Aerial shooting is unlikely to cause dispersal or consistent changes in the movements of feral pigs (Sus scrofa)

Andrew J. Bengsen; Sebastien Comte; Troy Crittle; Suzie Holbery; Darren Marshall; Lachlan Marshall; Lee Parker; David M. Forsyth

doi:10.1071/WR25024

RESEARCH ARTICLE (Open Access)

Next Contents Vol 52(6)

Aerial shooting is unlikely to cause dispersal or consistent changes in the movements of feral pigs (Sus scrofa)

Andrew J. Bengsen

^A ^* , Sebastien Comte

^B ^C , Troy Crittle ^D , Suzie Holbery ^E , Darren Marshall ^F , Lachlan Marshall ^F , Lee Parker ^A and David M. Forsyth

^B ^C

+ Author Affiliations

- Author Affiliations

^A NSW Department of Primary Industries and Regional Development, Vertebrate Pest Research Unit, 4 Marsden Park Road, Calala, NSW 2340, Australia.

^B NSW Department of Primary Industries and Regional Development, Vertebrate Pest Research Unit, 1447 Forest Road, Orange, NSW 2800, Australia.

^C Evolution & Ecology Research Centre, The University of New South Wales, Sydney, NSW, Australia.

^D NSW Department of Primary Industries and Regional Development, 4 Marsden Park Road, Calala, NSW 2340, Australia.

^E Riverina Local Land Services, 56 Lachlan Street, Hay, NSW 2711, Australia.

^F Centre for Invasive Species Solutions, University of Canberra, Building 22, University Drive, Bruce, ACT 2617, Australia.

^* Correspondence to: andrew.bengsen@dpi.nsw.gov.au

Handling Editor: Penny Fisher

Wildlife Research 52, WR25024 https://doi.org/10.1071/WR25024

Submitted: 21 February 2025 Accepted: 11 May 2025 Published: 29 May 2025

© 2025 The Author(s) (or their employer(s)). Published by CSIRO Publishing. This is an open access article distributed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND)

Abstract

Context

Aerial shooting is an important tool for managing feral pig damage to agricultural and biodiversity assets because it can rapidly reduce population densities over large areas. It should also be valuable for reducing host population densities in the event of an emergency animal disease incursion. However, recent tracking studies have not alleviated concerns that the intense disturbance caused by aerial shooting might cause pigs to disperse from target areas.

Aims

We investigated the responses of feral pigs to nine aerial shooting operations conducted at five large and divergent sites in south-eastern Australia.

Methods

We fitted 71 pigs with GPS tracking collars and monitored changes in their behaviour following exposure to aerial shooting operations that lasted between 1 and 11 days. Repeated exposure of some individuals provided 105 distinct samples. We examined the following three key traits: the location and size of activity ranges, daily activity and movement rates, and daily activity cycles.

Key results

We found inconsistent results between sexes and among operations. However, only one pig left the target area after shooting began. This pig did not return.

Conclusions

The fine-scale behaviour of pigs subjected to aerial shooting is likely to vary because of a complex interplay of social, environmental, and operational factors. Behaviour changes observed in this study were unlikely to cause the dispersal of feral pigs or their impacts.

Implications

Given our results, and those of previous studies, we believe that aerial shooting should continue to be used as a key method for managing feral pig populations and should also be considered for emergency animal disease response operations.

Keywords: aerial culling, behavioural responses, depopulation, feral swine, GPS tracking, movement ecology, population control, transboundary animal disease, wild boar, wildlife management.

References

African Swine Fever Feral Pig Task Group (2020) African Swine Fever (ASF) Feral Pig Task Group Report. Animal Health Committee, Australian Department of Agriculture, Water and the Environment, Canberra, ACT, Australia.

