How do Jackals Adapt to Changes in their Food Sources?

Based on the information provided, the most probable reason why the population of jackals did not decrease when a farmer started using collars on his sheep, even though none of his sheep were being killed, could be that the sheep were not a significant or primary part of the jackals' diet.

Like the example of the voles, when the degree of predation decreased, it didn't mean that their population would decrease as well. They simply adapted to find other food sources, similar to how herbivores might look for other primary producers when their primary food source becomes depleted.

This adaptability is a characteristic of many predator species, where shifts in available prey do not necessarily lead to significant population decreases.

The jackals' population did not decrease likely because the sheep were not their primary or a significant food source, so they adapted to find other sources of food.