Larsen Trap Use in England - Game & Wildlife ...

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Larsen
Trap Use in
England
The success of Larsen traps
Version 4.1 (2020)
Larsen traps were designed by a Danish the future of shooting depends on game
gamekeeper in the 1950s. In Denmark it management being conducted responsibly Written March 1991. Revised April
has been suggested that this trap alone and professionally and in a way which 2012, February 2014 and April 2020.
was responsible for a significant reduction delivers wider environmental benefits.
in the national magpie population from Having said this, we have experienced Why you should read
1965. very few captures of non-target species
Larsen traps will catch all corvid pest in Larsen traps – another point in their
this leaflet
species (i.e. crows, magpies, jackdaws, favour. In a survey of over 10,000 birds The use of Larsen traps is made lawful
jays, rooks) at all times of the year, but captured, only 1% were non-target species. by General Licences issued separately
their particular value is in catching crows Finches and tits often visit them, but are in each country of the UK. These
and magpies when they set up their too small to trigger the mechanism. Of will be reviewed by the Government
breeding territories. The Larsen trap course, many legally protected bird species, this summer with changes likely to
contains a separate compartment for a as well as gamebirds, suffer from corvid come in to place in August 2020. We
‘decoy’ bird, which is seen as an intruder predation on their eggs or young, and the believe this document is accurate at
the time of publication and efforts
in any corvid territory in which the trap Larsen trap is potentially an effective tool in
will be made to keep it up to date
is placed. Territory-holding birds attempt the conservation of these birds too. There
but please refer to your governing
to drive it away and get caught in the is no ‘natural balance’ between corvids authority to keep abreast of further
process. In the original design, the trap and the birds they prey on, because they changes. They are as follows - in
mechanism involves a spring door to each also feed to a great extent on other foods England: DEFRA and Natural England;
catching compartment which, when set, is provided, directly or indirectly, by man. Wales: Natural Resources Wales;
held open by a split perch. To enter the Recent Game & Wildlife Conservation Scotland: Nature Scot; Northern
trap, birds the size of a magpie or crow Trust research shows that corvid control Ireland: DAERA.
inevitably drop onto the perch. The perch can contribute to the conservation of
This advisory document aims to
gives way, and the bird’s momentum takes some, but not all, songbird species. It has
explain how Larsen traps work and
it past the bottom of the door, which flips also been proven to benefit wader species
how to run them to a high standard.
up – et voila! Later variants of the design such as lapwing and curlew. It provides detailed information
have introduced other, alternative door A second reason to catch corvids alive on the current legal requirements
mechanisms. is that each may in turn be used as a call- for using Larsen traps and what is
Larsens are live-catch traps. Why catch bird to attract further captures. Because considered best practice management
alive? Because of the risk of catching non- Larsen traps are small, they can easily be for the welfare of decoy and captive
target wildlife other than corvids. Virtually moved around to address further pairs birds. The document is supported
all non-target birds are protected by law, of crows or magpies, and a few traps can by our experience in the successful
use of Larsen traps since 1989
and the licences allowing Larsen trapping therefore cover quite a large area. In this
and explains why they are valuable
stipulate that they must be released way, the whole effort quickly grows to
tools in corvid control and wildlife
alive and unharmed. It is important to an effective scale within a single breeding conservation.
remember that in today’s countryside, season.

