Non-PRO English to Spanish Other Names (personal, company)

Here's a line in an English-language novel I'm editing in which many characters of Mexican descent speak Spanish as a first language:

"Such a strange pajarito, he thought—a little bird."

The character being described here is a girl, not a boy, so my question is: Wouldn't it be "pajarita" instead? Or does "pajarita" sound strange to native Spanish-speaking ears when used to describe a little girl? Thanks very much!