Estimating Wolf Population Size and Dynamics by Field Monitoring and Demographic Models: Implications for Management and Conservation.

We estimated the current size and dynamics of the wolf population in Tuscany and investigated the trends and demographic drivers of population changes. Estimates were obtained by two different approaches: (i) mixed-technique field monitoring (from 2014 to 2016) that found the minimum observed pack number and estimated population size, and (ii) an individual-based model (run by Vortex software v. 10.3.8.0) with demographic inputs derived from a local intensive study area and historic data on population size. Field monitoring showed a minimum population size of 558 wolves (SE = 12.005) in 2016, with a density of 2.74 individuals/100 km2. The population model described an increasing trend with an average annual rate of increase λ = 1.075 (SE = 0.014), an estimated population size of about 882 individuals (SE = 9.397) in 2016, and a density of 4.29 wolves/100 km2. Previously published estimates of wolf population were as low as 56.2% compared to our field monitoring estimation and 34.6% in comparison to our model estimation. We conducted sensitivity tests to analyze the key parameters driving population changes based on juvenile and adult mortality rates, female breeding success, and litter size. Mortality rates played a major role in determining intrinsic growth rate changes, with adult mortality accounting for 62.5% of the total variance explained by the four parameters. Juvenile mortality was responsible for 35.8% of the variance, while female breeding success and litter size had weak or negligible effects. We concluded that reliable estimates of population abundance and a deeper understanding of the role of different demographic parameters in determining population dynamics are crucial to define and carry out appropriate conservation and management strategies to address human-wildlife conflicts.

Multiple aspects of the maternal reproductive investment in a polytocous species: What do mothers really control?

One of the factors facilitating the expansion and proliferation of wild boar Sus scrofa is the plasticity of its reproductive biology. Nevertheless, the real influence of maternal and environmental factors on number and sex of the offspring is still controversial. While the litter size was shown to be related with the maternal condition, the strength of this relation remains to be understood, together with the possible role played by environmental conditions. Analogously, it is unclear whether wild boar females can adjust their offspring sex. We investigated multiple aspects of wild boar maternal investment by means of a 10-year dataset of female reproductive traits and a set of biologically meaningful environmental variables. The maternal condition slightly affected the litter size but not the offspring sex, and environment did not affect the litter size or the offspring sex. Moreover, mothers did not cope with the higher costs entailed by producing sons by placing them in the most advantageous intrauterine position, nor by allocating less resources on daughters. Our set of results showed that the female reproductive investment is quite rigid in comparison with other aspects of wild boar reproductive biology. Wild boar females seem to adopt a typical r-strategy, producing constantly large litters and allocating resources on both sexes regardless of internal and external conditions. Such strategy may be adaptive to cope with environmental unpredictability and an intense human harvest, contributing to explain the extreme success of wild boar within human-dominated landscapes.

It is time to mate: population-level plasticity of wild boar reproductive timing and synchrony in a changing environment.

On a population level, individual plasticity in reproductive phenology can provoke either anticipations or delays in the average reproductive timing in response to environmental changes. However, a rigid reliance on photoperiodism can constraint such plastic responses in populations inhabiting temperate latitudes. The regulation of breeding season length may represent a further tool for populations facing changing environments. Nonetheless, this skill was reported only for equatorial, nonphotoperiodic populations. Our goal was to evaluate whether species living in temperate regions and relying on photoperiodism to trigger their reproduction may also be able to regulate breeding season length. During 10 years, we collected 2,500 female reproductive traits of a mammal model species (wild boar Sus scrofa) and applied a novel analytical approach to reproductive patterns in order to observe population-level variations of reproductive timing and synchrony under different weather and resources availability conditions. Under favorable conditions, breeding seasons were anticipated and population synchrony increased (i.e., shorter breeding seasons). Conversely, poor conditions induced delayed and less synchronous (i.e., longer) breeding seasons. The potential to regulate breeding season length depending on environmental conditions may entail a high resilience of the population reproductive patterns against environmental changes, as highlighted by the fact that almost all mature females were reproductive every year.

Capital-income breeding in wild boar: a comparison between two sexes.

Organisms differ in the strategy adopted to fuel reproduction by using resources either previously acquired and stored in body reserves (capital breeding) or, conversely, acquired during their reproductive activity (income breeding). The choice of one or the other strategy is related to several internal and external factors which are counteractive in wild boar. Based on a large dataset of culled wild boar, we investigated individual body weight variability throughout the period of 1st September-31st January, which included the main part of the mating season, among different sex and age classes to determine their position along the capital-income breeding continuum. Though food resources were abundant during the rut, adult males lost body weight suggesting they adopted a predominantly capital breeding strategy, likely owing to the high intra-sexual competition entailed by the peculiar mating system of the species. On the contrary, subadult males seemed to behave as income breeders, likely enhancing the reproductive flexibility of wild boar populations. During the rut, females stored reserves, thus suggesting that they substantially relied on them to cover future reproductive costs.

Trichinella spiralis a new alien parasite in Italy and the increased risk of infection for domestic and wild swine.

In Europe, Trichinella spiralis, the most dangerous species for humans of the genus Trichinella, has a patchy distribution with important foci in Eastern countries and Spain. This zoonotic pathogen was apparently not circulating among wild and domestic animals of Italy. In 2016, muscle larvae belonging to this nematode species were detected in a red fox (Vulpes vulpes) shot in the Piacenza province (Northern Italy). This parasite may have been introduced into northern Italy from eastern Europe by hunters, by a hunting dog, or by immigrants, who illegally carried infected meat in their personal baggage. In the same year, T. spiralis infected sausages illegally introduced by personal baggage into Italy from Romania, were inadequately disposed of in the garbage of a central Italian town. Even though these two episodes may not be connected in time and space, they represent an increased risk of infection for domestic and wild swine, which are highly susceptible to this pathogen. In these animals, T. spiralis shows a higher larval burden and a longer survival time than other Trichinella species. Since most of the Italian pig production plants are in northern Italy, the circulation of T. spiralis should be strictly monitored in wildlife living in these areas.