Establishing protocols to apply repellents while hazing crop pests: importance of habitat, flock size, and time on blackbird (Icteridae) responses to a drone capable of spraying

Mallory G. White; Jessica L. Duttenhefner; Page E. Klug

doi:10.1071/WR24066

RESEARCH ARTICLE (Open Access)

Previous Next Contents Vol 52(3)

Establishing protocols to apply repellents while hazing crop pests: importance of habitat, flock size, and time on blackbird (Icteridae) responses to a drone capable of spraying

Mallory G. White ^A , Jessica L. Duttenhefner ^A and Page E. Klug

^B ^*

+ Author Affiliations

- Author Affiliations

^A Environmental and Conservation Sciences Program, Department of Biological Sciences, North Dakota State University, 1340 Bolley Drive, Fargo, ND 58102, USA.

^B United States Department of Agriculture, Animal and Plant Health Inspection Service, Wildlife Services, National Wildlife Research Center, Department of Biological Sciences, North Dakota State University, 1340 Bolley Drive, Fargo, ND 58102, USA.

^* Correspondence to: page.e.klug@usda.gov

Handling Editor: Peter Brown

Wildlife Research 52, WR24066 https://doi.org/10.1071/WR24066

Submitted: 17 April 2024 Accepted: 15 February 2025 Published: 6 March 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

Drones can be used as frightening devices to resolve avian-agriculture conflicts. Blackbird (Icteridae) flocks respond to drones making them a suitable scare device to protect sunflower (Helianthus annuus), but with limited efficacy on large flocks. Integrating a non-lethal avian repellent on the same drone as used for hazing may increase efficacy, but responses of flocks towards drones with spraying capabilities need to be evaluated to inform application protocols.

Aim

We evaluated flock responses to a drone capable of spraying when first approached and with 10 min of hazing, to inform protocols for delivering repellents on agricultural landscapes.

Methods

We used eye-in-the-sky drones to video the drone with spraying capabilities and observed whether flocks took flight within 80 m (i.e. range of potential spray drift). We measured flight initiation distance (FID) when close approach occurred (i.e. drone ≤80 m from flock). While hazing, we piloted the drone to (1) repeatedly cut through a flock and create chaos or (2) move along the flock edge to herd birds out of target habitat (i.e. sunflower or cattail). We recorded abandonment, flock reduction, and return rate of birds in response to drone hazing.

Key results

The probability of a close approach was greater with birds in cattail than in sunflower, but habitat did not influence mean FID when the drone was within 80 m (FID = 40 m ± 14.3 s.d.), abandonment (31 of 60 flocks), or mean percentage flock reduction (50% ± 37 s.d.). FID was shorter with smaller flocks, later in the day, but abandonment increased with smaller flocks as the day progressed. Although 52% of flocks abandoned, 81% returned after the end of hazing. Flight path of the drone (i.e. chaotic or herding) did not affect abandonment or flock reduction.

Conclusions

Although blackbirds perceived the drone approach as riskier (>FID) while foraging in sunflower earlier in the day, increased abandonment that occurred later in the day was likely to be due to satiation and movement to night-time roosts, instead of hazing impacts. Birds in sunflower interspersed with cattail used local refugia until the threat passed, then resumed foraging.

Implications

If applying an avian repellent with a spraying drone, protocols should consider time of day, flock size, and habitat. When selecting a flight path, pilots need to be concerned only with optimizing spray drift to reach areas with foraging blackbirds.

Keywords: antipredator behavior, crop damage, deterrent tools, human–wildlife conflict, remotely-piloted aircraft systems, UAS, UAV, vertebrate pests, visual deterrent.

