Can wild boar be surveyed using GPS?

The Global Positioning System (GPS) is an important new technology for spatial behaviour studies of terrestrial vertebrates. Although VHF telemetry has been substantially used, our study is the first report, to our knowledge, on GPS technology used to track free-ranging wild boars. Although the need for collars larger than those used for VHF tracking, the crowded vegetation of habitat and the particular features of social group behaviour of wild boars led to some technical difficulties, three adult sows were successfully fitted with two GPS collars and one dummy GPS. The collars remained on the wild boars for over 283 days without causing any injury to the animals. Forty-one daily cycles (24 hours), as well as daily locations over 142 days, could be recorded for a single animal. Detection efficiency and fixes were better during the night than during the day. In the light of these results, the GPS technique appears to be an efficient tool to study wild boar movements. Progress in the survey of animal movements at a fine scale is of prime interest for animal management programs in order to obtain and maintain a sustainable level of animal population regarding damage problems

Life-history patterns in female wild boars (Sus scrofa): mother-daughter post-weaning associations.

International audienc

Landscape effects on wild boar home range size under contrasting harvest regimes in a human-dominated agro-ecosystem

Agro-ecosystems can experience elevated human-wildlife conflicts, especially crop damage. While game management often aims at reducing number to mitigate conflicts, there is on-going debate about the role of hunting disturbance in promoting game to range over wider areas, thereby potentially exacerbating conflicts. Herein, we hypothesised that landscape configuration and non-lethal disturbance modulate the response to harvest disturbance. We used an information theoretic approach to test the effects of landscape and anthropogenic variables on wild boar ranging patterns across contrasting harvest regimes. We used 164 seasonal home ranges from 95 wild boar (Sus scrofa) radio-tracked over 6 years in the Geneva Basin where two main harvest regimes coexist (day hunt and night cull). Mean seasonal 95% kernel home range size was 4.01 ± 0.20 km2 (SE) and 50% core range size 0.79 ± 0.04 km2, among the smallest recorded in Europe. Range sizes were larger in the day hunt area than in the night cull area, with no seasonal effect. However, when accounting for landscape variables, we demonstrate that these patterns were likely confounded by the underlying landscape configuration, and that landscape variables remain the primary drivers of wild boar ranging patterns in this human-dominated agro-ecosystem with range size best explained by a model including landscape variables only. Therefore, we recommend accounting for landscape configuration and sources of non-lethal disturbance in the design of harvest strategies when the aim is to limit wide-ranging behaviour of wild boar in order to mitigate conflicts

Consistently high multiple paternity rates in five wild boar populations despite varying hunting pressures

International audienc

Responding to spatial and temporal variations in predation risk: space use of a game species in a changing landsape of fear

Predators generate a “landscape of fear” within which prey can minimize the risk of predation by selecting low-risk areas. Depending on the spatial structure of this “landscape”, i.e., whether it is coarse- or fine-grained, prey may respond to increased risk by shifting their home ranges or by fine-scale redistributions within these ranges, respectively. We studied how wild boar (Sus scrofa L., 1758) responded to temporal changes in risk in hunted areas (risky habitat) surrounding a nature reserve (refuge habitat). Animals with home ranges “in contact” with the reserve during the low-risk season were the only ones to shift toward the refuge when the risk increased. These shifts occurred at two temporal scales in response to the increased risk during the daytime and during the hunting season. Whereas animals not influenced by the reserve found food and shelter in forest during the hunting season, shifts to the refuge area were detrimental to the rather scarce forest areas in the reserve. This confirms that spatiotemporal changes in risk are major drivers of animal distribution when predation strongly limits their fitness. Their response is, however, scale-dependent and reflects at the individual level the perceived structure of their “landscape of fear”

Grow fast at no cost: no evidence for a mortality cost for fast early-life growth in a hunted wild boar population