www.gwct.org.uk

The legal position - England
The use of Larsen traps is permitted 1. WML GL 34 – To kill or take jackdaw and jay.
and regulated by the Open General certain species of wild birds 4. Any non-target captures that
Licences issued under section 16 of The to conserve wild birds and to are fit for release should be
Wildlife and Countryside Act, 1981. conserve flora and fauna released as soon as they are
Separate licences are issued in each of 2. WML GL 36 – To kill or take discovered at the capture
the devolved countries respectively by certain species of wild birds to location, or as close as is safe to
Natural England (NE), Nature Scot (NS), prevent serious damage do so.
Natural Resources Wales (NRW) and 5. Remove the decoy, food and
in Northern Ireland, the Department There is also a guidance document setting water if the trap is not in use
of Agriculture, Environment and Rural out how operators are expected to use 6. Make sure that the trap is
Affairs (DAERA). traps: rendered incapable of holding
Operators do not need to apply for or catching birds ‘when
these licences, but they must know and 3. Standard Licence Conditions outdoors and not in use’. Ideally,
comply with the conditions stipulated in for trapping wild birds and using remove the trap and place it in
the relevant licence. However, a recent decoys under a Natural England secure storage.
development in England (2019), is the licence (GL33)
need for operators undertaking control It is important to remember that the
in European designed sites (RAMSAR, The General Licences restrict the use licences are normally issued for a year
SPA, SACs) to have individual licences of Larsen traps to ‘authorised persons’ at a time (Jan - Dec), but they can be
granted by Natural England. (effectively landowners or persons with amended at any time and recently have
This applies not only to the site their permission). They also impose a been revised at shorter intervals because
itself but also within 300 metres of the series of licence conditions on the user of legal challenges. The current licences
boundary. In SSSIs, an individual licence which mainly relate to the welfare of will run until the 31st July 2020 at which
is not required if the SSSI is not inside the decoy bird. The Licensing system point there may be some changes. It is
or within 300m of a SPA, SAC or continues to grow in complexity but if you up to you to ensure you are aware of
RAMSAR site. However, the user of the follow the guidance given in this leaflet the current licence conditions, and that
General Licence must obtain consent, you should be well within the law. The you stick to them. You can view and
(if it is not already a consented activity following points should be emphasised: download the current licences on the
on that particular SSSI) from Natural NE, NS, NRW and DAERA websites.
England prior to trapping on a SSSI. The 1. Check your trap every day (at
boundaries of protected sites where bird intervals of not more than 24 Please take note of the welfare points
control takes place requires individual hours). This must be a physical mentioned in this leaflet. Look after your
licences can be found on the Magic inspection. call birds and keep your traps clean.
Maps portal online - https://magic.defra. 2. Provide adequate food, water at Strict adherence to our guidelines will
gov.uk/ all times, appropriate shelter and not only ensure keepers are working
a suitable perch. within the law, it will also help the public
In England the two licences relevant 3. Only the following five corvid accept this valuable trapping technique.
to agriculture, game management and species may be used as decoys:
conservation include: carrion crow, magpie, rook,

When to trap and why
We suggest that trapping effort is different foods from those of territorial any benefit to your wild bird population
restricted to spring and summer. This is birds. As a result, they may pose less of a in the breeding season. Also, consider that
the period of maximum prey vulnerability threat to conservation. Flock birds should when catching flock-living corvids you may
and the time when Larsen traps are be thought of as a reservoir of frustrated actually educate other members of the
most effective. In most areas, the overall would-be breeders or young birds. If a flock and make them trap-shy. This might
population of crows and magpies is far territory becomes vacant, it will normally jeopardise your efforts in spring when it
greater than the number of breeding pairs. be claimed by fresh birds of breeding age really counts.
This is apparently because only a limited from this reservoir. However, until they
number of territories with a suitable are established, newcomers are less likely
nest tree site can be fitted into a given to find the nests of vulnerable species.
landscape. Non-breeding birds usually feed If you trap outside the period March to
in flocks, roaming over areas much larger July, you will have to diminish the reservoir
than the usual territory size, and using population over a very large area to cause

Why call-birds work
A call-bird is a previously caught magpie
or crow, which is kept alive in the special
decoy compartment of the trap. Uncaught
territory holders think a single call-bird is
an intruder and will try to drive it away.
They are very aggressive, and if the trap is
left in peace, few are so shy that they will
not get caught. In a scientifically conducted
experiment by the Game & Wildlife
Conservation Trust in 1989, traps with
call-birds were 15 times more efficient
at catching crows, and 10 times more
efficient for magpies.

