Subsistence farmers are force to migrate when

Subsistence farmers are forced to migrate when they go in search of fodder for their animals.

Explanation:

Subsistence farming is a kind of life where communities focus in survival, the kinds of crops that they plant are determined according to the kind of soil and whether they have besides what they will need during the following year, a big part of their food necessities are covered by the animal product, that's the reason why they have to take care of what their animals eat and have to provide them with the correct food.

answer: buck is a dog living a charmed life on the estate of judge miller, during the time of the klondike gold rush in 1897. he is the king of all the animals on the estate and as such enjoys special privileges, such as the run of the estate and the admirable position of being the judge's favorite dog.

this all ends the day he accompanies manuel on a walk through the orchard to a flag station, where manuel sells him to a stranger. manuel sells buck, because he has gambling debts he needs to pay and a family to support.

this one act changes buck's life irrevocably. it is the catalyst for the rest of the story about buck and his transformation from domestic pet to wild animal.

explanation: read thoughroly ! and u will find your answer and the mean time i will be keeping my eye on you !