CDU Animal Ethics Committee1

Guidelines for field research on vertebrates

CHARLES DARWIN UNIVERSITY

GUIDELINES FOR FIELD RESEARCH ON VERTEBRATES

About this document

These guidelines have been prepared by the Charles Darwin University Animal Ethics Committee (AEC) with the objective of providing guidance to field researchers handling native vertebrate animals in the field in the Northern Territory. The guidelines do not cover laboratory experiments using native wildlife. The AEC can be consulted for further advice on issues considered below, and would be pleased to receive suggestions for further development or refinement of the guidelines.

1. Introduction

The conservation of wildlife depends on an adequate knowledge of their status, distribution and ecology. Field research contributes to such knowledge, and is a vital element in the management of wildlife, particularly of threatened, exploited and pest species. However, field research is potentially intrusive, disturbing and/or destructive to individual animals and possibly to whole populations of animals. These guidelines aim to ensure that researchers are aware of the potentially detrimental effects of their actions and of the means of minimising negative impacts.

These guidelines complement the recent (2004) 7th edition of the Australian code of practice for the care and use of animals for scientific purposes prepared by a joint working party of NHMRC, CSIRO, ARMCANZ and the state and territory governments. The Code of Practice contains an introduction to the ethical use of animals in field research and should be referred to for broader issues. These guidelines offer detail specific to research on wildlife in the Northern Territory. Other sources for more detail include Tribe and Spielman (1996) for the restraint and handling of captive wildlife, Oring et al. (1988) for a detailed review of the use of wild birds in research, Cuthill (1991) on the ethics of animal behaviour studies, ASIH et al. (1987a,b) for detailed guidelines on research on fish, amphibians and reptiles, and NHMRC (1995) on the care of individual Australian native mammals.

The trapping of animals for food or other products has been a universal feature of human ecology for thousands of years. Many of the techniques now used by wildlife biologists are based on methods developed by hunters, and require considerable modification to ensure that the wellbeing rather than the destruction of the animal is given primary consideration. Many other field techniques (such as radio-tracking) have developed rapidly over the last few decades, and animal welfare issues have sometimes lagged behind advances in technological sophistication. Sometimes, adverse impacts are difficult to predict or detect. In many cases, although separate impacts may be small, a series of effects on the same subject may produce more substantial cumulative impact.

Carefully selected experimental design will often reduce the impacts of wildlife research. In many cases, the amount of data required to answer the experimental questions can be determined a priori by statistical power analysis. In some cases, judicious use of modelling may signal the most efficient modes of data collection.

This document considers the more common elements of field research dealing with native animals, and outlines the risks to the subjects and preferred techniques for minimising such risks. A more comprehensive treatment is beyond its scope, as the research aims of field biologists and the techniques now used, are so extraordinarily varied.

2. Guiding principles

There are a few universally accepted guiding principles for field research against which research objectives and methods should be measured. These are:

  • to minimise the negative impacts of field research on wildlife individuals and populations;
  • to treat animals used in field research with as much care as is expected for the use of animals in laboratory-based research. Specifically, to use humane methods in all aspects of capturing, handling, holding and releasing animals;
  • the techniques of field research should alter the habitat as little as possible;
  • proposals for field research should demonstrate that researchers have adequately considered animal ethics issues, and made every attempt to minimise their negative effects;
  • researchers should aim to minimise the disruption to normal activities of individual animals;
  • the negative impacts of research on some individual animals should be weighed against the likelihood of beneficial outcomes of the research for the species (or environment) as a whole;
  • researchers should be suitably experienced and competent in the procedures being implemented;
  • projects should have feedback mechanisms built in to monitor the impacts on the animals affected, with action taken where necessary, to alter procedures to reduce such impacts;
  • researchers should consider possible wider impacts of their research, notably on non-target animals;
  • ethical guidelines should apply to feral and other “unwanted” animals: e.g., individual feral animals should not be exposed to any more suffering than native animals;
  • impacts should be documented honestly, and this information should be reported in order to enable refinement or a more informed assessment of techniques used or proposed in subsequent studies.

3. Observation and passive recording

Much field research can be undertaken without the need to trap, handle or mark individual animals. Axiomatically the detrimental impacts of such research are likely to be less than research using more intrusive techniques. However, the mere presence of researchers may lead to a failure to nest, increased risks of predation, increased stress and disturbance to normal behaviours. This applies especially to large nesting colonies, to low-level aerial surveys, to flighty species, to the use of attractants to promote detectability and/or observability (e.g. decoys, play-backs of territorial calls) and to frequent site visits. Individuals of rarely-seen bird species are known to have suffered harassment by, and ultimately death through, the enthusiasm of bird-watchers.