Taking care of your call-birds
Look after your call-birds well. They will
work best for you when in good health,
because they move about more in the
trap and catch the attention of territory
holders. They also call vocally but won’t if
they are miserable.
The General Licences impose a legal
obligation to physically visit each call-bird Look after your call-birds as they will work best for you when in good health.
at least once a day at intervals of not
more than 24 hours to renew food and weather conditions, whether hot or cold.] a few yards on to fresh ground each day
water. If call-birds are seen by territory Various kinds of food are suitable prevents a build-up of droppings and old
holders to be actively feeding, they will for feeding the decoy, but we have food in the decoy compartment. Rotten
arouse special jealousy. (Apart from this, found ‘sausages’ of brawn-type dog food, food is not a suitable diet and certainly
you are bound by animal welfare laws, fed with bread, to be very convenient. does not convey a best practice image.
and are furthermore responsible for the Another choice is complete diet dog The licences allowing use of Larsens
public reputation of game and wildlife food (soaked in water) or even lamb specify that you must provide adequate
management.) These birds drink a lot of pellets. If you feed your call-bird with food, water at all times, appropriate
water and the General Licences stipulate carrion, make sure it is cut up, or at least shelter and a perch.
that it should be free from chemical cut open, as magpies can have great Magpies and crows need a perch
additives and changed regularly to ensure difficulty in getting into an intact carcass. particularly for roosting at night, and the
that it is clean. Earthenware hamster Please also be aware that carrion can be licence requires you to provide the call-
bowls make good non-tipping receptacles, attractive to non-target species and may bird with a suitable perch “which will not
but a better look gruesome to members of the general cause discomfort to the bird’s feet”. Make
A nipple drinker provides a option is to public. We therefore suggest that the use sure the perch cannot accidentally fall
clean and reliable water use a nipple of complete dog food is probably the best down. There must be adequate shelter
supply for the decoy. drinker bottle policy. The use of fallen farmstock as bait from hot sun, rain or wind. When early
as used for or food in traps is illegal under EU and UK season trapping in upland areas it is worth
pet rabbits. Animal By-Products Regulations. considering the use of a side cowling to
This helps Remember to remove leftovers and keep the wind off the call-bird and fresh
to prevent clean the cages properly. Moving the trap captives.
the water The General Licences do not permit
becoming Soaked complete dog food is an ideal diet for call birds. you to keep decoys in Larsen traps that
dirty and are not set or not in use. Larsen traps are
reduces too small for long-term housing – you
evaporation must use a suitable aviary, large enough
loss in hot to allow the birds to stretch their wings
weather. freely, and it must have food, water,
Please also shelter and ideally more than one perch.
note if you A 3m x 1.5m A-frame shaped pen of the
are trapping in cold early spring weather, type often used for gamebirds has been
you must ensure that the water remains found to work well. Remember that birds
unfrozen in daylight hours. [Note that kept in an aviary should be checked every
under the current licences operators are day.
required to avoid using traps in extreme Do not wing-clip your birds!

A well-publicised court case addressed wing clipped until it is out of the trap. jackdaws and ring-necked or monk
the issue of whether a wing-clipped Interestingly, a recent study conducted by parakeets as decoys. Use of the parakeets
decoy (i.e. feather clipped) was ‘maimed’ GWCT looking at magpie predation on as decoys is advisable only where they are
and therefore illegal to use under the songbirds showed that leg-ringed magpies present in the wild, for example, in the
Provisions of the Wildlife and Countryside were often re-caught many times over, so south east of England.
Act, 1981. Although the case concluded released decoys which have been well- After a while, call-birds become
that wing clipping was not a maim, we cared for may well be recoverable. quite tame and phlegmatic. Some people
are against this practice not least because believe that recently caught territory-
it could be a legal grey area under the Which species to use as a call-bird holders make the best call-birds, as they
Animal Welfare Act 2006. In the wild, crows are dominant to are more restless and aggressive, but we
It does not enhance the welfare of magpies and drive them from their do not have evidence to support this. In
the decoy and does nothing to improve territories. For this reason, crows can be fact, we feel that keeping the same caller
the effectiveness of the trap. It also means caught to magpie decoys, but the reverse is easier and less disruptive to the birds. A
that if someone liberates your decoy is rarely true. bird like this could also be a good option
there is a high risk that it will suffer a The General Licences allowing Larsens for transferring to an aviary for the non-
slow death by starvation. The liberator specify that they may only be used with trapping period to help ensure a quick
is unlikely to realise that the decoy is carrion crows, magpies, jays, rooks, start to the next season.

