Guidelines for detecting birds listed as threatened under the Environment Protection and Biodiversity Conservation Act 1999
Environment Protection and Biodiversity Conservation Act 1999
The views and opinions contained in this document are not necessarily those of the Australian Government. The contents of this document have been compiled using a range of source materials and while reasonable care has been taken in its compilation, the Australian Government does not accept responsibility for the accuracy or completeness of the contents of this document and shall not be liable for any loss or damage that may be occasioned directly or indirectly through the use of or reliance on the contents of the document.
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This report was prepared by Michael Magrath, Michael Weston, Penny Olsen and Mark Antos, and updated in 2008 by Ashley Herrod.
We are grateful to Birds Australia’s Research and Conservation Committee, which attended a workshop on survey standards and reviewed this document: Barry Baker, John Blyth, Allan Burbidge, Hugh Ford, Stephen Garnett, Henry Nix, and Hugh Possingham.
Valuable contributions were also received from Simon Attwood, Jack Baker, David Baker-Gabb, Brent Barrett, Bill Brown, Belinda Cale, Peter Cale, Mike Clarke, Andrew Dunn, Don Franklin, Stephen Garnett, David Geering, Mark Holdsworth, Wayne Houston, Andrew Ley, Richard Loyn, Michael Mathieson, Peter Menkhorst, Trish Mooney, Brenda Newbey, Mike Newman, Lloyd Nielsen, Carol Palmer, Marcus Pickett, Owen Price, David Priddel, Ken Rogers, Geoff Smith, Jonathon Starks, William Steele, Chris Tzaros, Rick Webster and Eve Woolmore. We also thank Joe Benschemesh, Harry Recher, Richard Noske, Martin Denny (NSW Association of Consultants), Brett Lane, Roger Jaensch and Sylvana Maas.
HOW TO USE THESE GUIDELINES
The purpose of this document is to provide proponents and assessors with a guide to surveying Australia’s threatened birds listed under national environment law—the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act).
These survey guidelines will help to determine the likelihood of a species’ presence or absence at a site. They have been prepared using a variety of expert sources and should be read in conjunction with the Australian Government environment department’s Significant impact guidelines 1.1—Matters of national environmental significance. These guidelines are not mandatory.Proposals that fail to meet these survey guidelines because of efficiency, cost or validity will not necessarily mean that referral is required (that is, that a significant impact is likely), especially where the proponent provides an evidence-based rationale for an alternative survey approach. Alternatives to a dedicated survey may also be appropriate. For example, a desktop analysis of historic data may indicate that a significant impact is not likely. Similarly, a regional habitat analysis may be used to determine the importance of a site to the listed birds. Proponents should also consider the proposal’s impact in the context of the species’ national, regional, district and site importance to establish the most effective survey technique(s).
Failing to survey appropriately for threatened species that may be present at a site could result in the department applying the ‘precautionary principle’ when determining whether a significant impact is likely. That is, if no supporting evidence (such as survey results) is presented to support the claim of species absence then the department may assume that the species is in fact present. The department will not accept claimed species absence without effective validation such as through these survey guidelines, other survey techniques (for example, a state guideline or an accepted industry guideline), or relevant expertise. Where a claim of absence is made, proposals should provide a robust evaluation of species absence.
Biological surveys are usually an essential component of significant impact assessment and should be conducted on the site of the proposed action before referral. Surveys help evaluate impact on matters of national environmental significance by establishing whether a species is present or likely to be present. Before starting a survey, proponents may wish to contact the department’s relevant assessment section to discuss their project and seek advice on appropriate survey effort and design.
Doing a survey to this model and confirming that nationally protected species are at the site does not in itself predict a significant impact—it is one of many factors that increase the likelihood of significant impact and should be considered when establishing whether a significant impact is likely or certain. As part of the assessment process, sufficient information is usually required to determine whether a species’ presence at a site constitutes a ‘population’ or ‘important population’ as defined in the Significant impact guidelines 1.1. Surveys done using these guidelines will not necessarily be enough to determine whether the occurrence constitutes a ‘population’ or ‘important population’.
These guidelines help to determine presence or the probability of presence. They do not establish or assess species abundance, as the effort in terms of cost and time required for an abundance survey is much greater than that determining presence/absence. Effective abundance surveys would need to compare survey effort and techniques with further exploration of a proposal’s context, including important population location(s), habitat importance, ecological function and species behaviour.
This document provides a guide to planning and undertaking surveys on threatened birds listed under the EPBC Act, relevant to a referral to the federal environment minister. The individual taxa (species or subspecies) accounts provide a guide to appropriate survey methods and effort when assessing whether listed taxa occur at or near a specified site (‘study area’). These guidelines focus on assessing the presence or likelihood of presence of taxa in a study area and not on assessing the abundance of individuals.