Animal Health Australia (2023) ‘Operational manual: wild animal response strategy (version 5.0).’ (Australian Veterinary Emergency Plan (AUSVETPLAN): Canberra, ACT, Australia)

Artois M, Delahay R, Guberti V, Cheeseman C (2001) Control of infectious diseases of wildlife in Europe. The Veterinary Journal 162, 141-152.
| Crossref | Google Scholar | PubMed |

Bates D, Mächler M, Bolker B, Walker S (2015) Fitting linear mixed-effects models using lme4. Journal of Statistical Software 67, 1-48.
| Crossref | Google Scholar |

Bengsen AJ, Gentle MN, Mitchell JL, Pearson HE, Saunders GR (2014) Impacts and management of wild pigs Sus scrofa in Australia. Mammal Review 44, 135-147.
| Crossref | Google Scholar |

Bengsen AJ, West P, Krull CR (2017) Feral pigs in Australia and New Zealand: range, trend, management and impacts of an invasive species. In ‘Ecology, evolution and management of wild pigs and peccaries. Implications for conservation’. (Eds M Melletti, E Meijaard) pp. 325–338. (Cambridge University Press: Cambridge)

Bengsen AJ, Comte S, Parker L, Forsyth DM, Hampton JO (2024) Site fidelity trumps disturbance: aerial shooting does not cause surviving fallow deer (Dama dama) to disperse. Wildlife Research 51, WR24098.
| Crossref | Google Scholar |

Benhamou S (2011) Dynamic approach to space and habitat use based on biased random bridges. PLoS ONE 6, e14592.
| Crossref | Google Scholar |

Benhamou S, Cornélis D (2010) Incorporating movement behavior and barriers to improve kernel home range space use estimates. The Journal of Wildlife Management 74, 1353-1360.
| Crossref | Google Scholar |

Bevins SN, Pedersen K, Lutman MW, Gidlewski T, Deliberto TJ (2014) Consequences associated with the recent range expansion of nonnative feral swine. BioScience 64, 291-299.
| Crossref | Google Scholar |

Bjørneraas K, Van Moorter B, Rolandsen CM, Herfindal I (2010) Screening global positioning system location data for errors using animal movement characteristics. Journal of Wildlife Management 74, 1361-1366.
| Crossref | Google Scholar |

Brooks ME, Kristensen K, van Benthem KJ, Magnusson A, Berg CW, Nielsen A, Skaug HJ, Mächler M, Bolker BM (2017) glmmTMB balances speed and flexibility among packages for zero-inflated generalized linear mixed modeling. The R Journal 9, 378-400.
| Crossref | Google Scholar |

Calenge C (2006) The package ‘adehabitat’ for the R software: a tool for the analysis of space and habitat use by animals. Ecological Modelling 197, 516-519.
| Crossref | Google Scholar |

Campbell TA, Long DB, Leland BR (2010) Feral swine behavior relative to aerial gunning in southern Texas. The Journal of Wildlife Management 74, 337-341.
| Crossref | Google Scholar |

Campbell TA, Long DB, Lavelle MJ, Leland BR, Blankenship TL, VerCauteren KC (2012) Impact of baiting on feral swine behavior in the presence of culling activities. Preventive Veterinary Medicine 104, 249-257.
| Crossref | Google Scholar | PubMed |

Chalkowski K, Pepin KM, Lavelle MJ, Miller RS, Fischer J, Brown VR, Glow M, Smith B, Cook S, Kohen K, Sherburne S, Smith H, Leland B, VerCauteren KC, Snow NP (2025) Operational lessons learned from simulating an elimination response to a transboundary animal disease in wild animals. Preventive Veterinary Medicine 234, 106365.
| Crossref | Google Scholar |

Choquenot D, Hone J, Saunders G (1999) Using aspects of predator–prey theory to evaluate helicopter shooting for feral pig control. Wildlife Research 26, 251-261.
| Crossref | Google Scholar |

Coffey R, Parker G, Laurent K (1999) Assessing sow body condition. Publication ASC 158. Cooperative Extension Service, College of Agriculture, University of Kentucky, Kentucky, USA.

Commonwealth of Australia, Department of Climate Change, Energy, the Environment and Water 2024 (2016) Interim Biogeographic Regionalisation for Australia (IBRA), Version 7 (Regions)). Commonwealth of Australia, Department of Climate Change, Energy, the Environment and Water 2024.