Where to put the trap
If you are familiar with your land, you rookeries, unless you want a full-time job
will know the specific trees that always dispatching or releasing rooks, in which benefit of the trap not being easily seen
seem to attract crow or magpie nests. case a multi-catch trap is a better option by people.Where local situations allow,
If you are just getting to know the area, – please see our fact sheet on multi- for example, areas with low public access,
look out for nest-building activity from catch traps for more information. We placing the trap so the call-bird appears
the beginning of March. Before bud- suggest that crows and magpies are your dominant, such as in direct sunlight if
burst, magpie nests are very obvious in main target in the conservation of wild- conditions are not too hot, rather than in
the trees. Crows, and to a lesser extent breeding game birds and other vulnerable the shade, may improve trapping success.
magpies, often sit high in the trees near wildlife species. If you have not caught anything within
the centre of their territory, literally acting Place the trap on the ground, two days it could be either because the
sentinel. You should aim to position the especially for crows, which like to birds are not yet fully territorial or, the
trap in plain view of sentinels, and in a approach on the floor. However, when trap is not close enough to the heart
prominent location within 100 yards of trapping magpies among bushes, or in of the territory or, as can be the case
the nest site. If you haven’t time to watch a dense hedge, raising the trap above with crows, the call bird is a young bird
out for nests or sentinels, concentrate brambles gives it a better chance of being which possess little threat to the pair. In
on small copses and spinneys, thick seen. Do not be afraid to experiment some cases, it may be best to move the
hedges and woodland edges – but with setting traps in cover. A good call- trap and use it elsewhere. If you know
have you really got time to check the bird will often reply to the calls of the that there are dominant birds which will
traps every day if you cannot undertake territory holder even though the trap is not go in, rest the site for a few days
reconnaissance? out of sight. Indeed, this ploy can account and then bring back the trap with a new
Avoid placing traps too close to for trap-shy individuals, there is also the decoy.

How to catch both birds of a pair
It is not strictly necessary to catch both by the need to feed young, and they have compartment. This is one advantage
birds of a pair. They defend their territory little time to watch the movements of of the three-compartment Larsen trap.
together, and to remove one will prevent incubating game and songbirds. In a well- However, if you have not caught the
the remaining bird defending the area run trapping programme, you will have other bird by nightfall, you probably never
against a speculating pair of intruders; in caught each original pair before they have will, so take out the first capture. Do not
this way its breeding effort is disrupted. young, and then gone on to remove new leave trapped birds overnight without a
Furthermore, the male bird feeds the ones before they are fully established. perch and with no food and water until
female while she is incubating the eggs – if Crows and magpies learn very quickly, the next morning. Siting traps where you
he does not turn up, the hen bird must and a bird that witnesses its partner can view them with binoculars allows
leave the nest. If you keep up your use being removed from a trap by a human you to check without scaring potential
of Larsen traps throughout spring and and killed may subsequently be very captures. Do remember, however, that
summer, the establishment of territories shy of traps. If you catch a bird in one you are legally required to go to the trap
will be continually disrupted and, while compartment of a Larsen trap, leave and undertake a physical inspection of
present, fresh birds will be pre-occupied it disputing its case through the wire food and water at intervals of not more
with territorial defence and nest building. with the call-bird. Its partner will very than 24 hours.
Their demand for food is never swollen often join in and get caught in the other