Recent technological advances have allowed the development of recording devices for detecting the species-specific calls of many animals (notably frogs and bats), and hence the assessment of species composition and abundance without handling animals or any other interference. The use of such devices is obviously less intrusive than traditional methods and is to be encouraged wherever possible, but the novelty of these techniques means that many recorded calls still need verification by taking voucher specimens, and many research questions cannot be addressed so simply.

A fundamental guideline to research involving observation is the minimisation of disturbance and interruption to the “normal” behaviour of wild animals. This can be achieved by the observer maintaining a sufficient distance from the subject animals so as to be non-threatening; by the use of “hides”; by minimising the use of attractants or other artificial stimulants; by minimising the time spent in close contact; and by restricting observation to times at which disturbance is least likely to have impact (e.g. avoiding visiting seabird colonies in the middle of the day). Further information on measures to reduce impacts of visits to seabird colonies are given in WBM Oceanics Australia and Gordon Claridge (1997).

4. Capture

The capture of wild animals is often necessary for ecological investigations. There are a number of preferred techniques which minimise the risks associated with capture. The Code of Practice notes that the over-riding principle on trapping protocol is to minimise the impact on both target and non-target species, and that researchers should consider the time the animals will spend in the traps; protection of trapped animals from predators, parasites and/or disease (e.g. through ensuring that traps are clean); protection of trapped animals from environmental effects such as dehydration, hypothermia and drowning; deprivation of food and water; potential for impact via disruption of social structure; potential for impact on dependent young; and trap design and use (including deactivation after the research period, appropriate size and construction).

4.1. Capture by hand

The most common technique for capturing amphibian, reptilian and some mammalian species is by active search and hand-capture. This involves a search for the sites that animals roost or shelter in and their removal from under logs or rocks, behind loose bark, in old bird nests, or in holes and burrows. In some cases, this process may disturb or destroy the shelter site, and hence decrease the survival chances of the animal. Researchers should aim to minimise damage to important shelter sites, and wherever possible repair such damage.

4.2. Terrestrial mammal traps

A wide range of traps are commercially available for capturing mammals. Until recently, break-back traps (such as typical household mouse-traps) were widely used in wildlife surveys. There is no longer any justification for the use of destructive traps in wildlife research. Most commonly-used live mammal traps are either variants on wire-mesh cages or enclosed aluminium boxes, with trip/trapdoor mechanisms. Both may have substantial impacts on the animals they catch. Aluminium traps (such as Elliot traps) may become very cold or very hot. Cage traps may better reflect ambient temperatures, but many animals may injure their heads by poking their noses through the mesh. Both sorts of traps may occasionally injure tails when trapdoors shut. Ants may be attracted to trap bait, and cause discomfit or even death to trapped animals. Some types of mammals (e.g. quolls and bandicoots) may be especially stressed by trapping.

Trap impacts should be reduced by:

  • ensuring that all traps are clearly laid out and marked, so that none are missed and left behind;
  • ensuring that all traps are out of direct sunlight, and that they are checked within one hour of dawn - this is achieved by balancing the number of people, number of traps laid out, the time researchers get up and the distance between traps;
  • ensuring that the amount of bait in traps is sufficient to provide an adequate food resource for trapped animals;
  • placing insulation material within (e.g. grass, old cloth) or around (plastic bags) traps when overnight temperatures may become very low, and/or when rain is possible;
  • ensuring the trap will not be submerged in the event of rain;
  • closing traps on very cold nights and during hot days; and
  • monitoring ant activity around traps, and spraying insecticides if ant activity is high.

4.3. Pitfall traps

Pitfall traps are plastic or metal tubes or buckets dug into the ground. Depending upon their size, a variety of animals fall into them, and some of these cannot then get out. The probability of catching animals is often increased by the use of driftline fencing to direct animals into the pit. Pitfall traps may have a number of adverse impacts on the animals they catch:

  • trapped animals may be damaged or consumed by other trapped animals (particularly ants, but also centipedes, beetles, spiders) or by animals which can access the traps without themselves being caught (e.g. snakes, goannas and dasyurids);
  • pitfall traps may be very exposed to weather, becoming very hot on warm days, and potentially flooded with rain;
  • animals caught in pitfalls may be deprived of their food requirements;
  • lactating females with dependent young may be caught in the traps.