References

Abdulwahab UA, Osinubi ST, Abalaka J (2019) Risk of predation: A critical force driving habitat quality perception and foraging behavior of granivorous birds in a Nigerian forest reserve. Avian Research 10, 33.
| Crossref | Google Scholar |

Ampatzidis Y, Ward J, Samara O (2015) Autonomous system for pest bird control in specialty crops using unmanned aerial vehicles. In ‘Annual International Meeting, American Society of Agricultural and Biological Engineers’, ASABE Paper No. 152181748. (ASABE: St. Joseph, MI, USA). Available at https://doi.org/10.13031/aim.20152181748

Ballerini M, Cabibbo N, Candelier R, Cavagna A, Cisbani E, Giardina I, Orlandi A, Parisi G, Procaccini A, Viale M, Zdravkovic V (2008) Empirical investigation of starling flocks: A benchmark study in collective animal behaviour. Animal Behaviour 76, 201-215.
| Crossref | Google Scholar |

Bansal S, Lishawa SC, Newman S, Tangen BA, Wilcox D, Albert D, Anteau MJ, Chimney MJ, Cressey RL, DeKeyser E, Elgersma KJ, Finkelstein SA, Freeland J, Grosshans R, Klug PE, Larkin DJ, Lawrence BA, Linz G, Marburger J, Noe G, Otto C, Reo N, Richards J, Richardson C, Rodgers L, Schrank AJ, Svedarsky D, Travis S, Tuchman N, Windham-Myers L (2019) Typha (cattail) invasion in North American wetlands: Biology, regional problems, impacts, ecosystem services, and management. Wetlands 39, 645-684.
| Crossref | Google Scholar |

Barnas AF, Darby BJ, Vandeberg GS, Rockwell RF, Ellis-Felege SN (2019) A comparison of drone imagery and ground-based methods for estimating the extent of habitat destruction by lesser snow geese (Anser caerulescens caerulescens) in La Pérouse Bay. PLoS ONE 14, e0217049.
| Crossref | Google Scholar |

Besser JF, Berg WJ, Knittle CE (1979) Late-summer feeding patterns of red-winged blackbirds in a sunflower-growing area of North Dakota. In ‘Bird control seminars proceedings’. (Ed. WB Jackson) pp. 209–214. (Bowling Green University: Bowling Green, Ohio, USA). Available at https://digitalcommons.unl.edu/icwdmbirdcontrol/27.

Bhusal S, Khanal K, Karkee M, Steensma KM, Taylor ME (2018) Unmanned aerial systems (UAS) for mitigating bird damage in wine grapes. In ‘Proceedings of the 14^th international conference on precision agriculture’, Montreal, Quebec, Canada. (International Society of Precision Agriculture: Monticello, IL, USA)

Blumstein DT (2003) Flight-initiation distance in birds is dependent on intruder starting distance. The Journal of Wildlife Management 67, 852-857.
| Crossref | Google Scholar |

Burr PC, Samiappan S, Hathcock LA, Moorhead RJ, Dorr BS (2019) Estimating waterbird abundance on catfish aquaculture ponds using an unmanned aerial system. Human–Wildlife Interactions 13, 317-330 Available at https://digitalcommons.unl.edu/icwdm_usdanwrc/2302.
| Google Scholar |

Carlson JC, Tupper SK, Werner SJ, Pettit SE, Santer MM, Linz GM (2013) Laboratory efficacy of an anthraquinone-based repellent for reducing bird damage to ripening corn. Applied Animal Behaviour Science 145, 26-31.
| Crossref | Google Scholar |

Chilvers BL (2024) Techniques for hazing and deterring birds during an oil spill. Marine Pollution Bulletin 201, 116276.
| Crossref | Google Scholar |

Clark BA, Klug PE, Stepanian PM, Kelly JF (2020) Using bioenergetics and radar-derived bird abundance to assess the impact of a blackbird roost on seasonal sunflower damage. Human-Wildlife Interactions 14, 427-441.
| Crossref | Google Scholar |

Conover MR (2002) ‘Resolving human-wildlife conflicts: the science of wildlife damage management.’ (CRC Press: Boca Raton, FL, USA)

Cooper WE Jr, Blumstein DT (2015) ‘Escaping from predators: an integrative view of escape decisions.’ (Cambridge University Press: Cambridge, UK)

