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Introduction and General Information

There are now few areas of the world where there is no human presence, no disturbance of habitats or populations by human activities, and no potential for conflict between humans and animals. When such conflicts occur, individual animals may be considered "nuisances" and populations of a given species may be considered to be overabundant.

Wild animals which are being held in inappropriate conditions and/or illegally may be rescued by concerned individuals or organisations, or confiscated by government; often these animals cannot simply be released and other options have to be considered.

In zoos, whether due to great success in breeding, poor management, the growing need for more spaces for an ever-increasing number of species deemed to be endangered, or because zoos are given animals which have been confiscated or are no longer wanted by their owners, animals sometimes become surplus to the zoo's requirements.

Bear Consideration
  • In their native habitats, individual wild bears may become "nuisance bears", or populations of bears may damage crops, hives or tree plantations.
  • Bears are kept in a variety of inappropriate conditions, such as "dancing" bears, bears in bile farms, etc. These may be rescued by various organisations, which then need to provide appropriate alternative accommodation.
  • In zoos, due to the longevity of bears, their potentially high reproductive rate, and their requirement for large areas of secure accommodation, spaces in which to keep bears are limited and bears may become surplus to requirements.
Lagomorph Consideration While a number of lagomorph species are endangered, others are considered to be pests or nuisances. In particular, wild Oryctolagus cuniculus - European rabbit which have been introduced in many areas of the world are important pest species, particularly in Australia and New Zealand, but also in Europe, Argentina, and various small islands. (B143, B144, B147, B607.w20)
Ferret Consideration
  • In New Zealand, feral Mustela putorius furo - Ferret are a threat to endangered wildlife, and also can be involved in tuberculosis transmission to livestock. (D406.1.w1)
Bonobo Consideration
  • Bonobos are an endangered species. In their native habitat, they are more likely to be hunted than become pests.
  • Infant bonobos become orphaned when their mothers are killed as "bushmeat". These orphans are then kept as "pets" or sold illegally either within the country or internationally. (W758.Aug2011.w1)
Published Guidelines linked in Wildpro

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"Nuisance" Individual Wild Animals

An individual wild animal (or a pair or family) may be considered a nuisance if it is present in a location where it is not wanted by humans and/or engages in activity which is considered a nuisance. Examples include:
  • Mice, squirrels, bats, raccoons etc. which get into a house and are considered a nuisance by their presence or due to the damage they cause;
  • Rabbits eating garden vegetables;
  • Deer or other species eating crops;
  • Elephants raiding crops and damaging houses;
  • Wolves killing and eating livestock;
  • Foxes or raccoons removing rubbish from trash cans while feeding.
Bear Consideration Bears may become "nuisance" animals if they raid or damage crops, kill livestock, attack or threaten humans, or habitually search for food around human habitations. Some or all of these behaviours have been recorded for all seven bear species. Further information on pest or nuisance behaviours of bears are provided in the following pages:

There are four basic options for the management of individual "nuisance" bears: they may be translocated, subjected to negative conditioning (including being caught and released on-site), taken into permanent captivity, or killed. See also information below (Pest Populations or Overabundent Animals) for information on e.g. electric fencing.

Translocation
  • Problem bears can be caught in steel culvert traps (which can be mounted on a trailer) and relocated. (B486.28.w28)
  • Translocation of nuisance or problem bears often is unsuccessful; many bears return to their original location. (D283.w8, J345.14.w5, J345.15.w3, J435.100.w1)
    • Bears have good navigational abilities and memories; they learn the locations and seasonal availabilities of food resources. (D248.w6, J345.15.w3)
    • Translocation may be sufficient sometimes despite return of the bears to their original locations, to protect crops during a particular growth stage when they are highly attractive to bears and highly susceptible to damage. (P66.5.w1)
    • Translocating a bear which is being a nuisance to a different part of its range, where sufficient natural food is available, may be successful. However, individuals which have habituated to a human-conflicting behaviour pattern are likely to home in on the area where they previously caused a problem, or repeat the problem behaviour at another site. (D283.w8, J435.100.w1)
    • In sheep grazing areas in Oregon, where depredations were thought to occur due to territorial disturbance of bears by sheep flocks passing through their territory, relocation of bears (movement < 20 miles; it was not intended that the relocation would necessarily move the bear away from its territory) was used in response to depredation or repeated sightings of a bear near sheep flocks. This was found to be effective as an alternative to lethal control. (P69.16.w1)
    • Translocated subadult males may be more less likely to return than other bears. (J59.14.w2)
  • Translocated bears have lower survival rates. (J345.14.w5, J345.15.w3), 
    • Bears placed in an unfamiliar area lack the knowledge of physical location and seasonal availability of food resources which they normally have in their home range. This increases their nutritional stress. They also have to compete with resident bears who are familiar with the local resources. (J345.15.w3)
  • Bears which have been making use of human-related food resources may be larger than those which have been using only naturally available foods, and may then be unable to acquire sufficient food if released away from humans. (J345.15.w3)
  • If adult males are translocated out of a given location, sub-adult males may move into the area. (J345.14.w5)
Negative conditioning/Release on-site
  • Negative conditioning involves human body posture, voice, pyrotechnics, trained dogs etc. to teach bears to stay away from humans and human property. (W654.Nov06.w3)
  • Release on-site involves capture of the bear at the site where it is a nuisance, either in a culvert trap, a spring-activated Aldrich foot snare, or by darting. The bear is then ear tagged, tattooed and radio-collared before being released at the same site. (J345.14.w5)
    • The premise is that the bear will avoid the location where it had the aversive experience of being caught and handled. (J345.14.w5)
    • Bears released on-site have good post-release survival (0.88; 95% CI = 0.70 - 1.00). (J345.14.w5)
    • In several studies, this option has been shown effective in reducing recurrence of nuisance activity, at least until foods become available in fall (autumn), or until the bear dens for the winter. (J345.14.w5)
  • A study of non-lethal deterrent techniques used on Ursus americanus - American black bears in the Lake Tahoe Basin of the Sierra Nevada Range, western Nevada, USA, found that most bears returned in a few weeks to a few months following capture, anaesthesia and release on-site with use of deterrents such as pepper spray, cracker shells and rubber buckshot or a rubber slug, with or without additional chasing by dogs. Chasing by dogs in addition to the other methods appeared to produce a longer period before return of the bears. (J59.32.w1)
    • It was noted that these bears were all "nuisance" bears: individuals repeatedly found in urban situations, and that public education, plus regulations/laws/ordinances to prevent intentional or unintentional feeding of bears (e.g. requiring use of bear-proof garbage containers), may be more effective to reduce human-bear conflicts. (J59.32.w1)
  • Negative conditioning appeared successful for reducing crop raiding by Ursus thibetanus - Asiatic black bears in Nagano prefecture, Japan. (J59.27.w2)
Permanent captivity
  • Some problem bears may be provided with placements in zoos, reserves or sanctuaries. (B407.w5)
Killing/Euthanasia
  • Many nuisance bears are killed, legally or illegally. Killing of bears in protection of crops, livestock or humans often is permitted even in areas where bears are otherwise protected.
    • In North America, killing of nuisance bears is used mainly as a last resort. (J345.14.w5)
    • In Nagano prefecture, central Japan, it has been noted that systematic killing of Ursus thibetanus - Asiatic black bears is not a cost-effective method for reducing overall rates of crop depredations. (J59.27.w2)

(B147, B422.w14, B442.7.w7b, B442.8.w8, B442.10.w10b, B442.12.w12,  D318.II.w2, J59.27.w2, J345.14.w5, J345.15.w2, J345.16.w5)

Problem Prevention
If possible, development of nuisance bears should be avoided.

