1. Barton K (2013) MuMIn: multi-model inference. R package version 1.9.5. http://CRAN.R-project.org/package=MuMIn . Accessed 30 Oct 2013
2. Bivand RS, Pebesma E, Gomez-Rubio V (2013) Applied spatial data analysis with R, 2nd edn. Springer, New York
3. Bjørnstad ON (2012) ncf: spatial nonparametric covariance functions. R package version 1.1-4. http://CRAN.R-project.org/package=ncf Accessed 30 Oct 2013
4. Brown ME (1996) Assessing body condition in birds. Curr Ornithol 13:67–135
5. Burnham KP, Anderson DR (2002) Model selection and multimodel inference. A practical information-theoretic approach, 2nd edn. Springer, New York