Cowled BD, Garner MG, Negus K, Ward MP (2012) Controlling disease outbreaks in wildlife using limited culling: modelling classical swine fever incursions in wild pigs in Australia. Veterinary Research 43, 3.
| Crossref | Google Scholar |

Cox TE, Paine D, O’Dwyer-Hall E, Matthews R, Blumson T, Florance B, Fielder K, Tarran M, Korcz M, Wiebkin A, Hamnett PW, Bradshaw CJA, Page B (2023) Thermal aerial culling for the control of vertebrate pests populations. Scientific Reports 13, 10063.
| Crossref | Google Scholar |

Cromsigt JPGM, Kuijper DPJ, Adam M, Beschta RL, Churski M, Eycott A, Kerley GIH, Mysterud A, Schmidt K, West K (2013) Hunting for fear: innovating management of human–wildlife conflicts. Journal of Applied Ecology 50, 544-549.
| Crossref | Google Scholar |

Dalziel AE, Peck HA, Hurt AC, Cooke J, Cassey P (2016) Proposed surveillance for influenza A in feral pigs. EcoHealth 13, 410-414.
| Crossref | Google Scholar | PubMed |

Davis AJ, Leland B, Bodenchuk M, VerCauteren KC, Pepin KM (2018) Costs and effectiveness of damage management of an overabundant species (Sus scrofa) using aerial gunning. Wildlife Research 45, 696-705.
| Crossref | Google Scholar |

Davis NE, Forsyth DM, Bengsen AJ (2023) Diet and impacts of non-native fallow deer (Dama dama) on pastoral properties during severe drought. Wildlife Research 50, 701-715.
| Crossref | Google Scholar |

Denwood MJ (2016) runjags: an R package providing interface utilities, model templates, parallel computing methods and additional distributions for MCMC models in JAGS. Journal of Statistical Software 71, 1-25.
| Crossref | Google Scholar |

Dexter N (1996) The effect of an intensive shooting exercise from a helicopter on the behaviour of surviving feral pigs. Wildlife Research 23, 435-441.
| Crossref | Google Scholar |

Dexter N (1999) The influence of pasture distribution, temperature and sex on home-range size of feral pigs in a semi-arid environment. Wildlife Research 26, 755-762.
| Crossref | Google Scholar |

FAAST (2020) ‘The FAAST Manual. Version 2.3 (August 2020).’ (National Parks & Wildlife Service, NSW Local Land Services and NSW Department of Primary Industries, on behalf of the NSW Government: Sydney, NSW, Australia)

Fernández-Llario P (2004) Environmental correlates of nest site selection by wild boar Sus scrofa. Acta Theriologica 49, 383-392.
| Crossref | Google Scholar |

Fischer JW, McMurtry D, Blass CR, Walter WD, Beringer J, VerCauteren KC (2016) Effects of simulated removal activities on movements and space use of feral swine. European Journal of Wildlife Research 62, 285-292.
| Crossref | Google Scholar |

Gentle M, Wilson C, Cuskelly J (2022) Feral pig management in Australia: implications for disease control. Australian Veterinary Journal 100, 492-495.
| Crossref | Google Scholar | PubMed |

Ham C, Donnelly CA, Astley KL, Jackson SYB, Woodroffe R (2019) Effect of culling on individual badger Meles meles behaviour: potential implications for bovine tuberculosis transmission. Journal of Applied Ecology 56, 2390-2399.
| Crossref | Google Scholar | PubMed |

Kay SL, Fischer JW, Monaghan AJ, Beasley JC, Boughton R, Campbell TA, Cooper SM, Ditchkoff SS, Hartley SB, Kilgo JC, Wisely SM, Wyckoff AC, VerCauteren KC, Pepin KM (2017) Quantifying drivers of wild pig movement across multiple spatial and temporal scales. Movement Ecology 5, 14.
| Crossref | Google Scholar |

Keuling O, Massei G (2021) Does hunting affect the behavior of wild pigs? Human–Wildlife Interactions 15, 11.
| Crossref | Google Scholar |

Keuling O, Stier N, Roth M (2008) How does hunting influence activity and spatial usage in wild boar Sus scrofa L.? European Journal of Wildlife Research 54, 729-737.
| Crossref | Google Scholar |

Kwiatkowski D, Phillips PCB, Schmidt P, Shin Y (1992) Testing the null hypothesis of stationarity against the alternative of a unit root: how sure are we that economic time series have a unit root? Journal of Econometrics 54, 159-178.
| Crossref | Google Scholar |

Lima SL, Bednekoff PA (1999) Temporal variation in danger drives antipredator behavior: the predation risk allocation hypothesis. The American Naturalist 153, 649-659.
| Crossref | Google Scholar | PubMed |

Long JL (2003) ‘Introduced mammals of the world: their history, distribution, and influence.’ (CSIRO Publishing: Melbourne, Vic, Australia)