Catching the difficult ones breaking the skin of an adult human. head very hard against the edge of a hard
Perhaps as a result of a previous fright, However, it is wise to use a gardening surface. Alternatively, you can use a short
some magpies and crows can be very shy glove when handling them for health stick, or a fisherman’s ‘priest’. It takes a
of a Larsen trap. Crows, in particular, will reasons. Concentrate on handling the bird surprising force to kill one of these birds.
often dance around a trap but refuse to securely, but gently. As you put your hand Do all you can to make death instant.
jump on. Moving the trap deeper into into the trap, a magpie will flutter round Breaking the bird’s neck after this makes
the territory is the most likely route to the roof, whereas a crow will try to cram certain that you have not just stunned it.
success. Otherwise it can pay to lift the itself into a bottom corner. Pin the bird There is currently (March 2020) a
trap up onto a bale or some other solid gently against the floor, roof or side of the question mark over dispatching birds
object. Raising the decoy in this way trap, sliding your first and second fingers in sight of others of the same species.
sometimes infuriates the territory holder round its neck so that they meet at the Existing General Licences for Canada
into jumping on. Do not just add legs fingertips. The bird can’t bite you now, geese and Egyptian geese require that
though – if the territory holder can see and so long as you don’t let it wriggle its these birds must be killed out of sight
the decoy through the floor of the trap it head between these two fingers, it can’t of each other but there is no mention
may attack from below and never land on get away from you. Your palm will be of whether this applies to other trapped
the top. over the bird’s back, and you can use your species. GL33, the Standard Licence
Another popular choice is to use thumb and fourth and fifth fingers to pin Conditions for trapping wild birds and using
a side-entry Larsen. There are various the wings against the body as you pick it decoys under a Natural England licence,
versions available from different up. Both species grip with their feet: use proposes that all trapped birds must be
manufacturers, many of which work well. your free hand to gently prise them open killed out of sight of others of the same
However, please be careful to choose a again. When taking call-birds out of the species. It seems hugely anthropomorphic
trap of adequate size, we specifically warn decoy compartment of a Larsen trap, you to suppose the decoy bird will care a
against reducing any of the dimensions will find you have to bring them tail first jot about seeing the captured bird killed,
of compartments of the Larsen trap through the access hole. when a few moments earlier that bird
design dimensions as offered by the Birds can be transported humanely was trying to beat it up and drive it
GWCT. They are the minimum needed to another trap in a dark rigid box with away. GWCT advice at this stage is to
for the welfare of captive birds. Other proper ventilation. Remember it is in your take the precaution of killing all birds out
single-compartment traps with no decoy interests to look after the bird. A sack is of sight where possible until we have
compartment, known variously as Larsen not good enough and may well be illegal. further clarification. With Larsen traps
Mates, Larsen Pods or ‘clam traps’, have and the normal small number of captures,
become very popular. The intended How to dispatch a captured it doesn’t take much effort to turn your
use is either with bait alone (e.g. a good corvid humanely back or step behind the vehicle.
option to help catch the first call-bird); or Any birds to be killed under General
to catch birds that are unwilling to enter Licence must be dispatched humanely. Where to get your first call-bird
the Larsen trap catching compartment. The General Licences clearly describe Please do not contact us to ask where
These single-compartment traps are now humane dispatch as taking all reasonable you can get a call-bird. Ask your
explicitly lawful in Scotland, but in England precautions to ensure that any killing of gamekeeper friends or catch your own.
and Wales their use is currently a grey birds under licence is carried out by a Larsen traps work quite effectively with
area. We hope they will be explicitly single, swift action as soon as reasonably bait alone. You may even care to keep
approved in both England and Wales in practicable after discovery. If you are right- a couple of captive birds from year to
future GLs. handed, hold the bird as described above year to start you off each spring. They are
in your left hand. With your right hand, really fascinating creatures, and if you take
How to handle call-birds grip the legs, tail, and wing tips together. an interest, you will learn a lot. Please also
Both crows and magpies can give a In one movement, draw the bird out of remember that it is illegal to trade in live
fairly painful nip and their claws are also your left hand, so that it doesn’t have magpies and crows.
sharp, but neither are really capable of time to bite you, and strike the back of its

