If there were three things to pick that would convince you that Nat's family would survive in "The Birds," what three things would you pick?

Unfortunately I do not share your optimism. I think that
the ending of this excellent story actually clearly indicates that the birds will
triumph in the end. However, if I were of a more optimistic disposition, I would want to
focus on the following three elements that give hope to Nat's
family.

Firstly, note the following
quote:

He had
a new scheme for the windows, which was to fix barbed wire in front of the
boards.

Nat shows himself to
be ingenious and handy at creating defences against the birds, and the fact that he has
not lost hope is shown through his continual thinking of how to defend the house and his
family.

Secondly, the fact that the birds only attack every
six hours and then rest for six hours gives Nat and his family a chance to restock and
defend themselves once again, going to get food and provisions. In theory, they could
carry on like this endlessly, defending themselves and constructing new defences during
the lull in attack.

Lastly, and most importantly, I would
refer to the strength of the human spirit as demonstrated by Nat and the way that he is
determined to survive and keeps the spirits of his family up, taking care of
them.