Cresswell W (1994) Flocking is an effective anti-predation strategy in redshanks, Tringa totanus. Animal Behaviour 47, 433-442.
| Crossref | Google Scholar |

DeLiberto ST, Werner SJ (2024) Applications of chemical bird repellents for crop and resource protection: A review and synthesis. Wildlife Research 51, WR23062.
| Crossref | Google Scholar |

Devereux CL, Fernández-Juricic E, Krebs JR, Whittingham MJ (2008) Habitat affects escape behaviour and alarm calling in common starlings Sturnus vulgaris. Ibis 150, 191-198.
| Crossref | Google Scholar |

Dolbeer RA (1990) Ornithology and integrated pest management: red-winged blackbirds Agelaius phoeniceus and corn. Ibis 132, 309-322.
| Crossref | Google Scholar |

Dolbeer RA, Linz GM (2016) ‘Blackbirds.’ Wildlife damage management technical series. (US Department of Agriculture, Animal & Plant Health Inspection Service, Wildlife Services: Fort Collin, CO, USA). Available at http://digitalcommons.unl.edu/nwrcwdmts/1

Duttenhefner JL (2023) Dual-purpose use of drones: The hazing and monitoring of nuisance blackbirds damaging commercial sunflower. MS Thesis, Environmental and Conservation Sciences (Department of Biological Sciences), North Dakota State University, Fargo, ND, USA.

Duttenhefner JL, Klug PE (2024) Effective range of auditory frightening devices based on hearing capabilities and antipredator responses of nuisance blackbirds. Wildlife Society Bulletin 48, e1549.
| Crossref | Google Scholar |

Duttenhefner JL, Klug PE (2025) Observer estimation accuracy from drone-based imagery influenced by size of blackbird flocks foraging in sunflower. The Wilson Journal of Ornithology
| Crossref | Google Scholar |

Duttenhefner JL, Greives TJ, Klug PE (2024) Spraying drones: Efficacy of integrating an avian repellent with drone hazing to elicit blackbird flock dispersal and abandonment of sunflower fields. Wildlife Biology 2024, e01333.
| Crossref | Google Scholar |

Egan CC, Blackwell BF, Fernández-Juricic E, Klug PE (2020) Testing a key assumption of using drones as frightening devices: Do birds perceive drones as risky? The Condor 122, duaa014.
| Crossref | Google Scholar |

Egan CC, Blackwell BF, Fernández-Juricic E, Klug PE (2023) Dispersal of blackbird flocks from sunflower fields: Efficacy influenced by flock and field size but not drone platform. Wildlife Society Bulletin 47, e1478.
| Crossref | Google Scholar |

Ernst K, Elser J, Linz G, Kandel H, Holderieath J, DeGroot S, Shwiff S, Shwiff S (2019) The economic impacts of blackbird (Icteridae) damage to sunflower in the USA. Pest Management Science 75, 2910-2915.
| Crossref | Google Scholar | PubMed |

Fernández-Juricic E, Jimenez MD, Lucas E (2002) Factors affecting intra- and inter-specific variations in the difference between alert distances and flight distances for birds in forested habitats. Canadian Journal of Zoology 80, 1212-1220.
| Crossref | Google Scholar |

Fernández-Juricic E, Deisher M, Stark AC, Randolet J (2012) Predator detection is limited in microhabitats with high light intensity: An experiment with brown-headed cowbirds. Ethology 118, 341-350.
| Crossref | Google Scholar |

Forcey GM, Thogmartin WE, Linz GM, Mckann PC, Crimmins SM (2015) Spatially explicit modeling of blackbird abundance in the Prairie Pothole Region. The Journal of Wildlife Management 79, 1022-1033.
| Crossref | Google Scholar |

Friesenhahn BA, Massey LD, DeYoung RW, Cherry MJ, Fischer JW, Snow NP, VerCauteren KC, Perotto-Baldivieso HL (2023) Using drones to detect and quantify wild pig damage and yield loss in corn fields throughout plant growth stages. Wildlife Society Bulletin 47, e1437.
| Crossref | Google Scholar |

