Wild boar Sus scrofa has been extinct in Britain for several centuries. Recently, however, some conservationists have argued that it should be reintroduced. Here, we report that two populations of free-living wild boar are already present in Britain, in the south of England, ranging over areas of approximately 15 km² in the county of Dorset and 175 km² in the counties of Kent and East Sussex. Presence of the animals was indicated initially by unsolicited reports to the Department of Environment Food and Rural Affairs, and was confirmed by searching the relevant areas for field signs such as tracks, faeces, nests and rooted areas. Six carcasses of road-killed or shot animals were available for inspection from the Kent/East Sussex area and had the morphological characteristics of wild boar. Breeding was confirmed in the Kent/East Sussex area and is suspected in the Dorset population. A simple population dynamics model, based on an estimated initial population of 100 animals, suggests a growth rate, r, of between 0.016 and 0.267 for the Kent/East Sussex population. We conclude that the Kent/East Sussex population is likely to prove viable unless actively persecuted, and discuss the social, agricultural, ecological and conservational implications.

Feral pigs are well established in the lowland tropical forests of northeastern Queensland, Australia. Circumstantial evidence, e.g. the presence of a Melanesian tick, an exotic nematode and a dominant coat colour other than black, indicates that they do not originate from escaped domestic animals as feral pigs throughout other parts of Australia. It is likely that the ancestral population was established from animals originating from islands to the north and northwest of Australia, i.e. pigs domesticated from naturally occurring wild pigs in Indonesia and southeastern Asia. Pigs in lowland rainforests show relatively stable populations with a high reproductive potential in age classes 4–7. Seasonally there are negative interactions between residents and pigs. Pigs not only damage gardens and fruit orchards due to their rooting, they are also important vectors of zoonoses. Feral pigs are carriers of 11 Leptospirosis serovars, some of which are important zoonoses, e.g. L. australia, L. hardjo and L. zanoni. They also have a high burden of parasites. Lice Hematopinus suis and thorny headed worm Macracanthorhynchus hirudinaceous have been more frequently found in females than in males, whereas males seem to be more susceptible to ticks Ambylomma cyprium cyprium. The infection with lungworms Metastrongylus sp. is higher in younger pigs than older ones indicating that lungworms represent a major mortality factor of young pigs. In contrast, kidney worm Stephanurus dentatus and thorny headed worm is present at all ages. Leptospirosis, lung worm and kidneyworm are known causes of infertility and/or mortality in pigs and can be assumed to contribute to the lower than expected population density in this environment.

The present wild boar Sus scrofa population in Sweden mainly originates from animals that have escaped from enclosures. At some locations wild boars have evidently been released deliberately. Whatever their origin, rapid increases in both number and distribution of free-ranging wild boars have occurred. As wild boars are considered exotic in the Swedish fauna, sportsmen very often provide supplemental food in varying degrees, partly to facilitate and secure hunting possibilities, partly to keep wild boars out of farmed crops. In this paper we describe wild boar activity behaviour and intend to show how wild boar adjust their activity behaviour under different ambient conditions. The aim of our study was to increase the knowledge of managers to improve hunting effectivity and risk assessment concerning crop damage. The wild boars were, almost without exceptions, active during night. The mean time for an activity bout was 7.2 hours and the wild boars in the study area were only to a minor degree adjusting their activity bout to the prevailing night length. However, the hour of sunset seemed to be the cue which triggered the onset of activity bouts. The mean distance that the wild boars travelled during activity bouts was 7.2 km and the estimated mean activity range was 104.4 ha. The mean effort when roaming the activity range was 110.9 m/ha. A substantial variance was typical for all activity variables. For activity distance, 72% of the variation was explained by adding wind speed, season, minimum temperature and snow cover to our model. Significant effects of minimum temperature, snow cover and an interaction between activity time and minimum temperature explained 42% of the variation in activity range. The variation in relative air humidity explained 41% of the time active during an activity bout.

