The potential for biological control of stoats (Mustela erminea)

Abstract

Accelerating the mortality of stoats (Mustela erminea) using biological agents, or reducing their fertility using chemosterilants or biological agents, are increasingly seen as more sustainable and more humane than trapping and poisoning. Obligate delayed implantation in fertilised female stoats of all ages allows 10-11 months for an applied biological agent or chemosterilant to interfere with gestation. Two chemosterilants (cabergoline and mifepristone) disrupt pregnancy in some species and may be effective on stoats, although they are not species-specific and are probably more expensive than poisoning. For the longer term, more recent fertility control research has explored potentially more species-specific options for other species based on inducing an immune response to an animal's own reproductive hormones, gametes, or products from embryos. Conception will be difficult to disrupt in stoats because females are sexually mature and are mated in the nest during a short period before they are weaned. A large research effort will be required to determine which of the immunosterilants being developed could be suitable candidates for stoat control. There are fewer options apparent for using biological agents to increase stoat mortality, although species-specific strains of canine distemper virus may be effective against stoats.The greatest impediment to controlling stoat fertility will be effective delivery of sterilants. For the foreseeable future, it will probably be necessary to rely on baits, but they are unlikely to put all target stoats at risk, and will be incapable of delivery over larger scales than at present.

Advances in New Zealand mammalogy 1990–2000: Stoat and weasel

“…data), repellents (Spurr 1997), fertility control (Norbury 2000), and manipulation of diseases (McDonald & Lariviere in press) are under investigation. Control by habitat manipulation, e.g.…”

Effects of bait type and deployment strategy on uptake by free-living badgers

“…In large-scale bait deployment programs for vaccination or control of wildlife populations, the number of baits delivered should be kept to a minimum for the campaign to be cost-effective (Morgan 1982;Wandeler et al 1988;Linhart et al 1997;Norbury 2000) and to limit interference by non-target species (Morgan 1993;Delahay et al 2003). However, the number of individuals of the target species ingesting the bait should be maximised, thus avoiding bait monopolisation and possible overdosing (Bradley et al 1999).…”

Removal of American mink (Neovison vison) from the Uists, Outer Hebrides, Scotland

“…In addition, unmated female mink tend to remain on heat until mated. The remaining females may be inherently more trappable as they may be searching for mates, as seen in a number of mustelid species (Norbury 2000), and are as a result more mobile, and potentially more inquisitive with regards to artificially placed scents, and this could be exploited for landscape scale management of mink populations. The absence of free-living juveniles in the last 2 years of trapping on the Uists also supports the absence of successful breeding on the Uists in the final stages of the programme.…”