As with terrestrial mammal traps, these effects can be minimised by:

  • frequent checking (2-4 times a day, depending upon weather);
  • ensuring that all traps are checked within one hour of dawn;
  • placing adequate shelter and insulation in the bottom of pit-traps (a wet Chux-cloth or equivalent may be the best material, as it prevents dehydration in frogs - but soil and leaf litter is generally OK);
  • placing a small hole in the base of the bucket to allow rainfall to drain (though this will not work in heavy rainfall, and can let groundwater in);
  • monitoring ant activity around traps, and spraying insecticides if ant activity is high;
  • covering with a raised lid that still allows animals to fall in;
  • examining and determining the lactation status of the captured animal and releasing immediately any lactating females.

Some museum collectors and researchers place a layer of killing/preservative fluid in the bottom of pits (”wet pitfalls”). This technique obviously has a very high casualty rate, including many non-target animals, and should not be used.

4.4. Traps for aquatic vertebrates

Baited drum traps can be used to catch freshwater turtles. These typically are cylindrical in shape and composed of netting on a metal frame with a funnel entrance on each end and bait suspended about mid chamber. Like many fish traps the trap retains animals that are unable to locate the inverted funnel exit. Collapsible drum traps (Legler 1960) and variations on the drum trap that reduce the chance of escape (Kennett 1992) have been used successfully. Often these traps are set below the surface and traps must be checked regularly (say every 1-1.5 hours depending on conditions and species to prevent drowning. Alternatively traps can be set at the surface by fixing them to riverside vegetation or enclosing floats. In some areas this doe not reduce capture rates. All traps must be retrieved or they will continue to trap turtles after the researcher has left a site. Other factors to consider are the rare capture of crocodiles and other fauna such as goannas. More regular checking may be required in situations where non-turtle aquatic reptiles are likely to be caught.

4.5. Nets for catching birds and bats

Mist nets are routinely used for the capture of birds and bats, and work by entangling flying animals in a very fine mesh. Damage to captured animals may arise through injuries sustained when hitting the coarser shelf strings, predation (typically by ants, other birds or snakes), exposure (to excessive heat or cold) and/or from poor handling during untangling. Such risks have been well documented and mechanisms for minimising them well considered (e.g. Wilson et al. 1965; Lowe 1989), not least through a rigorous licensing system dependent upon substantial training and supervision by experts. As general principles, nets should not be operated at hot, cold or rainy times; the number of qualified researchers should be appropriate for the maximum number of animals which may be expected to be caught; nets should be checked at intervals of no more than 10 minutes, and birds should be removed from nets within 10 minutes of capture.

Cannon nets have been used more recently to trap flocks of birds (typically waders). These operate by firing a net strung between projectiles. As with mist nets, there is a rigorous training and licensing process required before researchers are permitted to use these devices. The use of cannon nets should be guided by similar principles to that described above for mist nets, with extra concerns relating to care with the firing of heavy projectiles around and above birds (a problem which becomes more serious if birds take off at the time of firing), and the timing and positioning of firing in relation to tides (for shorebirds). A more rudimentary analogue of cannon nets, “clap trap” (small nets attached to poles which snap together when released from guys), has been used recently to capture finches, but has proven to have an unacceptably high rate of mortality.

4.6. Harp traps

Harp traps (Tidemann and Woodside 1978) are now routinely used for capturing bats. These consist of a bank of vertical fishing-lines leading to a holding bag. Flying bats hit the lines and fall into the bag, from which they are extracted. Harp traps should be checked through the night at 3-4 hour intervals. Mortality or injury directly attributable to the trap is generally recognised to be very low, but cases have been reported of cannibalism of bats within the holding bag, or small predators (e.g. snakes, dasyurids, rodents) entering the bag and consuming the captured bats. The entry of non-bats can be minimised by careful trap placement (e.g. ensuring no vegetation leads from the ground to traps). Traps can also be checked during the night to reduce over-crowding and other interactions between captured bats. Traps should not be set on very cold, very hot or very rainy nights.

4.7. Capture of larger terrestrial mammals

A variety of methods are used to catch macropods (for a summary see Coulson 1996) and the suitability of a particular technique depends on the species and situation.

Smaller macropods can be caught using baited traps (Pollock and Montague 1991) or drive fences (Vernes 1993). They can also be caught in trap yards and either herded into nets (Lentle et al. 1997) or in some cases caught with hand nets. Early attempts to catch larger macropods involved trap yards and physical handling of the animals. This resulted in considerable mortality in some studies (e.g. Keep and Fox 1971). Other methods for catching medium and large macropods include “stunning” (Robertson and Gepp 1982), cannon netting (Clancy and Croft 1992), bait drugs such as alpha-chloralose (Arnold et al. 1986), draw string traps that exploit movement through fences (Coulson 1997) and darting (Higginbottom 1989; Stirrat 1997).