Macdonald DW, Riordan P, Mathews F (2006) Biological hurdles to the control of TB in cattle: a test of two hypotheses concerning wildlife to explain the failure of control. Biological Conservation 131, 268-286.
| Crossref | Google Scholar |

Maillard D, Fournier P (1995) Effects of shooting with hounds on size of resting range of wild boar (Sus scrofa L.) groups in Mediterranean habitat. Journal of Mountain Ecology 3, e107.
| Google Scholar |

Massei G, Genov PV, Staines BW, Gorman ML (1997) Factors influencing home range and activity of wild boar (Sus scrofa) in a Mediterranean coastal area. Journal of Zoology 242, 411-423.
| Crossref | Google Scholar |

Massei G, Roy S, Bunting R (2011) Too many hogs? A review of methods to mitigate impact by wild boar and feral hogs. Human-Wildlife Interactions 5, 10.
| Crossref | Google Scholar |

Morelle K, Podgórski T, Prévot C, Keuling O, Lehaire F, Lejeune P (2015) Towards understanding wild boar Sus scrofa movement: a synthetic movement ecology approach. Mammal Review 45, 15-29.
| Crossref | Google Scholar |

O’Dwyer-Hall E, Cox TE (2021) Hay thermal survey. New South Wales Department of Primary Industries, Orange, NSW, Australia.

Overend ED (1980) Badgers and TB – does gassing spread the disease? Oryx 15, 338-340.
| Crossref | Google Scholar |

Pavanato H, Fewster R, Redmond A, Bengsen AJ, Amos M, Forsyth DM, MacKenzie D (2025) Multi-species abundance estimates using three-observer mark–recapture distance sampling surveys in Cuttaburra Basin, New South Wales. Report for Department of Primary Industries, NSW, Australia, Proteus Client Report: 196. Proteus, Outram, New Zealand.

Pedrosa F, Salerno R, Padilha FVB, Galetti M (2015) Current distribution of invasive feral pigs in Brazil: economic impacts and ecological uncertainty. Natureza & Conservação 13, 84-87.
| Crossref | Google Scholar |

Pepin KM, Brown VR, Yang A, Beasley JC, Boughton R, VerCauteren KC, Miller RS, Bevins SN (2022) Optimising response to an introduction of African swine fever in wild pigs. Transboundary and Emerging Diseases 69, e3111-e3127.
| Crossref | Google Scholar | PubMed |

Plummer M (2003) JAGS: a program for analysis of Bayesian graphical models using Gibbs sampling. In ‘Proceedings of the 3rd International Workshop on Distributed Statistical Computing’. (Eds K Hornik, F Leisch, A Zeileis) pp. 1–8. (Technische Universität Wien: Vienna, Austria)

Prentice JC, Fox NJ, Hutchings MR, White PCL, Davidson RS, Marion G (2019) When to kill a cull: factors affecting the success of culling wildlife for disease control. Journal of The Royal Society Interface 16, 20180901.
| Crossref | Google Scholar |

Proboste T, Turnlund A, Bengsen AJ, Gentle M, Wilson C, Harriott L, Fuller RA, Marshall D, Soares Magalhães RJ (2024) Quantifying feral pig interactions to inform disease transmission networks. eLife 13, RP102643.
| Crossref | Google Scholar |

R Core Team (2024) ‘R: a language and environment for statistical computing.’ (R Foundation for Statistical Computing: Vienna, Austria)

Reinke H, König HJ, Keuling O, Kuemmerle T, Kiffner C (2021) Zoning has little impact on the seasonal diel activity and distribution patterns of wild boar (Sus scrofa) in an UNESCO Biosphere Reserve. Ecology and Evolution 11, 17091-17105.
| Crossref | Google Scholar | PubMed |

Riordan P, Delahay RJ, Cheeseman C, Johnson PJ, Macdonald DW (2011) Culling-induced changes in badger (Meles meles) behaviour, social organisation and the epidemiology of bovine tuberculosis. PLoS ONE 6, e28904.
| Crossref | Google Scholar |

Saïd S, Tolon V, Brandt S, Baubet E (2012) Sex effect on habitat selection in response to hunting disturbance: the study of wild boar. European Journal of Wildlife Research 58, 107-115.
| Crossref | Google Scholar |

