How to get ecology bib style not to truncate author list with et al. unless there are more than 3 authors?

Question

I am using the ecology bibliography style with a .bib file created in zotero.

How can I set the limit for the number of authors to be shown in an authoryear-style citation call-out? I.e., if there are up to 3 authors, then the reference should be (A, B and C, 2015) and not (A et al. 2015 ); if there are more than 3 authors, the citation call-out should be (D et al. 2010) and not (D,E,F,G,H,I and J, 2015).

Answer 1

Assuming you obtained the file ecology.bst from a site such as https://schneider.ncifcrf.gov/ftp/ecology.bst, I suggest you proceed as follows:

• Make a copy of the file ecology.bst and call the copy, say, ecology3.bst.

• Open the file ecology3.bst in a text editor. (The editor you use to edit tex files will do fine.)

• Locate the function format.lab.names. In my copy of the file, this function starts at line 1185.

• Delete the entire function (ca 23 lines), and insert the following code instead:

  FUNCTION {format.lab.names}
  {'s :=
   "" 't :=
    #1 'nameptr :=
    s num.names$ 'numnames :=
    numnames 'namesleft :=
      { namesleft #0 > }
      { s nameptr
        "{vv~}{ll}" format.name$
        't :=
        nameptr #1 >
          {
            nameptr #2 =
            numnames #3 > and
              { "others" 't :=
                #1 'namesleft := }
              'skip$
            if$
            namesleft #1 >
              { ", " * t * }
              {
                s nameptr "{ll}" format.name$ duplicate$ "others" =
                  { 't := }
                  { pop$ }
                if$
                t "others" =
                  {
                    " " * bbl.etal *
                  }
                  {
                    bbl.and
                    space.word * t *
                  }
                if$
              }
            if$
          }
          't
        if$
        nameptr #1 + 'nameptr :=
        namesleft #1 - 'namesleft :=
      }
    while$
  }
  

• Save the file ecology3.bst, either in the directory where your main tex file is located or in a directory that's searched by BibTeX. If you choose the latter option, be sure to update the filename database of your TeX distribution suitably.

• In your main tex file, change the instruction \bibliographystyle{ecology} to \bibliographystyle{ecology3} and perform a full recompilation (LaTeX, BibTeX, LaTeX, LaTeX) to fully propagate all changes.

Happy BibTeXing!

---

A full MWE:

\RequirePackage{filecontents}
\begin{filecontents}{sample.bib}
@misc{ab,author="Anne Author and Brenda Buthor", year=3001}
@misc{abc,author="Anne Author and Brenda Buthor and Carla Cuthor", year=3002}
@misc{defg,author="Doris Duthor and Eudora Euthor and Francine Futhor and Greta Guthor", year=3003}
\end{filecontents}

\documentclass{article}
\usepackage{natbib}
\bibliographystyle{ecology3}

\begin{document}
\citet{ab}

\citet{abc}

\citet{defg}
\bibliography{sample}
\end{document}