These guidelines are limited to recommending the effort with selected techniques to establish whether a target species is present, absent or in low abundance in a project area. A survey is interpreted as the first step in assessing the impact of a proposed project on any threatened bird species. The approaches in each species profile should be regarded as a minimum and should be included in any general fauna survey that seeks to determine the presence of threatened species. If threatened species are found during the survey, then different techniques may be required to establish whether the project area contains important habitat (nest sites, foraging sites, water sources and movement corridors) for those threatened species.
The taxa accounts relate to the 108 bird taxa that are classified as threatened under the EPBC Act (see Table A.1) as at June 2009. However, the EPBC Act threatened species list is dynamic and survey guidelines are likely to be applied to some taxa not currently listed. Hopefully, with ongoing conservation programs the populations of some taxa will recover and be removed from this list. Appendix 2 provides a general outline of the considerations and standard methods used for groups of related birds (for example, shorebirds).
Evidence of presence
A wide variety of survey methods have been developed to detect the presence of birds (for example, see Ralph & Scott 1981; Bibby et al. 1992; Watson 2004). The presence of a bird taxa is usually established by direct observation or the identification of species-specific vocalisations. The nature of the habitat, the survey method and the particular bird taxa will dictate which of these detection methods are most useful. For example, in dense forest more than 90 per cent of species recorded may be detected by call alone (Loyn 1986). Conversely, species that occur in open habitats, such as some ducks and shorebirds, are mostly detected by direct observation (Howes & Bakewell 1989). Several indirect evidence ‘signs’ can also indicate whether a particular species is present. These include distinctive droppings, regurgitated pellets, feathers, tracks, current or old nests and eggshell. For example, dung and footprints have been used to determine the distribution and habitat use of the threatened southern cassowary Casuarius casuarius in north Queensland (Westcott 1999). Similarly, surveys of the threatened mallee fowl Leipoa ocellata in areas where it occurs in low abundance have focused on detecting active nesting mounds rather than the birds themselves (TBN 2002).
Detection and search effort
Generally, the more time spent searching for a species that at least occasionally occurs in an area, the greater the likelihood of detecting it (Bibby et al. 1992; Slater 1994). The amount of time spent searching is referred to as the ‘search effort’, and is usually quantified in terms of ‘person hours’ or, if working in teams, ‘survey team hours’. Many bird species, however, occur at very low densities, are cryptic in nature, and/or vary greatly in abundance and distribution over time. Consequently, it is rarely possible to confidently prove the absence or local extinction of a species without exhaustive survey effort that is replicated in space (different locations at the same time) and time (same location at different times). So the failure to detect a species in a particular area at a particular time should be reported as ‘not detected’ rather than ‘absent’ (Resources Inventory Committee 1998a; NSW DEC 2004).
In some cases it may be impractical or inappropriate to conduct surveys for the presence of a particular taxon. This may be the case when a taxon rarely uses the area or its abundance is so low in a particular area that the survey effort required to determine absence would not be feasible or cost effective (see Planning and design of surveys). For example, many threatened albatross species at some time will visit most areas off southern Australia, but mounting a survey to detect the presence of one species at a particular location would generally be futile. In these situations it will be necessary to rely on previous records of presence in the region and/or predictive modelling to determine the likelihood of occurrence.
In cases where occurrence must be predicted, an accurate evaluation of the habitat characteristics of the study area and the relative importance of habitat sites will be critical in assessing the likely presence of threatened taxa. Detailed habitat descriptions will also be helpful if further efforts are required to implement targeted surveys (NSW DEC 2004). For some rare birds, the presence of another more common species may reliably indicate habitat suitability. For example, coastal heath occupied by the blue-winged parrot Neophema chrysostoma in south-east Australia will usually be suitable for the critically endangered orange-bellied parrot N. chrysogaster (Starks & Holdsworth 2004), although some sites are clearly preferred by one or other species (Loyn et al. 1986; Starks et al. 1992). Similarly, concentrations of foraging nectiviorous lorikeets and honeyeaters may provide clues to suitable habitat conditions for the endangered swift parrot Lathamus discolour (Swift Parrot Recovery Team 2001). If habitat suitable for a threatened species occurs in an area and an appropriate survey is not done to determine presence/absence, the department may follow the ‘precautionary principle’ and assume that the species is in fact present.
Planning and design of surveys
For any proposal, the timing of fieldwork is critical to the surveying and reporting process. Careful consideration of the necessary lead time is required, as it may be necessary to survey at specific times of the year depending on the ecology of the species in the subject area. Surveys over multiple years may be required where a single year’s data is not adequate to detect the species or to address the environmental factors. There may also be a time lag due to the availability of appropriate faunistic expertise. Proponents should allow for this lag when planning projects. Commissioning biodiversity surveys as early as practicable in the planning/site selection phase of a project will help to avoid potential delays in project approvals.
