I discovered another linguistic mystery while doing Shnaim Mikra V'Echad Targum this week. I have not found an answer in any of the meforshim in Mirka'os Gedolos or the Artscroll Chumash.
When HaShem tells Noach to gather the animals for preservation in the ark, the posuk mentions in 7:2 that of both animals that are considered "Tehorah" and "Lo Tehorah" (pure/kosher and not pure/not kosher, per the meforshim), Noach should take "Ish V'ishto" - literally "man and his wife."
Now fine, you may say that makes sense. If the purpose of collecting and preserving the animals in the ark was to ensure continuity of the species and that none of them were totally wiped out by the ravages of the flood, then of course you need a "man and wife" otherwise known as a breeding pair. To haphazardly choose a male and female that, for whatever biological reason, wouldn't choose to mate and produce offspring would be a disaster for that particular species/type of animal.
Yet, whenever collecting pairs of different sorts of animals are mentioned any other time, including the very next verse 7:3 regarding birds wherein the verse also says that the specific reason for all this is "to keep seed alive on the face of the earth," the verse says "Zachar V'Nekeivah," which means "male and female."
In verse 7:8-9 which talk about what happens when Noach enters the ark, it mentions,
"Of clean beasts, and of beasts that are not clean, and of fowls, and of every thing that creepeth upon the ground, there went in two and two unto Noah into the ark, male and female, as G-d commanded Noah."
when and again in 7:14-16,
...they [Noach and his family], and every beast after its kind, and all the cattle after their kind, and every creeping thing that creepeth upon the earth after its kind, and every fowl after its kind, every bird of every sort. And they went in unto Noah into the ark, two and two of all flesh wherein is the breath of life. And they that went in, went in male and female of all flesh, as God commanded him; and the LORD shut him in.
Checking Onkelos and Targum Yonatan for verse 7:3, they simply use the Aramaic for Zachar V'Nekeivah and don't use the Aramaic of "husband and wife." This would seem to indicate that the language is synonymous and not significant, otherwise they would preserve the difference in their translation.
Yet, the Torah uses the language of "husband and wife!"
If we need specifically breeding pairs, why not say that by the birds as well?
In fact, when I think of monogamous, paired/breeding for life creatures, I think of the well known example of geese - which are BIRDS.
After a very unscientific brief Googling, I found several websites (here, here, and here) that feature lists of monogamous animals, and by far, BIRDS are the largest of the categories, versus ungulates, rodents, reptiles, fish, primates, etc.
The most reputable of the 3, Scientific American, mentions in their introduction, "For instance, birds are quite socially monogamous, with some 92 percent of species sticking with one mate for at least a mating season." (emphasis mine)
The only thing I can think of, based on my brief research, is that if Noach were to find a pair of birds together, clearly male and female, odds are they are a breeding pair and the Torah takes that for granted. With regard to the other types of animals, wherein this is not nearly as certain, Noach would have to make sure these two animals, male and female, were really "together" as a mating couple before they were selected as the sample set to be preserved on the ark.
Update: another thought just occurred to me, related to the idea above, plus midrashim regarding certain illicit behaviors going on that led to the punishment of the flood.
First I found that Midrash Rabbah Bereishis 28:8 is the source for the fact that animals, not just humans, acted wrongfully in mating with animals of other species. Hence, I found a mention on this website that says HaShem wanted to preserve the individual examples of animals who stuck by mates of their own species and didn't become corrupted by cross-breeding. This would explain the language of "Ish V'ishto" - since they remained loyal to their same-kind mate.
According to what I said earlier, this would also make sense if the birds didn't participate in this, because of their more monogamous nature.
However, when I checked the Midrash Rabba on Bereishis 28:8 (scroll down) inside, the text gives two examples of this inter-species corruption. 1) Dogs chasing after wolves to mate and 2) Chickens chasing after peacocks to mate. Hence, there WERE birds involved in this behavior.
So categorically, birds, though some may have been more monogamous than others, would also need to be screened for pairs that remained faithful to their kind. If so, the question still stands: why didn't the Torah use the same referential language by the birds like it did by the other animals, and why don't the meforshim or metargumim seem to take notice of this?