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Wild boar populations up, numbers of hunters down? A review of trends and implications for Europe


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Across Europe wild boar numbers increased in the 1960s-1970s but stabilised in the1980s; recent evidence suggests that numbers and impact of wild boar grew steadily since the 1980s. As hunting is the main cause of mortality for this species, we reviewed wild boar hunting bags and hunter population trends in 18 European countries from 1982 to 2012. Hunting statistics and numbers of hunters were used as indicators of animal numbers and hunting pressure. The results confirmed that wild boar increased consistently throughout Europe whilst the number of hunters remained relatively stable or declined in most countries. We conclude that recreational hunting is insufficient to limit wild boar population growth and that the relative impact of hunting on wild boar mortality had decreased. Other factors, such as mild winters, reforestation, intensification of crop production, supplementary feeding and compensatory population responses of wild boar to hunting pressure might also explain population growth. As populations continue to grow, more human-wild boar conflicts are expected unless this trend is reversed. New interdisciplinary approaches are urgently required to mitigate human-wild boar conflicts that are otherwise destined to grow further.
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Received: 7 July 2014 Revised: 9 December 2014 Accepted article published: 16 December 2014 Published online in Wiley Online Library:
( DOI 10.1002/ps.3965
Wild boar populations up, numbers of hunters
down? A review of trends and implications for
Giovanna Massei,a* Jonas Kindberg,bAlain Licoppe,cDragan Gaˇ
rí Kamler,fEric Baubet,gUlf Hohmann,hAndrea Monaco,iJanis
Ozoli ¸nš,jSandra Cellina,kTomasz Podgórski,lCarlos Fonseca,mNickolay
Markov,nBoštjan Pokorny,oCarme Rosellpand András Náhlikq
Across Europe, wild boar numbers increased in the 1960s–1970s but stabilised in the 1980s; recent evidence suggests that
the numbers and impact of wild boar has grown steadily since the 1980s. As hunting is the main cause of mortality for this
species, we reviewed wild boar hunting bags and hunter populationtrends in 18 European countries from 1982 to 2012. Hunting
statistics and numbers of hunters were used as indicators of animal numbers and hunting pressure. The results confirmed that
wild boar increased consistently throughout Europe, while the number of hunters remained relatively stable or declined in
most countries. We conclude that recreational hunting is insufficient to limit wild boar population growth and that the relative
impact of hunting on wild boar mortality had decreased. Other factors, such as mild winters, reforestation, intensification of
crop production, supplementary feeding and compensatory population responses of wild boar to hunting pressure might also
explain population growth. As populations continue to grow, more human– wild boar conflicts are expected unless this trend is
reversed. New interdisciplinary approaches are urgently required to mitigate human–wild boar conflicts, which are otherwise
destined to grow further.
© 2014 Crown copyright. Pest Management Science © 2014 Society of Chemical Industry
Keywords: growth rate; hunting pressure; mortality; population control; Sus scrofa
Wild boar (Sus scrofa) are among the most widely distributed large
mammals in the world. The natural range of the species extends
from Western Europe and the Mediterranean basin to Eastern Rus-
sia, Japan and South-east Asia.1In Europe, wild boar has recently
recolonised Sweden, Finlandand Estonia.2,3I n the UnitedK ingdom
and in Denmark the species has become re-established following
farm escapes.46The presence of wild boar in Sweden meant the
species was expected to recolonise Norway,7and in 2013 the first
wild boar was shot 40 km from Oslo (
wild-boars-generate-worries-). Wild boar occur throughout a wide
spectrum of habitat types, ranging from semi-arid environments
to marshes, forests and alpine grasslands.1In Europe, increas-
ing numbers of wild boar sightings were reported in urban and
Correspondence to: Giovanna Massei, National Wildlife Management Cen-
tre, Animal and Plant Health Agency, Sand Hutton, York YO26 5LE, UK.
This article is published with the permission of the Controller of
HMSO and the Queen’s Printer for Scotland.
aNational Wildlife Management Centre, Animal and Plant Health Agency, York,
bDepartment of Wildlife, Fish and Environmental Studies, Swedish University of
Agricultural Sciences, Umeå, Sweden
cSPW-DEMNA-DNE, Laboratoire de la Faune Sauvage et de Cynégétique, Gem-
bloux, Belgium
dFaculty of Forestry,University of Belgrade, Belgrade, Serbia
eUniversity of Zagreb, Zagreb, Croatia
fMendel University, Brno, Czech Republic
gOffice National de la Chasse et de la Faune Sauvage, Birieux, France
hResearch Institute for Forest Ecology and Forestry Rhineland-Palatinate, Tripp-
stadt, Germany
iRegional Parks Agency – Lazio Region, Rome, Italy
jState Forest Research Institute ‘Silava’, Salaspils, Latvia
kAdministration de la Nature et des Forêts, Luxembourg, Luxembourg
lMammal Research Institute, Polish Academy of Sciences, Białowiė
za, Poland
mDepartment of Biology and CESAM, University of Aveiro, Aveiro, Portugal
nInstitute of Plant and Animal Ecology, Russian Academy of Sciences,Russia
oERICo Velenje and Environmental Protection College, Velenje, Slovenia
pMINUARTIA and FacultatBiologia Animal, Universitat de Barcelona, Barcelona,
qUniversity of West Hungary, Sopron, Hungary
Pest Manag Sci (2015) © 2014 Crown copyright.
Pest Management Science © 2014 Society of Chemical Industry G Massei et al.
suburban areas, for instance in Berlin, Barcelona, Rome, Vilnius and
Budapest (e.g. Náhlik A, unpublished; Monaco A, unpublished).8,9
In Belgrade, the number of wild boar killed in the suburban
area rose from 97 in 2004– 2005 to 374 in 2013–2014 (Ga ˇ
Among ungulates, wild boar are characterised by the highest
reproductive rate, with annual population growth rates that may
exceed 2.0.1012 The main causes of natural mortality for this
species are starvation due to extreme weather conditions,13,14
diseases15 and predation by wolf (Canis lupus).16,17 However, hunt-
ing, and to a lesser extent road traffic accidents, make the greatest
contribution to wild boar mortality.12,1722
The impact of wild boar on conservation and economic interests
includes spread of diseases to livestock and people, vehicle colli-
sions, and damage to crops and amenities, as well as reduction in
plant and animal abundance and richness.2328 As wild boar num-
bers appear to increase in many European countries, their impact
is also increasing;3,12,19,20,2931 and mitigating human wild boar
conflicts will present a significant challenge.
