Use of Judas goats

Standard Operating Procedure – GOA005

Background

Feral goats (Capra hircus) can have a significant impact on the environment and agricultural production and are a potential reservoir and vector of endemic and exotic diseases. Although often considered pests, feral goats are also an important resource, harvested commercially primarily for meat. Control methods include trapping, mustering, exclusion fencing, ground shooting and shooting from helicopters.

Radio-collared ‘Judas’ goats are used to locate groups of feral goats that are difficult to find by other methods. This technique involves attaching a radio collar to a feral goat and releasing it with the expectation that it will join up with other goats. Goats are particularly suited to the Judas method as they are a highly social species and will seek the companionship of any other feral goats in the area.

Once the position of the feral herd is established, the goats accompanying the Judas animal are either mustered or destroyed by shooting (refer to GOA001 Ground Shooting of Feral Goats, GOA002 Aerial Shooting of Feral Goats and GOA003 Mustering of Feral Goats for further details on these methods of control). The Judas goat is usually allowed to escape, so that it will search out other groups of feral goats. Once eradication is achieved the Judas goat is located, shot and the radio collar retrieved.

This standard operating procedure (SOP) is a guide only. It does not replace or override the legislation that applies in the relevant state or territory jurisdiction. The SOP should only be used subject to the applicable legal requirements (including OH&S) operating in the relevant jurisdiction.

Application

  • The Judas technique is commonly used to locate remnant individual animals or groups of feral goats in low-density populations. The technique may also be useful for quickly locating populations of goats in areas where the terrain is rugged or the vegetation is thick. Group sizes are smaller in thick vegetation and even when populations are dense, small groups are harder to locate than larger groups.
  • It is most effective when used to ‘mop up’ remnant populations of feral goats, particularly in rough country, that are proving difficult or costly to control. The technique is not efficient where there are large numbers of feral goats in the area.
  • The use of Judas goats to locate feral herds increases the effectiveness of ground and aerial shooting and mustering control operations, particularly when eradication is the aim of the program.
  • The Judas technique requires expensive equipment and skilled operators.
  • It is preferable to use local feral goats that are familiar with the area and are already part of the social structure of the target population. However, in some situations, feral goats from other areas or introduced farmed goats are used. Most goats that are moved into an unfamiliar area appear to quickly settle into the new herd, but there is a risk of causing some stress for the translocated animal. There is also a chance that they may not join up with the local animals or that they may move out of the target area.
  • Trained herding/sheep dogs are sometimes used to detect, herd or flush out feral goats so that they can be captured and used as Judas goats. It is unacceptable to set a dog onto a goat with the intention of bringing it down, holding or attacking it.

Animal welfare considerations

Impact on target animals

  • This technique can have negative impacts on the Judas goat through the following:
    • Capture, handling and restraint can cause anxiety and sometimes pain and injury when an animal struggles to escape.
    • Nearby shooting of cohorts can distress Judas goats, and the sound of gunshots and presence of people is likely to cause further fear and anxiety.
    • Repeatedly being isolated and having to find other goats can also cause fear and anxiety, as goats are highly social animals.
  • The collar must be fitted correctly to allow it to move up the tapered neck if the animal grows or gets fat. As the neck gets larger, the collar will shift higher up the neck, which prevents constriction. If the collar is initially too tight this movement can’t happen. If it is too loose it can catch in vegetation. Ill-fitting collars can also cause chafing or constriction. Adverse effects of wearing the collar should be monitored, by looking for skin irritation or hair loss under the collar.
  • The collar or antenna can occasionally become snagged or entangled in branches/vegetation and impede movement.
  • The weight of the collar and transmitter will not normally have a significant impact on the Judas goat, as goats are relatively large animals. The lightest collar/transmitter available should always be used (less than 5% of the animal’s body mass).
  • To prevent hyperthermia, it is preferable to avoid catching and restraining goats when the weather is hot and/or there is high relative humidity.
  • Goats that sustain injuries during capture/restraint that would compromise their survival in the wild should be euthanased quickly and humanely by a rifle shot to the brain.
  • If dogs are used to locate and flush feral goats out from heavily forested areas, they must be adequately controlled to prevent them from attacking goats. Only trained working dogs are to be used to assist in the handling of feral goats. Trained sheep dogs such as kelpies are preferred as they are not usually aggressive. As a precaution, muzzles can be fitted to dogs to prevent bite injuries.
  • Electric prods must not be used to assist in the handling of feral goats.
  • Whenever possible, avoid capturing and handling when female goats are kidding or have young at foot. Although feral goats have been observed to breed at all times of the year, there are periods when the majority of kidding occurs (eg in southwest Queensland, kidding mainly occurs in May to June).
  • If the goats must be transported to another area, it must be done with the minimum amount of stress, pain or suffering. Guidelines for these procedures can be found in relevant state or federal government guidelines; for example:
    • Pre-slaughter Management of Goats (Finn at al 2003)
    • Australian Standards and Guidelines for the Welfare of Animals — Land Transport of Livestock (AHA 2008).
  • Also, the following Model Codes of Practice for the Welfare of Animals might be useful:
    • The Goat (SCAAHC 1991b)
    • Air Transport of Livestock (AAHQS 1986)
    • Rail Transport of Livestock (AAHQS 1983)
    • Sea Transport of Livestock (AAHQS 1987).

