The use of faeces counts to estimate relative densities of wild boar in a Mediterranean area

Abstract

The monitoring of population trends of wild ungulates is important to evaluate their population dynamics and to develop sound conservation/management plans. The wild boar Sus scrofa can impose heavy impacts on ecosytems and human activities, as well as be responsible for disease transmission. Estimating abundance of wild boars is a challenging issue, because of some peculiar biological and ecological traits of this ungulate. Indices of relative abundance could be used to evaluate its population trends. In a Mediterranean area we used faeces counts, through a two-stage stratified sampling, to estimate relative densities of wild boars, between 2007 and 2014. Faeces density estimates increased not significantly between 2007 (151.5 faeces/100 ha) and 2010 (203.8 faeces/100 ha) and decreased significantly from 2010 to 2014 (95.5 faeces/100 ha). The decrease in faeces density estimates was consistent with the increased harvest effort (number of harvest days), performed from 2010 to 2013 to limit impact on ecosystems and reduce damages to crops. The variation of faeces density estimates was also consistent with that of harvest indices (total harvest to harvest effort), with significantly positive values of Pearson and rank correlation coefficients. Results suggest that faeces density estimates achieved with the adopted sampling strategies can be effectively used as indices of relative abundance

Camera traps and activity signs to estimate wild boar density and derive abundance indices

“…Several methods have been developed and applied to determine relative densities or population indices of wild boar. These methods include hunting statistics, pellet counts and activity signs, capture–mark–recapture based on faecal DNA or on marked animals, and distance sampling . The advantages, disadvantages and reliability of each of these methods have been widely discussed .…”

Strength of correlation between wildlife collision data and hunting bags varies among ungulate species and with management scale

“…Following the need of crossborder management (Linnell et al 2020), recent initiatives develop abundance models using hunting statistics at the European scale (ENETWILD-consortium et al 2019). Hunting bags, however, may not be reliable if the hunting effort of a species is not related to its density and when this relationship changes over time (Imperio et al 2010;Willebrand et al 2011;Ferretti et al 2016;Eriksen et al 2018). This may be particularly true for expanding species that occur at low densities or species that are not (yet) part of the mainstream monitoring and ungulate management.…”

Guidance on estimation of wild boar population abundance and density: methods, challenges, possibilities

“…Some of them are used for wild boar (Massei et al 1998, Ferretti et al 2014, Plhal et al 2014, Ferretti et al 2016). There are lots of methods based on counting the number of pellets or their frequency along transects or in plots.…”

“…There are lots of methods based on counting the number of pellets or their frequency along transects or in plots. Some of them are used for wild boar (Massei et al 1998, Ferretti et al 2014, Plhal et al 2014, Ferretti et al 2016 The present document has been produced and adopted by the bodies identified above as author(s). This task has been carried out exclusively by the author(s) in the context of a contract between the European Food Safety Authority and the author(s), awarded following a tender procedure.…”