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Publication
Modeling carcass removal time for avian mortality assessment in wind farms using survival analysis
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Advisor(s)
Abstract(s)
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 Portuguesewind 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.
Description
Keywords
Accelerated failure time model Bias correction factor Lifetime distribution Persistence rate Survival analysis
Citation
Environmental and Ecological Statistics, 20 (1), 147-165