Environmental Engineering Reference
In-Depth Information
ideally losing effi cacy. In fact if you do take Emerson's advice and build a better
mouse trap, someone will build an even better one, a process that has long been
ongoing and is probably accelerating as technological possibilities expand. One of
many such examples is a self-resetting electronic rat trap (US patent 5918409).
Traps, whether used for commercial fur harvesting or for pest control, and
whether for holding or killing the animal, may have to meet international humane-
ness standards. Attempts to set these standards began in 1987 but, apart from stand-
ards for testing traps (e.g. International Organization for Standardization 1999),
no consensus was reached. Two international standards may now be applied by
countries for the use of traps: the above testing standards or the European Union
Regulation No. 3254/91 of 1991, which essentially bans leghold traps from the
Union and from countries wishing to export fur to the Union. Some countries
have prohibited or are phasing out traps that do not meet national or international
testing standards (Warburton
et al
. 2008). Modern food hygiene standards have
also led to some innovative new traps. h ere is only one thing worse than a live
mouse in the food factory and that is a dead one and the toxins used to kill it.
European Union rules on these issues can close premises until the rodent and
toxins are removed, so commercial pest control companies have developed systems
that gas the rodent using CO
2
in an encased trap that sends off a radio signal to the
pest control fi rm who come and collect the victim (Brigham 2006).
Trapping (both lethal and live-trapping) and its variants remains the main or
only control tool for a surprisingly large number of vertebrate pests managed under
sustained control strategies. Trapping seems to be the main control tool for many
species with specialized diets (e.g. many predators and especially those that prefer
live prey such as musk shrews,
Suncus murinus
); where non-target species cannot
be easily avoided (e.g. for American raccoon,
Procyon lotor
; control in Hokkaido in
the presence of the native raccoon dog,
Nyctereutes procyonoides albus
, Ikeda 2006);
or where there are social constraints on lethal methods (e.g. mongoose,
Herpestes
javanicus
, control on Amami Island, Okinawa, Japan (Ishii
et al
. 2006).
However, traps have some disadvantages. While they may be eff ective and e -
cient at small scales, they require someone to set and check them. h ey are expen-
sive to apply at large scales or frequently, and individual animals can be, or become,
trap-shy (e.g. Tuyttens
et al
. 1999). h us, there are active research programmes
in many countries to fi nd alternative control methods for species currently man-
aged by trapping. For example, in New Zealand, the stoat (
Mustela erminea
) is a
major predator of native birds. It is mobile, generally at low densities, and has peri-
odic (seasonal or every few years) impacts on its prey. Control of stoats still relies
largely on trapping and is very expensive, even when applied for a short time when
impacts are at their worst, so costs prohibit applications at the large scale needed to
protect threatened bird populations (King and Murphy 2005). A major research
eff ort into alternative controls (baits and toxins suitable for broad-scale distribu-
tion, and preliminary work on fertility control) was undertaken in New Zealand
in the 1990s, as yet without a major breakthrough, but with incremental improve-
ments to the older techniques (Murphy and Fechney 2003).