Saunders G, Bryant H (1988) The evaluation of a feral pig eradication program during a simulated exotic disease outbreak. Australian Wildlife Research 15, 73-81.
| Crossref | Google Scholar |

Scheffer M, Bascompte J, Brock WA, Brovkin V, Carpenter SR, Dakos V, Held H, van Nes EH, Rietkerk M, Sugihara G (2009) Early-warning signals for critical transitions. Nature 461, 53-59.
| Crossref | Google Scholar | PubMed |

Scillitani L, Monaco A, Toso S (2010) Do intensive drive hunts affect wild boar (Sus scrofa) spatial behaviour in Italy? Some evidences and management implications. European Journal of Wildlife Research 56, 307-318.
| Crossref | Google Scholar |

Silk MJ, Hodgson DJ, Rozins C, Croft DP, Delahay RJ, Boots M, McDonald RA (2019) Integrating social behaviour, demography and disease dynamics in network models: applications to disease management in declining wildlife populations. Philosophical Transactions of the Royal Society B: Biological Sciences 374, 20180211.
| Crossref | Google Scholar |

Snow NP, Smith B, Lavelle MJ, Glow MP, Chalkowski K, Leland BR, Sherburne S, Fischer JW, Kohen KJ, Cook SM, Smith H, VerCauteren KC, Miller RS, Pepin KM (2024) Comparing efficiencies of population control methods for responding to introductions of transboundary animal diseases in wild pigs. Preventive Veterinary Medicine 233, 106347.
| Crossref | Google Scholar |

Sodeikat G, Pohlmeyer K (2003) Escape movements of family groups of wild boar Sus scrofa influenced by drive hunts in Lower Saxony, Germany. Wildlife Biology 9, 43-49.
| Crossref | Google Scholar |

Thaker M, Vanak AT, Owen CR, Ogden MB, Niemann SM, Slotow R (2011) Minimizing predation risk in a landscape of multiple predators: effects on the spatial distribution of African ungulates. Ecology 92, 398-407.
| Crossref | Google Scholar | PubMed |

Thurfjell H, Spong G, Ericsson G (2013) Effects of hunting on wild boar Sus scrofa behaviour. Wildlife Biology 19, 87-93.
| Crossref | Google Scholar |

van der Linden IFA, Voermans JJM, van der Linde-Bril EM, Bianchi ATJ, Steverink PJGM (2003) Virological kinetics and immunological responses to a porcine reproductive and respiratory syndrome virus infection of pigs at different ages. Vaccine 21, 1952-1957.
| Crossref | Google Scholar | PubMed |

van Doormaal N, Ohashi H, Koike S, Kaji K (2015) Influence of human activities on the activity patterns of Japanese sika deer (Cervus nippon) and wild boar (Sus scrofa) in central Japan. European Journal of Wildlife Research 61, 517-527.
| Crossref | Google Scholar |

Water NSW (2024) Real-time water data. Water NSW.

Waudby HP, Turner JM, Coulson G, Taggart D, Watson D, Bengsen AJ, Meek PD, Bower DS, Thompson S, Lumsden L, Hampton JO, Death C, Thompson G, Finlayson G, Hamilton DG, Petit S, Dunlop J, Bentley J, Vanderduys E, Ballard GA, Morrant DS (2022) Wildlife capture methods. In ‘Wildlife research in Australia – a practical guide’. (Eds B Smith, HP Waudby, JO Hampton) pp. 108–149. (CSIRO Publishing: Melbourne, Vic, Australia)

Williams SC, DeNicola AJ, Ortega IM (2008) Behavioral responses of white-tailed deer subjected to lethal management. Canadian Journal of Zoology 86, 1358-1366.
| Crossref | Google Scholar |

Wilson C, Gentle M, Marshall D (2023) Feral pig (Sus scrofa) activity and landscape feature revisitation across four sites in eastern Australia. Australian Mammalogy 45, 305-316.
| Crossref | Google Scholar |

Wood SN (2011) Fast stable restricted maximum likelihood and marginal likelihood estimation of semiparametric generalized linear models. Journal of the Royal Statistical Society Series B: Statistical Methodology 73, 3-36.
| Crossref | Google Scholar |

Zeileis A, Leisch F, Hornik K, Kleiber C (2002) strucchange: an R package for testing for structural change in linear regression models. Journal of Statistical Software 7, 1-38.
| Crossref | Google Scholar |