Effective surveys should always begin with thorough examination of the literature to identify the best times, locations and techniques for surveys. The profiles in this document provide a basis for effective surveys of bird species listed as nationally threatened.
Conducting surveys in six steps Step 1: Identify taxa that may occur in the study area
The first stage in the design and optimisation of surveys is to make a list of threatened birds that could potentially occur in the study area. A four-stage process is suggested below.
(i) Characterise the study area
The boundaries of the study area must be clearly established. A detailed map of the study area should then be made showing the type, locations and condition of native vegetation and important habitat features for birds, such as wetlands, rock outcrops and flowering trees. This process is not only critical to establishing which threatened species may occur in the area but also in the selection of appropriate survey methods and effort. An appropriate map will benefit almost every survey regardless of survey technique.
(ii) Establish the regional context
This stage requires an assessment of the habitat frequency and function. The regional context will help to judge how significant the loss or disturbance of habitat is likely to be. A useful test will involve the following questions:
Are the habitats rare or common?
Are the habitats likely to be critical to species persistence?
Are the habitats permanent or ephemeral?
How is the species likely to use the site (breeding, foraging, etc)? Survey design may need to be adjusted to determine these aspects.
(iii) Identify those threatened birds that are known to, likely to, or may occur in the region
This stage involves consulting a variety of sources to determine which threatened birds could occur in the surrounding region including the study area. A variety of sources should be consulted to create a list of taxa, including:
federal environment department databases, including the protected matters search tool and species profiles and threats (SPRAT) database, which allow you to enter the site of interest and generate predictive maps and information relating to threatened species distributions
state, territory and local government databases and predictive models
national and state recovery plans and teams for threatened species
reference books such as the latest (Barrett et al. 2003) or original (Blakers et al. 1984) Atlas of Australian Birds
museum and other specimen collections
unpublished environmental impact reports
local community groups, researchers and expert birdwatchers.
(iv) Prepare a list of threatened taxa that could occur in the study area
This can be determined by comparing the habitat requirements of each threatened taxa known or likely to occur in the locality (stage iii) with the habitat types and features present within the study area (stages i and ii).
The taxa identified in this process are referred to as ‘target’ taxa.
Step 2: Determine optimal timing for surveys of ‘target’ taxa
The timing of surveys is often critical to the likelihood of detecting the target taxa (Bibby et al. 1992). At any particular location, the abundance of many species fluctuates over the day, year and even between years (see Magrath et al. 2004). The detectability of many birds that are present also varies with the time of day and within and between years. Consequently, surveys should be timed so as to maximise the chance of detecting the target taxon.
If it is not possible to survey for target taxa that have been previously recorded in the general location of the study area during the appropriate time of day or season, it should be assumed that these taxa do occur in the study area if suitable habitat exists (NSW DEC 2004).
Time of day
To maximise the chance of detection, survey activities should be done at the time of day or night when the target species is most vocally or behaviourally active. Intensity of vocalisation and responsiveness to playback calls relates to the time of day and this may also differ with season.
Most diurnal birds are generally more vocal and active earlier in the day (Keast 1984; Bibby et al. 1992; Slater 1994; Drapeau et al. 1999), with calling often starting before sunrise. Some birds, however, prefer to call in the evening and may continue after sunset. For example, peak call detection of the endangered western ground parrot (Pezoporus wallicus flaviventris), occurs 30–45 minutes after sunset (Olsen et al. 2003). The larger soaring birds are typically easier to detect later in the day when thermals form.
Similarly, the likelihood of detecting nocturnal birds usually differs over the course of the night and is typically greater just after dusk and before dawn (Kavanagh & Peake 1993; Debus 1995).
Not all birds occupy the same habitat types throughout the day. For example, the areas of coastal habitat occupied by many shorebird species will vary over the course of the day in relation to tidal cycles (Howes & Bakewell 1989; Bibby et al. 1992; Resources Inventory Committee 1997). Other species use different habitats during the day compared with night. The critically endangered orange-bellied parrot flies from feeding areas to roost in trees for the night. The roosting sites can be some distance from the feeding grounds (Starks & Holdsworth 2004). Consequently, planning the timing of surveys must take into account potential daily changes in habitat use.
Seasonal changes in abundance and detectability
Several of Australia’s threatened birds are migratory and use only part of their range at any particular time of the year (Marchant & Higgins 1993; Baker-Gabb & Steele 1999; Griffioen & Clarke 2002; Barrett et al. 2003).
For example, most of the critically endangered orange-bellied parrot population spends the winter months in coastal salt marsh in south-east Australia but migrates to south-west Tasmania to breed between October–February (Starks & Holdsworth 2004). Other species make shorter movements—for example, leaving from higher altitudes in the colder months, particularly during the colder winters. Still other species are nomadic and may occur in an area over some periods of the year, though not as predictably as migratory species (Barrett et al. 2003). In such cases surveys focusing on particular species should be organised when individuals are likely to be present.
