist in assessing biodiversity values when preparing property vegetation plans under the Native Vegetation Act 2003.

OEH has provided a spreadsheet containing a definition of these vegetation types on a catchment management authority basis.

Each vegetation type is defined on the basis of the following attributes, where relevant:

  • dominant canopy species
  • main associated species
  • landscape position
  • characteristic mid-storey species
  • characteristic groundcover species
  • other diagnostic features.

All vegetation types in the study area should be identified, matched to a OEH BioMetric vegetation type, mapped and included in the final report. Some vegetation types will not fit neatly into any of the OEH BioMetric vegetation types listed for a catchment management authority area (e.g. where the vegetation lies in an ecotone between two types). In these cases, use professional judgement in deciding the appropriate vegetation type to use.

Establishing plots

OEH suggests less experienced consultants or those unfamiliar with the geographical region of the proposed development site use a number of plots to assist in determining the Biometric vegetation types. Plots should be established randomly within an area of homogenous vegetation.

Place plots randomly by:

  • marking points randomly on the site map in each area of homogenous vegetation, then establishing plots at these points, or
  • pacing a pre-determined but random distance into the area of homogenous vegetation and establishing a plot at this point, then repeating the process until the desired number of plots is established.

Use your professional judgement when placing plots and for increasing the number of plots as needed. Table 1 provides the minimum number of plots required for determining the BioMetric vegetation types, although you can add more plots if required.

Record all species in each plot. Full scientific names should be used and plants should be identified as far as possible to the species or subspecies level. If you are unsure of any species, send them to an expert for identification. The Botanic Gardens Trust offers a plant identification and botanical information service

Record the stratum in which each species belongs (i.e. canopy, mid-storey, groundcover - some species may be present in more that one stratum) and note the landscape position and main associated species. 

Match this information to the BioMetric vegetation types.

Minimum number of plots required per stratification unit

 Area of stratification unit (hectares)  Minimum number of plots
 0-4 1 plot per 2 hectares (or part thereof)
 5-20 3 plots
 21-50 4 plots
 51-100 5 plots
 101-250 6 plots
 251-1000 7 plots
 > 1000 8 plots

Vegetation condition

Once vegetation types have been determined, the vegetation condition of each vegetation type should be assessed. Vegetation condition will either be 'low' or 'not low',  that is, in medium or high condition, for the purpose of using the BioBanking Credit Calculator. Consult the BioBanking assessment methodology and credit calculator operational manual for a definition of vegetation in 'low condition'.

Other features of conservation significance

In addition to threatened species, populations and ecological communities, OEH BioMetric vegetation types listed as being 'over-cleared' (i.e. more than 70% has been cleared) which are not in low condition should also be noted as being of conservation concern.

6. Survey methods and effort

Unlike other scientific studies, surveys for impact assessments do not need to be for a predetermined length of time, nor do they need to be consistent between sites, as their aim is to determine if a threatened species is present, not to compare sites or monitor them. You need to spend enough time at each site to thoroughly survey the area of suitable habitat. Justify the level of effort employed, and include information on the size of the area and the amount of time spent searching.

This section provides general information on survey methods and effort that are relevant for all threatened species. Specific survey methods and the effort recommended for each threatened species will be added to these guidelines as they become available. Currently, specific guidelines are available for amphibians.

False absences and imperfect detection

While the presence of a target species can often be confirmed at a site relatively easily, it is generally impossible to confirm a species is absent. Unless a species has a 100% chance of being detected on a single visit (i.e. it has a probability detection of 1) non-detection does not necessarily mean the species is absent (MacKenzie et al 2002). Very few species are so conspicuous that they are always detected in each survey (MacKenzie et al 2002).

A species' detectability is influenced by several factors (Tyre et al 2003). Such factors include:

  • the species in question - fauna species with large home ranges are especially likely to go undetected in an area, as at any given time they may be in another part of their range
  • climatic conditions (e.g. temperature, rainfall)
  • experience of the surveyor/s
  • the survey methodology used.

An observed absence may be due to an observer failing to detect a species that is actually resident at the site, for example, a bird that was elsewhere in its home range at the time of the survey or failed to call during a point count (MacKenzie 2005). False absences have serious consequences for habitat modelling and monitoring studies as well as impact assessments. When fauna surveys are conducted for the purpose of impact assessment, false absences may result in inadequate conservation measures and an increased risk of local extinction (Wintle et al 2005).