International audienceAbstract From current theories on life-history evolution, fast early-life growth to reach early reproduction in heavily hunted populations should be favored despite the possible occurrence of mortality costs later on. However, fast growth may also be associated with better individual quality and thereby lower mortality, obscuring a clear trade-off between early-life growth and survival. Moreover, fast early-life growth can be associated with sex-specific mortality costs related to resource acquisition and allocation throughout an individual’s lifetime. In this study, we explore how individual growth early in life affects age-specific mortality of both sexes in a heavily hunted population. Using longitudinal data from an intensively hunted population of wild boar ( Sus scrofa ), and capture–mark–recapture–recovery models, we first estimated age-specific overall mortality and expressed it as a function of early-life growth rate. Overall mortality models showed that faster-growing males experienced lower mortality at all ages. Female overall mortality was not strongly related to early-life growth rate. We then split overall mortality into its two components (i.e., non-hunting mortality vs. hunting mortality) to explore the relationship between growth early in life and mortality from each cause. Faster-growing males experienced lower non-hunting mortality as subadults and lower hunting mortality marginal on age. Females of all age classes did not display a strong association between their early-life growth rate and either mortality type. Our study does not provide evidence for a clear trade-off between early-life growth and mortality

Many lifetime growth trajectories for a single mammal

International audienceDespite their importance in shaping life history tactics and population dynamics, individual growth trajectories have only been rarely explored in the wild because their analysis requires multiple measurements of individuals throughout their lifetime and some knowledge of age, a key timer of body growth. The availability of long-term longitudinal studies of two wild boar populations subjected to contrasting environments (rich vs. poor) provided an opportunity to analyze individual growth trajectories. We quantified wild boar growth trajectories at both the population and the individual levels using standard growth models (i.e., Gompertz, logistic, and monomolecular models) that encompass the expected range of growth shapes in determinate growers. Wild boar is a rather altricial species, with a polygynous mating system and is strongly sexually dimorphic in size. According to current theories of life history evolution, we thus expect wild boar to display a sex-specific Gompertz type growth trajectory and lower sexual size dimorphism in the poorer environment. While wild boar displayed the expected Gompertz type trajectory in the rich site at the population level, we found some evidence for potential differences in growth shapes between populations and individuals. Asymptotic body mass, growth rate and timing of maximum growth rate differed as well, which indicates a high flexibility of growth in wild boar. We also found a cohort effect on asymptotic body mass, which suggests that environmental conditions early in life shape body mass at adulthood in this species. Our findings demonstrate that body growth trajectories in wild boar are highly diverse in relation to differences of environmental context, sex and year of birth. Whether the intermediate ranking of wild boar along the precocial–altricial continuum of development at birth may explain the ability of this species to exhibit this high diversity of growth patterns remains to be investigated

How do conditions at birth influence early‐life growth rates in wild boar?

International audienc

How do conditions at birth influence early‐life growth rates in wild boar?

Weather conditions and population density individuals experience at birth influence their life-history traits and thereby population dynamics. Early-life individual growth is a key fitness-related trait; however, how it is affected by such conditions at birth remains to be explored. Taking advantage of long-term monitoring of three wild boar (Sus scrofa) populations living in contrasting ecological contexts, we assess how weather conditions (temperature and precipitation) and the number of removed individuals at birth influence early-life growth rates. We found that the number of individuals removed before the early-growth period had a positive effect on early-life growth rate across sites. This might be interpreted as a density-dependent response involving an increase in food availability per capita that favors faster growth. Alternatively, if the number of removed individuals increases with population density, this result might be attributable to decreasing litter sizes at high density, leading mothers to allocate more resources to individual offspring, which favors higher juvenile growth rates. Early-life growth rates also increased with springtime temperature and decreasing precipitation. Thus, early-life growth is expected to increase in response to warmer and drier springs, which should become more frequent in the future under current climate change. We found that conditions at birth explained very little among-year variation in early-life growth rates (i.e., weak cohort effects) and that within-year variation in early-life growth rates was more likely caused by strong individual differences