Impact on non-target animals

  • The use of Judas goats is target specific and has minimal impact on other species.
  • If dogs are used for locating feral goats they must receive adequate care at all times. This includes food, water, shelter, safe and comfortable transportation, current vaccinations, worming, flea, tick and heartworm prevention, where appropriate. For more details refer to GEN002 The care and management of dogs used for pest animal control.

Health and safety considerations

  • Take care to avoid accidental injury when capturing and restraining animals. Hands can be injured if fingers get caught between the horns of two goats. Goats can bruise your legs with their horns if they try to run past you. Protective clothing and footwear can reduce the chances of injury. Covering the goat’s eyes while handling will calm the animal. Raising one of goat’s back legs will also prevent the risk of injury to both handlers and the goat, because it cannot suddenly struggle to escape.
    Most transmitters run on a lithium cell. When lithium is exposed to air, it reacts violently and emits highly toxic fumes. If the lithium cell is accidentally ruptured (eg by a bullet when shooting goats), then the area should be avoided for a few hours to allow the fumes to disperse.
  • All people should stand well behind the shooter when animals are being shot. The line of fire must be chosen to prevent accidents or injury from stray bullets or ricochets.
  • Firearm users must strictly observe all relevant safety guidelines relating to firearm ownership, possession and use.
  • Firearms must be securely stored in a compartment that meets state legal requirements. Ammunition must be stored in a locked container separate from firearms.
  • Adequate hearing protection should be worn by the shooter and others in the immediate vicinity of the shooter. Repeated exposure to firearm noise can cause irreversible hearing damage.
  • Safety glasses are recommended to protect eyes from gases, metal fragments and other particles.
  • Care must be taken when handling goats, as they can carry diseases such as Q fever and scabby mouth (orf) that can affect humans and other animals. Routinely wash hands after handling goats or carcasses.
  • Operators working with goats and goat carcasses are at risk of contracting Q fever. They can become infected when they inhale droplets of urine, milk, faeces or birth products from infected animals. Infection can also occur from inhalation of aerosols created during slaughter of infected animals or dust from contaminated materials. Blood testing of personnel is recommended to assess previous exposure, followed by vaccination for susceptible individuals.

Equipment required

Transmitting system

  • The basic system includes a transmitter, power supply, antenna, material to protect the electronic components and a collar to attach the transmitter to the animal.
  • Collars and transmitters should be as lightweight as possible. The total weight (collar, transmitter, battery, aerial and bonding material) must be less than 5% (ideally 3%) of the animal’s bodyweight. Detailed information and advice regarding size and suitability of collars can be obtained from retailers of radiotelemetry equipment.
  • Collars should be made of materials that are durable, comfortable and safe for the animal, can withstand extreme environmental conditions, do not absorb moisture, and maintain their flexibility in low temperatures.
    Common materials used include: flat nylon webbing, butyl belting, urethane belting, PVC plastic and tubular materials. The collar is closed with one or two clamps.
  • Radio transmitters should always be tested before and after attachment to the animal (before release) to ensure they are functioning correctly.
  • Reliable radio transmitters with the longest battery life possible (ie around 5 years) should be used. It is preferable that they be fitted with mortality sensors.
  • Whip antennae should be incorporated into the collar wherever possible, to prevent them snagging on vegetation.

Receiving system

  • The receiving system detects and identifies signals from transmitters. A basic system consists of a battery-powered receiver, a receiving antenna, a recorder (human or mechanical) and accessories such as cables, a speaker or headphones. Although not a complex skill, some training in the interpretation of signal strength and direction is required.

Firearms and ammunition

  • If euthanasia of injured animals is required, a smaller-calibre rifle such as .22 magnum rimfire with hollow- or soft-point ammunition is adequate at short range (closer than 5 m).
  • If shooting animals at a distance, refer to GOA001 Ground shooting of feral goats for requirements.

