What is the plural of rifleman?

The common name of New Zealand’s smallest bird (Acanthisitta chloris) comes from an apparent resemblance of the male bird’s green plumage to the uniform of a colonial rifleman. Whether there is or isn’t a resemblance, there is one pressing question: What is the plural of rifleman? For birds with English names, it’s usually pretty clear: that bellbird/those bellbirds, that fantail/those fantails. And it’s clear for birds with Māori names, because with Māori nouns, the plural is the same as the singular: that kiwi/those kiwi, that kōkako/those kōkako, that tūī/those tūī. But do you write, “Rifleman are tiny,” “Riflemen are so fast they’re difficult to photograph” or “Riflemans are so aggressive that they’re hazardous to humans”? Clearly that last one is ridiculous, as “riflemans” is just odd and wrong. But do I write “those rifleman” or “those riflemen”? The plural of rifleman (the soldier) is riflemen, and so “riflemen” for the birds might seem to be the obvious answer, but I struggled to find references to “riflemen” in the context of the bird. Some websites choose to use the Māori name, tītipounamu, when referring to the bird in the plural. Some websites find ways to avoid having to choose between rifleman or riflemen by using phrases such as “male birds” or “adult birds”. Finally I arrived at Te Ara, the Encyclopedia of New Zealand, which, surely, we can trust to give us the low down on the rifleman/riflemen controversy? Their summary article on small forest birds refers to “the rifleman” while also talking about other small  forest birds in the plural. Does this mean “rifleman” is the plural? Ambiguous. But then their main rifleman article is titled “Riflemen”. Is that definitive? Maybe. Nobody seems to use it, though. Should I start using it? I just can’t make myself write “that pair of riflemen” and feel comfortable about it.