Survey guidelines for Australia’s threatened non-flying mammals

3.3.4Stagwatching

Stagwatching is primarily used to detect some arboreal mammals, owls and microchiropteran bat species emerging from tree hollows to forage at night. The technique is called stagwatching in reference to the stags in which Leadbeater's possum prefers to nest, and this technique is the recommended way of detecting this species’ presence (Smith et al. 1989) (see species profile). However, the principal is also applicable for detecting fauna emerging from dens (for example, quolls), burrows (for example, the greater bilby) or fauna (for example, kangaroos and wallabies) that come in to drink at water bodies in the arid zone (for example, dams, water holes or water troughs) at dusk, particularly when it is hot.
Observations are usually conducted either just before dusk or for a short time afterwards (time is species-specific) and involves stationing observers near fauna shelter sites (for example, dead or living hollow-bearing trees for arboreal species) so that they can identify and count the nocturnal species that emerge (Smith et al. 1989). Night vision goggles are also useful (Schulz pers. comm.).
This detection technique is relatively straightforward and involves a daytime habitat search to locate suitable shelter sites, followed by a period of observation at dusk. Survey duration varies in the literature but an observer should be stationed approximately half an hour before dusk and watch until early nightfall (approximately 40 minutes is generally recommended) (Harley et al 2005).
Trees: arboreal mammals

It is important that trees with hollows are identified on the subject site in advance and marked with a GPS and/or flagging tape. During the diurnal habitat search (Section 3.1), trees with scratches or sap-feeding scars (either fresh or old) should be noted and targeted for subsequent stagwatching and spotlight surveys. Experience in detecting tree hollows may be necessary as people not familiar with this kind of observation may underestimate the number of hollows in an area.

For the method to be most effective, multiple observers need to be available to simultaneously watch all the appropriate trees within the subject site. If multiple observers are not available, the survey effort should be conducted across the subject area using an appropriate stratified sampling design.
Burrows, dens and nests and habitat resources: ground-dwelling mammals

Observing ground-dwelling fauna emerge from their den, burrow or nest site after dusk is a modified version of stagwatching for arboreal fauna, and is applicable for many of the small and medium-sized listed mammals. It should be conducted at suitable shelter sites or habitat resources (for example, water sources) located within a site, and may require more than one observer per shelter site (for example, an observer at each burrow entrance). Observations should only be made at dens or burrows, or resources such as watering points that have signs of activity around them. If more than one such resource occurs on a site, then direct survey effort should be applied to the resource most likely to be used by the target fauna. Observers are placed near an active den or burrow (as far as possible from the site while still maintaining sight of the shelter site) at least 25 minutes before dusk, and watch for as long as is necessary before an animal emerges. Observers need to be sufficiently experienced to ensure they can distinguish target species from other fauna known to occur in the area. Binoculars and a spotlight should be used to confirm markings on animals.

Recommended survey method

Stagwatching survey effort will vary according to the target species and the number of potential shelter or resource sites present in the subject site. As a guide, a survey method for stagwatching should include the following:

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  conduct a search for potential habitat resources, including shelter sites (see Section 3.1) and locate, mark with flagging tape and record the position of all potential shelter sites or relevant habitat resources present within a subject site
  
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  station an observer at each potential shelter site or habitat resource at least 30 minutes before dusk and continue until 60 minutes after sunset for nocturnal species
  
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  ensure that the observer remains quiet so as not to disturb any fauna present, which may require the use of a hide if considered appropriate
  
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  watch the potential shelter site or habitat resource for at least an hour, or more if considered appropriate
  
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  use a hand-held spotlight (50 or 75 watt) or night scope to distinguish fauna after dark (adhere to methods in Section 3.3.3)
  
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  use binoculars to view distinguishing features of fauna to confirm a species’ identity.
  

3.3.5Call detection and call playback surveys

It is possible to detect species that make loud and distinctive vocalisations by call identification. Call detection surveys are carried out by passively listening for calls in suitable habitat, or alternatively eliciting calls by conducting call playback surveys.
Of the listed mammals, call detection surveys or call playback surveys are suitable for the fluffy glider (yellow-bellied glider), Petaurus australis unnamed subspecies, but not the mahogany glider, which does not make loud vocalisations. The fluffy glider from north-east Queensland has a loud and distinctive call, which it regularly uses as a form of intraspecific communication (Goldingay et al. 2001). The call playback survey comprises broadcasting a pre-recorded tape of the species call through a megaphone at regular intervals. Gliders will often call in response, and their location can be then identified by using a spotlight (Section 3.3.3). Yellow-bellied gliders are also known to respond to calls made by predatory owls such as the powerful owl, Ninox strenua, and hence can also be detected through call playback of the pre-recorded calls of this species.
Recommended survey method

Call detection and call playback surveys should be conducted in conjunction with stagwatching (Section 3.3.4) and spotlight surveys (Section 3.3.3), which are to be carried out on two nights per sampling location (for example, transect) within a subject site. NSW DEC (2004) specifies the following procedure:

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  initial listening period of 10–15 minutes
  
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  spotlight search of 10 minutes
  
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  broadcast pre-recorded calls intermittently for five minutes
  
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  listen for a response for 10 minutes
  
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  inspect the immediate vicinity with a spotlight to see if non-vocalising fauna have been attracted to the call (10 minutes)
  
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  two sites per stratification unit up to 200 hectares
  
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  each site surveyed twice on separate nights.
  

For call detection and call playback surveys conducted to detect the presence of the fluffy glider, a recommended standard survey method and minimum survey effort is as follows:

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  conduct a stagwatching survey (Section 3.3.4), and if the target species is not detected commence a call detection survey by having the observer remain at their station and quietly listen for the presence of calling gliders
  
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  the call detection survey should be conducted for approximately 20 minutes
  
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  if calls are not heard, then commence a call playback survey comprising a two minute call broadcast, followed by three minutes of listening
  
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  at the end of the call playback survey, shine a spotlight in the surrounding trees to see if individuals were attracted to the sound but did not call
  
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  then commence a spotlight survey on foot of the immediate surrounding habitat to see if any fauna has been attracted to the calls, or conduct a spotlight survey along a transect if part of the planned survey design
  
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  conduct a second call playback survey at the end or during the spotlight survey
  
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  replicate the survey on two separate nights if the target species is not detected during the first night.
  

Animal care and ethics considerations for call playback surveys

Investigators should check with the relevant animal care and ethics regulator to ensure surveys are consistent with current guidelines. The NSW Department of Primary Industries (NHMRC 2004) recommends that only two 15 minute call playback surveys should be played per night for the detection of nocturnal birds to avoid prolonged exposure and that call playback during the bird species' breeding season should be done with care so as not to disrupt the breeding of the resident pair. These considerations are also applicable to mammal surveys.