Growing public concerns about lethal methods to mitigate human–wildlife conflicts place increasing constraints on wildlife management options. Translocations, perceived as humane and non-lethal solutions, are increasingly advocated to resolve these conflicts. The present study summarises the literature on translocations of wild mammals, with particular emphasis on ‘problem’ animals, reviews the impact of translocations on survival, behaviour, animal welfare and potential spread of diseases, and evaluates the feasibility and effectiveness of translocations to mitigate human–wildlife conflicts. Translocations may have a detrimental impact on survival rates and lead to extreme dispersal movements. In some species, stress-related capture results in substantial mortality. In other species, homing causes animals to leave the release area. In addition, some animals resume the nuisance behaviour at the release site. Individuals that survive a translocation may suffer from malnutrition, dehydration, decreased immunocompetence and predation. Supportive measures such as acclimatisation pens and provision of food and shelter can drastically reduce post-release dispersal movements and mortality, although the adoption of these measures increases the cost of translocation. Translocations have the potential to spread diseases to conspecifics, humans, domestic animals and livestock. Health surveillance, seldom implemented, is likely to add significantly to the cost of translocation. Very few studies have reported the costs of translocations or addressed which stakeholders are expected to pay for translocating problem animals. Alternative management options are rarely mentioned. Despite the perceived humaneness of translocations to mitigate human–wildlife conflicts, the fate of translocated animals has been rarely monitored. In addition, very few studies have mentioned whether and for how long the conflict was resolved. We suggest that determining whether the translocation leads to the resolution of the problem should be the main criterion to evaluate the success of the translocation of problem animals. We propose a list of criteria to assist decisions regarding the suitability, effectiveness and humaneness of translocations to manage problems posed by wild mammals.

Summary 1.Norway rat Rattus norvegicus populations are usually controlled with toxic baits, but this approach is increasingly recognized as having negative welfare and environmental impacts. An integrated strategy that relies less on rodenticides is therefore required. Here we investigate the possibility of using a resource-based approach to rat population management. 2. Structurally complex habitats provide rat populations with nest sites and opportunities to avoid predators; modifying habitats to reduce structural complexity might reduce their potential to support rat populations. As part of an integrated approach, this could be more sustainable than relying exclusively on lethal control. However, in order to target habitat management efforts most effectively with minimum impact on other species, an understanding of habitat utilization by Norway rats is required. 3. In this study, rat populations on farms in the north-east of England were monitored by radiotracking and population counts before and after a single phase of habitat modification. Rats living near farm buildings utilized areas with high levels of cover; habitat modification reduced the survival rate and size of these rat populations. Rats living in field margins also preferred areas with high levels of cover, but they had significantly bigger home ranges than rats living near farm buildings and were largely unaffected by small-scale habitat management. 4. Synthesis and applications . Our results indicate that habitat management near farm buildings has the potential to reduce the size of rat populations. As part of an integrated approach, this technique offers a way of reducing reliance on rodenticides. Habitat use by rats within the wider farm landscape suggests that land management practices have the potential to influence the size and distribution of rat populations; many game-rearing practices and environmental policies designed to create habitats for 'desirable' farm wildlife, inadvertently create desirable habitats for rats.