A review of wild boar population trends carried out in the
1980s32 showed that the simultaneous increases in wild boar
numbers in different European countries between the 1960s
and the 1980s followed a logistic curve, with a sharp increase
in growth rate between 1965 and 1975 and a plateau in the
following decade, when numbers appeared to stabilise. These
trends in wild boar numbers were attributed to a combination
of species-specific biological factors (e.g. very high reproduc-
tive output and dispersal potential), as well as to other changes,
which included lack of large predators, reforestation, deliberate
releases for sport hunting, supplementary feeding, habitat alter-
ation due to human activities and mild winters which improved
survival.2,29,33 38
Three decades later, many of these factors are still operat-
ing, and current trends of landscape development indicate that
human–ungulate conflicts, and in particular human wild boar
conflicts, are increasing.3949 In parallel, the apparent decline in
hunter numbers observed in several western countries42 suggests
that the relative importance of hunting, as the main cause of
wild boar mortality, will decrease. Analysing wild boar population
trends in recent decades and understanding the factors affecting
these trends are crucial to managing the presence of this species
and its impact in the near future.
The aims of this paper were: (1) to describe wild boar population
trends in European countries over the last three decades; (2) to
illustrate hunter population trends in the same timeframe; (3) to
discuss the implications of wild boar and hunter population trends
for mitigation of human– wild boar conflicts.
Wild boar population numbers were derived from hunting bags
provided by local and national hunters associations or by focal
points (academic and research institutions, local authorities, etc.)
(see Appendix 1) from 18 selected European countries. Although
some countries have maintained hunting statistics since 1930,
most started collecting data in the mid-1970s. As trends for some
European wild boar populations had been analysed up to the early
1980s,32 this review focused on the last three decades, from 1982
to 2012 or 2013. For ease of presentation, countries were divided
into four arbitrary groups, based on the numbers of wild boar
harvested in the latest year as follows: <10 000, 10 000 –50 000,
50 001 –200 000 and >200 000.
For most countries, data were available at the national scale. For
some countries, data were collected only for part of the national
territory or extrapolated to the whole country as follows:
Italy A complete dataset was available for five out of the 21
regions. Based on hunting bags in other regions in recent years,
these five regions represent 73% of the total number of wild boar
harvested.43 The data reported in Fig. 1 are extrapolated to the
whole country (100%) by adding 27% of the wild boar annually
harvested in the five regions to the actual numbers harvested
in these five regions. However, the National Ungulate Databank
suggests that these statistics might be widely underestimated.43
Thus, we can hypothesise that the total number of wild boar culled
in Italy in recent years could be as high as 300 000 animals instead
of the ca 200 000 reported here (Monaco A, unpublished).
Belgium Wild boar are present throughout the country, but data
are reported only for the southern part of the country (Wallonia),
as wild boar colonised Flanders (North Belgium) only a few years
ago (data from 2006). Data from Wallonia in 2012 represented 98%
of the total hunting bag.
Russia The official statistics reported here are likely to underesti-
mate the true numbers of wild boar harvested, although the bias
was impossible to quantify.
Germany Owing to reunification in 1989/90, data on number of
hunters and wild boar harvested were likely to be accurate after
1989/90 (Hohmann U, private communication).
Croatia, Serbia and Slovenia The splitting of former Yugoslavia
into several countries did not influence the hunting statistics of
these countries, as population management and national hunting
statistics have been separated for each country since the 1950s.
However, data on the number of wild boar harvested in Serbia
and Croatia are highly underestimated (by >30%), while data from
Slovenia are very accurate (Pokorny B, unpublished).
Although the accuracy of hunting bags was acknowledged to
vary significantly between countries, we assumed that potential
biases would be relatively constant within each country over time,
and that these data would provide the best available indicators of
wild boar population trends.
To quantify wild boar population trends during the last three
decades, an index of annual population growth rate was esti-
mated for each country by dividing the number of wild boar har-
vested in one year by the number harvested the previous year.
Values were averaged across all the countries and reported for
the 1983–2012 period. The quinquennial changes in number of
wild boar were also considered because 5 year timeframes are
often used when planning population control strategies.42 The
quinquennial changes in number of wild boar harvested were
expressed by dividing the average number of animals harvested
in a 5 year period by the average number of wild boar harvested in
the previous 5 years. Values were averaged across all the countries
and reported for the 1986–2012 period.
Data on the number of hunters or on the number of hunting
licences (hereafter referred to as ‘number of hunters’) were derived
from the sources reported in Appendix 1 for 17 countries. While
in most instances it was not possible to determine the actual
proportion of hunters engaged in wild boar hunting, out of the
total population of hunters, the data were used as indicators of
trends at the national level. For ease of presentation, data on the
number of hunters were divided into four arbitrary groups, based
on latest numbers recorded, as follows: <30 000, 30 000 –100 000,
100 001 –500 000 and >500,000.
For each country, a linear regression was fitted between years
and the number of hunters; to account for autocorrelation in the © 2014 Crown copyright. Pest Manag Sci (2015)
Pest Management Science © 2014 Society of Chemical Industry
wild boar and hunter trends in Europe
Figure 1. Wild boar hunting bags from selected European countries.
data, an autoregressive model [AR(1)] was fitted to the error term.
To analyse overall trends in number of hunters versus number
of wild boar harvested in Europe, a linear regression was fitted
between these variables for the period between 1991 and 2011,
using the 16 countries for which these data were available. To
account for autocorrelation in the data, an autoregressive model
[AR(1)] was fitted to the error term. All analyses were carried out in
GenStat 17.1.
To illustrate overall trends in number of hunters and number
of wild boar harvested in Europe, the total number of wild boar
harvested and the total number of hunters across all countries
were plotted against time for the period between 1991 and 2011
when data were available for all countries.