Procedures

Capture of goats

  • Animals to be used as Judas goats should be caught without causing them injury and excessive stress.
  • It is preferable to capture and release animals from, and to, familiar surroundings. However, in some instances when the goat population is already very low, goats might have to be captured and brought in from other areas.
  • Judas goats are usually selected from a herd of goats that have been captured during trapping or mustering. Sometimes, individuals are caught using dogs to bail them up. If dogs are used, they should only bail the goat up, not bite or attack it.
  • Trained working dogs such as kelpies are preferred, as they are not usually aggressive. As a precaution, a muzzle can be fitted to the dog to prevent bite injuries. Once the goat is caught, the dogs should be restrained while the collar is being attached.
  • Adult goats (ie those with 4, 6 or 8 permanent teeth) are preferred for use as Judas animals. Both female and male goats have previously been used successfully as Judas goats.
  • Heavily pregnant females, females with young at foot, very young, very old or weak/sick/injured animals must not be used as Judas animals.

Fitting of collar and releasing of Judas goat

  • At least two people must be present when fitting a collar — one to restrain the animal and one to fit the collar. It should not be necessary to anesthetise the animal for fitting of collars providing the procedure is done quickly.
  • The collar should be fitted snugly on the neck to ensure that no irritating movement or rubbing occurs. At the same time, enough space should be left to allow the animal to behave normally and for it not to experience any discomfort while moving or feeding. As a general guide, you should be able to slip two fingers between the animal’s neck and the collar.
  • To reduce the risk of irritation on the neck, the collar should be fastened at the side and any metal fitting should be covered or as least smoothed on the inside.
  • The Judas goats should be clearly identifiable (eg with brightly coloured paint, highly visible collar or ear tags), so that they can be easily distinguished from other goats in the herd.
  • Remove magnet (battery stop) or turn on the collar if it is fitted with a magnetic switch and check transmitter frequency before releasing goat.
  • Once the collar has been attached, and before release, observe the animal for any unusual behaviour that could indicate that the collar might cause a problem (eg affecting balance, impeding movement or causing irritation to the skin).
  • In some situations it may be appropriate to give the Judas goats prophylactic vaccinations and anthelmintic treatment.
  • The collared Judas goat is relocated and released in the target area. If the animal needs to be transported in a vehicle, it must be appropriately restrained to prevent it from jumping out. Tying only its back legs together so that it can sit up will help to prevent the formation of bloat. Animals should not be tied up for more than one hour and they must be protected from extremes of temperature during transportation.
  • It is recommended that the number of Judas goats released is equivalent to at least 20%, and preferably 30%, of the number of herds initially in the population. However, no more than two Judas goats should be released into a herd area because groups of three will stick together and possibly not join other goats.

Location of feral goat herds

  • The Judas goats should be given enough time to meet up with other feral goats. The time needed will vary with the season and how far away the herds are. Release time should therefore be planned to precede the control program by the time expected for Judas goats to meet and settle with a herd.
  • Radio tracking is then begun and when the position of the feral herd is known, the goats are either mustered or destroyed by shooting. Refer to the appropriate SOP for further details:
    • GOA001 Ground shooting of feral goats
    • GOA002 Aerial shooting of feral goats
    • GOA003 Mustering of feral goats.
  • The process of tracking down the herd, and then shooting or mustering, is repeated every four to six months until only the Judas goat/s remain in the area. Those goats are then destroyed by shooting and the collar retrieved.

