Exclusions for resolving urban badger damage problems: outcomes and consequences.

Increasing urbanisation and growth of many wild animal populations can result in a greater frequency of human-wildlife conflicts. However, traditional lethal methods of wildlife control are becoming less favoured than non-lethal approaches, particularly when problems involve charismatic species in urban areas. Eurasian badgers (Meles meles) excavate subterranean burrow systems (setts), which can become large and complex. Larger setts within which breeding takes place and that are in constant use are known as main setts. Smaller, less frequently occupied setts may also exist within the social group's range. When setts are excavated in urban environments they can undermine built structures and can limit or prevent safe use of the area by people. The most common approach to resolving these problems in the UK is to exclude badgers from the problem sett, but exclusions suffer a variable success rate. We studied 32 lawful cases of badger exclusions using one-way gates throughout England to evaluate conditions under which attempts to exclude badgers from their setts in urban environments were successful. We aimed to identify ways of modifying practices to improve the chances of success. Twenty of the 32 exclusion attempts were successful, but success was significantly less likely if a main sett was to be excluded in comparison with another type of sett and if vegetation was not completely removed from the sett surface prior to exclusion attempts. We recommend that during exclusions all vegetation is removed from the site, regardless of what type of sett is involved, and that successful exclusion of badgers from a main sett might require substantially more effort than other types of sett.

Feeding of grey squirrels (Sciurus carolinensis) with the contraceptive agent DiazaCon™: effect on cholesterol, hematology, and blood chemistry.

Grey squirrels (Sciurus carolinensis) are an invasive species in Britain and Italy. They have replaced native red squirrels (Sciurus vulgaris) throughout most of Britain, and cause damage to trees. Currently, lethal control is used to manage grey squirrel populations in Britain, but nonlethal methods might be more acceptable to the public. One such method is contraception with 20,25-diazacholesterol dihydrochloride (DiazaCon™). DiazaCon™ inhibits the conversion of desmosterol to cholesterol, resulting in increasing desmosterol concentrations and decreasing cholesterol concentrations. Because cholesterol is needed for the synthesis of steroid reproductive hormones, such as progesterone and testosterone, inhibition of cholesterol synthesis indirectly inhibits reproduction. Desmosterol is used as a marker of efficacy in laboratory studies with species that do not reproduce readily in captivity. Grey squirrels were gavaged with a DiazaCon™ solution for 2 days, and then fed DiazaCon™-coated peanuts for an additional 8 days at target doses of 50 and 100 mg DiazaCon™ per kg body weight. There was a significant difference in cholesterol concentrations in the treatment groups compared to the control group. Cholesterol was reduced by ≥ 40% for 2 months in both treatment groups. There were no differences among groups with respect to blood chemistry and hematology parameters, and mean values are reported. The mean overall dose of DiazaCon™ received was 29.0 ± 1.6 and 55.3 ± 4.3 mg/kg in the low (50 mg/kg) and high dose (100 mg/kg) groups, respectively. DiazaCon™ might provide an effective, acceptable alternative to lethal control.

Reproductive success of rose-ringed parakeets Psittacula krameri in a captive UK population.

BACKGROUND: Rose-ringed parakeets Psittacula krameri (Scop.) have recently become established in several European countries, with potential for significant negative economic and ecological impacts. However, in northern Europe the potential for reproductive output is largely unknown. In 2005 the authors established a captive outdoor colony in north-east England and examined breeding success over 2 years. RESULTS: In 2006 (19 pairs, 15 clutches) the average first clutch size was 3.6 (+/-0.3) eggs. Six clutches were infertile, and overall the colony produced 1.4 (+/-0.5) fertile eggs per pair. Eleven pairs produced a second clutch following removal of the first; seven were infertile, and overall productivity was 0.7 (+/-0.4) fertile eggs per pair. Unsuccessful pairs were rearranged or replaced. In 2007, overall productivity was 2.5 (+/-0.4) and 1.8 (+/-0.4) fertile eggs per pair for the first and second attempts respectively. For pairs that remained unchanged through 2006-2007, productivity was consistent between years and breeding attempts. CONCLUSION: Where food and nest sites were not limiting, clutch sizes in north-east England were similar to those in the native range, and consistent between first and second attempts. This has implications for the future expansion and management of the species.