3.1 Wild boar population trends
The most recent wild boar hunting bags, in 2012 and 2013, indicate
that some countries such as Spain, Poland, France, Italy and Ger-
many harvest between 200 000 and 640 000 wild boar per year. The
trends in hunting bags are consistent with population growth in
all countries throughout the last three decades, although growth
rates differed among countries (Fig. 1). In many countries the num-
ber of wild boar harvested often appeared to stabilise for a few
years before further increase was observed. The mean annual pop-
ulation growth rate index (Fig.2) averaged across all countries
showed a fairly regular pattern, with peaks followed by troughs
at 3–4 year intervals. In four out of the 30 years considered for
the analysis, the mean wild boar population growth index across
Europe was lower than 1 (with 1 =stable population), while in
all other years the growth rate index varied between 1.00 and
1.46. The quinquennial population growth rate index mirrored the
yearly regular pattern and varied between 1.40 and 1.73.
1982 1987 1992 1997 2002 2007 2012
Mean (SE) growth rate
Annual growth rate
Five-year growth rate
Figure 2. Mean (SE) estimated growth rate of wild boar populations in
Europe, derived from hunting bag statistics calculated for each country
and averaged across 18 countries. Annual growth rate=number of wild
boar harvested per year divided by the number of animals harvested the
previous year.Five-year growth rate =mean number of wild boar harvested
in 5 years divided by the number of animals harvested the previous 5 years.
3.2 Trends in numbers of hunters
The trends in number of hunters suggest that, in 12 of the 17
countries examined, hunter numbers either declined (n=8 coun-
tries) or remained stable (n=4 countries) (Fig. 3). For, Luxembourg,
Serbia, France, Slovenia, Portugal, Sweden, Italy and Spain, we
found a negative correlation between year and number of hunters
(P<0.05 for all countries). Hunter numbers remained stable in
Montenegro, Croatia, the Czech Republic and Russia, with the
regression slope not significantly different from zero (P>0.05 for
all countries). In the remaining five countries, Belgium, Poland,
Austria, Hungary and Germany, we found a positive correlation
between year and number of hunters (P<0.05 for all countries).
In Belgium, Poland, Austria, Hungary and Germany the numbers
of hunters in 2012 were respectively 1.3, 1.2, 1.1, 1.5 and 1.2 times
Pest Manag Sci (2015) © 2014 Crown copyright.
Pest Management Science © 2014 Society of Chemical Industry G Massei et al.
Figure 3. Trends in the number of hunters in selected European countries. Numbersrefer either to hunters or to hunting licences.
higher than those recorded in 1990. In the same period, the num-
bers of wild boar harvested in Belgium, Poland, Austria, Hungary
and Germany in 2012 were respectively 4.4, 1.9, 3.8, 3.4 and 1.3
times higher than numbers harvested in 1990.
For most countries, it was impossible to establish whether the
actual number of wild boar hunters followed the same pattern as
the total number of hunters. For instance, in Sweden, while the
total number of hunters decreased owing to a decline in moose
population, the relative number of wild boar hunters increased
(Kindberg J, unpublished). In other countries, such as Italy, about
37–42% of the hunters in Tuscany (one of the five regions from
which the national data were extrapolated, accounting for 36.8%
of the total harvest in Italy) are wild boar hunters.43,44 In the same
region, while the number of hunters declined from 47 000 in 1999
to 41 000 in 2011, the proportion of hunters over 60 years of age
increased in the same period from 34% in 1998 to 55% in 2012. This
indicates an ageing population of hunters that are not replaced by
equivalent numbers of newcomers. Similar trends have occured
in other European countries: in Slovenia the current (2014) age
of hunters is 55.6 years old and has been increasing annually by
ca 0.3–0.4 years for the last two decades;45 in France the average
age of hunters was 45 years old in 1983– 1984 and 50 years old in
1998–1999 (Baubet E, unpublished).
The overall trends in total number of hunters and in number of
wild boar harvested in Europe (Fig.4) showed that since the early
1990s the number of hunters has decreased by about 18%, while in
the same period the number of wild boar harvested has increased
by about 150%.
There was a strong negative correlation (R2=0.873, F1,19 =131.3,
P<0.0001) between the total number of hunters and the number
1990 1995 2000 2005 2010
Number of hunters and wild
Total number of hunters
Total number of wild boar harvested
Figure 4. Total number of hunters (in millions) and wild boar harvested
(in millions) in selected European countries between 1991 and 2011, when
data for both variables were available for the following 16 countries:
Luxembourg, Serbia, Slovenia, Belgium, Croatia, Portugal, Austria, Russia,
Sweden, the Czech Republic, Hungary, Italy, Poland, France, Spain and
of wild boar harvested in 16 European countries between 1991 and
2011 (Fig. 5).
The review showed the continued growth of wild boar numbers
throughout Europe between 1982 and 2013. In 2012, a minimum
of 2.2 million wild boar were harvested across the 18 countries,
against ca 864 000 harvested in 1992 (when for the first time data
became available for all 18 countries). If the remaining countries
that were not included in this analysis were added, the total
number of wild boar annually harvested in Europe would be in © 2014 Crown copyright. Pest Manag Sci (2015)
Pest Management Science © 2014 Society of Chemical Industry
wild boar and hunter trends in Europe
7.2 7.4 7.6 7.8 8.0 8.2 8.4 8.6 8.8 9.0 9.2
Number of wild boar harvested
Number of hunters
Figure 5. Relationship between the total number of hunters (in millions)
and wild boar harvested (in millions) in selected European countries
between 1991 and 2011. The shade of the symbol indicates the year,
progressing from early years (in white) to recent years (in black).
excess of 3 million. Although numbers are expected eventually
to stabilise, the average growth rate index, expressed as annual
or quinquennial rate, has consistently exceeded 1 over the past
three decades, with the exception of four years. Over the same
period, the number of hunters has been comparatively stable or
even declined in most European countries.
As it was impossible to differentiate between hunting effort
(expressed, for instance, as the number of wild boar hunters,
or guns, or hunter-days, or distance covered by hunters46)and
hunting pressure, defined as the effect of hunting on wild boar
population dynamics,18,47,48 the number of hunters was used here
as a generic indicator of the potential impact of hunting on wild
boar numbers.
Assuming that the hunting bag statistics reflect the actual num-
ber of animals present, and that the number of hunters is a rea-
sonable indicator for mortality due to hunting, these findings have
several implications:
1. There is a mismatch between the consistent growth in number
of harvested wild boar across Europe and the numbers of
hunters, which in most countries are stable or declining. This
suggests that hunters may have increased their effort over time
and become more proficient, or that wild boar numbers have
grown. This latter hypothesis is supported by the increase in the
number of vehicle collisions and crop damage involving wild
2. For European wild boar populations, the relative mortality due
to hunting has declined over the past three decades, i.e. the
proportion of wild boar removed by hunters in each country
has been lower in recent years than in the 1980s or in the 1990s.
