Contains the code used to model the Siler mortality functions in the publication
L. Scherer, L. Lackey, M. Hahn-Klimroth, D. W. H. Müller, M. Roller, M. Bertelsen, J. Jebram, P. W. Dierkes, M. Clauss:
"Assessing zoo giraffe survivorship: methodological aspects, historical improvement, and a rapid demographic shift".
Under review at Journal of Zoo and Aquarium Research.