Passionates are a
class of individuals who are passionate just like enthusiasts are a class of individuals who are enthusiastic. The third person singular indicates it is referring to an individual (he/she/it) not a group, but it is referring to a singular class or category of person, and categories can include a plural number of people. Think of the phrase "passionates are passionate." "[
singular category of person that can include many people] is characterized by passion." However, just like the word "enthusiasts" it can be understood as a plural if used in the right context. You could say singular "the passionates" or you could say plural "those passionates." Either formulation would work.
If you wanted to get frisky and try to score with the grammar, you could try something like "passionateses" or "passionatesi" or "passionatesen" or something like that. But I have a hunch the coach would tell you to be content with a triple.
You could also just say "group of passionates" or a flock of passionates, or a herd, or a parliament if you are referring to a group of passionate owls.
In which case, leave the owls alone, they aren't bothering anyone.