Avoid attracting bears

  • Do not feed bears and do not leave pet food outside. (W655.Nov06.w1, W655.Nov06.w2)
  • Keep food in airtight containers when camping, or strung high up on poles or between two trees so they are inaccessible to bears. (W655.Nov06.w1) 
    • Don't eat or cook in your tent or camp trailer and avoid cooking near these as smells may linger. (W655.Nov06.w1)
  • Provide bird feeders only during winter when bears are hibernating (e.g. late November to end March in Massachusetts). (W655.Nov06.w2)
  • Use strong, heavy, sturdy, bear-proof garbage facilities, with tight, recessed, self-closing doors/lids, with bear-proof latches. Both hinges and latches must be sufficiently strong to withstand a bear. (J345.14.w5, W654.Nov06.w1)
    • If garbage cans are not bear-proof, place them out for collection in the morning when trash pick-up is expected, not the night before. (W655.Nov06.w2)
  • Avoid planting crops attractive to bears directly next to forests or other undeveloped lands containing bears.
  • Using protective devices such as metal collars on palm trees, or electric fencing.
    • A shocking device powered by two 6-volt batteries, linked in series, was found to be effective for protecting a concentrated food source (bird feeder) from Ursus americanus - American black bear in rural central Minnesota. It was acknowledged that bears might be more motivated to overcome the device during periods of food shortage. (J59.34.w1)
    • Temporary electric fencing can be used to protect crops such as corn, as well as for bee hives. Electric fences have to be kept properly maintained and charged. (J345.16.w3, W655.Nov06.w1, W655.Nov06.w2)
    • In a study in Okefenokee Swamp, Georgia, bee yards depredated by black bears either were not enclosed by electric fencing, or were enclosed but the batteries were depleted so the fence was not electrically active. (J345.16.w3)
  • Protect livestock by bringing them in or close to home at night, particularly pregnant females and females with small young. Birth inside, not in the field, if possible. (W655.Nov06.w1,W655.Nov06.w2)
  • Do not leave carcasses in fields or pastures or near these; incinerate them or bury them deeply. (W655.Nov06.w2)
  • Consider using guard animals for your livestock. (W655.Nov06.w2)
  • Do not place fruit or meat scraps in your compost, as these will attract bears. (W655.Nov06.w1)
  • Public education, plus regulations/laws/ordinances to prevent intentional or unintentional feeding of bears (e.g. requiring use of bear-proof garbage containers) may be effective to reduce human-bear conflicts. (J59.32.w1)

When near bears

  • If you see bears in the wild, do not approach them.
  • Be careful not to get between a female bear and her cubs.
  • Don't throw food or other items at a bear, as this teaches bears how to get food from people.

(W655.Nov06.w1) 

Care during rehabilitation

  • When rehabilitating wild bears, contact with humans should be minimised.
  • If contact is important/required, for example in hand-rearing young cubs, then limit contact to one individual.
  • Give cubs the opportunity to socialise with conspecifics
  • Release hand-reared cubs in areas well away from humans, particularly if the cubs have become tame during rearing.

(D252.w29, D270.X.w10, D270.VII.w7, P62.4.w2)

Education

  • People living in areas with bears, or visiting such areas, need to be educated about not attracting bears. (W654.Nov06.w2)
Lagomorph Consideration Where individual rabbits are causing a problem e.g. by entering a garden and eating vegetables or other plants, or damaging trees, rabbit-proof fencing could be used to prevent access. 
Fencing
  • Either a solid material or small mesh would be needed, particularly near ground level, as active juvenile rabbits can easily pass though 40 mm mesh.
    • Maximum 31 mm hexagonal mesh with 1.2 mm (18 gauge) diameter wire (1.0 mm i.e. 19 gauge is too thin as rabbits can chew through this), or 50 x 25 mm rectangular (weldmesh) is needed to prevent juvenile rabbits entering.
    • Fences need to be of sufficient height to stop rabbits leaping or climbing over at least 0.75 m (2 ft 6 inches) (D365, P69.12.w1); 0.9 m high with no point lower than 0.75 m (B551)
      • Angling the fence outwards at the top may be needed to prevent rabbits climbing over the fence.
      • Angle the top 15 cm (six inches) of fence, at a 45 degree angle. (D365)
    • The fence needs to be turned horizontally outwards for a further 15 cm, this being buried or covered in turf, to prevent rabbits digging under.
  • The fence should be put up totally around the area to be protected, or if this is not possible, then extending at least 150 m beyond each end of the area in which rabbit damage is a problem. (D365)
  • Netting should be strained with wires top and bottom. (D365)
  • Regular, frequent checks for continued integrity of the fence are essential, with maintenance and repair as needed (including blocking burrows dug underneath, repairing damage caused by fallen branches etc.)
    • [The frequency of checks may vary depending on the situation, e.g. daily or weekly for a garden, monthly on farmland] 
  • In the UK, badger gates must be installed if any badger tracks or paths are crossed by the fence. (D365)

(B551, D365, P69.12.w1)

Electric fencing

  • Electrified fencing can also be used effectively. (P69.16.w1)
    • It is important that the design includes a live (electrified) wire at a sufficiently low level (e.g. 5 cm rather than 10 cm above ground level) to ensure that a rabbit trying to crawl under the fence receives a shock. (P69.16.w1)
    • Two basic designs of electric fencing are in common use: (D365)
      • Electric netting, using heavy-duty polythene twine mesh with interwoven stainless steel wires in the horizontal strands (except the bottom strand, to prevent shorting). These are 0.5 - 0.75 m high (1 ft 8 inches to 2 ft 5 inches), available in 25 m or 50 m (82 or 164 ft) rolls with fence posts pre-included, making the fence easy and quick to put up and take down. (D365)
      • Electric strained-wire systems use seven parallel 7-strand 16-gauge medium tensile mild steel wires at 5, 10, 15, 20, 25, 30 and 40 cm above ground level (2,6,8,10,12 and 16 inches), with the lowest wire earthed an the remainder live. The wires are held by adjustable plastic insulators on metal stakes which can be placed up to 7 m apart (depending on how level the ground is); anchor posts are used at bends in the fence line and the system is tensioned at a reel post at the fence end. (D365)
      • Electric fences (either type) are powered by an energiser which must produce at least 1 joule at 500 ohms resistance. Batteries need to be changed regularly (every 2- 3 weeks for a fully-charged 70 Ah battery). Keeping at least 2.5 kV through the fence is important to deter rabbits. (D365)
      • The fence should be put up totally around the area to be protected, or if this is not possible, then extending at least 150 m beyond each end of the area in which rabbit damage is a problem. (D365)
      • To prevent shorting on vegetation, a 45 - 60 cm wide (18 - 24 inches) strip should be mown along the fence line. (D365)
      • Initially inspect every 2 - 3 days; later every 2 - 3 weeks may be sufficient. (D365)
    • In trials, a fence 0.45 m high with live wires at 5, 10, 20,30 and 40 cm above ground level was effective, as was a commercially available (Flexnet, Bramley and Wellesley Ltd, Gloucester, UK) fence 75 cm high with a 75 x 65 mm polywire mesh. (P69.16.w1)
    • A few rabbit may learn to jump through or over such fences. (P69.16.w1)
    • Rabbits show a conditioned avoidance of electrical fences. (J438.18.w1)
      • It is very important to ensure the fence remains electrified all the time in the first week affter it is put in place. (J438.18.w1)
    • A trial of two makes of commercially-available fences (Flexnet netting fence, Bramley and Wellesley Ltd, Gloucester, UK, about 50 cm high with about 80 x 80 mm mesh; Livestok netting fence, Bramley and Wellesley Ltd, Gloucester, UK, about 50 cm high with 500 mm x 50 mm mesh), found them to be 76 - 82% effective and equally cost-effective. Bother were powered by Hotline (AEC Electric Fencing Lits, Newton Abbott, UK) P500 energisers (about one joule measured into a 500 ohm resistance, pulsed every second, with a 1.0 - 1.5 m earth rod and using a 70 A h battery). (J438.18.w1)

Tree guards

  • To protect individual trees, tree guards can be used. 
  • To reduce rabbit damage effectively, guards need to be at least 0.6 m (2 ft) high. 
  • Plastic net guards, welded mesh cylinders, split plastic tubes and spiral plastic sleeves are all available.
  • Split plastic tubes can be used over stems of whips and standards; for feathered trees, spiral guards are available. 
  • It is important to ensure that if spiral guards are used no gaps are left between the spirals, since rabbits can gnaw if these is as little as a 5 mm wide gap. Note that spiral guards are easily displaced by animals or wind.

(B551, D365)

Chemical repellents
  • A number of chemical repellents based on synthetic forms of predator odours, which evoke a fear response, causing immediate avoidance, have been evaluated for use to protect plants, particularly young trees, against damage by rabbits and hares. Some of these are commercially available (e.g. "Aaprotect" in the UK, "Treepel" in New Zealand. (P69.13.w1, P114.1995.w1, P114.1995.w2)
  • Chemical repellents can be painted or sprayed onto vulnerable areas of tree bark, or sprayed onto a whole tree to protect it against browsing. (B551)
    • There may be problems with phytotoxicity of chemical repellents; this may vary depending on the application method used. (P114.1995.w2)
    • The effective repellent "Aaprotect" can be sprayed only mid-November to mid-February [UK], due to toxic effects on emerging foliage. (B551)
  • The effects of chemical repellents may be short-lived; they may need to be re-applies following rain, or after new growth of the plants being protected.

