To cite package ‘birdsize’ in publications use:

  Diaz R (2023). _birdsize: Estimate Avian Body Size Distributions_. R
  package version 0.0.0.9000, <https://github.com/diazrenata/birdsize>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {birdsize: Estimate Avian Body Size Distributions},
    author = {Renata Diaz},
    year = {2023},
    note = {R package version 0.0.0.9000},
    url = {https://github.com/diazrenata/birdsize},
  }