Using an online survey to assess the spatial distribution of wild boar (Sus scrofa L.) crop damage and factors influencing this distribution and severity in Limburg province, Belgium

Anneleen Rutten, Jim Casaer, Thierry Onkelinx, Lieven De Smet, Nele Witters, Frank Huysentruyt, Herwig Leirs


Wild boar (Sus scrofa L.) reappeared in Flanders (northern Belgium) in 2006 after almost half a century of absence. Interactions between wild boar and human activities are frequent due to extensive fragmentation of the landscape in Flanders. Complaints about agricultural damage are increasing but the actual extent of crop damage remains unknown. The goal of this study was to assess the current risk and the spatial distribution of crop damage, as well as factors influencing damage distribution in the province of Limburg (eastern Flanders). An online survey was sent to farmers by email. Moreover, as we expected potential respondent bias towards farmers that already experienced damage, we also conducted a follow-up non-respondent check by telephone. Our study showed that the current crop damage probability on a farm lies between 42% (likely an overestimation due to respondent bias in the online survey) and 22% (an underestimation based on the non-respondent check). There is considerable geographical variation in the proportion of farms that report boar damage; probability for crop damage due to wild boar is relatively high for farmers in Limburg but shows a geographically heterogeneous spread. Factors explaining the crop damage probability differed strongly between the online survey and the non-respondent check and no consistent results could be found. Our results show that using the online survey, it was possible to get an initial insight in the geographical distribution of crop damage. However, as we found differences between the results of the online survey and the non-respondent check, taking management decisions based solely on online survey results without conducting a non-respondent check could lead to misguided actions.


Human-Wildlife Conflict; online survey; damage probability; respondent bias

Full Text:



Acevedo P., Vicente J., Höfle U., Cassenello J., Ruiz-Fons F. & Gortazar C. (2007). Estimation of European wild boar relative abundance and aggregation: a novel method in epidemiological risk assessment. Epidemiology and Infections 135 (3): 519–527.

Barker R. J. (1991). Nonresponse bias in New Zealand Waterfowl harvest surveys. The Journal of Wildlife Management 55 (1): 129–131.

Bieber C. & Ruf T. (2005). Population dynamics in wild boar Sus scrofa: ecology, elasticity of growth rate and implications for the management of pulsed resource consumers. Journal of Applied Ecology 42: 1203–1213.

Bleier N., Lehocski R., Újváry D., Szemethy L. & Csanyi S. (2012). Relationships between wild ungulates density and crop damage in Hungary. Acta Theriologica 57: 351–359.

Briedermann L. (1990). Schwarzwild. Berlin, Germany.

Browne-Nuñez C. & Jonker S. A. (2008). Attitudes Toward Wildlife and Conservation Across Africa: A Review of Survey Research. Human Dimensions of Wildlife 13 (1): 49–72.

Cahill S., Llimona F., Cabañeros L. & Calomardo F. (2012). Habituation of wild boar (Sus scrofa) to urban areas: traits from Collserola Natural Park (Barcelona) and comparison with other cities. Animal Biodiversity and Conservation 35 (2): 221–233.

Carnis L. & Facchini F. (2012). Une approche économique des dégâts de gibier. Indemnisation, prix et propriété. In: Économie rurale, janvier-mars: 126–142. Available from [accessed 22 March 2019].

Carter N.H. & Linell J.D.C. (2016). Co-Adaptation Is Key to Coexisting with Large Carnivores. Trends in Ecology & Evolution 31 (8): 575–578.

Casaer J. & Licoppe A. (2010). Ungulates and their management in Belgium. In: Apollonio M., Putman R. & Andersen R. (eds) European Ungulates: 184–200. Cambridge University Press, Cambridge.

Demolder H., Schneiders A., Spanhove T., Maes D., Van Landuyt W. & Adriaens T. (2014). Hoofdstuk 4: Toestand biodiversiteit. In: Natuurrapport - Toestand en trend van ecosystemen en ecosysteemdiensten in Vlaanderen: 1­–83. Available from [accessed on 3 January 2017].