Validating census methods to measure changes in house mouse populations.

BACKGROUND: Tracking and census baiting are two techniques that are commonly advocated for monitoring the size of mouse populations. However, currently these techniques are only able to provide an index of population size, rather than an assessment of absolute numbers. In this study the authors tested the reliability of both tracking (footprints left on tiles of fixed size) and census baiting as indices of population size, and sought to calibrate levels of activity and bait consumption under both semi-natural and field conditions (inside farm buildings). RESULTS: Under semi-natural conditions, census baiting produced more satisfactory population estimates than those derived from tracking activity. An initial field trial established that the optimum bait point density for this technique was 1 point per 2 m. Subsequent field trials demonstrated that the bait census technique offers a way to estimate the approximate size of stable populations of mice (population size = (mean daily bait consumption - 36.3)/2.46). CONCLUSION: The results to date are sufficiently encouraging to support the use of this cost-effective approach to monitoring mouse numbers in the type of habitats investigated in this study.

Eighteen trinucleotide microsatellite loci for the solitary vespid wasp Monobia quadridens.

We identified 18 polymorphic, trinucleotide microsatellite loci for the solitary vespid wasp Monobia quadridens. These markers are to be used for parentage assessment and for studying population structure and inbreeding. Forty-eight diploid females from Southwest Michigan, USA were screened for allelic variation at each locus. Observed heterozygosities ranged from 0.50 to 0.88. The primers were also tested on two other solitary vespid wasps Ancistrocerus adiabatus and Ancistrocerus antilope.

Boosting silica levels in wheat leaves reduces grazing by rabbits.

Systemic application of sodium silicate can significantly enhance the levels of leaf silica in winter wheat (Triticum aestivum L. cv. Mercia), suggesting that this material could reduce the palatability of plants to vertebrate herbivores (e.g. rabbits, Oryctolagus cuniculus L.). A bioassay was developed using hydroponically grown wheat plants. Plants treated with sodium silicate were significantly more resistant to grazing by wild rabbits than untreated plants, with severe, potentially lethal feeding damage being reduced by over 50%. Further studies were carried out to develop more practical techniques for boosting silica levels in plants using silicon-rich 'fertilisers' including calcium silicate and calcium silicate slag (CSS). Silica levels were elevated in the plant 1.9-2.8 times over the control through the application of various silicon materials, in line with those of the hydroponic treatment. Encouragingly, levels of silica were elevated even in young wheat plants, which are most vulnerable to rabbit damage, and in a range of wheat varieties. The use of CSS is particularly promising because of its lower cost in comparison with calcium silicate, and it has a proven track record in slag fertilisation of rice and sugar cane crops. At the optimum CSS application rate of 3 g silicon L(-1) soil, wheat silica levels were approximately doubled, with no detrimental impacts on long-term growth or yield.

Masking the taste of the conditioned taste aversion agent levamisole using an ion-exchange resin, for practical application in wildlife management.

For a conditioned taste aversion (CTA) agent to be successful in wildlife management applications, the compound must not be detectable by the animal. Levamisole is an effective CTA agent when administered by oral intubation, but it is readily detected by a number of species when mixed directly in food. This paper describes the development of an ion-exchange resin complex (resinate) to mask the taste of levamisole. Two different resins were evaluated, Amberlite IRP-64 and Amberlite IRP-69, and release studies indicated that the resinate formed using IRP-64 resin would be most suitable for use in wildlife management. Although it contained a relatively low loading of levamisole (77 g kg(-1)), the results indicated that the IRP-64 resinate should be stable in the mouth and release the levamisole quickly in the acid environment of the stomach (93% of levamisole was released into 0.1 M HCl in 5 min). In a bioassay using laboratory rats (Rattus norvegicus Berk), we showed that the taste of levamisole was successfully masked in a biscuit bait using the IRP-64 resinate and that a CTA was generated to untreated bait. The use of ion-exchange resins is a new approach in the taste-masking of CTA agents and could be applied to other wildlife management applications.

Long-lasting systemic bait markers for Eurasian badgers.