Many ways of minimising the probability of false absences rely on knowing the probability of detecting a species in a specific area. For example, if the probability of detecting a species in a survey of an occupied location is 0.6, there is a 0.4, (that is, 1-0.6) probability of a false absence from a single survey (i.e. by not detecting the species when it is actually present). However, if two surveys are conducted, then the probability of not detecting the species at either survey reduces to 0.16, (that is, 1 - 0.6²), and after three surveys it reduces to 0.064, (that is, 1-0.6³). In other words, there is a 93.6% chance of detecting the species with three surveys, if it is present (MacKenzie 2005).

The probability of detecting the target species is generally determined by using the data already collected at the site. However, this relies on the species being detected at least once. Field et al (2005) notes that optimal survey design requires estimating occupancy and detectability in advance. It is generally thought that surveys consisting of a single visit are inadequate for determining the presence or absence of most fauna species, for example, the southern bell frog (Litoria raniformis) (Heard et al 2006), or the powerful owl (Wintle et al 2005). Field et al (2005) conclude that two or three visits to a site are generally sufficient unless occupancy is very high or detectability is low. MacKenzie and Royal (2005) recommend that sites should be surveyed a minimum of three times when detection probability is high, but that for rare species it is more efficient to survey more sites less intensively.

The approach taken to reduce the likelihood of false absences will vary between fauna and flora species. While increasing the number of visits to a site should increase the probability of detecting a target fauna species, increasing the time spent searching per survey is more likely to detect a target flora species (Garrard et al 2008).

7. Information to be included in the report

If you are conducting an assessment of significance or a species impact statement as part of a development application, you will need to produce a report to assist the consent authority to assess the impact of the proposal on threatened species. This report will need to include the details of the field survey, including:

  • a list of all threatened species possibly occurring on or using the development site and details of how this list was obtained, if the BioBanking Credit Calculator was not used (see section 3)
  • details of how these threatened species or their habitat will be affected by the proposal
  • a list of all species detected in the study area, whether threatened, not threatened or invasive
  • a detailed map or maps including the location of the development site, the study area, the BioMetric vegetation types, stratification units (if different to the vegetation types) and the location of all surveys undertaken (see section 4)
  • details of the habitat assessment (see section 5)
  • details of the survey methods used, including number of traps and transects, and the number of repetitions - you will need to provide a justification if this differs from the recommendations in these guidelines
  • weather conditions at the time of surveys
  • names and experience of all personnel involved in the field surveys
  • any other information outlined elsewhere in these guidelines that should be included in the report.

8. References

Field SA, Tyre AJ and Possingham HP 2005, 'Optimizing allocation of monitoring effort under economic and observational constraints', Journal of Wildlife Management 69, pp 473-482.

Garrard GE, Bekessy SA, McCarthy MA and Wintle BA 2008, 'When have we looked hard enough? A novel method for setting minimum survey effort protocols for flora surveys', Austral Ecology 33, pp 986-998.

Heard GW, Robertson P, Scroggie MP 2006, 'Assessing detection probabilities for the endangered growling grass frog (Litoria raniformis) in southern Victoria', Wildlife Research 33, pp 557-564.

Keith D 2004, Ocean shores to desert dunes: the native vegetation of New South Wales and the ACT, Department of Environment and Conservation NSW, Sydney.

Mackenzie DI 2005, 'What are the issues with presence-absence data for wildlife managers?', Journal of Wildlife Management 69, pp 849-860.

MacKenzie DI, Nichols JD, Lachman GB, Droege S, Royle A and Langtimm CA 2002, 'Estimating site occupancy rates when detection probabilities are less than one', Ecology 83, pp 2248-2255.

MacKenzie DI and Royle JA 2005 'Designing occupancy studies: general advice and allocating survey effort', Journal of Applied Ecology 42, pp 1105-1114.

Tyre AJ, Tenhumberg B, Field SA, Niejalke D, Parris K and Possingham H 2003, 'Improving precision and reducing bias in biological surveys: estimating false-negative error rates', Ecological Applications 13, pp 1790-1801. 

Wintle BA, Kavanagh RP, McCarthy MA, Burgman MA 2005, 'Estimating and dealing with detectability in occupancy surveys for forest owls and arboreal marsupials', Journal of Wildlife Management 69, pp 905-917.

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Page last updated: 13 December 2013