The Jataka, Vol. II, tr. by W.H.D. Rouse, , at sacred-texts.com
"A Quail was in his .feeding-ground," etc.--This story the Master told at Jetavana, about his meaning in the Bird Preaching 2.
One day the Master called the Brethren, saying, "When you seek alms, Brethren, keep each to your own district." And repeating that sutta from the Mahāvagga which suited the occasion,  he added, "But wait a moment: aforetime others even in the form of animals refused to keep to their own
districts, and by poaching on other people's preserves, they fell into the way of their enemies, and then by their own intelligence and resource got free from the hands of their enemies." With these words he related an old story.
Once upon a time, when Brahmadatta was king in Benares, the Bodhisatta came into the world as a young Quail. He got his food in hopping about over the clods left after ploughing.
One day he thought he would leave his feeding ground and try another; so off he flew to the edge of a forest. As he picked up his food there, a Falcon spied him, and attacking him fiercely, he caught him fast.
Held prisoner by this Falcon, our Quail made his moan: "Ah! how very unlucky I am! how little sense I have! I'm poaching on some one else's preserves! O that I had kept to my own place, where my fathers were before me! then this Falcon would have been no match for me, I mean if he had come to fight!"
"Why, Quailie, says the Falcon, "what's your own ground, where your fathers fed before you?"
"A ploughed field all covered with clods!"
At this the Falcon, relaxing his strength, let go. "Off with you, Quail! You won't escape me, even there!"
The Quail flew back and perched on an immense clod, and there he stood, calling--"Come along now, Falcon!"
Straining every nerve, poising both wings, down swooped the Falcon fiercely upon our Quail, "Here he comes with a vengeance!" thought the Quail; and as soon as he saw him in full career, just turned over and let him strike full against the clod of earth. The Falcon could not stop himself, and struck his breast against the earth; this broke his heart, and he fell dead with his eyes starting out of his head.
 When this tale had been told, the Master added, "Thus you see, Brethren, how even animals fall into their enemies' hands by leaving their proper place; but when they keep to it, they conquer their enemies. Therefore do you take care not to leave your own place and intrude upon another's. O Brethren, when people leave their own station Māra 1 finds a door, Māra gets a foothold. What is foreign ground, Brethren, and what is the wrong place for a Brother? I mean the Five Pleasures of Sense. What are these five? The Lust of the Eye... [and so on]. 2 This, Brethren, is the wrong place for a Brother." Then growing perfectly enlightened he repeated the first stanza:--
When he had thus perished, out came the Quail, exclaiming, "I have seen the back of my enemy!" and perching upon his enemy's breast, he gave voice to his exultation in the words of the second stanza:--
This discourse at an end, the Master declared the Truths and identified the Birth:--At the conclusion of the Truths many Brethren were established in the Paths or their Fruition:---"Devadatta was the Falcon of those days, and the Quail was I myself."
40:2 I have not been able to trace this Sakuṇovāda-sutta. Perhaps it refers to a speech of the Buddha as a bird; cp. Kukkurovādo i. p. 178 (Pāli).
41:1 Māra is Death, and is used by Buddha for the Evil One.
41:2 The passage is corrupt. We must read 'cakkhu-ādi-viññeyā.'