Elsevier

Biological Conservation

Volume 195, March 2016, Pages 156-168
Biological Conservation

Why do wolves eat livestock?: Factors influencing wolf diet in northern Italy

https://doi.org/10.1016/j.biocon.2016.01.003Get rights and content

Highlights

  • Understanding the factors in determining livestock use is important to reduce conflicts.

  • We examined diet of packs and dispersing wolves and modeled the livestock use.

  • Dispersing individuals consumed more livestock compared to stable packs.

  • Stable packs have the strongest negative influence on livestock predation.

  • Wolf–human coexistence will likely require supporting pack stable presence.

Abstract

Thanks to protection by law and increasing habitat restoration, wolves (Canis lupus) are currently re-colonizing Europe from the surviving populations of Russia, the Balkan countries, Spain and Italy, raising the need to update conservation strategies. A major conservation issue is to restore connections and gene flow among fragmented populations, thus contrasting the deleterious consequences of isolation. Wolves in Italy are expanding from the Apennines towards the Alps, crossing the Ligurian Mountains (northern Italy) and establishing connections with the Dinaric populations. Wolf expansion is threatened by poaching and incidental killings, mainly due to livestock depredations and conflicts with shepherds, which could limit the establishment of stable populations. Aiming to find out the factors affecting the use of livestock by wolves, in this study we determined the composition of wolf diet in Liguria. We examined 1457 scats collected from 2008 to 2013. Individual scats were genotyped using a non-invasive genetic procedure, and their content was determined using microscopical analyses. Wolves in Liguria consumed mainly wild ungulates (64.4%; in particular wild boar Sus scrofa and roe deer Capreolus capreolus) and, to a lesser extent, livestock (26.3%; in particular goats Capra hircus). We modeled the consumption of livestock using environmental features, wild ungulate community diversity, husbandry characteristics and wolf social organization (stable packs or dispersing individuals). Wolf diet varied according to years and seasons with an overall decrease of livestock and an increase of wild ungulate consumption, but also between packs and dispersing individuals with greater livestock consumption for the latter. The presence of stable packs, instead of dispersing wolves, the adoption of prevention measures on pastures, roe deer abundance, and the percentage of deciduous woods, reduced predation on livestock. Thus, we suggest promoting wild ungulate expansion, the use of prevention tools in pastures, and supporting wolf pack establishment, avoiding lethal control and poaching, to mitigate conflicts between wolf conservation and husbandry.

Introduction

The wolf (Canis lupus), because of its adaptability to different environments and its ability to re-colonize territories when no persecution occurs, has in just a few decades expanded its range in Europe (Balciauskas, 2008, Breitenmoser, 1998, Chapron et al., 2003, Chapron et al., 2014). The Russian wolf population is the largest in Europe, supporting those of Baltic and North-European countries, and it is contiguous with the populations of Eastern Europe from which wolves began the re-colonization of Central Europe (Ansorge et al., 2006, Linnell et al., 2005). The Spanish wolf Canis lupus signatus (2200–2300 individuals) is slowly extending its distribution (Mech and Boitani, 2003).

Wolves greatly declined in Italy, surviving in two small isolated subpopulations confined to the southern and central part of the Apennines. At their nadir in the early seventies of the last century, wolves in Italy numbered about 100 individuals (Zimen and Boitani, 1975). Since the late eighties, wolves have shown a spontaneous rapid recovery, re-colonizing all the Apennines and reaching the western Italian and French Alps (Boitani, 2000, Breitenmoser, 1998, Fabbri et al., 2007, Marucco and McIntire, 2010, Valière et al., 2003).

The re-colonization of the Alps would be a fundamental step for wolf conservation in Italy and Central Europe as well (Genovesi, 2002). Moreover, the early and ongoing wolf expansion from the eastern Alps will predictably increase chances to originate mixed packs and increase the local genetic diversity as has been already described (Fabbri et al., 2014, Randi, 2011).

