Increase in crop damage caused by wild boar (Sus scrofa L.): the “refuge effect”

Abstract

The occurrence of crop damage by wild boars raised dramatically in the last decades, implying an increase in social conflicts, expenditures for compensation and a risk to natural ecosystems. Many researchers have explained this phenomenon by considering wild boar biology, behaviour and abundance. Little or no attention has been devoted to wildlife management and the agricultural mosaic. We hypothesised that the agricultural structure of the landscape and wildlife management planning, including hunting, can play a relevant role in causing crop damage. We studied a Mediterranean area in central Italy that is characterised by a patchy agriculture, dividing the surface into hexagons. A large number of terrain parameters were calculated at the large (hexagons) and local (buffer) scale, including the topography, land use and agricultural management. We also considered wildlife variables such as the number of wild boar shot down, hunting management and the legal status of the wild boar. The terrain and management data for each hexagon were submitted to a generalised binomial stepwise multiple logistic regression. The resultant model demonstrated an accuracy of 0.76, a misclassification rate of 0.24 and an odds ratio of 10.41. The most important variables selected by the regression were the woods in the area where hunting was banned (P< 0.001), a 1-km buffer of intensively cultivated farmland close to the woods where hunting was banned (P<0.001), a 1-km buffer of intensively cultivated farmland along the river (P<0.05), the forest edge (P<0.001), and the mean number of wild boar that were shot (P<0.05). In this study, we proved that an important factor in explaining crop damage is the "refuge effect" (a buffer close to the wooded areas where hunting was banned) and the 1-km buffer along possible dispersion routes.

Secrets of Success in a Landscape of Fear: Urban Wild Boar Adjust Risk Perception and Tolerate Disturbance

“…In contrast to rural wild boar in our study area, urban wild boar do not use agricultural areas, even though agriculture is available in close proximity to the used habitats (Supplementary Figure 1, Figure 2). Agricultural areas usually provide attractive foraging opportunities for wild boar (Herrero et al, 2006;Amici et al, 2012;Frackowiak et al, 2013;Ficetola et al, 2014). But wild boar are known to be opportunistic omnivores whose diet, in any particular instance, is largely determined by the relative availability of different food types (Schley and Roper, 2003).…”

“…Wild boar (Sus scrofa), a social mammal with a growing population throughout Europe (Massei et al, 2015;Keuling et al, 2016), is increasingly present in urban areas (Dinter, 1991;Cahill et al, 2003Cahill et al, , 2012Jansen et al, 2007;Podgorski et al, 2013). Wild boar frequently interfere with people, as they annoy garden owners (e.g., by rooting), can destroy agricultural crops (Amici et al, 2012;Ficetola et al, 2014;Jarolimek et al, 2014;Laznik and Trdan, 2014) and are potential transmitters of zoonotic diseases or diseases relevant to livestock (Fernández et al, 2006;Jansen et al, 2007;Chiari et al, 2015). Therefore, they are a useful model to study the ability of urban wildlife to perceive and respond to spatial variation in the landscape of fear.…”

Seasonal variations of wild boar Sus scrofa distribution in agricultural landscapes: a species distribution modelling approach

“…The important density in rivers and streams within the study area probably explain that access to water is not a limiting factor in Wallonia. Though the region is relatively flat, we expected that topographic variables, particularly the slope present along the river channel could have been expected to favour wild boar presence, owing to their relative quietness (Amici et al 2012). We attribute the relative weak importance of these variables to the chosen resolution that does not reflect the potential use of these areas, rich in cover and hardly accessible for hunters, as highly suitable for the species.…”

“…It has been demonstrated that the absence or banning areas of hunting create a refuge effect favouring the risk of damages to crops (Amici et al 2012). Therefore, an effort on the management and control strategies of wild boar in these landscapes should be promoted.…”

“…Use of agricultural crops by wild boar is thus probably not a recent fact but is rather concomitant to the development of agriculture by human, explaining why wild boar has now become so common in these agro-forested landscapes that cover 40 % of Europe (Estreguil et al 2012). In these areas, use of field crops by wild boar generally induces damages that can result in important economic consequences and cause conflicting issues between hunters and farmers (Amici et al 2012;Barrios-Garcia and Ballari 2012;Herrero et al 2006;Schley et al 2008). Shifting to agricultural environments during the growing season not only offers energetic advantages to wild boar (Rosell et al 2012) but also provides a quiet environment, preserved from the numerous human activities observed in forests (Colson et al 2010).…”