Weather conditions such as wind velocity, precipitation, temperature, cloud cover and light intensity can all affect bird behaviour and observer performance. In general, the detectability of birds will be significantly compromised when:
wind velocity exceeds about 10 kilometres per hour (grass, leaves, or twigs constantly moving), especially for species that are usually detected by soft or high frequency calls. Wind velocity of less than 10 kilometres per hour is also recommended for small boat surveys (Resources Inventory Committee 1999)
rainfall intensity is above a drizzle
conditions are misty or foggy, especially for species that are usually detected by sight
temperatures are either well below or above the seasonal average.
It is recommended that surveyors avoid any one or combination of these weather conditions unless it is known that the detectability of the target species will be affected only minimally.
Generally, territorial species are more easily detected early in the breeding season because vocalisations are more intense and frequent when birds are in the process of establishing or re-defining territories (Bibby et al. 1992). Similarly, colonial species may be most detectable as breeding colony size peaks.
Many species will also vary in detectability between seasons because of behavioural differences or variation in habitat conditions (Bibby et al. 1992; Debus 1995). In wetlands, for example, the growth of emergent vegetation over the spring and summer can dramatically reduce the visibility of waterbirds (Resources Inventory Committee 1998b). The timing of migrations and breeding seasons may vary geographically and between years, depending on conditions.
Changes in abundance between years
In many parts of Australia, environmental conditions can vary dramatically between years. Drought, flooding and fire can radically change the availability and distribution of suitable foraging and breeding habitat (Recher 1988). These annual variations in conditions can result in substantial fluctuations in the abundance of birds between years, creating problems with assessment of the potential value of a site for threatened taxa. For example, recent fire often renders an area temporarily unsuitable for many of its usual inhabitants, sometimes for many years (Garnett & Crowley 2000; Abbott et al. 2003).
In addition to in situ changes in abundance, many Australian birds make irregular movements in relation to highly variable environmental conditions. For example, many nomadic species move between coastal areas and areas further inland in response to fire, drought and flooding. Some ephemeral wetlands may only become suitable for waterbirds once in five to 10 years, following inundation (Lane 1987). In some cases, existing records can provide information on the use of such sites by particular species. However, in many areas, especially inland, previous surveys will be few or absent (MacNally et al. 2004). In these cases, assessment of the habitat will be vital and could provide the only practical indication of whether the site is likely to support threatened species in some years.
Step 3: Determine optimal location of surveys
In some circumstances, the study area will be small enough to allow a comprehensive search of the entire area within a reasonable period of time. The size of the searchable area will depend on the nature of the target taxa, and the habitat and topography of the study area. For example, searching for highly cryptic species in dense scrub will take far longer than searching for large, conspicuous species in open grassland. If a comprehensive search is feasible, then sampling will not be required, and the data collected will be representative of the entire area. In many cases, however, the study area will be too large to allow a complete search within a reasonable timeframe and selective searches or sampling procedures will be required (Bibby et al. 1992; Royle & Nichols 2003).
Many study sites will contain a variety of distinct habitat types, especially if the area is large. Some of these habitats may be unsuitable for the target taxa. For example, most wetland birds will rarely be observed in dry, open grassland. An effective strategy to maximise the likelihood of detecting a particular taxon is to concentrate the search effort within habitat that is favoured by the targeted taxon (Bibby et al. 1992; Resources Inventory Committee 1998a). This means that the study area will need to be divided up, or stratified, into regions of similar habitat types.
When stratifying a study area, the study area is usually partitioned first on biophysical attributes (for example, landform, geology, elevation, slope, soil type, aspect, water depth), followed by vegetation structure (for example, forest, woodland, shrubland, sedgelands). Strata can be pre-determined based on landscape features indicative of habitat that can be derived from topographic maps, aerial photographs that show habitat types, or existing vegetation maps. Preliminary assessment of the study area before starting the surveys will be useful to check stratification units and further stratify the area if necessary (Bibby et al. 1992; NSW DEC 2004). In other situations, such as the inundation of vast floodplains, there may be little alternative but to use a form of stratified sampling based on the habitat’s accessibility throughout the survey.
Focusing search effort on favoured habitat can be a valuable strategy to maximise the likelihood of detecting target taxa. However, this approach requires that the habitat preferences of target taxa are adequately known, which for many threatened species may not be the case. The fewer habitat association records reported for a taxon, the more likely that any apparent habitat preference will be an artifact of the small sample. Subsequent surveys then tend to focus on these apparently preferred habitats, which can further distort the perception of habitat preference. Consequently, investigators should not exclude particular habitat strata from survey designs, unless it is well established that these habitat types are consistently less favoured by the target taxa than other types within the study area.