Data from: Accurately quantifying the shape of birds' eggs

Describing the range of avian egg shapes quantitatively has long been
recognised as difficult. A variety of approaches has been adopted, some of
which aim to capture the shape accurately and some to provide intelligible
indices of shape. The objectives here are to show that a (four-parameter)
method proposed by Preston (1953) is the best option for quantifying egg
shape, to provide and document an R program for applying this method to
suitable photographs of eggs, to illustrate that intelligible shape
indices can be derived from the summary this method provides, to review
shape indices that have been proposed, and to report on the errors
introduced by using photographs of eggs at rest rather than horizontal.