Context. Fertility control appears as a publicly acceptable alternative to lethal methods for limiting population growth in wildlife. Recently developed single-dose immunocontraceptive vaccines have induced infertility in several mammals. However, the potential side-effects and the long-term effectiveness of these contraceptives have been poorly investigated.Aims. We tested the long-term effectiveness and potential side-effects of the single-dose gonadotrophin-releasing hormone (GnRH) vaccine GonaConÔ on captive female wild boar.Methods. We carried out two sequential trials: Trial 1 (n = 6 GonaConÔ-treated and 6 control wild boar) and Trial 2 which started two years later and replicated Trial 1. We assessed the effectiveness of GonaConÔ to cause infertility by measuring GnRH antibody titres, by monitoring the oestrous cycle through the concentration of faecal progesterone and by recording the sows' reproductive output in the 4-6 years following treatment. We evaluated the potential side-effects by monitoring behaviour, bodyweight and haematological and biochemical variables.Key results. GnRH-antibody titres decreased with time but were still detectable in all females six years after vaccination with a single dose of GonaConÔ. In Trial 1 none of the treated females gave birth in the six years after vaccination. In Trial 2, progesterone indicated that two of the six treated females were cycling. One of the cycling treated females gave birth one year after vaccination; the other five, including the second cycling sow, did not reproduce in the four years following vaccination. We found no differences in bodyweight, haematology, biochemistry and behaviour and no obvious sign of injection site reaction.Conclusions. GonaConÔ can suppress reproduction in wild boar with no long-term effects on behaviour and physiology. Therefore, GonaConÔ can be regarded as an effective and safe contraceptive for this species.Implications. The lack of evidence of adverse effects and the longevity of effect of GonaConÔ suggest that this contraceptive could be now tested in field trials and in contexts where culling of overabundant populations of wild boar is unfeasible, illegal or unacceptable. These instances include urban areas, parks, and management of diseases where culling might cause social perturbation and result in increased disease transmission rates.

Bait‐delivered pharmaceuticals, increasingly used to manage populations of wild boar (Sus scrofa) and feral pigs, may be ingested by nontarget species. Species‐specificity could be achieved through a delivery system. We designed the BOSTM (Boar‐Operated‐System) as a device to deliver baits to wild pigs. The BOSTM consists of a metal pole onto which a round perforated base is attached. A metal cone with a wide rim slides up and down the pole and fully encloses the base onto which the baits are placed. We conducted a pilot, captive trial and found that captive wild boar fed from the BOSTM either directly, by lifting the cone, or indirectly, by feeding once another animal had lifted the cone. Thus, we tested whether free‐living wild boar fed from the BOSTM and whether the BOSTM could prevent bait uptake by nontarget species. We observed that free‐living wild boar fed regularly from the BOSTM and that the device successfully prevented bait uptake by nontarget species. The BOSTM should be trialed more extensively to confirm its effectiveness and species‐specificity to distribute pharmaceuticals to wild suids. If successful, the BOSTM could be used to deliver vaccines in disease control programs as well as contraceptives to manage overabundant populations of wild suids.

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SUMMARYTrials of rodenticidal baits containing 50 p.p.m. difenacoum, 50 p.p.m. bromadiolone or 20 p.p.m. brodifacoum were carried out on farmsteads against populations of Rattus norvegicus containing difenacoum-resistant individuals. Six difenacoum treatments failed in 14-42 days of baiting. Two treatments with bromadiolone succeeded in 23 and 33 days, but four further treatments lasting 35-56 days failed to eradicate the populations. Brodifacoum gave virtually complete control of six populations in 21-73 days and of the ten residual populations left behind by the other two compounds, after baiting for a further 11-85 days. The performance of both bromadiolone and brodifacoum was well below that reported by previous investigators, indicating the possibility of low-grade resistance to these compounds in the difenacoum-resistant strain.

For the first time, it has been unequivocally shown that multiple‐feed second‐generation anticoagulant rodenticides were ineffective against a population of rats in N.W. Berkshire, UK because of an unusually high prevalence and high degree of resistance. Use of the non‐anticoagulant rodenticide calciferol led to a substantial reduction in the population, although primary poisoning of small birds appeared to be greater than with anticoagulant baits. There was strong evidence that many of the surviving rats had developed an aversion towards calciferol‐treated bait. A reduction in the degree of anticoagulant resistance in the population was evident after a period of 17 months without anticoagulant use. The long‐term strategy to manage the resistant population should integrate non‐anticoagulant and anticoagulant rodenticide use to take advantage of possible pleiotropic costs of resistance.

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