(B551, D380, J438.18.w1, P69.12.w1, P69.13.w1, P69.16.w1, P114.1995.w1, P114.1995.w2)

Sticky repellents
  • A commercially available, very sticky, non-toxic compound , designed to prevent insects crawling up trees, was found to be very effective against Ochotona rufescens - Afghan pika, when applied to apple trees in Baluchistan, Pakistan. The compound was applied on the trunk and major branches to one metre above ground level. it appeared that the pikas did not like getting the sticky substance, which they could not lick off, on themselves. In trials, this treatment prevented tree damage except to a few trees which were not coated effectively (the comppound had been thinned down, banding was incomplete and too thin). (P69.9.w1)
Ferret Consideration
  • An individual problem escaped ferret can be live trapped and rehomed. (V.w5)
  • To catch an escaped ferret, a length of pipe is useful, leading into a box containing a treat food. (B652.3.w3)
Bonobo Consideration --
Associated techniques linked from Wildpro --

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Pest Populations or Overabundant Animals

Populations of mammals may be considered pests, or may be present in numbers considered too high for e.g. available food resources.

Numbers of animals in pest populations, or overabundant animals, may be controlled by:

  • Killing large numbers of animals. This has been the standard approach to pests species of all sizes and taxa. (B458.1.w1)
    • Depending on the species and the terrain, a very high effort may be required to effectively reduce populations.
  • Introducing of disease (e.g. myxomatosis used in control of rabbit populations). (B458.1.w1)
  • Controlling reproduction. (B458.1.w1, P69.22.w1)
    • Restricting breeding to limit population growth is most easily applicable to captive animals.
    • There is considerable interest in the possibilities of contraceptive products useable in free-living wild animals, and in particular the development of immunocontraceptive vaccines. (P69.22.w1)
    • One limitation is that reproductive control methods may have a considerable long term effect on population growth, but are not effective in themselves for short-term population reduction, particularly with long-lived species. (P69.22.w1)
    • It is probable that the use of wildlife contraceptives will be limited; they may be useful in urban/suburban areas when traditional methods such as trapping and hunting cannot be used. (P69.22.w1)
    • Further information on controlling reproduction is provided in Reproductive Management of Mammals - Control of Reproduction
  • NOTE: decreasing population density by decreasing the population, e.g. by translocation or culling, is likely to be effective only in the short term, as new individuals are usually recruited into the population by reproduction and/or by immigration from other areas.
  • The use of culling in population control of free-living species is frequently controversial, particularly when native species are concerned, or the population causing damage/nuisance is rare or endangered, and when there is a conflict of interest between different sections of society (e.g. those who like Procyon lotor - Common Raccoons present to enhance their local park or garden and those who consider them at best a nuisance and at worst a health risk).
  • It is essential that all interested parties should be kept informed and should be involved in the decision making process. 
  • Non-lethal methods of population control should be considered and applied whenever possible.
  • The welfare implications of possible methods of control should always be taken into consideration.
  • The decision to cull, or to kill limited number of animals e.g. to enhance the effectiveness of scaring efforts, should be made on the basis of sound scientific data.
  • Note: Use of some forms of population control may be prohibited or restricted by national and international legislation. Information on legal restrictions and requirements for licences should be sought prior to the implementation of control measures. 
  • Management actions may be required on a regional basis, not just at a single affected site: different areas may be used at different times of year, and mammals moved from one site may adversely affect another site.
  • Relevant human health and safety legislation, animal welfare legislation, any other relevant legislation and potential risks of control measures to other species must be considered before implementing culling operations.

Alternatively, long-term regulation may be possible by manipulation of the behaviour bringing the species into conflict with humans. (B458.1.w1)

  • This may include e.g. providing an alternative food source for an animal which raids crops at certain times of year when its normal foods are poorly available. (B458.1.w1)
Bear Consideration Populations of bears may be discouraged from raiding human-created food resources by the use of electric fencing, or by providing alternative food resources, or ensuring that bear attractants are not close to human habitations.
  • For Ursus americanus - American black bear, populations feeding at dump sites are not necessarily nuisances. At campsites, providing a dump at some distance from the campsite (e.g. 1 km distant) may even reduce bear nuisance, by providing a food source away from the camp. (P78.1989.w1)
  • Providing an alternative food source has been used to reduce damage to trees by bears in spring. (N24.2003.w1, J40.65.w2, J59.34.w2)
    • In western Washington State, USA, a spring supplemental feeding program was shown to be an effective non-lethal method of protecting conifers from bear damage during spring, with a significant (P <0.001) reduction in number of trees damaged on sites with supplemental feeding stations, compared to control sites without feeding stations. It was further shown that, despite start-up costs and ongoing maintenance costs, this was cost-effective in the long term. (J40.68.w2, J59.34.w2, P69.16.w2)
    • Pellet feeding in spring did not result in bears becoming larger or in better physiological condition; although it did result in more mass gain over the spring, other bears easily compensated later in the year. (J40.65.w2)
  • Electric fencing can be used to reduce depredation on crops, bee hives (apiaries, bee yards) and other artificial food sources. However, to be effective they must be properly built and maintained, and power must be available (mains, battery). (J59.27.w2)
    • Electric fencing is relatively expensive and labour-intensive to build properly and maintain in operation, requiring strong posts (particularly corner posts), adequate wires of the correct tension, insulation of wires (e.g. using insulated posts), available electricity, and correct distance between wires. It requires considerable maintenance - checking the tightness of the lines, batteries/voltage, cutting weeds which have grown to touch the fence, and removal of e.g. fallen pine needle or leaves which may form insulating mats (resulting in insufficient grounding). (J59.27.w2)
    • Electric fencing is effective for protecting bee hives from bears. (J59.34.w1, J345.16.w3, P69.14.w2, P66.5.w1)
    • Electric fencing is not effective if the batteries become depleted so the fencing is no longer "live". (J345.16.w3)
    • A shocking device running off two six-volt lantern batteries has been developed which can be attached to individual bee hives. It has been shown to be effective for protecting individual hives. It uses energy only when activated and has reduced set-up and maintenance costs and problems compared with electric fencing. It is probably most suitable for use for protecting a single or small number of bee hives or other bear attractants (e.g. a few bird feeders, or a small number of fruit trees). (J59.34.w1)
    • Electric fences in combination with aversive conditioning using lithium chloride (emetic) in baits has been used. (P104.1975.w1)
    • Note: bee yards in close proximity to bear habitat such as ravines and forested areas are much more susceptible to bear attacks than are bee yards further from bear habitat. (P104.1975.w1)
    • Temporary electric fencing can be used to protect crops such as corn, as well as for bee hives. Electric fences have to be kept properly maintained and charged. (J345.16.w3, W655.Nov06.w1, W655.Nov06.w2)
    • In a study in Okefenokee Swamp, Georgia, bee yards depredated by black bears either were not enclosed by electric fencing, or were enclosed but the batteries were depleted so the fence was not electrically active. (J345.16.w3)
  • Lure crops may be planted to divert bears away from short-maturity corn (maize) varieties which are highly attractive to bears. (P66.5.w1)
Lagomorph Consideration Oryctolagus cuniculus - European rabbit is an important pest species in many areas of the world where it has been introduced. Other lagomorph species are also important pests in some areas (e.g. Lepus americanus - Snowshoe hare damaging tree seedlings) (P114.1995.w2). A wide variety of methods have been used to control rabbits and reduce damage caused by them.

Note: 

  • "The aim of rabbit control should be to minimise rabbit damage, not simply to reduce rabbit density." (B552.7.w7)
  • The effect of eradication of an introduced pest such as the rabbit cannot always be predicted. (D368.w8, D368.w53)
  • In the UK:
    • Under The Wild Mammals (Protection) Act 1996, it is an offence to intentionally inflict unnecessary suffering, as specified in that Act, on any wild mammal. This legislation should be considered when considering the destruction of rabbit-occupied warrens/burrow systems. (D365)
    • Under Section 1 of Pests Act 1954 (as amended) , England and Wales (except for the City of London, the Isles of Scilly and Skokholm Island) have been designated a Rabbit Clearance Area, in which every land occupier is responsible for the killing or taking of rabbits on his land and must take necessary steps to prevent them from causing undue damage,, where destruction of the rabbits is not reasonably practical. (D365)
Modification of land management practices
  • Rabbit-sensitive crops can be planted away from rabbit areas.
  • Burning practices may be adjusted to make land less suitable for rabbits.

