“We’re doing well here,” Hazel began, “or so it seems to me We’re certainly not a bunch of hlessil any more. But all the same, there’s something on my mind. I’m surprised, as a matter of fact, that I should be the first one of us to start thinking about it. Unless we can find the answer then this warren’s as good as finished, in spite of all we’ve done.”
“Why, how can that be, Hazel?” said Bigwig.
“Do you remember Nildro-hain?” asked Hazel.
“She stopped running. Poor Strawberry.”
“I know. And we have no does – not one – and no does means no kittens and in a few years no warren.”
It may seem incredible that the rabbits had given no thought to so vital a matter. But men have made the same mistake more than once – left the whole business out of account, or been content to trust to luck and the fortune of war. Rabbits live close to death and when death comes closer than usual, thinking about survival leaves little room for anything else. But now, in the evening sunshine on the friendly, empty down, with a good burrow at his back and the grass turning to pellets in his belly, Hazel knew that he was lonely for a doe. The others were silent and he could tell that his words had sunk in.
-- “Kehaar”, Watership Down