Wa alaykum assalam wa rahmatullah wa barakatuh

In the Name of Allah, the All-Merciful, the Mercy-Giving

All praise is due to Allah. Peace and blessings be upon His Messenger Muhammad.

There are so many kinds of birds and it is difficult to give one ruling for all. But as a general rule, all birds that can be used for valid purposes are valid for sale.

For example, it is permissible to keep, sell and buy pet birds, such as parrots and other colorful birds, which people keep for their lovely colors or beautiful songs.

Scholars have inferred such permissibility from a hadith narrated by Anas ibn Malik in which he reported that his little brother had a little sparrow he used to play with and that the Messenger of Allah (peace be upon him) would ask the child about the bird when he visited them. (Al-Bukhari)

However, a group of scholars consider it undesirable to buy such birds because this is a kind of wasting money and a sign of sumptuous living.

Carnivorous birds are also permissible to buy and sell as long as they are used for a valid purpose, such as hunting.

Almighty Allah knows best.