Mbh 12.102.2a

"'Bhishma said, "I shall tell thee, O bull of Bharata's race, all the well-known indications of the (future) success of an army. When the gods become angry and men are urged by fate, persons of learning, beholding everything with the eye of heavenly knowledge, perform diverse auspicious acts and expiatory rites including homa and the silent recitation of mantras, and thus allay all evils.[304] That army in which the troops and the animals are all undepressed and cheerful, O Bharata, is sure to win a decided victory. The wind blows favourably from behind such troops. Rainbows appear in the sky. The clouds cast their shadows upon them and at times the sun shines upon them. The jackals become auspicious to them, and ravens and vultures as well. When these show such regard to the army, high success is sure to be won by it. Their (sacrificial) fires blaze up with a pure splendour, the light going upwards and the smokeless flames slightly bending towards the south. The libations poured thereon emit an agreeable fragrance. These have been said to be the indications of future success. The conchs and drums, blown and beat, send forth loud and deep peals. The combatants become filled with alacrity. These have been said to be the indications of future success. If deer and other quadrupeds be seen behind or to the left of those that have already set out for battle or of those that are about to set out, they are regarded auspicious. If they appear to the right of the warriors while about to engage in slaughter, that is regarded as an indication of success. If, however, they make their appearance in the van of such persons, they indicate disaster and defeat. If these birds, viz., swans and cranes and Satapatras and Chashas utter auspicious cries, and all the able-bodied combatants become cheerful, these are regarded as indications of future success.