By Hugo Straker, Scotland and Ireland Advisor
To optimise red grouse production to allow sustainable driven or walked-up shooting, upland keepers rely heavily on legal, humane predator control to achieve success. The deployment of significant numbers of lethal tunnel traps to control mustelids forms a major part of most predation control campaigns, particularly in spring and summer. 1 April 2020 heralded ‘all change’ to the practice of tunnel trapping throughout the UK, and the change will likely have most impact where wild game populations are being managed, with an emphasis on stoat and weasel control. Landowners, managers and keepers must all embrace this change – like it or not.
The 2018/19 Spring Traps Approval Orders for England, Scotland, Wales and Northern Ireland formalised the end of the historically popular Fenn-type spring traps (amongst others) for stoat control. As of 1 April 2020, these must be replaced with a new generation of traps, which have been approved by Defra for stoat capture. These currently include the DOC trap series (150, 200 and 250), Tully trap and Goodnature A24 stoat and rat trap. All have been designed to enhance animal welfare by killing target species within a specified time frame.
Throughout 2019, most grouse keepers have been experimenting with both the Tully and the DOC 150 to determine which one works best for them. Regardless of trap type, each must be deployed in a way that minimises the risk of injury or killing non-target species.
Approved stoat traps being used on ‘rails’ set over ditches and watercourses should be placed in either wooden boxes or weldmesh ‘tunnels’ with the latter the most popular as resistance against high water flows is minimised and they are less obtrusive.
25mm square weldmesh should ideally be used for tunnel construction to help minimise the risk of mountain hares, lambs and birds from being caught by the leg from above. The tunnel, whether run-through or blind-ended and baited, must have excluders at the entrance(s) to help minimise the risk of non-target capture.
In the case of DOC traps, tunnel construction must adhere to manufacturer’s guidelines; choice of materials can be flexible, but positioning of traps in relation to the baffles must be according to the DOC trap instructions as presented to the UK by the New Zealand Department of Conservation in 2019.
If excluder and baffle apertures are aligned as
shown here, you must satisfy yourself that
non-targets cannot trigger the trap by reaching
in with paw or beak. Alternatives are to stagger
the holes, or lengthen the distance.DOC traps must be used with a baffle alongside the trap to ensure a humane strike. In addition – as with all spring traps – use of the trap must (by law) reasonably balance the successful capture of target species with minimal risk to non-target species. Non-target animals larger than the target species can be prevented from reaching the trap by adding an ‘excluder’ to the tunnel entrance(s). For decades it has been common practice to narrow the entrance using two sticks or whatever came to hand. Nowadays there is at least some knowledge of the size of gap that different species can get through (depending how much they want to, of course) and something less arbitrary is expected. However, to allow for the many different circumstances and personal preferences, there is no definitive requirement. Every trapper must consider the non-target species exposed to traps in their area and be prepared to defend their tunnel design.
For those wanting a recommendation, we suggest that where stoats and weasels are the main target, tunnel excluders should have apertures no larger than the 51mm used in the DOC run-through trap baffle. This keeps things simple, is defensible, and is amply big enough for stoats and weasels to enter. Excluders can be set back inside the tunnel entrance, but we suggest they should be at least 15cm away from the trap, to avoid non-target species reaching the trap by inserting beaks, heads or paws.
For trappers targeting grey squirrels (and rats) with DOC traps, a larger excluder aperture is better. To minimise exposure of non-targets, we recommend that trapping (in woodland) is concentrated into short periods of a week or ten days, repeated 2-3 times a year, each time preceded by pre-baiting for at least a week with whole maize. For grey squirrels, DOC traps must be used in single-entry tunnels, which should also be baited with maize (DOC traps in run-through configurations have not been approved for grey squirrels).
Designs for Tully tunnels are up to individual operator discretion but must minimise the risk of non-target capture; again, we recommend a 50mm aperture for excluders.
Positioning of traps in tunnels is also important and will determine the length of each tunnel. Traps need to be kept far enough back from the entrance to minimise the risk of non-target capture by paw, claw or beak; we recommend 130-150mm back from the entrance. For example, with a DOC 150 trap placed in the middle of a run-through tunnel, the total tunnel length will then be at least 470mm (18½”). A Tully trap housing would need to be 100mm longer.
Where red squirrels are present, we strongly discourage the use of rail traps. Trappers should always carefully assess the risk of non-target capture as there are some areas where the risk of catching non-targets is more likely to occur and red squirrels seem naturally drawn to rails; particularly those set across waterways. In Scotland, under the Wildlife and Countryside Act 1981, as amended, it is illegal to set any trap likely to kill or cause bodily injury to any wild animal in schedules 5 and 6. Continued use of rail traps in or close to red squirrel woods could jeopardise future use of rail traps as part of a legitimate predator control programme. If in doubt, do not set a trap.
The popular Fenn-type trap will remain a legal trap for weasels after 1 April, but trappers must reduce excluder apertures on any boxes/rails that remain with these traps to minimise the risk of stoat capture. Because of the overlap in body size between weasels and stoats, it is unlikely that any physical excluder can be devised that will allow weasels to pass through while excluding stoats. We therefore urge trappers to embrace change and demonstrate full compliance with the law by switching to new generation stoat traps for both species.
This change to trapping will likely mean fewer traps being deployed due to the expense of new approved stoat traps. Whilst the extra expense may challenge some shoot budgets, we encourage trappers to work away with these new humane traps and learn how to incorporate them into their hill trapping strategies.
Our FAQ on the implementation and consequences of the Agreement on International Humane Trapping Standards (AIHTS) can be found here.