Tunnel trapping describes the use of spring traps (kill traps) to catch small mammalian predators and pests. Under the Pest Act 1954, the only kill traps allowed are those approved by the appropriate Ministry (currently Defra) and listed in statutes (Spring Trap Approval Orders). Trap approval generally has conditions attached including one to the effect that traps must be used within a suitable tunnel. (Exceptionally a tunnel is integral to the trap). This condition is designed to prevent the capture of birds or larger mammals.
The origins of tunnel trapping
The outlawing of the gin trap in England and Wales through the Pest Act 1954 was probably the first statutory restriction of animal trapping methods by a national government on grounds of humaneness. The gin trap had been considered inhumane as a foot-hold trap used to catch medium-sized mammals such as foxes or cats, and indiscriminate in the wide range of mammal and bird species it was capable of catching, killing or maiming. But the ban on the gin trap left a methodological void, as many of its intended targets were seen as pests. One of these, the fox, could still be killed legally by other methods such as hunting with hounds and terriers, and newer methods emerged such as wire neck snares and spotlights to allow night shooting with a rifle.
Gin traps had also been used to catch smaller mammalian predators such as weasels, stoats, and rats in the context of wild gamebird management, and mammalian pests of agriculture and forestry such as rabbits and grey squirrels. The Fenn Humane Trap (A.A.Fenn, FHT Works, High Street, Astwood Bank, Redditch, Worcestershire, UK; British Patent No. 763,891) was introduced in the 1950s to deal with these species, and has become a standard tool for gamekeepers. Its popularity reflects its low cost and ease of use, and for a long time the absence of serious competitors.
Fenn traps were developed through a series of models. Field trials using early versions were carried out by the Ministry of Agriculture, Fisheries and Food, and Fenn Mk I, II and III traps were authorised by the Spring Traps Approval Order 1957. To prevent the accidental or deliberate capture or maiming of non-target species, a condition was imposed that the traps must be used in a suitable tunnel.
Trials by staff of the Eley Game Advisory Station, forerunner of the present-day Game & Wildlife Conservation Trust, were reported in 1961 and documented 2,500 trap-days and 130 captures of 6 species (Bateman, 1988). The report suggested that the Fenn should not be regarded as the last word in humane traps, and expressed the hope that even better traps might be expected in the future (Bateman, op.cit.). It is not clear whether the perceived shortcomings were in humaneness or catching efficiency. The Fenn Mk IV in use today was added in 1970 by means of the Spring Traps Approval (Variation) Order 1970 (SI 1970 No 50), and the larger Mk VI in 1982 by the Spring Traps Approval (Variation) Order 1982 (SI 1982 No 53).
Alternatives to Fenn traps
A number of direct copies of the Fenn trap are also available today and approved for use. These include the long-established Springer No 4 and No 6 (AB Country Products), and the Solway Mk 4 and Mk 6 (Solway Feeders Ltd, Main Street, Dundrennan, Kirkcudbright, Scotland, DG6 4QH. UK).
There are also other styles of traps approved for the same range of species. These are listed on Defra's own website, and include Magnum and Conibear 'revolving jaw' traps, and the unique and extremely powerful Kania traps. These all depend on a wire trigger rather than a treadle plate, although the wire trigger of the revolving jaw traps can be adapted to as a treadle plate. A recent development has been the approval of DOC traps for use in the UK. Like the Fenn traps, these feature a treadle plate trigger, and are intended to bring improved humaneness with similar ease of use.
As stated above, the purpose of the trap tunnel is to impose selectivity over the range of species that can be caught, by excluding those too big to fit into the tunnel. It has long been standard advice to restrict the tunnel entrance further by the addition of two sticks at each end, primarily to discourage the entry of small birds. Towards the end of the 20th century, the geographical recovery of the polecat, the declining conservation status of the hedgehog, and the proposed assisted recovery of the pine marten raised anxiety about the capture of these species (all protected under Schedule 6 of the Wildlife & Countryside Act 1981) in tunnel traps.
A contract to the GWCT from English Nature led to the development of physical baffles designed to exclude these species while allowing the entry of smaller ones. These were trialed in the field to test their effect on target capture rate. While no effect on stoat or weasel capture rate was detected, the use of excluders significantly decreased captures of rats and grey squirrels (Short & Reynolds, 2001). The use of physical excluders remains discretionary for the tunnel trap operator, who must weigh up the risk of catching a protected non-target against the utility of the trap for its intended purpose. Pre-baiting of tunnels before traps are deployed to concentrate target captures into a short trapping period is clearly advantageous in the case of squirrel and rat control.
UK legislation governing to the use of tunnel traps
- Bateman, J.A. (1988) Animal Traps and Trapping, London: David & Charles. 288 pages.
- Short, M.J. & Reynolds, J.C. (2001). Physical exclusion of non-target species in tunnel-trapping of mammalian pests. Biological Conservation 98(2): 139-147