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COUNTRYSIDE ALLIANCE BRIEFING NOTE
Larsen Traps in Wales
Wednesday 20 June 2018
Background
· Larsen traps are a live-catch trap used to capture and contain magpies and crows.
· Magpies and crows are subject to control under the terms of the General Licences, which are issued every year by Natural Resources Wales. The General Licenses are relied upon by farmers, gamekeepers and other conservationists to allow them to undertake legal pest control.
Countryside Alliance Position:
· Crows and magpies are agricultural pests. Crows in particular can cause extremely distressing injury and even death to lambs.
· Crows and magpies in high densities near vulnerable populations of ground nesting birds or farmland songbirds can cause declines to birds of high conservation value, due to nest predation.
· Larsen traps are an invaluable tool in controlling magpie and crow populations. They are effective and they are humane. Because they are live-catch traps they are also extremely selective.
· It is vital that land managers can continue to use Larsen traps in accordance with the conditions laid out in the General Licence.
Why Control Crows and Magpies?
· There is no ‘natural balance’ between crows and magpies on the one hand and the birds on which they prey on the other. This is because crows and magpies also feed to a great extent on waste food produced by man, which greatly inflates their populations leading to intolerable levels of predation on ground nesting birds, songbirds and farm livestock.
· Although seldom recorded, Welsh sheep farmers report crows attack, maim and kill ewes and their lambs. This pressure is lessened on estates undertaking legal crow control[1].
· Crow and magpie predation has been implicated in declines in birds of high conservation value. In the uplands birds such as black grouse, curlew and lapwing only thrive in areas subject to predator control, while in the lowlands predator pressure has been shown to limit grey partridge recovery and crow and magpie predation has been shown to impact on thrushes and some farmland songbirds[2].
· A nine-year study undertaken in Northumberland showed that reducing numbers of carrion crows, alongside fox control, significantly improved breeding success of lapwing, curlew and golden plover[3]. The RSPB says the UK is arguably the most important country in the world for curlew conservation[4], and this study showed that populations of these globally-threatened waders declined when there was no predator control.
· Conservation charities recognise the need to control crows. In 2012/ 2013 153 carrion and hooded crows were killed to protect ground nesting birds on 4 different RSPB reserves[5]
· Predation control of crows and magpies using Larsen traps can improve the breeding success of farmland hedgerow-nesting songbirds[6]. In one study covering 4 years and 32 paired farmland sites, crows and magpies were removed at half the sites during the breeding season using Larsen traps; no removal took place at the other sites. The key finding was that overall nest success of the hedgerow-nesting songbird community was down by 10 per cent on the sites without Larsen trapping. Excluding 2012 data because of exceptionally high spring rainfall that year, in the other three years nest success was down 16% on the sites without Larsen trapping.
· The impact of crows and magpies on songbirds is important. The JNCC Farmland Bird Index, which includes many of the songbird species affected by crow and magpie predation, is down by 56% since 1970[7]. In the same timeframe, the crow population has doubled and continues to grow[8].
Larsen Traps
· Larsen traps are extremely selective. It is very rare to catch anything other than the target species, and on the rare occasions non-target species are caught they can be released unharmed. In a survey of over 10,000 birds captured in Larsen traps, only 1% were non-target species[9].
· The value of Larsen traps is in catching crows and magpies when they set up their breeding territories. Because Larsen traps are small, they can easily be moved around different breeding territories. Traps can be moved to deal with specific pairs of crows or magpies, and a few traps can therefore cover quite a large area.
· Larsen traps selectively trap the most damaging individuals. They use a captive bird to aggravate the territorial instinct of breeding birds in a particular area. It is breeding birds that are likely to be scouring that area for food, finding and destroying the nests of other bird species. Flocking birds that are not breeding are likely to be passing through and are both less likely to be causing damage and less likely to be caught in a Larsen trap.
· The trap mechanism involves a spring door to each catching compartment which is held open by a split perch. To enter the trap, birds the size of a magpie or crow inevitably drop onto the perch. The perch gives way, and the bird’s momentum takes it past the bottom of the door, which flips up and traps the bird in the compartment. No harm is caused to the caught bird.
Larsen Traps and Welfare
· It is noteworthy that the RSPB are not opposed to legal, site-specific control of magpies, nor to the legal use of Larsen or other cage traps, as long as the general licence conditions are strictly adhered to[10].
· The captive bird used to draw breeding crows and magpies to enter the trap is called a call-bird. The General Licence imposes a legal obligation to visit each call-bird at least once a day at intervals of not more than 24 hours, and specifies that food, water, shelter and an appropriate perch must be available to the call-bird at all times[11].
· Any birds killed in accordance with the General Licence must be killed in a quick and humane manner as soon as reasonably practicable after discovery. Any bird held captive prior to being killed must be killed out of sight of other captive birds.
For more information please contact:
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Rachel Evans Director for Wales |