Environmental and Ecological Statistics

, Volume 20, Issue 1, pp 147–165 | Cite as

Modeling carcass removal time for avian mortality assessment in wind farms using survival analysis

  • Regina Bispo
  • Joana Bernardino
  • Tiago A. Marques
  • Dinis Pestana


In monitoring studies at wind farms, the estimation of bird and bat mortality caused by collision must take into account carcass removal by scavengers or decomposition. In this paper we propose the use of survival analysis techniques to model the time of carcass removal. The proposed method is applied to data collected in ten Portuguese wind farms. We present and compare results obtained from semiparametric and parametric models assuming four main competing lifetime distributions (exponential, Weibull, log-logistic and log-normal). Both homogeneous parametric models and accelerated failure time models were used. The fitted models enabled the estimation of the carcass persistence rates and the calculation of a scavenging correction factor for avian mortality estimation. Additionally, we discuss the impact that the distributional assumption can have on parameter estimation. The proposed methodology integrates the survival probability estimation problem with the analysis of covariate effects. Estimation is based on the most suitable model while simultaneously accounting for censored observations, diminishing scavenging rate estimation bias. Additionally, the method establishes a standardized statistical procedure for the analysis of carcass removal time in subsequent studies.


Accelerated failure time model Bias correction factor Lifetime distribution Persistence rate Survival analysis 


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Supplementary material

10651_2012_212_MOESM1_ESM.pdf (54 kb)
ESM 1 (PDF 54kb)
10651_2012_212_MOESM2_ESM.pdf (36 kb)
ESM 2 (PDF 36kb)


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Copyright information

© Springer Science+Business Media, LLC 2012

Authors and Affiliations

  • Regina Bispo
    • 1
    • 2
    • 3
  • Joana Bernardino
    • 4
  • Tiago A. Marques
    • 3
    • 5
  • Dinis Pestana
    • 3
  1. 1.ISPA-Instituto UniversitárioLisbonPortugal
  2. 2.Departamento de Estatística e Investigação OperacionalFaculdade de Ciências da Universidade de LisboaLisbonPortugal
  3. 3.CEAUL, Centro de Estatística e Aplicações da Universidade de LisboaLisbonPortugal
  4. 4.Bio3, Estudos e Projectos em Biologia e Valorização de Recursos NaturaisAlmadaPortugal
  5. 5.Centre for Research into Ecological and Environmental ModelingUniversity of St. Andrews, The ObservatorySt. Andrews, ScotlandUK

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