Or HaChaim on Deuteronomy 14:13/אור החיים על דברים י״ד:י״ג

1 והראה ואת האיה, and the aforementioned birds, etc. It appears that every one of the 24 categories of unclean birds listed here has numerous sub-categories. This is the reason the Torah does not write למינה, "according to its kind," but למינהו, "according to their kind" (Chulin 63). When the bird mentioned is the only one of its kind or there are only a few variants of that category, the Torah speaks of למינו, "its kind." The proof for this theory is that the Torah does not write למינו in connection with the נשר (often translated as eagle), and the Talmud in Chulin 61 when not certain about a particular bird suggests that it may belong to the family of the נשר. Clearly, the sages of the Talmud considered the word נשר as a collective term for quite a variety of birds of its category.