Gill JA, Norris K, Sutherland WJ (2001) Why behavioural responses may not reflect the population consequences of human disturbance. Biological Conservation 97, 265-268.
| Crossref | Google Scholar |

Hahn N, Mwakatobe A, Konuche J, de Souza N, Keyyu J, Goss M, Chang’a A, Palminteri S, Dinerstein E, Olson D (2017) Unmanned aerial vehicles mitigate human–elephant conflict on the borders of Tanzanian Parks: A case study. Oryx 51, 513-516.
| Crossref | Google Scholar |

Hintz JV, Dyer MI (1970) Daily rhythm and seasonal change in the summer diet of adult red-winged blackbirds. The Journal of Wildlife Management 34, 789-799.
| Crossref | Google Scholar |

Homan H, Slowik A, Linz G (2005) Fall dispersal patterns of red-winged blackbirds (Agelaius phoeniceus) migrating from the Prairie Pothole Region of North Dakota. Final Report: North Dakota Crop Protection Product Harmonization and Registration Board (Agreement No. 04-73-38-5502-TF).

Jarrett D, Calladine J, Cotton A, Wilson MW, Humphreys E (2020) Behavioural responses of non-breeding waterbirds to drone approach are associated with flock size and habitat. Bird Study 67, 190-196.
| Crossref | Google Scholar |

Kaiser BA, Johnson BL, Ostlie MH, Werner SJ, Klug PE (2021) Inefficiency of anthraquinone-based avian repellents when applied to sunflower: The importance of crop vegetative and floral characteristics in field applications. Pest Management Science 77, 1502-1511.
| Crossref | Google Scholar | PubMed |

Klosterman ME, Linz GM, Slowik AA, Homan HJ (2013) Comparisons between blackbird damage to corn and sunflower in North Dakota. Crop Protection 53, 1-5.
| Crossref | Google Scholar |

Klug PE (2017) The future of blackbird management research. In ‘Ecology and management of blackbirds (Icteridae) in North America’. (Eds GM Linz, ML Avery, RA Dolbeer) pp. 217–234. (CRC Press/Taylor & Francis: Boca Raton, FL, USA)

Klug PE, Shiels AB, Kluever BM, Anderson CJ, Hess SC, Ruell EW, Bukoski WP, Siers SR (2023) A review of nonlethal and lethal control tools for managing the damage of invasive birds to human assets and economic activities. Management of Biological Invasions 14, 1-44.
| Crossref | Google Scholar |

Laursen K, Kahlert J, Frikke J (2005) Factors affecting escape distances of staging waterbirds. Wildlife Biology 11, 13-19.
| Crossref | Google Scholar |

Lima SL, Dill LM (1990) Behavioral decisions made under the risk of predation: A review and prospectus. Canadian Journal of Zoology 68, 619-640.
| Crossref | Google Scholar |

Linz GM, Knittle CE, Cummings JL, Davis JE, Jr., Otis DL, Bergman DL (1991) Using aerial marking for assessing population dynamics of late summer roosting red-winged blackbirds. Prairie Naturalist 23, 117-126.
| Google Scholar |

Linz GM, Sawin RS, Lutman MW, Homan HJ, Penry LB, Bleier WJ (2003) Characteristics of spring and fall blackbird roosts in the northern Great Plains. In ‘Proceedings of the 10^th wildlife damage management conference’. (Eds KA Fagerstone, GW Witmer) pp. 220–228 (USDA National Wildlife Research Center: Hot Springs, AR, USA). Available at https://digitalcommons.unl.edu/icwdm_usdanwrc/242

Linz GM, Avery ML, Dolbeer RA (2017) ‘Ecology and management of blackbirds (Icteridae) in North America.’ (CRC Press/Taylor & Francis: Boca Raton, FL, USA)

