What are two possible reasons a frog population can change

These causes include habitat modification and fragmentation, introduced predators or competitors, introduced species, pollution, pesticide use, or over-harvesting. However, many amphibian declines or extinctions have occurred in pristine habitats where the above effects are not likely to occur.

I don't know for sure because my answer is simple but, A frogs population could change because they could get hunted and they could reproduce

Step-by-step explanation:

A frogs predator could kill and eat the frogs which would make the population decrease. A frogs predator could get hunted and killed off and the frogs could live and reproduce