Deutskens E., De ruyter K., Wetzels M. & Oosterveld P. (2004). Response rate and response quality of internet-based surveys: An experimental study. Marketing letters 15 (1): 21–36.

Duda M.D. & Nobile J.L. (2010). The Fallacy of Online Surveys: No Data Are Better Than Bad Data. Human Dimensions of Wildlife: 15: 55–64.

Engeman R.M., Massei G., Sage M. & Gentle M.N. (2013). Monitoring wild pig populations: a review of methods. Environmental Science and Pollution Research 20: 8077–8091.

Evans J.R. & Mathur A. (2005). The value of online surveys. Internet Research 15: 195–219.

FAUNAFONDS. (2014). Jaarverslag Faunafonds: 2014: 4–54. Available from [accessed on 22 March 2019].

Ficetola G.F., Bonardi A., Mairota P., Leronni V. & Padoa-Schioppa E. (2014). Predicting wild boar damages to croplands in a mosaic of agricultural and natural areas. Current Zoology 60 (2): 170–179.

Fox J. & Monette G. (1992). Generalized collinearity diagnotics. Jounal of the American Statistical Association: 87 (417): 178–183.

Focardi S., De Marinis A. M., Rizzotto M. & Pucci A. (2001). Comparative evaluation of thermal infrared imaging and spotlighting to survey wildlife. Wildlife Society Bulletin 29 (1): 133–139.

Focardi S., Isotti R. & Tinelli A. (2002). Line transect estimates of ungulate populations in a Mediterranean forest. The Journal of Wildlife Management 66 (1): 48–58.

Frederik J.M. (1998). Overview of wild pig damage in California. In: Baker R.O. & Crabb A.C. (eds) Proceedings of the Eighteenth Vertebrate Pest Conference (1998): 82–86. University of California, Davis.

Hu S. (2007). Akaike information criterion. Center for Research in Scientific Computation: 93.

Keuling O., Strauß E. & Siebert U. (2016). Regulating wild boar populations is “somebody else’s problem”! - Human dimension in wild boar management. Science of the Total Environment: 554–555, 311–319.

Lard C., Willis D.B., Salin V. & Robison S. (2002). Economic assessments of red imported fire ant on Texas’ urban and agricultural sectors. Southwestern Entomologist 25: 123–137.

Lefever S., Dal M. & Matthiasdottir A. (2007). Online data collection in academic research: advantages and limitations. British Journal of Educational Technology 38: 574–582.

Linell J.D.C., Swenson J.E. & Andersen R. (2001). Predators and people: conservation of large carnivores is possible at high human densities if management policy is favourable. Animal Conservation 4: 345–349.

Lombardini M., Meriggi A. & Fozzi A. (2016). Factors influencing wild boar damage to agricultural crops in Sardinia (Italy). Current Zoology: 63 (5): 507–517.

Massei G., Genov P.V., Staines B.W. & Gorman M.L. (1997). Factors influencing home range and activity of wild boar (Sus scrofa) in a Mediterranean coastal area. The Zoological Society of London: 242: 411–423.

Massei G., Kindberg J., Licoppe A., Gacic D., Sprem N., Kamler J., Baubet E., Hohmann U., Monaco A., Ozolins J., Cellina S., Podgorski T., Fonseca C., Markov G., Pokorny B., Rosell C. & Nahlik A. (2015). Wild boar populations up, numbers of hunters down? A review of trends and implications for Europe. Pest Management Science 71: 492–500.

Melis C., Szafranska P.A., Jedrzejewske B. & Barton K. (2006). Biogeographical variation in the population density of wild boar (Sus scrofa) in western Eurasia. Journal of biogeography 33: 803–811.

