Ecology, Conservation and Management of Wild Pigs and Peccaries

Chapter 36: Ecological impact of wild boar in natural ecosystems

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research (Appendix 36.1). Negative impacts are associated with
plants and more specifically with seedlings, while the negative
impact on bulbs and birds appears to be especially evident. The
95 per cent confidence ellipse does not contain the origin. The
negative impact on birds (a category much distant from ther
origin) is mediated by nest predation. Carpio et  al. (2014b)
showed a direct impact of wild boar on the red-legged partridge
(Alectoris rufa) because of nest predation, but also suggested
an indirect impact through reduction of invertebrate food
items for this bird. Wildlife management may act as a negative
cofactor increasing nest predation by implementing artificial
feeding of wild boar (Selva et  al. 2014). Roda (2014) showed
that wild boar may reduce the population of several species of
passerine birds. Considering the food habit of wild boar, it is
not surprising to find that bulbous plant species are damaged
by rooting. Sims et al. (2014) recorded short-term impacts on
bluebells (Hyacinthoides non-scripta) in the UK. Interestingly,
Palacio et al. (2013) registered a positive effect of rooting on sev-
eral geophytes, whose storage organs got larger and contained
more nutrients in rooted than in undisturbed areas, even if the
study design did not allow determination of whether rooting is
a causal factor of this variation. Positive impacts are associated
with native wild boar populations, invertebrates, forests, and

seed dispersal, but its 95 per cent ellipse does contain the ori-

gin. Arrington and Koebel (1999) described an increased spe-

cies richness in rooted areas of floodplain vegetation in Florida;

Brunet et  al. (2016) showed a similar effect in deciduous for-

ests in Sweden. Weaker association is found for null impacts

(80 per cent ellipse) weakly associated with water and verte-

brates. Introduced populations are intermediate to negative and

positive impacts.

There are 29 papers which allow a direct estimate of the

impact of wild boar on biodiversity (21 report a negative effect,

three positive, and eight no effect). The impact of wild boar on

biodiversity is displayed in Figure 36.2. One may note that nega-

tive effects are associated with introduced, island, grassland and

to a lesser extent to subtropical, boreal and alpine ecosystems.

Null effects are closely associated with native, tropical, for-

est, temperate and Mediterranean ecosystems, while positive

effects are loosely associated with continental and plain ecosys-

tems, although no ellipse could be computed. Marginally, the

95 per cent ellipse for null effects does not contain the origin

and this impact is associated with native populations, temper-

ate, tropical, and forest. On the contrary, the ellipse for negative

effect is far from the origin and clearly associated with islands,

boreal, Alpine and grasslands.

Figure 36.1 Correspondence

analysis. We report the observed

impact (Effect) of wild boar relative to

the column GAx (variable Argument in

Appendix 36.1) in relation to the origin

of populations (Origin) in a sample

of 114 peer-reviewed publications.

Confidence ellipses refer to null (black

dotted line, 80 per cent), negative

(black continuous line, 95 per cent),

and positive (grey broken line, 95 per

cent) effects.

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