Is the coming of dawn known by hearing birds chirp?

Fajr is known by the spread of its horizontal light across the horizon, and this is the true dawn (al-Fajr al-Sadiq) with which the time for prayer begins. The chirping of birds or the crowing of roosters has no relation to the beginning of Fajr time, except that Allah has accustomed some birds to chirp at the time of prayer. It is not permissible to rely solely on the crowing of a rooster to determine the prayer time unless it has been proven and is consistent; in such a case, it can then serve as a sign and indication of the time's entry when there is doubt.