(B552.7.w7)

Fencing
  • Fencing can be used to exclude rabbits from an area and deter immigration into an area. Wire-netting fences are needed for long-term exclusion.
  • It is important to maintain rabbit-proof fences in good repair; this means regular patrols, maintenance and ongoing costs associated with these.
  • Electric fencing can be very useful, including during baiting operations to keep rabbits away from their usual food source and increase uptake of baits.
  • Any breaches of a rabbit-proof fence make it ineffective very quickly.
  • Wire netting fences must be of the appropriate mesh size - 30 mm mesh will prevent juveniles slipping through the fence, while 40 mm mesh will not.
  • In general, the ongoing costs restrict the use of fencing to small areas and areas of high conservation value.

(D364.5.10.w5j)

Poisoning
  • Poisoning is generally effective only in the short term if used alone, due to recolonisation, but can be effective in combination with warren ripping or fumigation and with follow-on control. (D364.5.10.w5j)
  • Baits can be distributed by ground vehicle or aerially; the later is not applicable where non-target animals are in habitat close to the control area.
  • Selectivity of poisoning can be increased by:
    • Pre-baiting (laying non-poisoned bait) and making sure only rabbits are taking the bait;
    • Using baits highly attractive to rabbits;
    • Using the lowest effective rabbit-killing concentration of toxin;
    • Laying bait in prime rabbit feeding areas;
    • Collecting carcasses to reduce secondary poisoning of predators/scavengers.

    (D364.5.10.w5j)

1080

  • 1080 is commonly used in Australia. It is cheap, effective and quickly eliminated from animals which ingest a non-lethal dose.
  • It is used where there is little risk of poisoning domestic livestock or dogs.
  • Usually, pre-baiting, using non-poisoned bait, is used before poisoned bait is laid.
  • An alternative "one shot" approach uses high concentration of poison in the "one in a hundred" poisoned grains (the rest being unpoisoned.
    • This method has caused severe non-target losses.

    (D364.5.10.w5j)

Anticoagulants

  • Second generation anticoagulants and pindone have been used.
  • Pindone is expensive has the advantage that there is an antidote for use if there is a significant risk of dogs or people being poisoned.
    • Note: Australian marsupials are very sensitive to pindone. 
  • Second-generation anticoagulants are expensive relative to 1080.

(D364.5.10.w5j)

Fumigation/ Gassing
  • Fumigation involves use of any of a variety of toxins including carbon monoxide, carbon dioxide, chloropicrin, calcium cyanide or phosphine gas. These methods are labour-intensive and useful for small areas only. Efficacy can be increased if dogs are used to drive rabbits into the warren first. Following fumigation, warren entrances should be securely blocked to make the warren unusable. (D364.5.10.w5j)
    • Pressure fumigation requires sealing of all warren entrances, after which a pump is used to force the toxin through the warren system. Usually, carbon monoxide, chloropictin and thick smoke are used in combination. 
      • This is slow and useful only for small areas.
      • Use of chloropictin in this method is percieved to be inhumane; it is also dangerous to operators.
      • Note: it is difficult to ensure all warren entrances have been sealed. (V.w144)
    • Diffuse fumigation uses chloripicrin liquid or aluminium phosphide pellets (releasing phosphine gas). These are placed in newspaper or paper towel, moistened with water and sealed into the burrow.
      • This method does not require much specialised equipment.
      • Use of phosphine may be more humane than use of chloropictin.
      • This method is useful for small areas.

    (D364.5.10.w5j)

  • Gassing can reduce the rabbit population by up to 80% when used correctly. (D365)
  • Rabbits should be driven into the warren system before gassing and all entrances to the warren system need to be found and treated. (D365)
  • It may be necessary to selectively clear scrub to access burrow entrances. (D365)
  • NOTE: in the UK, it is important to check for the possible presence of badger setts (gassing badgers is illegal) and for fox earths (no fumigants are licensed for use against foxes. Gassing therefore cannot be used on warrens in or around badger setts or fox earths. (D365)
  • Also consider the possible effect on other wildlife which may be living in burrows. (D365)
  • In the UK, commercially available fumigants include formulations generating phosphine gas on contact with moisture (previously, Cymag [a sodium cyanide formulation] was available also). (D365)
  • The effectiveness of gassing is decreased in: (D365)
    • porous soils;
    • low temperatures (below 5 C);
    • low soil moisture.

    (D365)

  • Note: fumigants can be lethal to humans. gassing/fumigation should be carried out only by personnel who are trained in the use of the fumigant and are familiar with the necessary precautionary measures. (D365)
  • In the UK, users need to comply with the Control of Substances Hazardous to Health Regulations 2002 (S.I. 2002/2677), for general provisions and provisions specifically relating to fumigants. (D365)
  • To check effectiveness, the treated are should be checked after 48 hours for signs of fresh rabbit activity, with follow-up treatment of re-opened holes as required. (D365)
Trapping
  • Use of traditional steel leg-hold traps is not recommended; they cause unnecessary pain and suffering and remove too few rabbit to be effective in population control. (D364.5.10.w5j)
  • Barrel traps or soft catch traps can be used in the control of small isolated populations of rabbits. (D364.5.10.w5j)
  • Rat snap traps baited with apple have been used to control populations of Ochotona rufescens - Afghan pika around apple orchards in Baluchistan, Pakistan. Regular trapping throughout the summer and autumn is needed to effectively protect against pika damage. (P69.9.w1)
  • In the UK:
    • Baited cage trapping can be used. These should be set in short, open vegetation and checked twice daily (early morning, late afternoon), with captured rabbits being dispatched humanely. (D365)
    • Where sufficient personnel are available for checking traps, these can reduce rabbit populations by about 65%. (D365)
    • They are most useful for protection of high-value crops. (D365)
    • Drop box trapping can be used in conjunction with wire netting. Rabbits enter a tunnel, which is either inserted at right angles to a fenceline or parallel to the fence on the rabbit-side of the fence. They then fall through a hinged flap into a buried box. These should be checked at least once a day (preferably early morning) and any trapped rabbits dispatched humanely.
      • These should not be set where there is a risk of the box flooding. (D365)
    • Spring traps can be used only if designed to catch and kill rabbits humanely (Pests Act 1954 (as amended)). Approved traps under the Spring Traps Approval Order 1995 include: "Imbra Trap Mark I and Mark II, Juby Trap, Fenn Rabbit Trap Mark I, Fenn Vermin Trap Mark VI (Dual Purpose), Springer No. 6 (Multi Purpose), Victor Conibear 120-2, BMI Magnum 116, and clones of any of these listed spring traps." (D365)
      • Livestock and pets should be excluded from the trapping area. (D365)
      • Traps must be set "only within the overhang of natural or artificial tunnels" in order to minimise risk to non-target species.
      • Note: "The Protection of Animals Act 1911 [Protection of Animals Acts 1911-2000] requires that all spring traps set for the purpose of catching rabbits (or hares) should be inspected at reasonable intervals and at least once every day between sunrise and sunset." (D365)
    • Snares can be used. These are intended to tether animals so that they can be humanely dispatched. Snares with an "eye" or "stop" about 14 cm (five inches) from the eye ensure the loop cannot close fully (therefore the rabbit is tethered not killed by the snare). 
      • Snares should be set in short vegetation on well-used rabbit runs near to rabbit harbourage from which the rabbits are accessing crops. (D365)
      • They are generally not effective in dry or frosty weather. (D365)
      • " It is recommended that they are inspected at dawn and dusk, and that they are not set where livestock are present or if there is a risk to domestic pets.2 (D365)
      • NOTE: under the Wildlife and Countryside Act 1981, use of self-locking snares is prohibited and free-running snares must be inspected daily; it is also illegal under the Act to set snares to catch certain animals, including Meles meles - Eurasian Badger and Lutra lutra - European otter. "All reasonable precautions should be taken to avoid catching non-target animals". Under the Deer Act 1991 it is an offence to use snares to kill or take deer. (D365)
Destruction of warrens
  • Destruction of warrens can be a highly effective rabbit control technique where rabbits are highly dependent on the shelter of burrows for protection from predators and extremes of climate, such as in semi-arid and arid zones of Australia.
  • For effectiveness, it is important to destroy the entire warren system.
  • The most commonly used method is warren ripping.
  • There are potential problems with erosion after warren ripping. These can be minimised by ripping along, not down, contours, seeding with vegetation after ripping, and avoiding ripping when heavy rains are likely.
  • Ripping is most effective when:
    • Surface cover is removed before ripping
    • Dogs are used to send rabbit underground before ripping, reducing the number surviving on the surface.
    • Other control techniques are used after ripping, or it is used repeatedly.
    • It is used when the rabbit population is low, reducing the chance of rabbit survival and recolonisation.
    • Appropriate control measures are used on adjacent areas.

