Good ending! I like to see a writer go for something powerful.
Anyway, a few more observation:
Watch your tense! Settle on a tense, either past or present, and stick with it all the way through to the end of the story. I noticed a little flip-flopping going on and it was a bit distracting.
Try to avoid phrases like "this squirrel" or "our friend." Just refer to him as "the squirrel" or "he" and it will read much more smoothly.
I have to say, I do like the repetition of theme! The first conflict, bidding him against another male, threatening his purpose to procreate but eventually impregnating the female, coupled with the second, overcoming the danger of fire and death and the planting of the seed, works very well. You have a good eye for repetitive underlying themes, try to always do this in your work!
I'm glad you posted this second half! Originally I said that I felt like this work felt like the beginning of a story and this was definitely a good conclusion.
One last thing.
When the story calls for it, ignore all of the advice I just gave you. Writing is a creative process. Standard, universal rule do help build the foundation, but after that, the choice of what you wish to create is up to you. (Grab a copy of House of Leaves by Mark Z. Danielewski to truly see what it means to laugh in the face of standard writing rules.)