Why do fur and other things I gain from hunting keep disappearing?

I send my hunters. They bring stuff, but the ratio is always negative, so it ends up disappearing...

Why does this happen? Are they only temporary? If not, how do I get this to stop happening?

Solution 1:

It gets consumed, in exchange for a higher happiness factor (visible in the village tab, it's 10% increase for each luxury good). Higher happiness result in a higher production rate of other resources.

Solution 2:

These are luxury resources, which are consumed at a rate based on each Kitten, similar to Catnip. Each kitten costs 0.01 furs per tick, 0.007 ivory per second, and 0.001 spice per tick. As long as you have a non-negative amount of each luxury resource, you get +10% happiness for each; having all three gives +30% happiness. Happiness acts as a global multiplier to production, so this amounts to a 30% production boost. Also, note that hunters alone will only find furs and ivory; spice must be gained through diplomacy and trading with other races.

Early in the game, you may find it quite difficult to maintain a supply of these resources, and you definitely won't be able to maintain them while idle. Fortunately, once you research Architecture, you will unlock the Mint building. Mints, when active, consume 0.75 Catpower per tick and 0.005 gold per tick, and creates both furs and ivory, with the exact amounts being based on your max Catpower, and the number of mints you have. In general, a small number of mints will be able to easily leave you with a net gain of furs and ivory per second. This is crucial later in the game; furs are used for making parchment, and thus all the other science resources made from them, and ivory is useful in trade for minerals, and also for making some of the spoiler-y religion-related stuff later on.