    (D364.5.10.w5j)

  • Explosives are useful in some areas where mechanical ripping of warrens is not possible, such as in rocky areas and along rivers.
    • Correctly used, explosives destroy the whole warren system.
    • Use of excessive explosives can create pulversied soil in which rabbits can dig more easily to recolonise.

    (D364.5.10.w5j)

Shooting
  • Shooting can be a humane method of killing rabbits. However, it is rarely effective for reducing population levels. It may be useful in keeping numbers low after other methods have caused significant reductions in numbers. (D364.5.10.w5j)
  • Shooting is most effective at night using a spotlight. (D365)
  • On Round Island, intensive observation and shooting was used to kill the few remaining rabbits following gross population reduction by poisoning. A previous shooting effort which had killed nearly 900 rabbits had not been successful at eliminating the population. (J51.24.w1)
  • Appropriate legislation should be followed. In the UK, a variety of legislation covers the right to possess guns and shoot rabbits, including the Firearms Act 1968, the Ground Game Act 1988 and the Wildlife and Countryside Act 1981. (D365)
Ferreting
  • Ferrets are sent down into burrows; rabbits driven out by the ferrets are caught with nets over the burrow entrances, or shot as they emerge. (D365)
  • It is more successful outside the breeding season. (D365)
  • This generally catches more females than males, and may be useful in some circumstances, but is generally ineffective used in isolation. (D365)
Disease introduction
  • When Myxomatosis was first released into Australia, very high mortality was seen; this also occurred when it was first released in other countries with populations of Oryctolagus cuniculus - European rabbit, such as the UK. (B209.8.w8, B601.13.w13, D364.5.10.w5j)
    • After introduction, attenuation of the virus and development of resistance in the rabbits reduced mortality. (B611.10.w10, D364.5.10.w5j)
    • The European rabbit flea and later the Spanish flea were introduced to increase spread of myxomatosis in Australia.(D364.5.10.w5j)
    • Although virulence has remained lower than on initial introduction, it still has an important effect on Australian rabbit populations. (D364.5.10.w5j)
  • Rabbit Haemorrhagic Disease (viral haemorrhagic disease) escaped into mainland Australia in 1995. In some South Australian rabbit populations it has caused mortality rates over 90% and recurring outbreaks have resulted in the population remaining at only 17% of the level seen before RHD arrived. However, in more humid sites there has been less effect from this disease. (B209.16.w16, D364.5.10.w5j)
  • Note: In the UK it is not legal to deliberately spread Myxomatosis or viral haemorrhagic disease (Rabbit Haemorrhagic Disease):
  • It has been suggested that a virulent or genetically modified Trypanosoma nabiasi (see: Trypanosomiasis in Waterfowl, Elephants, Bears and Lagomorphs) could be developed and used as a biological control against Oryctolagus cuniculus - European rabbit, for example in Australia. (J335.14.w1)
Immunocontraception
  • There has been considerable interest in and research regarding the used of immunocontraception in rabbits, particularly involving delivery of rabbit zona pellucida proteins in a recombinant myxoma virus (D364.5.10.w5j, J371.74.w1)
  • While temporary infertility in e.g. 70% of female rabbits has been achieved, development of permanent infertility using this method "has proved elusive." [2005](D364.5.10.w5j)
    • To be effective, such a recombinant virus would need to infect a high proportion of rabbits (to produce infertility in at least 80% of female rabbits) while competing with existing myxoma virus strains. (D364.5.10.w5j, P115.1993.w2)
  • Note: There are concerns regarding the possibility of an effective immunosterilizing recombinant myxoma virus being transported to, and infecting, populations of rabbits which are considered desirable or even endangered. (P115.1993.w2)
  • For further information on this research see: Reproductive Management of Mammals - Control of Reproduction
Integrated Management Strategies

As with many other pest species, integrated management strategies improves effectiveness. (B552.7.w7, D364.5.10.w5j, J47.22.w1)

In addition to use of several different rabbit control techniques, control should be integrated with other land management practices as well as with seasonal cycles affecting weather, vegetation etc., and taking advantage of cyclic aspects of rabbit population biology as well as Myxomatosis outbreaks. (B552.7.w7) 

  • Combinations of poisoning, then warren ripping, then fumigation can be effective and cost effective. (P69.12.w2)
  • Warren ripping after reduction of a rabbit population due to myxomatosis produced a nearly rabbit-free area for many years, while in a nearby area where no control was used after the same myxomatosis outbreak, high rabbit numbers soon recurred. (D364.5.10.w5j)
  • In the Southern Tablelands of eastern Australia, the most effective and cost-effective approach was to combine poisoning followed by warren-ripping, or warren ripping then fumigating, or poisoning, then warren-ripping then fumigating, with subsequent maintenance in the form of phosphine-diffusion fumigation. (J47.22.w1)
  • On Cabbage Tree Island, New South Wales, Australia, introduced rabbits were eradicated in order to protect the breeding habitat of the endangered Pterodroma leucoptera leucoptera - Gould's petrel. There were three phases, involving biological control and use of poison:
    • A natural outbreak of Myxomatosis reduced the rabbit population from about 250 to about 100.
    • Rabbit Haemorrhagic Disease was introduced deliberately by live-trapping, infecting and releasing rabbits, which were fitted with radiocollars before release. When they died (after 2 - 6 days), the carcasses were distributed to strategic locations. Of the 30 susceptible rabbits, 16 died of RHD within 23 days of the virus being introduced and one was taken by a raptor. 
      • A further 33 adult females survived because they had been vaccinated prior to release of the RHD (this was done due to the role of the eradication as a study exercise; these females were also sterilised (tubal ligation) so as not to jeopardise the success of the operation).
    • Brodifacoum, an anticoagulant, was distributed: 300 kg of poisoned bait dispersed using a helicopter. All the remaining rabbits died five to 13 days after the bait was distributed and in 42 of the rabbits the cause of death was confirmed as broudifacoum poisoning (extensive internal haemorrhages).

    (J17.94.w1)

  • On Round Island, rabbit numbers were hugely decreased by two rounds of intensive baiting with brodifacoum poisoned baits, 14 days apart. Dead rabbits were found starting seven days after baiting and peaking 10 -11 days after bait application. By 14 days after the second bait application, "rabbit populations in all areas had collapsed totally" with a reduction from an estimated 2,500 - 3000 rabbits down to just 14. The few remaining rabbits were then eliminated by intensive observation and shooting. (J51.24.w1)
Ferret Consideration In places where feral ferrets are a serious problem, such as New Zealand, they may be controlled, to protect threatened wildlife or to prevent spread of bovine tuberculosis, by trapping or poisoning. (D406.1.w1)
  • Ferrets are not difficult to trap, but trapping is time consuming and presents logistical problems. Many traps used for ferrets are not humane. (D406.3.w3)
    • Live capture traps are humane if they are checked daily. The trap must be checked within 12 hours of sunrise of the day following the day in which they were set/last checked. They minimise the risk to non-target animals and are safe for use around housing and where children may be present, but they are relatively bulky and the trapped animal needs to be killed after being trapped. The rate of capture of non-target animals (particularly hedgehogs in New Zealand) can be high. (D406.3.w3)
    • Only one kill trap tested by the NAWAC in new Zealand was found to be humane; this was the DOC250. This is a light and compact trap, but must be set inside a robust wooden box, making it too large and heavy for use in many situations - but useful for permanent trapping positions. (D406.3.w3)
    • Leg hold traps show variable effectiveness as well as being questionable on welfare grounds. They cause soft tissue damage and sometimes leg fractures and/or lacerations. Some leg-hold traps have been banned in New Zealand due to welfare considerations. The traps are small and can be effective when used by experienced personnel. The trap must be checked within 12 hours of sunrise of the day following the day in which they were set/last checked. The ferret still needs to be killed. If the trap is not secured properly, it may be possible for the trapped animal to move away with the trap attached. There is a risk of non-target animals being captured, even if the trap is covered. (D406.3.w3)
  • Bait based on fish paste and containing the anticoagulant diphacinone have been developed specifically for poisoning ferrets in New Zealand. (D406.3.w3, J194.32.w1)
    • Other toxins can only be used in New Zealand with a Control Substances licence. (D406.3.w3)
    • Poison should always be placed under a cover/tunnel to reduce access to the bait by non-target species. (D406.3.w3)
  • Secondary poisoning as a result of poisoning rabbits and rodents with bait containing the anticoagulant brodifacoum was found to be fairly effective during field research in New Zealand. (J194.23.w1) However, this is not considered an acceptable method of targeting ferrets, due to concerns regarding the long-term persistence of brodifacoum in the food chain. (D406.3.w3)
  • Immediately following rabbit control operations with 1080, about 15% of local ferret populations will die due to scavenging poisoned carcasses. (D406.3.w3)
Bonobo Consideration --
Associated techniques linked from Wildpro

