Answer:
The basic resources a living organism needs to survive are sustinence, shelter, and heat. Sustinence is not an unlimited source and wild animals have to hunt to get their food, and if they hunt too much, the food chain will fall out of balnce to where there is no more of that species.
Shelter or safe homes can also be limited, from animals that find natural spots, or make their own homes out of resources, it can be difficult to not be constantly exposed to the natural environment.
Heat is dependant on climate, and is provided by the sun. Nonetheless, in the winter, it isn't reliable, and in the summer, animals may overheat. In conclusion overall, all of these resources are limited or depending on such circumstances.