This means that recreational hunting per se is currently not
sufficient to limit wild boar population growth.
3. There is no indication that the growth rate index of wild
boar populations has decreased in recent years, as would be
expected if populations stabilised. If the main cause of wild boar
mortality, namely hunting, is decreasing or remaining stable,
and the growth rate index remains >1(with1=no growth,
<1=decline, >1=growth), then wild boar populations will
continue to increase and more human– wild boar conflicts will
be expected.
The limitations of data based on hunting bags or on number
of hunters have been widely acknowledged,39,49 and the accuracy
of reports of wild boar harvested is difficult to assess. In some
countries the number of wild boar harvested is linked to hunting
quotas imposed by local authorities; in these instances, hunters
may under- or overreport the number of animals harvested to
meet these quotas.39
Biases in actual numbers harvested may also be due to poaching
or illegal hunting, which was not accounted for by official statistics,
changes in hunting seasons across the years and differences in
equipment and hunting practices in different countries (including
the use of more efficient guns, spotlight or infrared binoculars or
scopes, and off-road vehicles). In addition, some countries have
poor records and/or lack centralised data collation, particularly at
the national scale.
Although some of these factors may affect the total number of
wild boar harvested, as well as the slope of the trend between
some years, the generally consistent pattern of growth through-
out Europe suggests that wild boar numbers have significantly
increased since 1982. The fact that these trends have been par-
alleled by a simultaneous growth in number of vehicle collisions
and wild boar agricultural damage further supports the hypoth-
esis that the number of animals has grown. For instance, in Swe-
den the number of wild boar–vehicle collisions rose from about
50 per year in the early 2000 to ca 1000 in 2005 and over 4000
in 201230 ( In the Netherlands this number rose
from 142 in 1995 to 320 in 2003,50 and in Switzerland, in the same
period, the number increased from 212 to 412.51 In Germany, out
of the 227 000 traffic accidents with deer and wild boar in 2005,
13 700 involved wild boar.43 In Catalonia (north-eastern Spain)
the number of accidents involving animals increased by 41.6%
between 2007 and 2011, with wild boar responsible for 85% of the
accidents.52 In terms of impact on crops, compensation for crop
damage caused by wild boar in France rose from ca €2.5 million
in 1973 to €21 million in 2005 and €32.5 million in 2008.53,54 In
Luxembourg, compensation for crop damage caused by wild boar
increased from ca €100 000 in 1971 to €900 000 in 2004,55 and in
Slovenia from €292 000 in 2005 to €575000 in 2013.56
The number of hunters across Europe appears to have been sta-
ble or even declining over the past three decades, and recruitment
to hunter populations is low. These data reflect those reported for
large game hunters in other countries. Declining trends in number
of big game hunters have been recorded in the United States,
Canada and Japan for a number of years, in parallel with increased
numbers of ungulates.42,57 The growing mismatch and increasing
gap between the number of hunters and the number of wild boar
harvested means that the relative impact of hunting on wild boar
population dynamics has probably decreased. If this is correct,
trends in numbers of wild boar culled may underestimate the
true growth of boar populations. Although wild boar mortality
due to road traffic accidents has also increased, this is still small
compared with hunting-induced mortality. For instance, between
2004 and 2010, hunting was the cause of death for ca 38% of the
1613 tagged wild boar in Wallonia, while road traffic accidents
accounted for less than 1% of the recorded deaths.22 In Sweden,
94% of wild boar mortality is caused by hunting, 4% is due to
traffic accidents and 2% is ascribed to natural mortality.7These
figures are even more extreme in Slovenia, where hunting repre-
sents 97–98% of wild boar mortality, road mortality accounts for
1–1.5% and natural mortality for <1%.45
Other factors frequently quoted to explain the increase in wild
boar numbers in Europe are the scarcity of large predators, refor-
estation, supplementary feeding and mild winters, which have
improved survival. The wolf is the only large predator that has
an impact on wild boar mortality, and in the last 30 years the
populations of wolves across Europe have increased or remained
stable.16,5863 The mortality of wild boar owing to wolf predation
Pest Manag Sci (2015) © 2014 Crown copyright.
Pest Management Science © 2014 Society of Chemical Industry G Massei et al.
is relatively small when compared with the mortality imposed
by hunters.64 For instance, in Poland, wolves annually removed
19–38 wild boar per 100 km2(or 4 8% of spring– summer den-
sities of wild boar), compared with hunters who annually har-
vested 45– 142 wild boar per 100 km2.60 In Spain, estimated wolf
predation caused 12% of the mortality of wild boar, compared with
31% caused by hunting.16
The mortality due to hunters and predators affects different
wild boar age classes: predators such as wolves remove pri-
marily young wild boar, while hunters remove relatively more
adult animals.12,16,6065 The implications for population dynam-
ics are significant: as young animals have lower survival rates
than adults, some of the mortality due to predation replaces mor-
tality that might otherwise be affected by other natural causes,
such as starvation.66 Conversely, higher mortality of adult animals
owing to hunting removes individuals that might have survived
longer and would have contributed more to population growth.
