Camera-Trapping Versus Conventional Methodology in the Assessment of Carcass Persistence for Fatality Estimation at Wind Farms

  • Luís RosaEmail author
  • Tiago Neves
  • Diana Vieira
  • Miguel Mascarenhas


In the last decades, there has been a worldwide increase in wind energy. Despite its advantages, wind farms carry negative impacts on bird and bat populations, such as direct mortality due to collision with wind turbines.

Carcass searches beneath the turbines are mandatory to access this impact, as well as the assessment of two correction factors: searcher efficiency and probability of carcass persistence. The latter considers the possibility of carcass removal by scavengers (or any other event such as decomposition) between monitoring sessions, influencing the number of carcasses detected.

Carcass persistence trials consist in randomly placing carcasses under the turbines and, in this study, checking them daily during a 15-day period. Camera traps are looked as an alternative that might reduce human and financial effort while allowing the collection of the exact removal time and characterization of the scavenger’s guild.

We conducted trials in three different wind farms, in a total of seven campaigns (15-day carcass checking periods), across different seasons.

We compared the camera-trapping with the conventional methods and analyzed the influence of using continuous vs. censored data on the correction factor estimate and have not found significant differences.

Camera traps allowed the recording of the exact removal time and the identification of the removal agent for most of the carcasses and allowed a significant reduction of the field work and the costs associated.

We present a few guidelines to be taken into consideration when using this method.

Camera-trapping demonstrated to be a good method to replace the conventional method, ensuring at least the same results, while allowing the characterization of the scavenger’s guild and a significant cost reduction.


