Citing style for Animal Conservation
It looks to me like ZRSS isn't a citation style, just a list of journals.  You can refer to that list to figure out how to abbreviate the name of a journal (e.g. Animal Conservation might be abbreviated as Anim. Conserv.) but it isn't supposed to show you how to format the rest of the citation.

If you keep reading right below there in the Guidelines for Authors, it contains more information about how to format citations, with several examples, and provides style files for EndNote and Reference Manager.  It is possible that someone else has written one for Mendeley, or you could do it.

If you need more detailed information than what is in the Guidelines, you will need to ask the editors.  If you look on the left side of the Guidelines page, there is a Contact link, which gives an email address for someone in the editorial office, who can be contacted with questions about "submitting a manuscript".