Thus, hunters have greater potential than wolves for regulating
Hunting can also induce compensatory population response:
where hunting pressure is high, wild boar may give birth earlier,
which in turn allows juvenile females to grow for longer and to
reach the threshold size for giving birth at 1 year of age.18 In
addition, under high hunting pressure, a higher proportion of
yearling females give birth compared with populations where
hunting pressure is less pronounced.47
Reforestation and climate change have often been quoted to
explain the increased densities of ungulates in Europe.32,47 Over
the last 20 years, the forest area has expanded in all European
regions.69 The increased cover of forests, as well as the shelter
provided by some crops such as rapeseed, sunflower and maize,
is likely to have favoured the spread of wild boar to previously
unoccupied areas, although this is not the case for boreal forests
in Northern Europe (Kindberg J, unpublished).70,71 Milder winters
and reduced winter mortality are also likely to affect recruitment
via increased survival of all age classes.15,64,72
Supplementary feeding of wild boar, which is widespread across
most European countries, as well as an increased availability of
agricultural crops throughout the year, has certainly contributed
to increase survival.10,29,73 The highest litter size and reproductive
output recorded for wild boar are associated with availability of
energy-rich crops (maize and sunflower) in summer and autumn,
often coupled with supplementary food provided by hunters in
Wild boar reproductive rates are significantly affected by food
availability;35,73,76 78 the fact that sows can maximise reproductive
success by adjusting their relative allocation to littermates in
relation to the amount of food available could also contribute to
population growth.79
In conclusion, wild boar have increased significantly across
Europe during the past three decades, probably facilitated by a
decrease in numbers of hunters but also by a combination of other
extrinsic factors. Although the importance of each of these fac-
tors is likely to be country specific, a major finding of this review
is that, across the continent, recreational hunting has not pre-
vented the growth of wild boar populations and is unlikely to
do so in the near future without substantial changes to hunting
practices. Although in most European countries wild boar are val-
ued as game, hunters might have little incentive for reducing wild
boar populations even when the market value of carcasses out-
weighs the costs that hunters accrue via compensation payments
to farmers for crop damage caused by this species.39,80 An ageing
extant hunter population coupled with low hunter recruitment
suggests that new strategies may be required if the number of
wild boar and their impacts are to be controlled.81 With regard to
hunters, these strategies could include identifying and address-
ing the reasons for lack of retention of hunters and promotion
of hunter recruitment.42 Preventing further wild boar population
growth will rely on shifting the focus of hunters towards specific
age classes,12,67,79,82 involving other stakeholders as well as profes-
sional hunters, introducing more effective hunting methods and
equipment and exploring the use of new tools for hunting. More-
over, educating the public in wild boar control83,84 and testing
new methods such as fertility control in areas where hunting is
unfeasible40,85 may assist in controlling wild boar. It is conceivable
that recreational hunting of wild boar will be progressively sub-
stituted by professional hunting, community service or civic duty
carried out by other stakeholder groups.42 Cooperation between
landowners, hunters and conservation groups, as well as educa-
tion in wild boar hunting and provision of equipment to increase
hunting efficiency, will play an important role in decreasing wild
boar populations in the future. Adopting effective strategies to
reduce human– wild boar conflicts will be a major challenge in
the future.39,41 Successfully meeting this challenge could provide
a model for mitigating other human– wildlife conflicts.
Many thanks to Stéphane Pietravalle for statistical advice.
Table A1 Source of data and acknowledgements
Austria STAT cube – statistical database of statistics,
Austria (
Belgium Service Public de Wallonie – Département
de la Nature et des Forêts. Thanks to
Michel Villers
Croatia Ministry of Agriculture, Information System
of Central Hunting Records
Croatian Hunting Association. Thanks to
Ivica Budor and Marko Tomljanovi´
Czech Republic Ministry of Agriculture of the Czech Republic
France Réseau Ongulés Sauvages ONCFS-FNC-FDC
(Wild UngulatesNetwork
ONCFS =French National Agency for
sauvages-ru104); FNC =National Hunters
Feder ation; FDC =Departmental Hunters
Federation. ONCFS – Validation of
hunting license (Budget Division). Thanks
to C Saint-Andrieux (ONCFS) and field
staff at the Réseau Ongulés Sauvages, and
to D Soulie (ONCFS)
Germany Deutscher Jagdschutzverband (German
Hunter Association) (see
/jahresstrecken?meta_id =267 and
meta_id=116) © 2014 Crown copyright. Pest Manag Sci (2015)
Pest Management Science © 2014 Society of Chemical Industry
wild boar and hunter trends in Europe
Table A1 (continued)
Hungary National Game Management Database,
o, Hungary.
Thanks to the Foundation of the
Hungarian Government (USZT) within
project VKSZ_12-1-2013-0034
Agroclimate 2
Italy National Ungulates Databank, ISPRA
(Institute for Environmental Protection
and Research)
Italian National Institute of Statistics
( Thanks to Maria
Luisa Zanni, Enrico Merli, Andrea Marsan,
Maddalena Mattii, Aurelio Perrone,
Sandro Bertolino and Barbara Franzetti
Latvia The State Forest Service of Latvia (SFS)
Luxembourg Administration de la Nature et des Forêts,
Ministère du Développement Durable et
des Infrastructures, Département de
l’Environnement, Luxembourg. Thanks
Poland Forestry Statistical Yearbooks (1975–2013),
Central Statistical Office of Poland
Portugal Portuguese Institute for Nature
Conservation and Forests (
Portuguese Science Foundation (FCT)
within project PEst-C/MAR/LA0017/2013
Russia Russian Committee for Statistics
Roskomstat (
Serbia Statistical Office of the Republic of Serbia
( Hunting Association
of Serbia
Slovenia Statistic Yearbooks of the Republic of
Slovenia (1982-2012), annual hunting
management plans for all 15 Hunting
Management Districts (2009-2013)
Slovene hunting information system
(2001-2013). Thanks to Marko Jonozoviˇ
Department for Wildlife and Hunting,
Slovenia Forest Service
Spain Spanish Ministry of Agriculture, Food and
Environment and Spanish Hunters
Federation. Thanks to Antonio Solís from
the Spanish Ministry of Agriculture
Sweden The Swedish Association for Hunting and
Wildlife Management, Swedish
Environmental Protection Agency
Switzerland Office Fédéral de l’Environnement OFEV
Statistique de la Chasse
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... Assessing factors in uencing wild boar rooting in grasslands, also including seasonality, landscape con guration and wild boar density, would allow to identify sites and times of year more vulnerable to disturbance, thus favouring the identi cation of spatio-temporally explicit management strategies. Identifying key-factors in uencing rooting would be especially relevant for Mediterranean areas that are facing a recent, sharp increase in wild boar numbers (Massei et al. 2015). These areas face signi cant seasonal variations in weather patterns, ranging from near-drought to rainy periods, with respect to which wild boar rooting is expected to act as a substantial, additive stress for plants. ...