The sub-population of wolves inhabiting the Liguria region thus plays a crucial role in assuring the linkage between the wolves of central Italy and those of the Western Alps (Fabbri et al., 2007). If this link should break, the wolf population of the Western Alps would be isolated, perhaps failing to recolonize the remaining part of the Alps.

The distribution of wolves is usually determined by the abundance of its preys, environmental characteristics, and the risk associated with the presence of humans (Eggermann et al., 2011, Jędrzejewski et al., 2004, Massolo and Meriggi, 1998). This last point is the key problem of wolf conservation because wolves can have a dramatic impact on livestock breeding, affecting human attitudes that can lead to illegal killing, increasing the risk of extinction (Behdarvand et al., 2014, Kovařík et al., 2014).

The impact of wolves on livestock is different according to geographical region. In regions with a very low abundance of wild ungulates, as in Portugal and Greece, wolves feed mainly on livestock (Migli et al., 2005, Papageorgiou et al., 1994, Vos, 2000). On the other hand, in Germany attacks on livestock are rare because shepherds equip the pastures with electric fences to protect their herds and because the wild ungulate availability is high (Ansorge et al., 2006).

In other new-recolonizing areas such as France or North Italy, wild ungulates are the main prey of wolves, but the use of livestock is still noticeable (MEEDDAT–MAP, 2008, Meriggi et al., 2011, Milanesi et al., 2012).

Systematic research on wolf feeding ecology has been carried out since 1987 in the Ligurian Apennines. These studies showed an increasing use of wild ungulates in the time but also a medium–high use of livestock species as prey (Meriggi et al., 1991, Meriggi et al., 1996, Meriggi et al., 2011, Schenone et al., 2004). Consequently, wolf presence in Liguria, as well as in other areas of natural re-colonization, causes a conflict with human populations that perceive predator presence as a negative element that can compromise a poor rural economy. Thus, wolves suffer a high mortality mainly due to illegal killing and accidents. This situation makes the population vulnerable and actions aimed at a greater protection of the species are required.

Usually wolf populations are structured in stable packs and lone wolves; packs are formed by a pair of adults, by their offspring and other related individuals (i.e. the offspring of previous years), and sometime by adopted individuals, whereas lone wolves are erratic individuals that can temporarily establish in an area without packs. In general lone wolves are young dispersing from packs but they can also be adults moving far from their original pack because of pack disruption or break off for several causes (killing by humans, low prey availability and related increasing aggressiveness, natural death of the dominant pair) (Mech and Boitani, 2003). Packs are established in areas with high prey availability, because only a high availability of preferred prey can dampen the aggressiveness of the pack members and avoid pack disruption (Thurber and Peterson, 1993). Dispersing and erratic individuals use the areas without wolf packs that can be considered suboptimal habitats because of the low prey availability, high human disturbance, and possibly potential problems with local people (Fritts and Mech, 1981). Illegal killing can break the packs, increasing erratic wolves and reproductive pairs that can have a greater impact in particular on livestock rearing (Wielgus and Peebles, 2014).

The objective of the present study was to determine which factors influence wolf diet, in particular, the choice of livestock as prey, which is the first step to find solutions for wolf conservation. With this aim, we determined wolf diet, by analyses of scats collected in the whole Liguria region from 2008 to 2013. We highlighted the factors influencing it, i.e. years, seasons, ungulate abundance, and social structure of wolves (packs or dispersing individuals). Then we related livestock consumption to environmental features, wild ungulate abundance and diversity, husbandry characteristics, wolf grouping and habitat occupancy behavior (stable packs or dispersing individuals).

