(Killing birds)

The answer – and Allah is the One who grants success – is that there is no objection to protecting crops and the like from birds and other creatures. This protection of wealth from such things is regarded as preserving wealth, which Allah has ordered in His saying: “And do not give the weak-minded your property, which Allah has made for you a means of sustenance…” [al-Nisāʾ:5] What we have said here is also the position of the madhhab, as in the marginal notes on Sharḥ al-Azhār.

Source: Min Thimār al-ʿIlm wa al-Ḥikmah vol.2