... For instance, a recent study has shown that the rooting activity may locally create favourable habitat conditions for some butter ies' species (Labadessa and Ancillotto 2023). However, several anthropogenic factors have led to a modi cation in habitat cover, as well as in uenced wild boar distribution and abundance (e.g., through arti cial releases, supplemental feeding or by providing highly energetic food through agriculture) (Barrios-Garcia and Ballari 2012; Massei et al. 2015), potentially emphasising the negative consequences of wild boar activity for habitat conservation. Over the last centuries, human-made landscape modi cations have reduced the extent of woodlands in favour of open areas suitable for grazing and agriculture. ...
... Herbivore selectiveness on nutrient-rich plant species is expected to increase the dominance of plants with nutrient-poor epigean parts and richer belowground parts (Tilman 1988), increasing the potential for grasslands to be attractive for wild boar rooting (Bueno et al. 2011). This process, together with the increase of wild boar densities at a continental scale, has exposed vulnerable environments such as grasslands and scrublands to additive threats, making the impact on those habitats a priority for their conservation and management (Barrios-Garcia and Ballari 2012; Massei et al. 2015). ...
Full-text available
Wild ungulates can influence various trophic levels, regulating carnivore abundance as well as affecting habitat structure. Conservation problems can arise when high ungulate densities threaten species or habitats with conservation concern. Assessing factors influencing the intensity of their impact is important to identify appropriate measures enhancing the conservation of protected habitats. We assessed seasonal and ecological factors influencing wild boar Sus scrofa pressure on EU priority grasslands in three protected areas of central Italy, by modelling the effects of habitat/topography-related variables, as well as wild boar population density, on indices of rooting activity. We seasonally surveyed 136 sampling plots from spring 2019 to spring 2021 to estimate rooting, and we used faecal counts to estimate wild boar densities in summer. Estimates of density and rooting varied from 3.5 to 22.2 individuals/km ² and from 1.5 to 22.2% of rooted ground, respectively. We detected a clear seasonal trend in rooting activity, that peaked in autumn and winter. We also found a positive correlation between spring-summer rooting and summer density, across sites. Rooting intensity was negatively related to the local extent of rock cover and increased with the size of the grassland patch and with the percentage of forest around each plot. These results emphasise the wild boar tendency to exploit feeding sites in ecotonal areas, i.e., at the interface between forest and meadows, which maximises security and ease of finding food resources. Actions aiming at the protection of focal plants in grassland habitats, as well as reducing wild boar densities, are supported.
... The wild boar (Sus scrofa) is a widely distributed mammal species from Europe to East Asia (Massei and Genov 2004). Recently, due to population increase and expansion of their distribution area, conflicts between humans and wild boars have become a serious social problem in many areas (Acevedo et al. 2014;Massei et al. 2015). Conflicts with wild boars include damage to crops and living facilities, traffic accidents, and the spread of diseases to livestock and people. ...
... Conflicts with wild boars include damage to crops and living facilities, traffic accidents, and the spread of diseases to livestock and people. Particularly, significant economic losses were reported to often occur with respect to damage to crops and livestock (Schley et al. 2008;Barrios-Garcia and Ballari 2012;Massei et al. 2015). ...
Full-text available
Classical swine fever (CSF) has been widespread among wild boars in Japan since the first outbreak in September 2018 after 26 years of absence. Although oral vaccination against CSF has been implemented, CSF infections are ongoing in the wild boar population. Therefore, increasing the effectiveness of oral vaccination in wild boars by distributing the vaccine in an environment where wild boars are likely to ingest the vaccine is necessary. This study aimed to investigate the landscape elements that facilitate the uptake of oral vaccines by wild boars. We used data from the oral vaccine campaign in Gunma and Tochigi prefectures in eastern Japan and analyzed the vaccine uptake rate and landscape structure at the vaccine distribution sites in two seasons. The uptake rate of the oral vaccine was significantly higher in the first season (Gunma: 41.5%, Tochigi: 37.1%) than in the second season (Gunma: 28.5%, Tochigi: 25.7%). We also found that broadleaf forest and bamboo woodland were negatively associated with vaccine uptake in Gumma Prefecture in the first and second seasons, respectively. These results indicate that vaccine uptake may be influenced by seasonal changes in wild boar food resources. Moreover, the results suggest that the uptake of oral vaccination may increase in environments with high landscape diversity, i.e., forest edge environments, which contain mainly forest elements and a small amount of cultivated land and city areas, whereas it may decrease in environments with mainly cultivated land and city areas and less forest elements due to the influence of human activities.
... The local harvest of wild pigs by hunters is closely correlated to pig population size and density (Massei et al. 1997(Massei et al. , 2015Merli and Meriggi 2006;Imperio et al. 2010). The United States Department of Agriculture Animal and Plant Health Inspection Service-Wildlife Services (WS) is the federal agency tasked with mitigating human-wildlife conflicts. ...
Vehicle collisions with wild pigs (Sus scrofa) are reported almost everywhere this species is found. However, this is one of the least studied and characterized forms of damage that these invasive animals cause in the United States (U.S.). We analyzed 518 wild pig-vehicle collisions (WPVCs) that took place statewide in Georgia between 2015 and 2021. From that dataset, we analyzed several parameters in order to better understand and characterize these accidents on a scale that had previously not been done in the U.S. Wild pig-vehicle collisions were reported from 105 out of the 159 counties in Georgia, increasing in number annually over the seven-year period. WPVCs were most likely to occur in the fall (37%). A duration weighted time of day analysis showed that WPVCs were most frequent at dusk. Most (97%) reported accidents were caused by live wild pigs, with the remainder being due to collisions with already dead or road-killed pigs. Most (86%) collisions involved a single wild pig while the remainder occurred with two or more pigs. Collisions occurred mostly with passenger cars on dry, straight, and level two-lane blacktop roads under dark, unlighted conditions. Nine percent of the vehicle accidents involving wild pigs resulted in injuries to the drivers and passengers. Some of the most severe injuries reported were caused by swerving to avoid striking wild pigs. No human fatalities were recorded due to these accidents. Wild pig-vehicle collisions are costly and dangerous and should be closely monitored and mitigated by the agencies responsible for motorist safety, transportation infrastructure, and wildlife management.
... The wild boar population in Europe is constantly growing due to its high fertility rate and remarkable ability to adapt to different conditions and environments. The rise of these wild ungulates is increasingly causing economic, environmental, and public health issues (Massei et al., 2015;Croft et al., 2020;Johann et al., 2020). Wild boars may represent a reservoir for several pathogens, and they can therefore be involved in the diffusion and transmission of diseases towards both humans and domestic animals (Fredriksson-Ahomaa, 2019;Altissimi et al., 2023). ...