This study was carried out to assess whether Rhodamine B, ethyl-iophenoxic acid (EtIPA), and propyl-iophenoxic acid (PrIPA) can be used as long-lasting systemic bait markers for free-living badgers (Meles meles). Between June and November 2003, these chemicals were incorporated into bait distributed around badger setts. Serum, hair, and whiskers from individually marked badgers were collected in the following 4 to 24 wk. Rhodamine B was detectable as fluorescent bands up to 24 wk after ingestion of the bait. Individual badgers were found positive for EtIPA and PrIPA up to 20 wk and 18 wk after exposure, respectively. This study indicates that Rhodamine B, PrIPA, and EtIPA could be used as long-lasting markers for badgers.

Improving the persistence of a formulation of the avian repellent cinnamamide, for the protection of autumn-sown oilseed rape.

In a previous pilot field trial on autumn-sown oilseed rape (Brassica napus L), a suspension concentrate formulation of the avian repellent cinnamamide, using Acronal 4D (50 g litre(-1)) as the sticker, was shown to reduce damage by woodpigeons (Columba palumbus L). However, the persistence of cinnamamide on rape leaves was poor. This paper describes the development of a weather-resistant formulation by the inclusion of a more effective sticker. In vitro studies were used to investigate wash-off of cinnamamide, which was identified as being the major mechanism of loss in the field. Rainfastness of cinnamamide was assessed by washing deposits on glass slides and rape leaves using a 'rain-washing machine'. A number of stickers were evaluated and the effect of sticker concentration, ageing of deposits, freezing and intermittent washing on rain-fastness was investigated. None of the candidate stickers showed increased rainfastness compared to Acronal 4D. However, two of the stickers, Crovol T40 G and Emoleo L1, when combined with Acronal 4D in small amounts, did reduce wash-off compared with Acronal 4D alone. Freezing led to an increase in wash-off of cinnamamide, but inclusion of Emoleo L1 with Acronal 4D reduced this effect. Increasing the concentration of the sticker was also shown to improve the rainfastness; doubling the concentration of Acronal from 50 to 100 g litre(-1) halved the wash-off of cinnamamide.

Functionally reproductive diploid and haploid males in an inbreeding hymenopteran with complementary sex determination.

It has become a matter of orthodoxy that among wasps, ants, bees, and other insects in the order Hymenoptera, only uniparental haploid males that arise from unfertilized eggs are capable of reproduction. This idea is of interest because the best understood and perhaps most widespread sex determination system among these insects [known as single locus complementary sex determination (sl-CSD)] does not depend on ploidy alone and, paradoxically, consistently results in small numbers of diploid biparental males. To date, the reproductive potential of diploid males has been studied in 13 of the perhaps 200,000 hymenopterans world-wide; in each of these instances, the diploid males are genetic dead ends because they are inviable or sterile. The data from these species have resulted in a general conclusion that has been invoked for virtually all species with sl-CSD and has become the basis for assumptions regarding conservation biology, sex ratio analysis, and the evolution of social behavior. Here, we report that in the solitary vespid wasp Euodynerus foraminatus, both diploid and haploid males are fertile, which documents normal fertility in diploid males of a hymenopteran with sl-CSD. This wasp has high levels of inbreeding because of frequent brother-sister mating in nature; therefore, diploid males are more frequently produced and thus more likely exposed to selection favoring their fertility. Because inbreeding and diploid male production may be important features of the population biology of many hymenopterans, we sound a cautionary note regarding ideas about the evolutionary ecology of these insects.

Inbreeding in a natural population of Euodynerus foraminatus (Hymenoptera: Vespidae), a solitary wasp with single-locus complementary sex determination.

The solitary wasp Euodynerus foraminatus has single-locus complementary sex determination (sl-CSD), which is normally incompatible with inbreeding because it increases the production of sterile or inviable diploid males. Previous field observations of E. foraminatus have suggested that high levels of sibling mating are present in this species. However, conclusions about inbreeding and its genetic consequences could be flawed if based solely upon behavioural observations. Through microsatellite DNA genotyping of 102 E. foraminatus females in southwest Michigan, we estimate that between 55% and 77% of the matings in this population take place between siblings, but the frequency of diploid males is lower than expected. Our data suggest that a mixture of inbreeding and outbreeding persists in E. foraminatus despite the presence of sl-CSD.