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
- 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
- Controlling reproduction. (B458.1.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.
- 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
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
- 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
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
Alternatively, long-term regulation may be possible by
manipulation of the behaviour bringing the species into conflict with
- 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)
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.
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,
- 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,
- 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,
- 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
- 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,
- 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)
- 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.
- 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.
- "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,
- In the UK:
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
- Fencing can be used to exclude rabbits from an area and deter
immigration into an area. Wire-netting fences are needed for long-term
- It is important to maintain rabbit-proof fences in good repair; this
means regular patrols, maintenance and ongoing costs associated with
- 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
- In general, the ongoing costs restrict the use of fencing to small
areas and areas of high conservation value.
- 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
- 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
- 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
- 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
- This method has caused severe non-target losses.
- 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.
- 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.
- Gassing can reduce the rabbit population by up to 80% when used
- 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
- 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.
- 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.
- 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)
- 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
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."
- Livestock and pets should be excluded from the trapping area.
- Traps must be set "only within the overhang of natural or artificial
tunnels" in order to minimise risk to non-target
- 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."
- 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
- 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
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.
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
- 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
- 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
- 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.
- 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.
- 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)
- 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.
- 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)
- When Myxomatosis
was first released into Australia, very high mortality was seen; this
also occurred when it was first released in other countries with
Oryctolagus cuniculus - European rabbit,
such as the UK. (B209.8.w8,
- After introduction, attenuation of the virus and development of
resistance in the rabbits reduced mortality. (B611.10.w10,
- 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
- Rabbit Haemorrhagic Disease
(viral haemorrhagic disease) escaped into mainland Australia in 1995. In some South
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,
- Note: In the UK it is not legal to deliberately spread
or viral haemorrhagic disease (Rabbit Haemorrhagic Disease):
- It has been suggested that a virulent or genetically modified Trypanosoma
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)
- 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,
- While temporary infertility in e.g. 70% of female rabbits has been
achieved, development of permanent infertility using this method "has
proved elusive." (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
- 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,
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
- 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.
- 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
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).
- 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)