What would most likely happen if the kangaroo rats were killed off and removed from the food chain?

Anything that relied on the kangaroo rats as a source of energy and nothing else would soon die off. and the other animals that have another source of energy will become smaller and smaller because itd be the main source. now for the energy source provided to the kangaroo rats can become over populated depending on the enviromental factors of how many other animals it provides energy to