Collserola Park in northeastern Spain is an 8,000 ha Mediterranean forest park surrounded by the Barcelona metropolitan area with a population of some three million inhabitants. Wild boar Sus scrofa are common in Collserola and cause specific management problems. We obtained information on their activity and habitat use in different areas of the park by use of two field methods: prospecting of non-linear transects at night on foot and periodic monitoring of sign-survey plots. Prospecting of routes on foot provided information on summer nocturnal activity in different natural and semi-natural environments: feeding activity takes place mainly during 00:00–05:00, and the maximum amount of movements was registered during 20:00–00:00 and at dawn. Wild boar feeding activity was significantly lower on dry slopes than in other habitat types such as riparian woodland, valley bottoms and agricultural areas. Pellet-group density varied significantly between habitats, being higher in agricultural habitats, intermediate in riparian woodland and lowest on wooded slopes. In general, pellet-group density was higher on level ground than on slopes. The mean surface area rooted by wild boar was less than 5% in all survey periods. Rooting activity, which was dominated by surface rooting, was highest in winter and lowest in summer when soil conditions for rooting were poorest. Rooting activity varied significantly between habitat types, and distinct seasonal patterns were observed within individual habitat areas. The results we obtained support the view that the summer is a critical period for wild boar in Mediterranean environments and highlight the importance of ensuring certain scarce habitats for foraging activities during this season.

We estimated birth rates in wild boar Sus scrofa by counting embryos in the uterus of females killed in individual or drive hunts. Counting corpora lutea in the ovaries gave information on embryo:corpus luteum rate, which can be useful for estimating birth rates in early stages of pregnancy. Birth rates were estimated separately for the different age groups. Age was estimated by means of teeth wear. Survival was estimated by direct observations counting the piglet:female ratio in matrilineal groups. The method is suitable for assessing summer survival only, as 8–9 months after birth, matrilineal groups begin to disintegrate. Average estimated birth rate was 6.7 ± 2.1 (N = 51).We found a positive linear relationship between conception rate and age of female, conception rate and body mass, and conception rate and body length, respectively. In late stages of pregnancy, embryo:corpus luteum rate proved to be 0.83 ± 0.15. Recruitment of piglets to the female population was low; more than half of the piglets had perished by the end of September. The highest mortality rate occurred in the first weeks of the piglets' lives.

The population density of wild boars in Lower Saxony, Germany, has increased drastically during the last decade. High wild boar density causes severe damage to crops and increases the risk of occurrence and distribution of the Classical Swine Fever disease (CSF). Consequently, a reduction of the population density by hunting wild boar in hog cholera zones is necessary. An effective hunting method is the drive hunt performed with beaters, hunters and dogs (terriers), which force wild boars to leave their resting sites. Drive hunt, however, increases the risk of spreading wild boars over a wider area, and this leads to a greater risk of infecting other wild boars with the CSF-virus. Since 1998, ecological and behavioural data of a wild boar population in Lower Saxony, Germany, have been collected. Based on telemetric observations, data of home range size, habitat use and daily and nightly movements were collected. We investigated the effects of several drive hunts on the movements of seven radio-marked wild boar groups, and analysed 10 hunting situations and wild boar escape behaviour. In spite of heavy hunting pressure, in six of the 10 hunting situations, the escaping wild boar groups remained within their home range; in four hunting situations, the wild boar groups left their core area after the drive hunt and relocated up to 6 km away. But after four to six weeks at the latest, the groups had returned to the centres of their home ranges.

In order to estimate age at natal dispersal and dispersal distance, wild boars Sus scrofa were studied in Sweden by use of mark-recapture and telemetry. To describe the average natal dispersal in the population, we applied a sigmoid regression model to analyse the age specific distance to the natal site. We used the first and second order derivatives of the model to determine at which average age dispersal begins, reaches its maximum rate and ceases. The average dispersal distance was estimated by the maximum value of the model. Using this method, we reached the conclusion that male wild boars begin to disperse at the age of 10 months, reach their maximum dispersal rate at the age of 13 months, and that dispersal ceases at the age of 16 months. At that age, they have dispersed 16.6 km from their natal sites. For females, the corresponding ages were 7, 9 and 11 months, with a dispersal distance of 4.5 km. The results follow the prevalent opinion on natal dispersal in polygynous mammals. Dispersal distances are generally short with a negative exponential probability distribution. Dispersal reaches its maximum rate during the age at which sexual maturity is occurring, and males disperse longer distances than females.