Lunn RB, Blackwell BF, DeVault TL, Fernández-Juricic E (2022) Can we use antipredator behavior theory to predict wildlife responses to high-speed vehicles? PLoS ONE 17, e0267774.
| Crossref | Google Scholar |

Metcalfe NB (1984) The effects of habitat on the vigilance of shorebirds: is visibility important? Animal Behaviour 32, 981-985.
| Crossref | Google Scholar |

Mohamed WMW, Naim MNM, Abdullah A (2020) The efficacy of visual and auditory bird scaring techniques using drone at paddy fields. In ‘IOP conference series: materials science and engineering’. p. 012072. (IOP Publishing). Available at https://iopscience.iop.org/article/10.1088/1757-899X/834/1/012072

Paranjape AA, Chung S-J, Kim K, Shim DH (2018) Robotic herding of a flock of birds using an unmanned aerial vehicle. IEEE Transactions on Robotics 34, 901-915.
| Crossref | Google Scholar |

Penny SG, White RL, Scott DM, MacTavish L, Pernetta AP (2019) Using drones and sirens to elicit avoidance behaviour in white rhinoceros as an anti-poaching tactic. Proceedings of the Royal Society B: Biological Sciences 286, 20191135.
| Crossref | Google Scholar |

Pfeiffer MB, Blackwell BF, Seamans TW, Buckingham BN, Hoblet JL, Baumhardt PE, DeVault TL, Fernández-Juricic E (2021) Responses of turkey vultures to unmanned aircraft systems vary by platform. Scientific Reports 11, 21655.
| Crossref | Google Scholar |

Pfeiffer MB, Pullins CK, Beckerman SF, Hoblet JL, Blackwell BF (2023) Investigating nocturnal UAS treatments in an applied context to prevent gulls from nesting on rooftops. Wildlife Society Bulletin 47, e1423.
| Crossref | Google Scholar |

Rhoades CA, Allen PJ, King DT (2019) Using unmanned aerial vehicles for bird harassment on fish ponds. In ‘Proceedings of the 18^th wildlife damage management conference’. (Eds JB Armstrong, GR Gallagher) pp. 13–23. (USDA National Wildlife Research Center: Starkville, MS, USA) Available at https://digitalcommons.unl.edu/icwdm_usdanwrc/2290

Rodriguez-Prieto I, Fernández-Juricic E, Martín J (2008) To run or to fly: Low cost versus low risk escape strategies in blackbirds. Behaviour 145, 1125-1138.
| Crossref | Google Scholar |

Rosenberg KV, Dokter AM, Blancher PJ, Sauer JR, Smith AC, Smith PA, Stanton JC, Panjabi A, Helft L, Parr M, Marra PP (2019) Decline of the North American avifauna. Science 366, 120-124.
| Crossref | Google Scholar | PubMed |

RStudio Team (2020) RStudio: Integrated Development for R. RStudio, PBC, Boston, MA, USA. Available at http://www.rstudio.com/

Ryckman MD, Kemink K, Felege CJ, Darby B, Vandeberg GS, Ellis-Felege SN (2022) Behavioral responses of blue-winged teal and northern shoveler to unmanned aerial vehicle surveys. PLoS ONE 17, e0262393.
| Crossref | Google Scholar |

Sauer JR, Niven DK, Hines JE, Ziolkowski DJJ, Pardieck KL, Fallon JE, Link WA (2019) The North American breeding bird survey, results and analysis 1966–2019. Version 2.07.2019 USGS Patuxent Wildlife Research Center, Laurel, MD, USA.