Moore N., Whiterow A., Kelly P., Garthwaite D., Bishop J., Langton S. & Cheeseman C. (1999). Survey of badger Meles meles damage to agriculture in England and Wales. Journal of Applied Ecology 36: 974–988.

Moors I. (2014). De Limburgse Land- en Tuinbouw in Kaart: Analyserapport: 1–34. De deputatie van de provincieraad van Limburg, Hasselt.

Morelle K., Fattebert J., Mengal C. & Lejeune P. (2016). Invading or recolonizing? Patterns and drivers of wild boar population expansion into Belgian agroecosystems. Agriculture Ecosystems & Environment 222: 267–275.

Nulty D.D. (2008). The adequacy of response rates to online and paper surveys: what can be done? Assessment & Evaluation in Higher Education 33: 301–314.

R Core TEAM. (2016). R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria.

Reiter D.K., Brunson M.W. & Schmidt R.H. (1999). Public attitudes towards wildlife damage management and policy. Wildlife Society Bulletin 27 (3): 746–758.

Riley S.J., Siemer W., Decker D., Carpenter L., Organ J. & Berchielli L. (2003). Adaptive Impact Management: An Integrative Approach to Wildlife Management. Human Dimensions of Wildlife 8: 81–95.

Rutten A., Casaer, J. Vogels M.F.A., Addink E.A., Vanden Borre J. & Leirs H. (2018). Assessing agricultural damage by wild boar using drones. Wildlife Society Bulletin 42 (4): 568–576.

Saez-Royuela C. & Telleria J.L. (1986). The increased population of the Wild Boar (Sus scrofa L.) in Europe. Mammal Review 16 (2) 97–101.

Scheppers T. & Casaer J. (2012). Overzicht van mogelijke telmethoden voor everzwijn. INBO rapport: 1–40. Available from [accessed on 17 March 2017].

Scheppers T., Huysentruyt F., Neukermans A., Vercammen E., Verschaffel E. & Casaer J. (2014). Grofwildjacht in Vlaanderen - Cijfers en statistieken 2013. INBO rapport, INBO, Brussels. Available from [accessed on 17 March 2017].

Schley L., Dufrêne M., Krier A. & Frantz A.C. (2008). Patterns of crop damage by wild boar (Sus scrofa) in Luxembourg over a 10-year period. European Journal of Wildlife Research 54 (4): 589–599.

Sexton N.R., Miller H.M. & Dietsch A.M. (2011). Appropriate uses and considerations for online surveying in human dimensions research. Human Dimensions of Wildlife 16 (3): 154–163.

Signorille A.L. & Evans J. (2007). Damage caused by the American grey squirrel (Sciurus carolinensis) to agricultural crops, poplar plantations and semi-natural woodland in Piedmont, Italy. Forestry 80 (1): 89–98.

Stone C.P. (1973). Bird damage to agricultural crops in the United States - a current summary. Bird Control Seminars Proceedings 1: 263–267.

Treves A., Wallace R.B., Naughton-Treves L. & Morales A. (2006). Co-managing human–wildlife conflicts: A Review. Human Dimensions of Wildlife 11: 383–396.

Trouwborst A. (2010). Managing the carnivore comeback: international and EU species protection law and the return of lynx, wolf and bear to Western Europe. Journal of Environmental Law 22 (3): 347–372.

White P.C.L., Jennings N.V., Renwick A.R. & Barker N.H.L. (2005). Questionnaires in ecology: a review of past use and recommendations for best practice. Journal of Applied Ecology 42: 421–430.

Widar J. & Luxen P. (2016). Statistiques de dégâts agricoles de la faune sauvage, issues des données des experts : évolution de 2008 à 2014. Fourrages mieux: 1–124.



  • There are currently no refbacks.

The Royal Belgian Society of Zoology acknowledges the Universitarian Foundation of Belgium and the National Fund of Scientific Research for their financial support in publishing the Belgian Journal of Zoology.