The Larsen trap is crucial for protecting vulnerable breeding game and wild birds, luring in the corvids to drive away the decoy bird held inside
Of all the pest control activities that we carry out, Larsen trapping for crows and magpies is perhaps the most visible. It therefore follows that the better we do it, the more likely we are to make the right impression on passers-by. Filthy Larsen traps, with dejected-looking decoys, standing on a heap of splattered droppings and flyblown carcass remains are not a good advertisement for gamekeeping.
There are lots of reasons for Larsen trapping, but for most of us the key aim is to prevent nest predation on wild breeding game. We probably hope that other vulnerable species, such as lapwings, curlews, blackbirds and song thrushes, will benefit too.
For the uninitiated, Larsens work by territorial intrusion — birds get caught not because they want to make friends with the decoy in the trap, but because they want to drive it away. Crows and magpies start to get seriously territorial in late March, at much the same time as the first game eggs are beginning to appear. So this is the time to start, for it is the eggs that are most vulnerable. Once the game chicks have hatched and are away with their parents, they are much less vulnerable.
My annual plan with Larsens is to start then, having scrounged crow and magpie decoys. By deploying my first captives in extra traps, I can soon have several running within a week and my aim is to remove the territorial pairs of both species by early April. From then on, it is just incomers that I am after.
This strategy also has a view to the welfare of the corvids themselves. By removing pairs before they start nesting and taking out incomers, I am making sure that there are no orphaned chicks. Breeding pairs from over the boundary will not abandon a nesting attempt — it is the non-breeding “lower orders” that are looking for vacant territories to colonise. You never know where a new colonist will turn up, so do not leave your trap in the same place for long.
Better results generally come from being mobile. I rarely leave a Larsen trap in the same place for more than two days. By then, if I have not caught, I am probably not going to, at least for the moment.
Choice of trap
The original trap, as invented by Danish gamekeeper Mr Larsen, had a wooden frame with wire netting. However, times have moved on and these days I much prefer an all-weldmesh version. The Rhemo model, which comes in two halves for easy transport, is well built and has a positive trip mechanism in both of its catching compartments, so there are few miscatches. The all-weldmesh design has several other advantages, not least being that it is more robust than a wooden-framed model, so it is less prone to both accidental damage and vandalism. The lack of an obvious wooden frame makes it more difficult to spot from a distance too, so it is less likely to be investigated by trespassers.
The open general licences that allow us to use Larsens have different wording between England, Wales, Scotland and Northern Ireland, but they all impose the same basic welfare criteria. You do not need to apply for a licence, nor even have a copy, but you are legally obliged to follow the terms and conditions. In particular, you must supply appropriate food, water at all times, a decent perch and adequate shelter from adverse weather.
I always site my trap in the lee of a hedge or large tree, to supplement the roof shelter that is built in. For water, I am completely sold on rabbit drinkers from pet shops. They keep the water clean and healthy, and avoid the risk of bowls being tipped over and birds defecating in their water. The 600ml size is best, as it is less likely to be dislodged from the side of the trap than the smaller one.
For food, I fix a bowl to the side of the trap and use complete diet dog food kibble, soaked with extra water. This is clean, easy to use and provides balanced nutrition for birds whose natural diet is similar to the needs of a dog. It is also less likely to attract the attention of scavengers compared with bits of carcase — I have never had to evict a buzzard from a trap fed with dog food.
You are legally obliged to physically check your Larsen every day at intervals of not more than 24 hours. In practice this means that you need to check more often, because you cannot afford to be even a few minutes late. I usually go twice a day, but I try to site my Larsens where I can spy on them from a distance. In this way, if there is a bird about to get caught and my 24 hours are not up, I can leave the situation to develop.
When removing captives, I always wear gardening gloves to give me confidence and avoid being pecked. This is not being sissy — people have died of septicaemia from corvid bites, so be sensible. It also means that I can grab the bird quickly and rap its head hard on the first available suitable object. This should kill it outright, but I always break the neck too, just to be sure.
Signs on Traps
I hope that this will give you a well-thought-through plan for trapping corvids in a publicly acceptable way. I take pride in doing my Larsen trapping as humanely as possible as part of a serious game and wildlife conservation package and I find that most sensible people are won over, even if they were sceptical. I also put signs on my traps to explain this, so that even trespassers can begin to understand.