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Rescued and Confiscated Animals

Wild animals may need to be rescued or confiscated when they are held in inappropriate conditions and/or illegally. Management options for such animals include returning them to the wild, placement in zoos or other long-term captive facilities, or euthanasia. (B432.w2, B449.w4 [full text included], D275 [full text included], J54.24.w4)
  • Decisions have to be made on a case-by-case basis. (J54.24.w4)
  • It is important to make a well-informed decision as speedily as possible to avoid wasting resources. (J54.24.w4)
Return to the wild

The IUCN/SSC Re-introduction Specialist Group suggests in their Guidelines for the Placement of Confiscated Animals [full text included] that confiscated animals might be returned to the wild under strictly limited circumstances, in accordance with the IUCN Guidelines for Re-introductions [full text included]. (B449.w4)

Benefits

Potential benefits of returning animals to the wild include: (B449.w4 [full text included])

  • Where the existing wild population is severely threatened, improving the long-term conservation potential of the species or a local population;
  • Making a strong political and educational statement about the fate of animals; it may be possible to promote local conservation values through such a return;
  • Giving the animals the possibility of continuing to fulfil their biological and ecological roles.

Risks

  • There are considerable difficulties in reintroduction programmes and serious potential detrimental effects on wild habitats if reintroductions are not carried out in a proper manner. (B456 [full text included], J54.24.w4, W631.Jun06.w3)
  • Concerns regarding returning animals to the wild include: (B449.w4)
    • Welfare concerns for the released animal. It has been suggested that the released animal should have about the same prospects for survival as its wild conspecifics of the same age and sex.
    • Conservation concerns; the released individual must not threaten existing populations of the same or co-existing species;
    • Disease: pathogens which the animal may have been introduced to while in captivity, and may introduce to the wild population (conspecifics or other species);
    • Whether the precise origin of the confiscated animal is known. Lack of this information may lead to mixing of subspecies or distinct local races, which may damage the local population.
    • On the "precautionary principle", "if there is no conservation value in releasing confiscated animals to the wild or no management programme exists within which such release can be undertaken according to conservation guidelines, the possibility of accidentally introducing a disease, or behavioural and genetic aberrations that are not already present into the environment, however unlikely, should rule out returning confiscated specimens to the wild as a placement option." (B449.w4 [full text included])
Placement in zoos or other facilities
  • The IUCN/SSC Re-introduction Specialist Group suggests that confiscated animals might be placed with: (B449.w4 [full text included])
    • Zoos or aquaria;
    • Rescue centres which have been set up to care for injured or confiscated animals;
    • Life-time care facilities which are devoted to caring for confiscated animals;
    • Specialist societies for a particular species or taxonomic group, if the group or individual members can care for the animals;
    • Humane societies which are in a position to place confiscated animals with private individuals capable of providing life-time care;
    • Commercial captive breeders who are willing to take the animals;
      • Such breeders may have the resources, including technical skills, required to care for the animals.
      • Production of captive-bred animals may reduce demand for wild-caught animals.
    • Research institutes using animals in humane research.

      (B449.w4 [full text included])

  • Note: "As a general rule, where confiscated animals are of high conservation value, an effort should be made to place them in a captive facility that ensures their availability for conservation efforts over the long term, such as with a zoo, ex-situ research programme, or an established captive breeding programme or facility." (B449.w4 [full text included])
  • Zoos are often offered animals by the public (e.g. former pets), and may be "more or less required" to accept animals which have been confiscated by relevant authorities. (J54.24.w4)
  • Note: Zoos and aquaria should accept confiscated animals only when they have the necessary expertise and can provide appropriate accommodation and care for the animal(s) in the long term. (D275 [full text included])

Benefits

  • Educational value of the animals, in exhibits or other uses;
    • When a zoo accepts an animal from a member of the public, this is an opportunity to educate that person about the conservation and welfare implications of buying/possessing wild animals. (J54.24.w4)
    • Note: 
      • "Zoos and aquariums having confiscated animals on display should take the opportunity to inform the public about the reason, which led to the confiscation. In particular, they should make the public aware of the threats unsustainable and illegal trade poses to wild species and of the role CITES plays in combating such trade." (D275 [full text included])
  • The satisfaction that the animals have an increased chance for survival;
  • Potential use of the animals in captive breeding programmes which could replace wild-caught animals as a source of animals for trade;
  • Potential for captive breeding for conservation programmes, including re-introduction programmes;
  • Potential for the use of the animals in conservation and other research projects.
  • Potential for using the animals to raise funds supporting in situ projects with the species. (B432.w2, D275 [full text included])

(B432.w2, B449.w4 [full text included], D275 [full text included], J54.24.w4)

  • Note: For many people, conservation and welfare are not seen as separate entities; it may be harmful to the reputation of a zoo if it does not take an animal when it is offered, since members of the public may consider this evidence of an uncaring attitude. (J54.24.w4)

Risks/Concerns

  • Confiscated animals may be carrying diseases, many of which cannot be screened for and cannot be eliminated by even prolonged quarantine, which could affect conspecifics and/or other species.
    • Permanent isolation, or euthanasia, is necessary if it is not possible to adequately ensure, through quarantine and testing, that confiscated animals are free of important diseases.
  • If confiscated animals are maintained in an ex situ collection, there is a risk they may escape and become pests or invasive species, with all the attendant potential for damage.
  • It may be difficult to find appropriate institutions which are willing and able to accept the animals, particularly if there are large numbers of individuals to be housed and/or they require specialised accommodation or care. (P85.1.w2, V.w5)
  • Housing and veterinary care for confiscated animals can be substantial, and it may be difficult to identify institutions/individuals which are willing to accept these costs.
  • Housing of confiscated animals of common species may put a strain on available facilities and take up valuable space which could be used for endangered species. (B432.w2)
  • Placing confiscated animals with individuals or institutions risks encouraging trade in the species.

(B432.w2, B449.w4 [full text included], P85.1.w2, V.w5)

Ownership and Payments

  • There are complex legal and ethical issues to be considered in transferring animals from the confiscating authorities to facilities providing long term care. (B432.w2)
  • It is essential to consider the ownership of the animals and their progeny, and any fees payable.
  • It is important to set down an agreement regarding the transfer of ownership or custody of the animals, including any conditions regarding restrictions on exhibition, educational use, breeding, commercial or non-commercial use of the animals, or on obligations to include the animals in a breeding programme. The agreement should include conditions for: (B449.w4)
    • Subsequent transfer of ownership or custody;
    • Changes in use by the custodian or new owner;
    • Consequences if the new owner or custodian violates the conditions set out in the agreement.
    • Note: there may be specific legal provisions for the species.

    (B449.w4 [full text included])

  • In some circumstances, captive facilities may be willing to accept animals if the confiscating authorities give a payment to the captive facility to assist with the costs associated with housing and caring for the animals. (B449.w4)
    • Zoos as well as government authorities have limited or scarce resources. (J54.24.w4)
    • To minimise duplication of efforts and cost, it has been suggested that if a zoo (with trained staff and available, although not unlimited, accommodation) agrees to accept confiscated animals, the governmental authorities should assist with initial maintenance (feeding, health care) and if necessary construction of enclosures, with the zoo taking on full responsibility and costs once the animal has been integrated into the zoo collection. (J54.24.w4)
    • Care is required to ensure that valuable resources needed for in situ conservation efforts are not diverted into care of confiscated individuals. (J54.24.w4)
  • In some circumstances, the confiscating authority may ask for a fee from the captive facility. Potential problems of this include: (B449.w4)
    • Perception that the confiscating authority is benefiting by trade in the animals;
    • May weaken the impact of confiscation as a deterrent;
    • It may further limit the captive facilities willing to accept the animals.