References

  1. AAHQS (Australian Agricultural Health and Quarantine Service) (1983). Model Code of Practice for the Welfare of Animals — Rail Transport of Livestock. Department of Primary Industry, Canberra.
  2. AAHQS (1986). Model Code of Practice for the Welfare of Animals — Air Transport of Livestock. Department of Primary Industry, Canberra.
  3. AAHQS (1987). Model Code of Practice for the Welfare of Animals — Sea Transport of Livestock. Department of Primary Industry, Canberra.
  4. Agriculture and Resource Management Council of Australia and New Zealand (2000). AUSVETPLAN (Australian Veterinary Emergency Plan). Wild Animal Management Manual: Strategic and Operational Guidelines. Edition 2.0, version 2.1.
  5. AHA (Animal Health Australia) (2008). Australian Standards and Guidelines for the Welfare of Animals — Land Transport of Livestock. AHA, Canberra.
  6. Allen LR (1991). The eradication of feral goats from an island national park. Australian Vertebrate Pest Conference, Adelaide South Australia, April, 1991. South Australian Animal and Plant Control Commission. Pp 22–26.
  7. American Veterinary Medical Association (2007). AVMA Guidelines on Euthanasia (formerly The Report of the AVMA Panel on Euthanasia).
  8. Animal Care and Use Committee (1998). Guidelines for the Capture, Handling and Care of Mammals. American Society of Mammalogists.
  9. Biodiversity Group, Environment Australia (1999). Threat Abatement Plan for Competition and Land Degradation by Feral Goats. Environment Australia under the Natural Heritage Trust.
  10. Department of Natural Resources and Mines (2001). Feral Goat (Capra hircus). NRM facts PA18. Department of Natural Resources and Mines, Queensland.
  11. Casburn G, Hacker R and Brill T (1999). Evaluation of Cooperative Feral Goat Harvesting/Control Techniques. Vertebrate Pest Program, Project 94/1. NSW Agriculture, Orange.
  12. Department of Conservation (DOC) (2002). Judas Workshop. Proceedings of a Workshop on the Use of Radio Telemetry for Animal Pest Control, Otago Conservancy, Dunedin, New Zealand.
  13. Finn J, Greenwood P and May T (2003). Pre-slaughter Management of Goats. Agfact A7.1.12. NSW Agriculture.
  14. Harden B and Bayne P (1998). Judas Goats. Notes from the Vertebrate Pest Unit, 2 (4/98). Pp 4–10. NSW Agriculture, Orange.
  15. Henzell RP (undated). Controlling Feral Goats with the Aid of Judas Goats. Department of Primary Industries and Resources, South Australia.
  16. Henzell RP (1987). Methods of controlling feral goats in special situations: a progress report. Australian Vertebrate Pest Control Conference 8:264–267.
  17. Jago B (1999). Feral Goat (Capra hircus) in Queensland. Pest Status Review Series, Land Protection. Department of Natural Resources and Mines, Queensland.
  18. Keegan DR, Coblentz BE and Winchell CS (1994). Feral goat eradication on San Clemente Island, California. Wildlife Society Bulletin 22:56–61.
  19. Kenward RE (2001). A Manual for Wildlife Radio Tagging. Academic Press, London.
  20. King D (1991). Goat Control Methods. Infonote 21/91. Agriculture Protection Board of Western Australia.
  21. Longair JA, Finley GG, Laniel MA, MacKay C, Mould K, Olfert ED, Roswell H and Preston A (1991). Guidelines for euthanasia of domestic animals by firearms. Canadian Veterinary Journal 32:724–726.
  22. Mech LD and Barber SM (2002). A Critique of Wildlife Radio-Tracking and its Use in National Parks: A Report to the U.S. National Park Service. US Geological Survey, Northern Prairie Wildlife Research Centre, Jamestown, ND, USA.
  23. National Consultative Committee on Animal Welfare (1992). Animal welfare considerations. In: Proceedings of the National Workshop on Feral Goat Management: Planning for Action, Dubbo, NSW. Bureau of Resource Sciences, Canberra.
  24. Parkes J, Henzell R and Pickles G (1996). Managing Vertebrate Pests: Feral Goats. Bureau of Resource Sciences and Australian Nature Conservation Agency. Australian Government Publishing Service, Canberra.
  25. Putman RJ (1995). Ethical considerations and animal welfare in ecological field studies. Biodiversity and Conservation 4:903–915.
  26. Samuel MD and Fuller MR (1996). Wildlife radiotelemetry. In: TA Bookhout (Ed), Research and Management Techniques for Wildlife and Habitats. 5th edition, The Wildlife Society, Bethesda. Pp 370–418.
  27. SCAAHC (Standing Committee on Agriculture, Animal Health Committee) (1991a). Model Code of Practice for the Welfare of Animals: Feral Livestock Animals – Destruction or Capture, Handling and Marketing. CSIRO Publishing, Australia.
  28. SCAAHC (1991b). Model Code of Practice for the Welfare of Animals: The Goat. CSIRO Publishing, Australia.
  29. Taylor D and Katahira L (1988). Radio telemetry as an aid in eradicating remnant feral goats. Wildlife Society Bulletin 16:297–299.

The Centre for Invasive Species Solutions manages these documents on behalf of the Environment and Invasives Committee (EIC). The authors of these documents have taken care to validate the accuracy of the information at the time of writing. This information has been prepared with care but it is provided “as is”, without warranty of any kind, to the extent permitted by law.

Connect with Government

It is important to ensure before you use Judas goats as part of your feral goat management plan to connect with the relevant government authority to ensure you have the right permits in place.

Connect

How to reference this page:

Trudy Sharp, 2012. Use of Judas goats. Standard Operating Procedure. PestSmart website. https://pestsmart.org.au/toolkit-resource/use-of-judas-goats accessed 28-10-2020