Full-text available
The management and numerical control of wild boars mainly depend on hunting practices, even if other alternative strategies such as the use of traps and cages can be adopted. There is little information available on the quality of captured wild boar meat. The aim of this study was to evaluate the meat quality of wild boars captured with a large corral-style trap compared to still hunting and collective hunting methods. Longissimus dorsi samples were collected from 60 wild boars, 20 of which were obtained by trapping, 20 by still hunting, and 20 by collective hunting. The animals considered were 32 males and 28 females, weighing between 42 and 68 kg. Muscle pH has been recorded after 1, 24, and 48 hours post-mortem. Furthermore, after 24 hours, color, drip loss, cooking loss, and Warner-Bratzler shear force were also evaluated. Trapping with large enclosures such as corral-style traps, if properly managed, does not seem to adversely affect the quality traits of wild boar meat, which were found to be like those obtained by the still hunting method.
... During the last decades, a complex network of biological, environmental, and anthropic aspects provided a significant increase of the wild boar (Sus scrofa) populations density in most of Europe, with a high impact on human activities (Massei et al., 2015;Troiano et al., 2021). This overabundance led to an increasing boar consumption, to date popular not only among hunters and their families, but also in the international trade (Acevedo et al., 2014;Fredriksson-Ahomaa, 2019;Guardone et al., 2022) potentially enhancing the human exposure to foodborne pathogens, mainly through raw/undercooked meat and meat products (e.g., sausages) (Fredriksson-Ahomaa, 2019). ...
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The increase of wild boar populations density and their meat consumption across Europe could expose humans to a plethora of foodborne diseases as sarcocystosis, caused by the zoonotic protozoan Sarcocystis suihominis. Humans become infected by eating raw or undercooked pig (Sus scrofa domesticus) containing S. suihominis sarcocysts. Despite this, to date very few data are available on the risk of infection by this parasite to wild boar (Sus scrofa) meat consumers. Thus, the present study aimed to assess the occurrence of Sarcocystis spp. in wild boars from southern Italy, applying both histology and a new multiplex PCR assay targeting the cox1 gene. Between 2019 and 2020, 997 muscle tissues (i.e., n = 269 oesophagus, n = 277 diaphragms, n = 298 hearts, n = 153 tongues) from 311 wild boars were collected and screened by a combined histological and molecular approach. Overall, 251 (80.7%) animals tested were positive for Sarcocystis spp., and S. miescheriana whose definitive hosts are canids, was the only molecularly identified species. A statistically significant difference (p < 0.05) in the prevalence of Sarcocystis infection was found according to the wild boar age and muscle tissue. Findings outlined the low zoonotic potential of infection to humans via wild boar meat consumption in Italy and the importance of the application of new molecular methods in distinguishing different Sarcocystis species.
Rabies caused by the Classical Rabies Virus (Lyssavirus rabies abbreviated RABV) in the European Union has been close to elimination mainly thanks to Oral Rabies Vaccination (ORV) campaigns targeting wildlife (primarily red foxes). ORV programmes co-financed by the European Commission include a monitoring-component to assess the effectiveness of the ORV campaigns at national level. This assessment is performed by a random collection of red foxes in the vaccinated areas with control of antibodies presence by serological analysis and control of bait uptake by detection of biomarkers (tetracycline incorporated into the baits) in the bones and teeth. ORV programmes aim to a vaccine coverage high enough to immunize (ideally) 70% of the reservoir population to control the spread of the disease. European Union (EU) programmes that led to almost elimination of rabies on the territory have been traditionally found to have a bait uptake average of 70% (EU countries; 2010-2020 period) while the seroconversion data showed an average level of 40% (EU countries; 2010-2020 period). To better understand variations of these indicators, a study was been set up to evaluate the impact of several variables (linked to the vaccination programme itself and linked to environmental conditions) on the bait uptake and the seroconversion rate. Thus, pooling data from several countries provides more powerful statistics and the highest probability of detecting trends. Results of this study advocate the use of a single serological test across the EU since data variation due to the type of test used was higher than variations due to field factors, making the interpretation of monitoring results at regional level challenging. In addition, the results indicates a negative correlation between bait uptake and maximum temperatures reached during ORV campaigns questioning the potential impact of climatic change and associated increase of temperatures on the ORV programmes efficiency. Several hypotheses requesting additional investigation are drawn and discussed in this paper.
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The natural regeneration of the temperate oak forests is often insufficient. Acorns of the oak serve as the basis of the recruitment and key food resources in these ecosystems, thus the crop size, the germination success and seed predators have crucial roles in the process. Wild boar (Sus scrofa) is often considered as one of the main mitigating agents in oak regeneration. Therefore, in our study we analyzed and compared the spatial patterns of the acorn density and the patches rooted by wild boar within and among the different examined time intervals in a 28 ha Turkey-sessile oak (Quercus cerris, Q. petraea) forest stand. Data were collected between 2016 October and 2019 December. In the acorn density patterns, intra-annual similarities were recognized mainly, regardless of the crop size. Meanwhile, rooting patterns showed inter-and intra-annual similarities in mast years and intra-annual overlaps in non-mast years, indicating that masting is a fundamental driver of wild boar foraging behavior. However, a direct local connection between the rooting intensity and the acorn density could not be shown, as wild boars never fully depleted the acorns, even in intensively used patches. This study can help in predicting the intensively rooted forest patches, providing opportunities to manage wildlife conflicts.