Section snippets

Study area

This research was carried out in the Liguria region, north Italy (44°30′16″, 8°24′10″). The study area spreads over 5343 km2 including a part of the Northern Apennines and of the Western Italian Alps, until the border with France. The region is divided in four provinces, Imperia, Savona, Genoa and La Spezia, respectively from the western to the eastern part (Fig. 1). Altitude ranges from 0 to 2153 m a.s.l.; 36% of the area is between 0 and 400 m a.s.l., 35% between 400 and 800 m, 21% between 800 and

Genetic analysis

Genetic identifications of the 403 samples yield 205 (50.8%) reliable multilocus genotypes, corresponding to 58 wolves (31 males M and 27 females F), 5 dogs (4 M, 1 F), 9 wolf × dog hybrid individuals (8 M, 1 F). Wolf individuals were sampled from a minimum of 1 to a maximum of 10 times. The hybrids were sampled from 1 to 3 times while the 5 dogs once each.

Parentage analyses led to the assigning of 20–21 wolves to five distinct packs (Fig. 1, Table 1), respectively named: Imperia pack, Savona

Discussion

The diet of wolves in the Liguria region is characterized by a medium–high occurrence of wild ungulates and by an important part consisting of large domestic prey, the other food categories being a negligible fraction of the diet. This picture places the food habits of wolves in our study area between those of populations preying almost exclusively on wild herbivores and those of wolves living mainly at the expense of livestock and other food of human origin, that can be found in human altered

Conclusion

In Liguria, as in many countries of southern Europe, conflicts between wolf conservation and husbandry are far from being solved and they are an important threat to wolf conservation, as the high number of wolves found illegally killed demonstrates (12 individuals out of 16 confirmed dead between 2007 and 2014 in the whole region). Poaching by shooting and poisoning is the main mortality factor of wolves in the region and in Italy, and can be related to the damage to livestock farms (Lovari et

Acknowledgments

This research was supported by the Liguria Region, by the Regional Park “M. Antola” (Regional Operational Program — European Regional Development Fund 2007–2013 - CUP B37E12000040009). We thank F. Puopolo, L. Schenone, D. Signorelli, and M. Zanzottera for their help in field work as well as the personnel of the Forestry Corp and Provincial Police who helped in collecting data. V. Devictor, S. Lovari, and an anonymous referee provided helpful comments to an early draft of the manuscript.

References (101)

  • L. Iacolina et al.

    Y-chromosome microsatellite variation in Italian wolves: a contribution to the study of wolf–dog hybridization patterns

    Mamm. Biol.

    (2010)
  • B.J. Kernohan et al.

    Analysis of animal space use and movments

  • P. Kovařík et al.

    Sheep and wolves: is the occurrence of large predators a limiting factor for sheep grazing in the Czech Carpathians?

    J. Nat. Conserv.

    (2014)
  • H. Sand et al.

    Effects of hunting on group size snow depth and age on the success of wolves hunting moose

    Anim. Behav.

    (2006)
  • D. van Lière et al.

    Farm characteristics in Slovene wolf habitat related to attacks on sheep

    Appl. Anim. Behav. Sci.

    (2013)
  • H. Akaike

    Maximum likelihood identification of Gaussian autoregressive moving average models

    Biometrika

    (1973)
  • M.J. Anderson

    NPMANOVA: A FORTRAN Computer Program for Non-parametric Multivariate Analysis of Variance (for any two-factor ANOVA design) Using Permutation Tests

    (2000)
  • M.J. Anderson

    A new method for non-parametric multivariate analysis of variance

    Austral Ecol.

    (2001)
  • D.R. Anderson et al.

    Null hypothesis testing: problems, prevalence and an alternative

    J. Wildl. Manag.

    (2000)
  • D.R. Anderson et al.

    Suggestion for presenting the results of data analyses.J

    Wildl. Manag.

    (2001)
  • H. Ansorge et al.

    Feeding ecology of wolves Canis lupus returning to Germany

    Acta Theriol.

    (2006)
  • D.E. Ausband et al.

    Recruitment in a social carnivore before and after harvest

    Anim. Conserv.

    (2015)
  • L. Balciauskas

    Wolf numbers and distribution in Lithuania and problems of species conservation

    Ann. Zool. Fenn.

