I haven't played vanilla FfH in a while (mostly been playing Wild Mana), so apologies if this has already been implemented. Hawks are extremely powerful for scouting out a neighbor's territory prior to invasion -- almost too powerful, since there's nothing in the game (AFAIK) that can shoot them down. It seems odd that a hawk would be perfectly safe flying over a city with 4 garrisoned archery units... why not allow archers (and other ranged units) to function like SAM infantry in vanilla Civ and be able to shoot down hawks on a recon mission? That would at least force me to think before using my hawks for enemy recon -- right now it's a no-brainer, since there's zero downside. And any no-brainer decision with zero downside usually indicates a place where game balance could be improved.