Ecology, Conservation and Management of Wild Pigs and Peccaries

Part III: Conservation and Management

340

The fact that the undoubted increase of the populations was

going on simultaneously and almost synchronously in differ-

ent countries of Europe, irrespective of the feature of the hunt-

ing regulations, suggests that similar factors were at play across

the continent, resulting in the expansion of the populations

(Figure 31.2).

A series of factors affecting the growth and density of the

populations has been demonstrated. Associations between the

relative abundances of wild boar and wolves were found (Segura

et al. 2014). Thus, predation could be an important factor affect-

ing wild boar populations, but we believe that it can happen only

in cases with low densities and/or in regions with suboptimal

habitats for wild boar with low recruitment of the species (see

also Kanzaki et al. 1998 and Melis et al. 2006). Predation, natural

mortality, and road mortality usually have a low impact on wild

boar populations (Keuling et  al. 2013). In Poland and Spain,

wolf predation caused only a small decrease in the wild boar

population (Jędrzejewski et al. 2000; Nores et al. 2008).

While predation is usually not presumed to be a limiting fac-

tor on wild boar population densities, the harshness of winter

induces density-independent mortality on wild boar popula-

tions at higher latitudes, as investigated on a large scale by Melis

et  al. (2006). Mean annual temperature was found to have a

positive effect on the density of wild boar populations locally

(Jędrzejewska et al. 1997). Consequently, it is logical to conclude

that climate changes that lead to milder winters will result in

faster population growth of wild boar. Indeed, as shown by Vetter

et al. (2015) through a large-scale and long-term investigation,

climate change drives population growth of wild boar directly

by alleviating the negative effect of cold winters on survival and

reproduction, and indirectly by increasing food availability.

A series of other factors influencing the population growth

and/or the density of wild boar populations were found such as

reforestation, habitat alteration due to human activities, supple-

mentary feeding, heavy crops of oak and beech mast (Okarma

et al. 1995; Jędrzejewski et al. 2000; Melis et al. 2006; Cellina 2008;

Borowik et al. 2013). The latter has only a temporary effect. Very

pronounced increases in wild boar numbers were observed one

year after mast years; these were followed by substantial declines

a year later (Lebedeva 1956 cited in Okarma et al. 1995). All the

other factors listed were present in all the European countries;

moreover, as it seems that all of these factors affect the recruit-

ment of wild boar – with the exception of reforestation – the

result should be an increase in the growth rates of the European

population. However, as shown by Massei et al. (2015), there has

been no change in either the annual growth rate or the five-year

growth rate during the past few decades (Figure 31.3).

We conclude that although many of the factors listed above

can speed up the growth of the population, their effect cannot be

decisive because harvest by hunting is the main mortality factor of

the species. The growing mismatch and increasing gap between

the number of hunters and the number of wild boar harvested – a

fact demonstrated by Massei et al. (2015) – has resulted in an under-

harvest; this fact suggests that the explosion in the population

numbers would have happened – sooner or later – even if the fac-

tors facilitating the recruitment of the population were lacking. It

is quite apparent that recreational hunting per se is currently insuf-

ficient to limit the growth of the wild boar population in Europe.

14 000

Luxembourg

Slovenia

Czech Republic

Italy

Russia Spain

Sweden

Hungary

Serbia

Switzerland

12 000

10 000

8 000

6 000

4 000

2 000

0

0

50 000

100 000

150 000

200 000

250 000

50 000

40 000

30 000

Belgium

Portugal

Poland

France

Germany

Croatia

Austria

Latvia

20 000

10 000

0

100 000

200 000

300 000

Number of harvested wild boar

Number of harvested wild boarNumber of harvested wild boar Number of harvested wild boar

400 000

500 000

600 000

700 000

0

1980 1980

1980 1990 2000 2010

1990 2000 2010

1980 1985 1990 1995 2000 2005 2010

1990 2000 2010

Figure 31.2 Wild boar hunting bags from selected European countries (from Massei et al. 2015). (A black and white version of this figure will appear in some formats.

For the color version, please refer to the plate section.)

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