Thanks for your reply!
I have more variables, but the ones that I would need here is only the individual animal's id and the trapping session (I have several dates for each session, but I will find a way to group these into sessions). Hope this makes sense?
And, thank you!
ID, date
individual_id1, june
individual_id2, june
individual_id2, june
individual_id3, june
individual_id1, july
individual_id1, september
individual_id3, september