Tactics for the Swamp (Fortress).

It's not a pity to lose wyverns... the wood is usually not well-guarded... but there's still a limited number of them...
You have to fight gnolls and archers, of course, in the first week... but there are many neutral creatures with whom losses will be significant with such an army...
I buy wyverns in the second week, and not at the beginning of the week, but in the middle or at the end... my experience has shown that buying wyverns pays off... if there is a different approach, I don't argue...