Praise be to Allah.
Zakaah is due on an’aam animals (camels, cattle and sheep), if they reach the nisaab (minimum threshold) and graze freely, eating plants that grow in the ground, and their owner does not spend money on feed for them.
See the answer to question no. 40156.
With regard to other animals, no zakaah is due on them, unless they are prepared for sale (trading).
If these birds are being raised for sale, to make money from them, then zakaah is due on their value at the end of the year. If they are being raised for some purpose other than sale or trade, then no zakaah is due on them.
Shaykh Ibn ‘Uthaymeen (may Allaah have mercy on him) was asked: Some people raise birds – is any zakaah due on them?
He replied: If those who raise birds do so for the purpose of trade, then zakaah is due from them, because they are trade goods, i.e., the person buys and sells them and earns money thereby.
But if they want to raise them to eat them or sell those that are surplus to their needs, then no zakaah is due on them, because zakaah is only due on three kinds of animals: camels, cattle and sheep, subject to the well known conditions. End quote.
Majmoo’ Fataawa Ibn ‘Uthaymeen (18/54).
And Allaah knows best.