    (2008)
  • L. Barabesi et al.

    Random versus stratified location of transects or points in distance sampling: theoretical results and practical considerations

    Environ. Ecol. Stat.

    (2013)
  • L. Barabesi et al.

    Sampling properties of spatial total estimators under tessellation stratified designs

    Environmetrics

    (2011)
  • C. Bieber et al.

    Population dynamics in wild boar Sus scrofa: ecology, elasticity of growth rate and implications for the management of pulsed resource consumers

    J. Appl. Ecol.

    (2005)
  • L. Boitani

    Action plan for the conservation of wolves in Europe (Canis lupus)

  • A. Brangi et al.

    Predation by wolves (Canis lupus) on wild and domestic ungulates in northern Italy

  • T.S. Breusch et al.

    A simple test for heteroscedasticity and random coefficient variation

    Econometrica

    (1979)
  • L. Brillouin

    Science and Information Theory

    (1956)
  • H. Brunner et al.

    The Identification of Mammalian Hair

    (1974)
  • K.P. Burnham et al.

    Model Selection and Multimodel Inference: A Practical Information-Theoretic Approach

    (2002)
  • R. Caniglia et al.

    An improved procedure to estimate wolf abundance using non-invasive genetic sampling and capture–recapture mixture models

    Conserv. Genet.

    (2012)
  • R. Caniglia et al.

    Noninvasive sampling and genetic variability, pack structure, and dynamics in an expanding wolf population

    J. Mammal.

    (2014)
  • L. Carnevali et al.

    Banca dati Ungulati. Status, distribuzione,consistenza, gestione e prelievo venatorio delle popolazioni di Ungulati in Italia. Rapporto 2001–2005

    Biol. Conserv. Fauna

    (2009)
  • G. Chapron et al.

    Recovery of large carnivores in Europe's modern human-dominated landscapes

    Science

    (2014)
  • P. Ciucci et al.

    Home range, activity and movements of a wolf pack in central Italy

    J. Zool.

    (1997)
  • F. Corsi et al.

    A large-scale model of wolf distribution in Italy for conservation planning

    Conserv. Biol.

    (1999)
  • L. Cuesta et al.

    The trophic ecology of the Iberian Wolf (Canis lupus signatus Cabrera,1907) — a new analysis of stomach's data

    Mammalia

    (1991)
  • E. Curio

    The Ethology of Predation

    (1976)
  • A.M. De Marinis et al.

    Hair identification key of wild and domestic ungulates from southern Europe

    Wildl. Biol.

    (2006)
  • S. Debrot et al.

    Atlas des poils de mammifères d'Europe

    (1982)
  • O. Dondina et al.

    Wolf predation on livestock in an area of northern Italy and prediction of damage risk

    Ethol. Ecol. Evol.

    (2014)
  • J.A. Endler

    Interactions between predators and prey

  • N. Espuno et al.

    Heterogeneous response to preventive sheep husbandry during wolf recolonization of the French Alps

    Wildl. Soc. Bull.

    (2004)
  • E. Fabbri et al.

    From the Apennines to the Alps: colonization genetics of the naturally expanding Italian wolf (Canis lupus) population

    Mol. Ecol.

    (2007)
  • D. Falush et al.

    Inference of population structure from multilocus genotype data: linked loci and correlated allele frequencies

    Genetics

    (2003)
  • S. Focardi et al.

    Piano d'azione nazionale per il capriolo italico (Capreolus capreolus italicus)

    Quad. Cons. Nat.

    (2009)
  • C. Fonseca

    Winter habitat selection by wild boar Sus scrofa in southeastern Poland

    Eur. J. Wildl. Res.

    (2008)
  • S.H. Fritts et al.

    Dynamics, movements, and feeding ecology of a newly protected wolf population in northwestern Minnesota

    Wildl. Monogr.

    (1981)
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