Translation:These birds are singing, and those birds are sleeping.
Well...in Biblical Hebrew you would have used האלה for these and ההם or ההן for those. Quite a lot of Biblical Hebrew grammar still exists, especially in formal Hebrew, so it could, in theory, still be used. But the modern trend is to simplify the language, hence so many feminine forms being dropped, especially plural forms.
Btw - Yashan in Hebrew means old as in SOMETHING old, not SOMEONE old. When you want to say that someone is old you will say Zaken(m) / Zkena(f). Yashan(m) / Yeshana(f) will be used for instance when you want to say that a record is old.
For that matter, if you want to say 'The birds are old', then you should say - 'הציפורים זקנות' / Hatziporim Zkenot
Interesting. The distinction between ישן and זקן has something to do with something vs. someone, but it seems not to be the decisive factor. English, BTW, makes exactly the same distinction - not with "old" but at the opposite end. A person is young whereas a car is new; but birds are young, trees are young, planets and stars are young! Note that all the last ones take the "it" pronoun.
So what does determine the use of "young" vs. "new"? Maybe it's when we can apply the "life cycle" concept, or metaphor. Check out "a new company" vs. "a young company", they would mean slightly different things.