Operating with bait alone
As mentioned above, Larsen traps do Where to put the trap farm yard may reduce the time taken to
catch crows, magpies and other corvids Although the trap should be obvious, catch the first bird). So anticipate quite
when used with bait and no call-bird. birds will be more wary of it when there a long effort but do check your traps
You may need several traps to be sure is no call-bird. So it is probably unwise daily. Pre-baiting (with the trap unset) is
of success and the strategy is rather to stand it out in the open. Put it among completely unnecessary - if a bird goes in,
different from the call-bird approach. bushes, or at the base of a hedge or tree. you might as well catch it.
Without the ability to get a decoy bird In contrast to using call-birds, it may If your trap catches nothing at first,
from someone else who already has a take a while for your bait to be spotted don’t blame the trap. It is probable that
spare bird (perhaps from aviary stock) the (because it doesn’t move), or for birds no corvids have found your bait, (after all,
only option is to use bait to make the first to overcome their natural fear of novel many natural bird nests escape predation).
capture when your trapping season starts. objects (placing the trap in a livestock After 10 to 14 days without success, it

may be best to move the trap to try to be very effective and it is the freshly aim to make the offering look like a
another site glistening viscera that attracts corvids. Both depredated nest. Make a ‘nest’ of dead
crows and magpies have limited powers grass in one (only one) of the catching
What bait? of opening carcasses, so this presents an compartments and arrange a clutch of
The bait most likely to achieve success easy option for them. Be aware that meat five or six eggs in it. Cracked or oversize
is probably the one the birds in the local baits may increase the risk of non-target gamebird eggs from the laying pen are
area are familiar with and switched on capture of species such as buzzards. If ideal, but hens’ eggs (brown or white)
to. Therefore, be mindful that seasonal persistent problems are encountered, seem just as attractive. Break two or
variations are likely to apply and there is then a change in approach to non-meat three eggs around the trap, and leave the
some evidence to suggest that effective baits is a responsible move. Of the non- eggshells lying about. Most importantly, on
spring and summer baits, such as eggs, meat options, white bread can be used: the flat board that shelters the call-bird
are less effective outside of the nesting it is eye-catching, fairly common in the when present, or on the flat top between
season. Outside of the spring and summer countryside, and corvids develop a taste the two catching compartments, carefully
meat baits comprised of healthy fallen for it. Again, a scattering of bait is more break an egg so that the contents lie in a
wildlife (livestock use is prohibited) or noticeable, but don’t overdo it, or the tempting puddle. Renew this egg regularly:
other recognisable food items may be birds will see no reason to enter the trap. it is the glistening fresh egg that catches
the best option. Of the meat baits, open During the nesting season the best the corvid eye.
rabbits or grey squirrels have been found bait by far is the egg. When using them,

When you have finished trapping Keep in touch
A number of incidents of accidental if a top entry trap is left with its doors There is still much to be learnt about
captures of protected species have been closed, a heavy bird or animal landing the efficient control of corvids. If you
reported when traps have been left out. on one of them could force the door have experiences at variance with
As a result, the licence requirements now down and trap itself. We recommend the advice given here, or make any
state that the trap must be rendered that wherever possible, traps that are significant improvements to the trap,
incapable of catching or holding birds not in use are taken in for storage. This bait, or strategy, please contact the
Game & Wildlife Conservation Trust’s
when not in use, examples of how to do prevents the risk of accidental captures,
Advisory Service on 01425 651013, or
this include securing the door in a fully avoids the chance of someone else setting email advisory@gwct.org.uk
open or closed position or removing the or vandalising the trap and extends its
doors completely. Please remember that working life.

Game & Wildlife Conservation Trading Limited, is a company limited by guarantee (Registered number 1503620) which carries out all trading and advisory activities
for the Game & Wildlife Conservation Trust. VAT Reg No. 323 7013 94.

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