Sausse C, Baux A, Bertrand M, Bonnaud E, Canavelli S, Destrez A, Klug PE, Olivera L, Rodriguez E, Tellechea G, Zuil S (2021) Contemporary challenges and opportunities for the management of bird damage at field crop establishment. Crop Protection 148, 105736.
| Crossref | Google Scholar |

Schneider CA, Rasband WS, Eliceiri KW (2012) NIH image to ImageJ: 25 years of image analysis. Nature Methods 9, 671-675.
| Crossref | Google Scholar | PubMed |

Schroeder NM, Panebianco A (2021) Sociability strongly affects the behavioural responses of wild guanacos to drones. Scientific Reports 11, 20901.
| Crossref | Google Scholar |

Shwiff SA, Ernest KL, Degroot SL, Anderson AM, Shwiff SS (2017) The economic impact of blackbird damage to crops. In ‘Ecology and management of blackbirds (Icteridae) in North America’. (Eds GM Linz, ML Avery, RA Dolbeer) pp. 207–216. (CRC Press/Taylor & Francis: Boca Raton, FL, USA)

Stonefish D, Eshleman MA, Linz GM, Jeffrey Homan H, Klug PE, Greives TJ, Gillam EH (2021) Migration routes and wintering areas of male Red-winged Blackbirds as determined using geolocators. Journal of Field Ornithology 92, 284-293.
| Crossref | Google Scholar |

Sumpter DJ (2010) ‘Collective animal behavior.’ (Princeton University Press: Princeton, NJ, USA)

Teräväinen M (2022) Push and pull strategies: Behaviour of geese in relation to scaring and set-aside fields. Lic Thesis, Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden.

Tracey J, Bomford M, Hart Q, Saunders G, Sinclair R (2006) ‘Managing bird damage to fruit and other horticultural crops.’ (Bureau of Rural Sciences: Canberra, ACT, Australia)

Vas E, Lescroël A, Duriez O, Boguszewski G, Grémillet D (2015) Approaching birds with drones: first experiments and ethical guidelines. Biology Letters 11, 20140754.
| Crossref | Google Scholar |

Wandrie LJ, Klug PE, Clark ME (2019) Evaluation of two unmanned aircraft systems as tools for protecting crops from blackbird damage. Crop Protection 117, 15-19.
| Crossref | Google Scholar |

Wang Z, Griffin AS, Lucas A, Wong KC (2019) Psychological warfare in vineyard: using drones and bird psychology to control bird damage to wine grapes. Crop Protection 120, 163-170.
| Crossref | Google Scholar |

Wang Z, Fahey D, Lucas A, Griffin AS, Chamitoff G, Wong KC (2020) Bird damage management in vineyards: Comparing efficacy of a bird psychology-incorporated unmanned aerial vehicle system with netting and visual scaring. Crop Protection 137, 105260.
| Crossref | Google Scholar |

Werner SJ, Homan HJ, Avery ML, Linz GM, Tillman EA, Slowik AA, Byrd RW, Primus TM, Goodall MJ (2005) Evaluation of Bird Shield™ as a blackbird repellent in ripening rice and sunflower fields. Wildlife Society Bulletin 33, 251-257.
| Crossref | Google Scholar |

White MG (2021) An evaluation of the social perceptions and biological efficacy of unmanned aircraft systems for avian-agriculture conflict. MS Thesis, Environmental and Conservation Sciences (Department of Biological Sciences). North Dakota State University, Fargo, ND, USA.

White MG, Duttenhefner JL, Klug PE (2024) Data for analysis of blackbird flock responses toward a spraying drone in an agroecosystem: Importance of flock size, habitat, and time of day. Research Dataset Series. USDA, APHIS, WS National Wildlife Research Center, Fort Collins, CO, USA.

Whittingham MJ, Evans KL (2004) The effects of habitat structure on predation risk of birds in agricultural landscapes. Ibis 146, 210-220.
| Crossref | Google Scholar |

Wilson JP, Amano T, Fuller RA (2023) Drone-induced flight initiation distances for shorebirds in mixed-species flocks. Journal of Applied Ecology 60, 1816-1827.
| Crossref | Google Scholar |

Zuur A, Ieno EN, Walker N, Saveliev AA, Smith GM (2009) ‘Mixed effects models and extensions in ecology with R.’ (Springer Science+Business Media: New York, NY, USA)