Well, actually, it was MEN who said birds sang.Nowhere is GOD quoted as saying such.
I don't think anything an ANIMAL does pleases or displeases God. He is concerned with what MEN do.
No one seriously believes spiders & birds THINK, but yet spiders make very-intricate webs & many bird species make intricate nests. That's because God built INSTINCTS into them, not because they're "smart". That same nest-building bird will repeatedly attack its own reflection in a mirror.
But I WILL agree they glorify God by displaying His ability to make wondrous, beautiful(to man) things.
And i will repeat that few, if any, ancient men knew why birds sing.
Sorry, you are wrong. What Zephaniah wrote about birds singing in 2:14 is the Word of God; it was not his own ideas.
Zephaniah 1:1
The word of the LORD which came unto Zephaniah the son of Cushi, the son of Gedaliah, the son of Amariah, the son of Hizkiah, in the days of Josiah the son of Amon, king of Judah.
Zephaniah 2:9
Therefore as I live, saith the LORD of hosts, the God of Israel, Surely Moab shall be as Sodom, and the children of Ammon as Gomorrah, even the breeding of nettles, and saltpits, and a perpetual desolation: the residue of my people shall spoil them, and the remnant of my people shall possess them. 10 This shall they have for their pride, because they have reproached and magnified themselves against the people of the LORD of hosts. 11
The LORD will be terrible unto them: for
he will famish all the gods of the earth; and men shall worship him, every one from his place, even all the isles of the heathen. 12 Ye Ethiopians also, ye shall be slain by
my sword. 13 And
he will stretch out his hand against the north, and destroy Assyria;
and will make Nineveh a desolation, and dry like a wilderness. 14 And flocks shall lie down in the midst of her, all the beasts of the nations: both the cormorant and the bittern shall lodge in the upper lintels of it;
their voice shall sing in the windows; desolation shall be in the thresholds:
for he shall uncover the cedar work. 15 This is the rejoicing city that dwelt carelessly, that said in her heart, I am, and there is none beside me: how is she become a desolation, a place for beasts to lie down in! every one that passeth by her shall hiss, and wag his hand.
Zephaniah prophesied the Word of God--he was not stating his own opinion when he spoke of flocks, all the beasts of the nations, birds, and desolation in 2:14.
More importantly, if you believe that only what is recorded in the Bible as direct speech from God is the Word of God, you have a very seriously wrong notion about the Bible (2 Tim. 3:16-17; 2 Pet. 1:20-21).