Bird fatalities Bat fatalities Carcass removal Camera-trapping Scavengers 


  1. 1.
    Bernstein, M.A., Griffin, J., Lempert, R.: Impacts on Energy Expenditures of Use Technical report prepared for the energy future coalition. RAND Corporation, Santa Monica (2006)Google Scholar
  2. 2.
    Coelho, H., Mesquita, S., Mascarenhas, M.: How to design an adaptive management approach? In: Mascarenhas, M., Marques, A.T., Ramalho, R., Santos, D., Bernardino, J., Fonseca, C. (eds.) Biodiversity and Wind Farms in Portugal, pp. 208–224. Springer, Cham (2018)Google Scholar
  3. 3.
    Drewitt, A.L., Langston, R.H.W.: Assessing the impacts of wind farms on birds. Ibis. 148, 29–42 (2006)CrossRefGoogle Scholar
  4. 4.
    Arnett, E.B., Inkley, D.B., Johnson, D.H., Larkin, R.P., Manes, S., Manville, A.M., et al.: Impacts of Wind Energy Facilities on Wildlife and Wildlife Habitat. Bethesda, Maryland (2007a)Google Scholar
  5. 5.
    Arnett, E.B., Inkley, D.B., Johnson, D.H., Larkin, R.P., Manes, S., Manville, A.M., Mason, J.R., Morrison, M.L., Strickland, M.D., Thresher, R.: Impacts of Wind Energy Facilities on Wildlife and Wildlife Habitat Wildlife Society Technical Review 07-2. The Wildlife Society, Bethesda (2007b)Google Scholar
  6. 6.
    NRC: Environmental Impacts of Wind-Energy Projects. National Research Council of the National Academies. The National Academic Press, Washington, DC (2007)Google Scholar
  7. 7.
    Arnett, E.B., Baerwald, E.F., Mathews, F., Rodrigues, L., Rodríguez-Durán, A., Rydell, J., et al.: Impacts of wind energy development on bats: a global perspective (Chapter 11). In: Voigt, C.C., Kingstom, T. (eds.) Bats in the Anthropocene: Conservation of Bats in a Changing World. Springer, Berlin (2016)Google Scholar
  8. 8.
    Barclay, R.M.R., Baereals, E.F., Gruver, J.C.: Variation in bat and bird fatalities at wind energy facilities: assessing the effects of rotor size and tower height. Can. J. Zool. 85, 381–387 (2007)CrossRefGoogle Scholar
  9. 9.
    Kunz, T.H., Arnett, E.B., Erickson, W., Hoar, A.R., Johnson, G.D., Larkin, R.P., Strickland, M.D., Thresher, R.W., Tuttle, M.D.: Ecological impacts of wind energy development on bats: questions, research needs, and hypotheses. Front. Ecol. Environ. 5, 315–324 (2007)CrossRefGoogle Scholar
  10. 10.
    Baerwald, E.F., D’Amours, G.H., Klug, B.J., Barclay, R.M.R.: Barotrauma is a significant cause of bat mortalities at wind turbines. Curr. Biol. 18, 695–696 (2008)CrossRefGoogle Scholar
  11. 11.
    Santos, J., Marques, J., Neves, T., Marques, A.T., Ramalho, R., Mascarenhas, M.: Environmental impact assessment methods: an overview of the process for wind farm’s different phases – from pre-construction to operation. In: Mascarenhas, M., Marques, A.T., Ramalho, R., Santos, D., Bernardino, J., Fonseca, C. (eds.) Biodiversity and Wind Farms in Portugal, pp. 35–86. Springer, Cham (2018)CrossRefGoogle Scholar
  12. 12.
    Bernardino, J., Bispo, R., Costa, H., Mascarenhas, M.: Estimating bird and bat fatality at wind farms: A practical overview of estimators, their assumptions and limitations. N. Z. J. Zool. 40(1), 63–74 (2013)CrossRefGoogle Scholar
  13. 13.
    Erickson, W., Johnson, G., Young, D.A.: Summary and comparison of bird mortality from anthropogenic causes with an emphasis on collisions. Technical report, USDA Forest Service (2005)Google Scholar
  14. 14.
    Sinclair, K., DeGeorge, E.: Framework for testing the effectiveness of bat and eagle impact-reduction strategies at wind energy projects. National Renewable Energy Laboratory. Technical Report NREL/TP-5000-65624 (2016)Google Scholar
  15. 15.
    Smallwood, K.S.: Comparing bird and bat fatality-rate estimates among North American wind-energy projects. Wildl. Soc. Bull. 37(1), 19–33 (2013)CrossRefGoogle Scholar
  16. 16.
    Miller, A.: Patterns of avian and bat mortality at a utility scaled wind farm on the southern high plains. PhD thesis, Texas Tech University (2008)Google Scholar
  17. 17.
    Johnson, G.D., Erickson, W.P., Strickland, M.D., Sheperd, M.F., Sheperd, D.A., Sarappo, S.A.: Mortality of bats at a large-scale wind power development at Buffalo Ridge, Minnesota. The American Midland. Naturalist. 150(2), 332–342 (2003)Google Scholar
  18. 18.
    Paula, J., Augusto, M., Neves, T., Bispo, R., Cardoso, P., Mascarenhas, M.: Comparing field methods used to determine bird and bat fatalities. In: Mascarenhas, M., Marques, A.T., Ramalho, R., Santos, D., Bernardino, J., Fonseca, C. (eds.) Biodiversity and Wind Farms in Portugal, pp. 135–149. Springer, Cham (2018)CrossRefGoogle Scholar
  19. 19.
    Reyes, G.A., Rodriguez, M.J., Lindke, K.T., Ayres, K.L., Halterman, M.D., Boroski, B.B., et al.: Searcher efficiency and survey coverage affect precision of fatality estimates. J. Wildl. Manag. 80(8), 1488–1496 (2016)CrossRefGoogle Scholar
  20. 20.
    Huso, M.M.P., Dalthorp, D.: Accounting for unsearched areas in estimating wind turbine-caused fatality. J. Wildl. Manag. 78(2), 347–358 (2014)CrossRefGoogle Scholar
  21. 21.
    Korner-Nievergelt, F., Korner-Nievergelt, P., Behr, O., Niermann, I., Brinkmann, R., Hellriegel, B.: A new method to determine bird and bat fatality at wind energy turbines from carcass searches. Wildl. Biol. 17(4), 350–363 (2011)CrossRefGoogle Scholar
  22. 22.
    Morrison, M.: Searcher Bias and Scavenging Rates in Bird/Wind Energy Studies Technical Report NREL/SR-500–30876, p. 5. National Renewable Energy Lab, Golden Colorado (2002)CrossRefGoogle Scholar
  23. 23.