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Aim The non‐stationarity in habitat selection of expanding populations poses a significant challenge for spatial forecasting. Focusing on the grey wolf (Canis lupus) natural recolonization of Germany, we compared the performance of different distribution modelling approaches for predicting habitat suitability in unoccupied areas. Furthermore, we analysed whether grey wolf showed non‐stationarity in habitat selection in newly colonized areas, which will impact the predictions for potential habitat. Location Germany. Methods Using telemetry data as presence points, we compared the predictive performance of five modelling approaches based on combinations of distribution modelling algorithms—GLMM, MaxEnt and ensemble modelling—and two background point selection strategies. We used a homogeneous Poisson point process to draw background points from either the minimum convex polygons derived from telemetry or the whole area known to be occupied by wolves. Models were fit to the data of the first years and validated against independent data representing the expansion of the species. The best‐performing approach was then used to further investigate non‐stationarity in the species' response in spatiotemporal restricted datasets that represented different colonization steps. Results While all approaches performed similarly when evaluated against a subset of the data used to fit the models, the ensemble model based on integrated data performed best when predicting range expansion. Models for subsequent colonization steps differed substantially from the global model, highlighting the non‐stationarity of wolf habitat selection towards human disturbance during the colonization process. Main Conclusions While telemetry‐only data overfitted the models, using all available datasets increased the reliability of the range expansion forecasts. The non‐stationarity in habitat selection pointed to wolves settling in the best areas first, and filling in nearby lower‐quality habitat as the population increases. Our results caution against spatial extrapolation and space‐for‐time substitutions in habitat models, at least with expanding species.
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Salmonella is one of the most spread foodborne pathogens worldwide, and Salmonella infections in humans still represent a global health burden. The main source of Salmonella infections in humans is represented by contaminated animal-derived foodstuffs, with pork products being one of the most important players. Salmonella infection in swine is critical not only because it is one of the main causes of economic losses in the pork industry, but also because pigs can be infected by several Salmonella serovars, potentially contaminating the pig meat production chain and thus posing a significant threat to public health globally. As of now, in Europe and in the United States, swine-related Salmonella serovars, e.g., Salmonella Typhimurium and its monophasic variant Salmonella enterica subsp. enterica 1,4,[5],12:i:-, are also frequently associated with human salmonellosis cases. Moreover, multiple outbreaks have been reported in the last few decades which were triggered by the consumption of Salmonella-contaminated pig meat. Throughout the years, changes and evolution across the pork industry may have acted as triggers for new issues and obstacles hindering Salmonella control along the food chain. Gathered evidence reinforces the importance of coordinating control measures and harmonizing monitoring programs for the efficient control of Salmonella in swine. This is necessary in order to manage outbreaks of clinical disease in pigs and also to protect pork consumers by controlling Salmonella subclinical carriage and shedding. This review provides an update on Salmonella infection in pigs, with insights on Salmonella ecology, focusing mainly on Salmonella Choleraesuis, S. Typhimurium, and S. 1,4,[5],12:i:-, and their correlation to human salmonellosis cases. An update on surveillance methods for epidemiological purposes of Salmonella infection in pigs and humans, in a “One Health” approach, will also be reported.
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We estimated birth rates in wild boar Sus scrofa by counting embryos in the uterus of females killed in individual or drive hunts. Counting corpora lutea in the ovaries gave information on embryo:corpus luteum rate, which can be useful for estimating birth rates in early stages of pregnancy. Birth rates were estimated separately for the different age groups. Age was estimated by means of teeth wear. Survival was estimated by direct observations counting the piglet:female ratio in matrilineal groups. The method is suitable for assessing summer survival only, as 8–9 months after birth, matrilineal groups begin to disintegrate. Average estimated birth rate was 6.7 ± 2.1 (N = 51).We found a positive linear relationship between conception rate and age of female, conception rate and body mass, and conception rate and body length, respectively. In late stages of pregnancy, embryo:corpus luteum rate proved to be 0.83 ± 0.15. Recruitment of piglets to the female population was low; more than half of the piglets had perished by the end of September. The highest mortality rate occurred in the first weeks of the piglets' lives.
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Reproduction of wild boar in a cropland and coastal wetland area: implications for management.- The reproductive parameters of a wild boar population located in a coastal landscape with a mosaic of cropland and wetland habitats were analysed and compared with those observed in wild boar populations living in other habitats. A total of 296 reproductive tracts of females captured year round at the Aiguamolls de l'Empordà Natural Park were collected and analysed from 2000 to 2010. The foetuses were counted, sexed and aged and the mating and birth periods were determined. The weight and age of each female were also recorded. In accordance with the pattern observed in most European populations, a marked main mating season from October to January was observed. Within this season, there was a peak during November and December, in which 64% of the conception dates were recorded. The proportion of breeding females, ovulation rate and litter size increased with the weight of the reproductive females. A mean litter size of 5.01 ± 1.33 (range from two to eight) foetuses was recorded. This value is the highest known litter size recorded in wild Iberian populations and is similar to values observed in central Europe. Furthermore, it is not in accordance with the pattern reported for other European populations in which a positive correlation between litter size and latitude was observed. The most likely explanation for the high reproductive output in the study area is the availability of food year round, and especially the high consumption of crops such as maize and sunflower. Our results suggest that colonisation of cropland and wetland areas is contributing to the rise in the wild boar population density. Control strategies should consider not only reducing numbers of adult females but also applying measures to reduce food resources available to wild boar.
In the Kurpiowska Forest, in 1975-1976, wild boars uprooted 305 ha of litter and herb layer, ie. 13.2% of the surface area of dry pine forest, and in 1976-1977, 48 ha (2.1% of dry wood) and also destroyed 41% of a pine sawfly population (Diprion pini). The level of rooting activity in the forests depended on climatic conditions, food abundance and the outbreak of harmful insects. A reverse relation was observed between the level of rooting activity and the damage done on fields: 78% of all damage on fields was made between May and September. The greatest damage was recorded on potato, rye and oat fields (90% of all damage). -from Author
Until recently, geographic isolation has protected Britain from the widespread increases in wild boar populations seen elsewhere in Europe, but following the development of wild boar farming in the 1980s a number of escapes and releases have occurred, resulting in the re-establishment of the species in the wild in England. The present study monitored the establishment and presence of wild boar in England by collating reports of escapes or releases and ground-truthing evidence of animals in the wild. This data is used to give an up-to-date indication of the distribution of the species in England. In the twenty years from 1989/90 to 2008/9 an average of one to two escape/release incidents occurred each year, with individual incidents involving from one to more than 50 individuals. These have resulted in the establishment of at least four distinct populations, the largest of which probably has a pre-breeding population in excess of 200 animals. None of the escapes or releases involving five or fewer individuals is believed to have led to establishment of a population. Based on the availability of woodland, there is potential for a total population in England of around 30,000 – 40,000 animals. However, future development of local populations is likely to be constrained over much of the country because of low woodland cover and culling pressure, and it is likely to take many years for a population of this size to develop, if at all.