    (B449.w4)

  • Zoos may pay for transportation of animals, but should refrain from buying the animals. (D275 [full text included])
  • Note: If zoos accept animals from members of the public, they should keep good records about the animal, including its region of origin (and the area of origin of the donor); the way the animal was obtained by the person donating it (e.g. bought, found, captured, given as a gift); the animal's age, and when it was obtained; as well as information on the individual animal's health, behaviour and previous husbandry and why it is being given to the zoo. This information may assist management decisions for the animal and also may provide information about the trade in animals (J54.24.w4)

(B432.w2, B449.w4 [full text included], D275 [full text included], J54.24.w4)

Euthanasia

Euthanasia should be considered as an option which may be the most appropriate and responsible option for the animal, for humane and conservation considerations as well as economic considerations. (B449.w4)

Euthanasia may be necessary when:

  • Animals are in very poor health; (J54.24.w4)
  • Animals have contracted an incurable disease and are a risk to other animals;
  • The provenance of the animals is unknown or uncertain, and there may be genetic or other differences which could compromise the integrity of wild or captive populations if these animals were placed into those populations;
  • Sufficient resources are lacking for returning the animals to the wild in accordance with proper biological and welfare guidelines; and/or
  • There are no feasible options for keeping the animals in a captive situation.

(B449.w4 [full text included], J54.24.w4)

Benefits

  • When considering the conservation of the species, there are fewer risks of disease, genetic pollution or biological invasion if the animal is euthanased than if it is maintained in captivity or returned to the wild.
  • Euthanasia may be the best, or the only, solution to an acute situation with confiscated animals. 
    • There are not always options available for short term maintenance in captivity or for long-term maintenance in adequate facilities providing good welfare for the animal(s).
    • Survival prospects for animals returned to the wild may be low, due to risks of disease, starvation or predation.
    • Since euthanased animals are lost to the captive animal trade with no hope of recovery, euthanasia of confiscated animals may discourage the actions which led to confiscation. 
    • The choice of euthanasia can be used to educate people about the problems of the trade in live wild animals, and about other conservation problems such as invasive species, and problems associated with release of animals without proper safeguards.
    • Euthanasia may be inexpensive compared to other options, and therefore it does not divert funds which might otherwise be available for other conservation and related activities.
    • Note: When animals are euthanased, or die in captivity, every effort should be made to make the best possible scientific use of the resource they represent - for pathological or other research, or in reference collections of universities, research institutes etc.

    (B449.w4 [full text included])

  • For animals offered to zoos by members of the public, euthanasia may be the best choice if there is no space for the animal in the receiving zoo or other appropriate collections. (J54.24.w4)

  • The need for euthanasia of a confiscated animal might be used to raise concern and awareness about the illegal trade in and use of wild animals.

(B432.w2, B449.w4 [full text included], J54.24.w4)

Risks

  • Euthanasia of confiscated animals risks producing a negative perception of the confiscating authorities. The same is true if a zoo euthanases an animal given to it by a member of the public.
    • It is important to minimise this risk by providing the rationale for the decision to euthanase.
  • Unique behavioural, genetic and ecological material could be lost, which, if maintained, could be of value for the conservation of the animal's species.

(B449.w4 [full text included], J54.24.w4)

Bear Consideration All the general points noted above must be considered for bears.
Maintenance in long-term care (zoos, purpose-built sanctuaries)
  • Where space is available, confiscated bears may be housed in zoos or private sanctuaries.
    • Zoo spaces for bears are limited, and long-term resources are required to house bears, since they are long lived. (B432.w2, B432.w13)
  • Where available, bears rescued from situations such as bear bile farms and "dancing" bears can be re-homed in purpose-built sanctuaries. (J311.27.w1)
    • The Bear Forest in Ouwehand Zoo, Rhenen, provides accommodation in a large enclosure for former dancing and circus Ursus arctos - Brown bear. (J345.12.w1)
  • Note:
    • Providing housing for confiscated bears may be beneficial in terms of public relations. (B432.w5)
    • Negative aspects of bear use, such as medicinal exploitation, use in circuses etc., and the illegal wildlife trade can be highlighted when rescued individuals are accepted. (B432.w2)
    • Providing housing for confiscated bears may put severe financial pressure on organisations which do not have funds for this purpose. (B432.w5)
Release to the wild
  • This is not appropriate for bears of unknown origin. (B432.w13)
  • Bears which have been held for some time may cause negative impacts on a wild bear population (e.g. disease, public safety, public acceptance) if they are released. (B432.w13)
  • If rehabilitated bears are released, it must be to into their own population or one with similar adaptations, and public attitudes must be positive. (B432.w13)
  • Post-release monitoring is essential. (B432.w13)
Euthanasia
  • Rescued individuals with severe disease problems which cannot be rectified may need to be euthanased. (J311.27.w1)
  • Euthanasia may be the most appropriate option when release into the wild is not appropriate, and proper facilities for life-long care of the bear are not available. (B432.w13)
Lagomorph Consideration "Around 35,000 rabbits end up in UK rescue centres each year. If you are thinking about getting a rabbit as a pet, please do the responsible thing and consider rehoming a rescue rabbit. Baby rabbits are cute, but older rabbits make excellent pets as many are already housetrained, neutered and vaccinated." (W716.Dec08.w1)
  • If you have a rabbit which you no longer want, then:
    • Make sure your rabbit is vaccinated and neutered; this will help it find a new home.
    • Find a friend or colleague who would like your rabbit(s). 
    • Ask your local veterinary practice if they know of anyone who would like a rabbit, or whether you can put up a notice that you are looking for a good home.
    • Ask your local rabbit rescue centre if they have room for your rabbit (they may not have room immediately);
    • Check on websites such as Rabbit Rehome in the UK, Rabbit Advocates in the USA.
    • Always check that the intended home will provide appropriate housing, food, exercise and accommodation.

    (W716.Dec08.w2)

Ferret Consideration "PLEASE! if you find you cannot keep your ferret try to rehome him responsibly. Do not dump him or "let him go" into the wild. FERRETS ARE NOT WILD ANIMALS AND CANNOT SURVIVE ALONE. Released ferrets that are not picked up by rescue agencies face a long, slow death from starvation or are attacked and killed by other animals." (W755.Sept11.w1)
Bonobo Consideration There is one orphanage for bonobos. The Lola ya Bonobo (Paradise for Bonobos) sanctuary is situated close to Kinshasa in the Democratic Republic of Congo. (W758.Aug2011.w1)
  • Infant bonobos found for sale e.g. in Kinshasa are confiscated by inspectors of the Ministry of Environment for the Democratic Republic of Congo under C|TES and under Congolese law on protection of endangered species, and are sent to Lola ya Bonobo. (W758.Aug2011.w1)
  • Bonobos arrive at the sanctuary having been confiscated or after being handed in by people who were keeping them illegally. Many are in very poor condition when they arrive, with problems such as dehydration, poor body condition, swollen abdomen and hair loss, from incorrect feeding and care, as well as for example wounds due to ropes used to tether them, parasites, respiratory disease etc.  (W758.Aug2011.w1)
  • More than 80 orphaned bonobos have been rescued. Some are too weak to survive by the time they arrive, but the annual survival rate averages 95%. (W758.Aug2011.w1)
  • Some of the bonobos have now been released back into the wild, into a specially designated forest block which was previously used by wild bonobos, with agreement from the local Po community. The first release took place in June 2009. (W758.Jan2012.w1)
Associated techniques linked from Wildpro

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Management of Surplus Animals in Zoos

In the wild, more young animals are produced each year than the local environment can hold, but many die from predation, starvation, disease etc. In zoos, these mortality factors are generally removed. (B429.28.w28) In addition to decreased neonatal mortality, animals in zoos may live longer and have increased breeding success. These factors can lead to a surplus of animals. (J370.57.w1)

Every animal acquired by or born within a zoo ought to have a place within the zoo's overall collection plan. (J23.38.w3) However, surplus animals may be present due to:

  • Breeding of surplus animals.
    • This may be accidental; (B429.40.w40)
    • There may be an excess of one sex; (B429.40.w40, D271.w2)
      • This may be a true excess, or a relative excess of males in species which are kept in single-male (or few-male), multi-female groups. (B429.28.w28)
    • In animals which produce large litters, production of "excess" animals may be inevitable since often only one or a few animals may be required (for genetic reasons) from a given pair but many more will be born in a single litter;
    • Circumstances may change such that animals were bred in the belief that there was an appropriate placement for them (e.g. another zoo, a release programme), but that placement no longer exists.
    • Animals thought to be pure bred and of genetic value for conservation may be found to be hybrids and therefore not useful for a breeding programme. (B444.w1)
    • Note: even well-managed breeding programmes will result in the production of surplus animals, since it is not possible, practically speaking, to breed precisely the required number and sex of offspring from chosen parents and to do so at such a time that the parents will die as the offspring become mature and require their own space. (B444.w1)
    • While completely uncontrolled reproduction is not a part of responsible zoo management, "breed and cull" may be an important strategy in the management of some species. (V.w108)
      • This is particularly true for species in which breeding does not resume after animals have been prevented from breeding either by keeping males and females separate or by use of contraception.
      • If this strategy is used, animals should be euthanased (i.e. killed in a humane manner) at a time when deaths might be expected in the wild (e.g. at the time of normal break-up of the family and dispersal of the offspring). (V.w108)
  • Animals which have been smuggled or held illegally and are confiscated.
  • Rescued animals presented to a zoo.
  • Closure of a zoo.

(B429.40.w40, B444.w1, D271.w2)

Zoos have a responsibility to properly regulate their animal stocks in order to ensure that their animals are housed and cared for in an appropriate manner. Methods of reducing animal numbers within a collection include:

  • Relocation to other appropriate facilities such as properly managed zoos. (B429.28.w28, B444.w2) 
    • An appropriate zoo may be an accredited zoo in the same geographical region, or in another geographical region. (B429.28.w28)
  • Relocation to responsible private individuals or institutions. (D271.w2, V.w5)
    • This has limited applicability. (B429.28.w28)
  • Relocation to sanctuaries. As with zoos and private individuals, it is the responsibility of the organisation from which the animal is coming to ensure that the sanctuary is providing an appropriate level of accommodation and husbandry. 
  • Note: Whenever animals are relocated, it is the responsibility of the originating institution to ensure that the receiving facility is appropriate in terms being able to provide appropriate accommodation and having skilled personnel who are able to maintain a high standard of husbandry and welfare, meeting the animal's physiological and behavioural needs. (D271.w2, D273)
  • Release into the wild. (B429.28.w28)
    • This must occur only within the framework of a coordinated species recovery programme. It is not appropriate to release animals simply because they are surplus. (D271.w2, D272, B456.4.w4)
  • Euthanasia. 
    • This is an appropriate option for animals which no longer have an adequate quality of life due to ill health/chronic pain. (D271.w2, D273)
    • This is also an appropriate option for animals which are healthy but for whom otherwise the only option is permanent transfer to unsuitable accommodation within which the animal cannot experience an appropriate quality of life. (D271.w2, D273, J23.38.w3, N18.51.w1)
    • This is appropriate where there is no other suitable or available method of population management, or for young animals born despite reproduction-limited methods or recommendations, which have reached weaning or the age at which they would normally leave their parent(s)/natal group. (D271.w2)
    • Euthanasia may be appropriate for animals known to be hybrids, or of unknown/undefined subspecies, where subspecific status is important in the context of a managed breeding programme. (D271.w2)
    • Euthanasia may be appropriate for animals which cannot make a direct or indirect breeding contribution. (D271.w2)
    • Note: opinions differ regarding whether euthanasia is an appropriate option for "surplus" animals in zoos. (J54.10.w3, J54.10.w4)
    • Euthanasia, carried out correctly, provides a humane, painless death. (B429.28.w28)
    • Euthanased healthy surplus animals may be valuable to provide information on "normal" anatomy, against which abnormalities in other individuals may be noted. (B429.28.w28)
      • Every effort should be made to make optimum use of materials made available by euthanasia. (D271.w2)
    • Necropsy of euthanased sick or old animals may provide information valuable for decision making about other such animals in the future. (B429.28.w28)
    • Animals euthanased by physical, rather than chemical, methods may be used as food for other zoo animals (depending on health and hygiene restrictions). (B429.28.w28)

Where possible, production of surplus animals should be reduced, for example by controlling reproduction. (J370.57.w1) See: Reproductive Management of Mammals - Control of Reproduction

Responsible zoos and regional organisations recommend a variety of actions to minimise the production of surplus animals in zoos. For example, the BIAZA Animal Transactions Policy states: (D271.w2)

"The following measures may be taken to reduce or prevent the production of surplus:
(a) adhering to breeding/non-breeding recommendations by species managers;
(b) planning collections nationally/regionally, thereby increasing the ability to predict demand and to breed accordingly;
(c) employing appropriate husbandry techniques (Appendix 1);
(d) employing appropriate veterinary techniques (Appendix 1);
(e) euthanasia (including culling) (Appendices 1 and 8).
N.B. Efforts should be made to document and publish techniques to limit births for those species in regular surplus, and discussions with those directly involved should be held before the introduction of culling as an institution policy."

(D271.w2 - full text included)

Bear Consideration

In zoos, bears have the potential to breed well, with good survival of cubs and long lives for adults. This leads to potential overcrowding and lack of space for holding bears. Individual bears in a zoo may be considered surplus if they are no longer required for breeding or education.
  • Bears can live for a long time, are solitary rather than social animals, and are large, strong, potentially dangerous animals which require large, robustly-built enclosures containing appropriate natural vegetation and furnishings to meet their behavioural needs, and large amounts of food. These requirements increase costs of keeping bears and the space required to keep them.
  • Many bears bred easily in zoos and it may become difficult to find good homes for the young bears. (B407.w6)
  • Collection plans for both individual zoos and regional zoo associations change in time, for example reflecting changes in understanding of conservation priorities. On conservation grounds, it may be decided that available spaces for bears in a zoo or zoos should be allocated to different bear species, or to species other than bears.
  • Bears should not be allowed to reproduce if it is known the offspring will be surplus. (B432.w3) Reproduction can be prevented by various means, reducing the need for euthanasia of surplus individuals (J370.57.w1) - see: Reproductive Management of Mammals - Control of Reproduction
Relocation to another zoo
  • Relocation to another zoo, either within the same geographical area, or in another geographical area, is an appropriate option for surplus bears. 
  • However, spaces for bears in zoos are limited. 

(N18.51.w1)

Relocation to a sanctuary
  • Placing a bear into a sanctuary is an appropriate option for surplus bears if a suitable sanctuary, with appropriate facilities and expertise, has space to take the animal.
  • The Bear Forest in Ouwehand Zoo, Rhenen, provides accommodation in a large enclosure for surplus Ursus arctos - Brown bear as well as former dancing and circus bears. (J345.12.w1)
Release to the wild
  • Note: Release to the wild should not be used a method of disposal of surplus stock. (B456, D271.w2 - full text provided)
Euthanasia
  • Bears in zoos can live for many years past the age at which they would normally have died in the wild. Studies have shown that old bears may develop painful skeletal problems (See: Arthritis and Skeletal Disease in Bears). While painkillers and anti-inflammatory drugs may be used to reduce pain in these bears, euthanasia should be considered as a humane option to prevent prolonged suffering. (P28.2000.w2, N18.51.w1)
  • Euthanasia is appropriate for bears suffering from other painful or terminal diseases. (J311.27.w1)
  • Euthanasia also may be considered for healthy bears for whom there is no appropriate captive situation, for example for young bears which have reached the time at which they would normally separate from their mother and disperse, and for whom no appropriate facility can be identified.
  • Note: Euthanasia is preferable to bears being maintained in inadequate conditions.
Lagomorph Consideration No information available on excess wild lagomorphs in zoos.
Ferret Consideration No information available on excess wild mustelids in zoos.
Bonobo Considerations Bonobos in zoos are all in breeding and management programs (SSP in North America, EEP in Europe). The low number of bonobos in zoos means that every individual is important.
  • Males which are genetically overrepresented or genetically undesirable may be housed in an all-male group. (D386.App1.w6)
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Authors & Referees

Authors Debra Bourne MA VetMB PhD MRCVS (V.w5)
Referee Liz Carter BSc MSC (V.w144); Neil Dorman (V.w104); Mike Jordan (V.w30); Chris Lasher (V.w110)

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