    Smallwood, K.S.: Estimating wind turbine-caused bird mortality. J. Wildl. Manag. 71(8), 2781–2791 (2007)CrossRefGoogle Scholar
  24. 24.
    Travassos, P., Costa, H.M., Saraiva, T., Tomé, R., Armelin, M., Ramírez, F.I., et al.: A energia eólica e a conservação da avifauna em Portugal. SPEA, Lisboa (2005)Google Scholar
  25. 25.
    Bispo, R., Bernardino, J., Marques, T.A., Pestana, D.: Discrimination between parametric survival models for removal times of bird carcasses in scavenger removal trials at wind turbines sites. In: Lita da Silva, J., et al. (eds.) Advances in Regression, Survival Analysis, Extreme Values, Markov Processes and Other Statistical Applications, Studies in Theoretical and Applied Statistics. Springer, Berlin (2013)Google Scholar
  26. 26.
    Paula, J.J., Bispo, R.M., Leite, A.H., Pereira, P.G., Costa, H.M., Fonseca, C.M., Bernardino, J.L.: Camera-trapping as a methodology to assess the persistence of wildlife carcasses resulting from collisions with human-made structures. Wildl. Res. 41(8), 717–725 (2015)CrossRefGoogle Scholar
  27. 27.
    Silva, B., Barreiro, S., Alves, P.: Factors influencing carcass removal at wind-farms, in mountain areas of the center-north region of Portugal. In: Abstracts XIst European Bat Research Symposium, pp. 18–22. Agosto, Roménia (2008)Google Scholar
  28. 28.
    APA: Guia para a Avaliação de Impactes Ambientais de Parques Eólicos (2009)Google Scholar
  29. 29.
    Bernardino, J., Bispo, R., Torres, P., Rebelo, R., Mascarenhas, M., Costa, H.: Enhancing carcass removal trials at three wind energy facilities in Portugal. Wildl. Biol. Pract. 7, 1–14 (2011)CrossRefGoogle Scholar
  30. 30.
    Jones, A.: Animal scavengers as agents of decomposition: the postmortem succession of Louisiana wildlife. Masters thesis, Louisiana State University, Baton Rouge, LA, USA (2011)Google Scholar
  31. 31.
    Smallwood, K.S., Bell, D.A., Snyder, S.A., DiDonato, J.E.: Novel scavenger removal trials increase wind turbine–caused avian fatality estimates. J. Wildl. Manag. 74(5), 1089–1097 (2010)CrossRefGoogle Scholar
  32. 32.
    DeVault, T.L., Brisbin Jr., I.L., Rhodes Jr., O.E.: Factors influencing the acquisition of rodent carrion by vertebrate scavengers and decomposers. Can. J. Zool. 82, 502–509 (2004)CrossRefGoogle Scholar
  33. 33.
    Cunningham, P.D., Brown, L.J., Harwood, A.J.: Predation and scavenging of salmon carcasses along spawning streams in the Scottish Highlands. Final report for the Atlantic Salmon Trust (2002)Google Scholar
  34. 34.
    Kostecke, R.M., Linz, G.M., Bleier, W.J.: Survival of avian carcasses and photographic evidence of predators and scavengers. USDA National Wildlife Research Center – Staff Publications. Paper 510 (2001)Google Scholar
  35. 35.
    SNH: Monitoring the Impact of Onshore Wind Farms on Birds Guidance Note. Scottish Natural Heritage, Scotland (2009)Google Scholar
  36. 36.
    Duffy, K., Steward, M.: Turbine Search Methods and Carcass Removal Trials at the Braes of Doune Windfarm Natural Research Information Note 4. Natural Research Ltd., Banchory (2008)Google Scholar
  37. 37.
    Cox, D.R., Oakes, D.: Analysis of Survival Data, vol. 21. CRC Press, Boca Raton (1984)Google Scholar
  38. 38.
    Bispo, R., Palminha, G., Bernardino, J., Marques, T., Pestana, D.: A new statistical method and a web-based application for the evaluation of the scavenging removal correction factor. In: VIII Wind Wildlife Research Meeting on Proceedings, pp. 19–21. Lakewood. October (2010)Google Scholar
  39. 39.
    Burnham, K.P., Anderson, D.R.: Multimodel inference: understanding AIC and BIC in model selection. Sociol. Methods Res. 33(2), 261–304 (2004)CrossRefGoogle Scholar
  40. 40.
    Huso, M.: An estimator of wildlife fatality from observed carcasses. Environmetrics. 10(22), 318–329 (2010)Google Scholar
  41. 41.
    R Development Core Team R Development Core Team: R: A Language and Environment for Statistical Computing. R Foundation for Statistical Computing, Vienna (2013)Google Scholar
  42. 42.
    Bates, D., Maechler, M., Bolker, B., Walker, S.: Fitting linear mixed-effects models using lme4. J. Stat. Softw. 67, 1–48 (2015)CrossRefGoogle Scholar
  43. 43.
    Linz, G.M., Bergman, D.L., Bleier, W.J.: Estimating survival of song bird carcasses in crops and woodlots, p. 842. USDA National Wildlife Research Center-Staff Publications (1997)Google Scholar
  44. 44.
    Ponce, C., Alonso, J.C., Argandoña, G., García Fernández, A., Carrasco, M.: Carcass removal by scavengers and search accuracy affect bird mortality estimates at power lines. Anim. Conserv. 13(6), 603–612 (2010)CrossRefGoogle Scholar
  45. 45.
    Blanco, J.C.: Mamíferos De España, vol. I and II. Ed. Planeta, Barcelona (1998)Google Scholar
  46. 46.
    Palomo, L.J., Gisbert, J., Blanco, J.C.: Atlas y Libro Rojo de los Mamíferos Terrestres de España. Dirección General de Conservación de la Naturaleza – SECEM-SECEMU, Madrid (2007)Google Scholar
  47. 47.
    Dell’Arte, G.L., Laaksonen, T., Norrdahl, K., Korpimaki, E.: Variation in the diet composition of a generalist predator, the red fox, in relation to season and density of main prey. Acta Oecol. 31, 276–281 (2007)CrossRefGoogle Scholar
  48. 48.
    Webbon, C.C., Baker, P.J., Cole, N.C., Harris, S.: Macroscopic prey remains in the winter diet of foxes Vulpes vulpes in rural Britain. Mammal Rev. 36, 85–97 (2006)CrossRefGoogle Scholar

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© Springer Nature Switzerland AG 2019

Authors and Affiliations

  1. 1.BioinsightOdivelasPortugal

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