Answer:
New predatory animals .
Explanation:
A valid reason on why a "predatory" animal would disappear or decrease in great numbers is new animals being involved such as animals eating those "predatory" animals or them eating the food source of the original animal . Humans are also a factor but i'm pretty sure they are not hunting them ! I hope this helped
Any process to have heat transfer from a cooler to a hotter object as its sole result.